Category: Class 11

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 13 Hydrocarbons Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 13 Hydrocarbons

11th Chemistry Guide Hydrocarbons Text Book Back Questions and Answers

Textbook Evaluation:

I. Choose the best answer:

Question 1.
The correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is
a) The eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain.
b) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
c) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain.
d) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has no torsional strain.
Answer:
b) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.

Question 2.
C₂H₅ Br + 2Na C₄H₁₀ + 2NaBr.
The above reaction is an example of which of the following
a) Reimer Tiemann reaction
b) Wurtz reaction
c) Aldol condensation
d) Hoffmann reaction
Answer:
b) Wurtz reaction

Question 3.
An alkyl bromide (A) reacts with sodium in ether to form 4, 5 – diethyloctane, the compound (A) is
a) CH₃(CH₂)₃Br

b) CH₃(CH₂)₅Br

c) CH₃(CH₂)₃ CH(Br)CH₃

d)
Answer:
d)

Question 4.
The C – H bond and C – C bond in ethane are formed by which of the following types of overlap
a) sp³ – s and sp³ – sp³
b) sp² – s and sp² – sp²
c) sp – sp and sp – sp
d) p – s and p – p
Answer:
a) sp³ – s and sp³ – sp³

Question 5.
In the following reaction,

Answer:
c)

Question 6.
Which of the following is optically active
a) 2 – methyl pentane
b) citric acid
c) Glycerol
d) none of these
Answer:
a) 2 – methyl pentane

Question 7.
The compound formed at anode in the electrolysis of an aqueous solution of potassium acetate are
a) CH₄ and H₂
b) CH₄ and CO₂
c) C₂H₆ and CO₂
d) C₂H₄ and Cl₂
Answer:
c) C₂H₆ and CO₂

Question 8.
The general formula for cyclo alkanes
a) C_nH_n
b) C_nH_2n
C) C_nH_2n-2
d) C_nH_{2n + 2}
Answer:
b) C_nH_2n

Question 9.
The compound that will react most readily with gaseous bromine has the formula
a) C₃H₆
b) C₂H₂
c) C₄H₁₀
d) C₂H₄
Answer:
a) C₃H₆

Question 10.
Which of the following compounds shall not produce propene by reaction with HBr followed by elimination (or) only direct elimination reaction
a)
b) CH₃ – CH₂ – CH₂ – OH
c) H₂C = C = O
d) CH₃ – CH₂ – CH₂Br
Answer:
c) H₂C = C = O

Question 11.
Which among the following alkenes on reductive ozonolysis produces only propanone?
a) 2 – Methyl propene
b) 2 – Methyl but – 2 – ene
c) 2, 3 – Dimethyl but – 1- ene
d) 2, 3 – Dimethyl but – 2 – ene
Answer:
d) 2, 3 – Dimethyl but – 2 – ene

Question 12.
The major product formed when 2 – bromo – 2 – methyl butane is refluxed with ethanolic KOH is
a) 2 – methylbut – 2- ene
b) 2 – methyl butan – 1 – ol
c) 2 – methyl but – 1 – ene
d) 2 – methyl butan – 2- ol
Answer:
a) 2 – methylbut – 2- ene

Question 13.
Major product of the below mentioned reaction is, (CH₃)₂ C = CH₂
a) 2 – chloro – 1 – iode – 2 – methyl propane
b) 1 – chloro – 2 – iodo – 2 – methyl propane
c) 1, 2 – dichloro – 2 – methyl propane
d) 1, 2 – diiodo – 2 – methyl propane
Answer:
a) 2 – chloro – 1 – iode – 2 – methyl propane

Question 14.
The IUPAC name of the following compound is

a) trans – 2- chloro – 3- iodo – 2- pentane
b) cis – 3- iodo – 4 chloro – 3 – pentane
c) trans – 3 – iodo – 4 – chloro – 3 – pentene
d) cis – 2 – chloro – 3 iodo – 2 – pentene
Answer:
a) trans – 2- chloro – 3- iodo – 2- pentane

Question 15.
Cis – 2- butene and trans – 2 – butene are
a) conformational isomers
b) structural isomers
c) configurational isomers
d) optical isomers
Answer:
c) configurational isomers

Question 16.
Identify the compound (A) in the following reaction

Answer:
a)

Question 17.
CH ≡ CH , where A is,
a) Zn
b) conc. H₂SO₄
c) alc. KOH
d) dil. H₂SO₄
Answer:
c) alc. KOH

Question 18.
Consider the nitration of benzene using mixed con H₂SO₄ and HNO₃ if a large quantity of KHSO₄ is added to the mixture, the rate of nitration will be
a) unchanged
b) doubled
c) faster
d) slower
Answer:
d) slower

Question 19.
In which of the following molecules, all atoms are co-planar
a)

b)

c)
d) both (a) and (b)
Answer:
d) both (a) and (b)

Question 20.
Propyne on passing through red hot iron tube gives
a)

b)

c)
d) none of these
Answer:
a)

Question 21.
is

a)

b)

c) both (a) and (b)

d)
Answer:
d)

Question 22.
Which one of the following is non aromatic?
a)

b)

c)

d)
Answer:
d)

Question 23.
Which of the following compounds will not undergo Friedal – crafts reaction easily?
a) Nitro benzene
b) Toluene
c) Cumene
d) Xylene
Answer:
a) Nitro benzene

Question 24.
Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating?
a) – COOH
b) – NO₂
c) -C ≡ N
d) -SO₃H
Answer:
b) – NO₂

Question 25.
Which of the following can be used as the halide component for friedal – crafts reaction?
a) Chloro benzene
b) Bromo benzene
c) Chloro ethene
d) Isopropyl chloride
Answer:
d) Isopropyl chloride

Question 26.
An alkane isobtainedbydecarboxylation of sodium propionate. Same alkane can be prepared by
a) Catalytic hydrogenation of propene
b) action of sodium metal on iodomethane
c) reduction of 1 – chloro propane
d) reduction of bromomethane
Answer:
b) action of sodium metal on iodomethane

Question 27.
Which of the following is aliphatic saturated hydrocarbon
a) C₈H₁₈
b) C₉H₁₈
c) C₈H₁₄
d) All of these
Answer:
a) C₈H₁₈

Question 28.
Identify the compound ‘Z’ in the following reaction

a) Formaldehyde
b) Acetaldehyde
c) Formic acid
d) none of these
Answer:
a) Formaldehyde

Question 29.
Peroxide effect (Kharasch effect) can be studied in case of
a) Oct – 4 – ene
b) hex – 3 – ene
c) pent – 1 – ene
d) but – 2 – ene
Answer:
c) pent – 1 – ene

Question 30.
2 – butyne on chlorination gives
a) 1 – chloro butane
b) 1, 2 – dichloro butane
c) 1, 1, 2, 2 – tetrachlorobutane
d) 2, 2, 3, 3 – tetra chloro butane
Answer:
d) 2, 2, 3, 3 – tetra chloro butane

II. Write brief answer to the following questions:

Question 31.
Give IUPAC names for the following compounds
1) CH₃ – CH = CH – CH = CH – C ≡ C – CH₃

2)

3) (CH₃)₃ C – C ≡ C – CH(CH₃)₂

4) ethyl isopropyl acetylene

5) CH ≡ C – C ≡ C – C ≡ CH
Answer:
1)

2)

3)

4) ethyl isopropyl acetylene

5)

Question 32.
Identify the compound A, B, C and D in the following series of reactions

Answer:

Question 33.
Write short notes on ortho, para directors in aromatic electrophilic substitution reactions.
Answer:
All the activating groups are ‘ortho-para’ directors.
Example: – OH, – NH₂, -NHR, -NHCOCH₃, -OCH₃ -CH₃ – C₂H₅ etc.
Let us consider the directive influences of phenolic (-OH) group. Phenol is the resonance hybrid of following structures.

In these resonance structures, the (-) charge residue is present on ortho and para position of ring structure. It is quite evident that the lone pair of electron on the atom which is attached to the ring involves in resonance and makes the ring more electron rich than benzene. The electron density at ortho and para positions increases as compared to the meta position. Therefore phenolic group activates the benzene ring for electrophilic attack at ‘ortho’ and ‘para positions and hence -OH group is an ortho-para director and activator.

In aryl halides, the strong -I effect of the halogens (electron withdrawing tendency) decreases the electron density of benzene ring, thereby deactivating for electrophilic attack. However the presence of lone pair on halogens involved in the resonance with pi electrons of benzene ring, increases electron density at ortho and para position. Hence the halogen group is an ortho-para director and deactivator.

Question 34.
How is propyne prepared from an alkene dihalide?
Answer:

Question 35.
An alkylhalide with molecular formula C₆H₁₃Br on dehydro halogenation gave two isomeric alkenes X and Y with molecular formula C₆H₁₂. On reductive ozonolysis, X and Y gave four compounds CH₃COCH₃, CH₃CHO, CH₃CH,CHO and (CH₃)₂ CHCHO. Find the alkyihalide.
Answer:

Question 36.
Describe the mechanism of Nitration of benzene.
Answer:
It is prepared by the action of a mixture of con. HNO₃ and con. H₂SO₄ (nitrating mixture) on benzene maintaining the temperature below 333 K.
Nitration:

Sulphuric acid generates the electrophile – NO₂⁺, nitronium ion-from nitric acid. This is an example of aromatic electrophilic substitution reaction.

The generation of nitronium ion
H₂SO₄ + HONO₂ → + HSO₄^–

To the nitronium ion (being an electron deficient species) the π bond of benzene, donates a pair of electrons forming a 6-bond. A species with a + ve charge is formed as an intermediate. This is called ‘arenium ion’ and is stabilised by Resonance.

In the last step, the hydrogen atom attached to the carbon carrying the nitro group is pulled out as a proton, by the Lewis base HSO₄^–, so that stable aromatic system is formed.

Question 37.
How does Huckel rule help to decide the aromatic character of a compound.
Answer:
In 1865, August Kekule suggested that benzene consists of a cyclic planar structure of six carbon with alternate single and double bonds.
There were two objections:
Benzene forms only one ortho disubstituted products whereas the Kekule’s structure predicts two o-di substituted products as shown below.

Kekule’s structure failed to explain why benzene with three double bonds did not give addition reactions like other alkenes.To overcome this objection, Kekule suggested that benzene was mixture of two forms (1 and 2) which are in rapid equilibrium.

Resonance description of benzene:
The phenomenon in which two or more structures can be written for a substance which has identical position of atoms is called resonance. The actual structure of the molecule is said to be resonance hybrid of various possible alternative structures. In benzene, Kekule’s structures I & II represented the resonance structure, and structure III is the resonance hybrid of structure I & II.
The structures 1 and 2 exist only in theory. The actual structure of benzene is the hybrid of two hypothetical resonance structures.

Spectroscopic measurements:
Spectroscopic measurements show that benzene is planar and all of its carbon- carbon bonds are of equal length 1.40 Å. This value lies between carbon-carbon single bond length 1.54 Å and carbon- carbon double bond length 1.34 Å.

Molecular orbital structure:
The structure of benzene is best de¬scribed in terms of the molecular orbital theory. All the six carbon atoms of benzene are sp² hybridized. Six sp² hybrid orbitals of carbon linearly overlap with six 1 s orbitals of hydrogen atoms to form six C – H sigma bonds. Overlap between the remaining sp² hybrid orbitals of carbon forms six C – C sigma bonds.

Formation of Sigma bond in benzene

All the σ bonds in benzene lie in one plane with bond angle 120°. Each carbon atom in benzene possess an un hybridized p-orbital containing one electron. The lateral overlap of their p-orbital produces 3 π- bond. The six electrons of the p-orbitals cover all the six carbon atoms and are said to be delocalised. Due to delocalization, strong π-bond is formed which makes the molecule stable. Hence unlike alkenes and alkynes benzene undergoes substitution reactions rather addition reactions under normal conditions.

All carbon atoms have the delocalized π MO is formed by p-orbitais the overlap of six p-orbitals.

Representation of benzene:
Hence, there are three ways in which benzene can be represented.

Question 38.
Suggest the route for the preparation of the following from benzene.
1) 3 – chloro nitrobenzene
2) 4 – chlorotoluene
3) Bromo benzene
4) m – dinitro benzene
Answer:
1) 3 – chloro nitrobenzene

2) 4 – chlorotoluene

3) Bromo benzene

4) m – dinitro benzene

Question 39.
Suggest a simple chemical test to distinguish propane and propene.
Answer:
Propene decolourises Br₂/H₂O it forms dibromo compound but propane does not react with Br₂/ H₂O.

Question 40.
What happens when Isobutylene is treated with acidified potassium permanganate?
Answer:

Question 41.
How will you convert ethyl chloride into
(i) ethane
(ii) n – butane
Answer:
(i) ethane

(ii) n – butane

Question 42.
Describe the conformers of n – butane.
Answer:
Conformations of n-Butane:
n-Butane may be considered as a derivative of ethane, as one hydrogen on each carbon is replaced by a methyl group

Eclipsed conformation:
In this conformation, the distance between the two methyl group is minimum. So there is maximum repulsion between them and it is the least stable conformer.

Anti or staggered form:
In this conformation, the distance between the two methyl groups is maximum and so there is minimum repulsion between them. And it is the most stable conformer.

The following potentially energy diagram shows the relative stabilities of various conformers of n-butane.

Question 43.
Write the chemical equations for combustion of propane.
Answer:
C₃H₈(g) + 5O₂(g) ) → 3CO₂(g) + 4H₂O(l)
propane

Question 44.
Explain Markovnikoff’s rule with suitable example.
Answer:
Markovnikoff ‘s rule:
“When an unsymmetrical alkene reacts with hydrogen halide, the hydrogen adds to the carbon that has more number of hydrogen and halogen add to the carbon having fewer hydrogen”. This rule can also be stated as in the addition reaction of alkene/alkyne, the most electro negative part of the reagent adds on to the least hydrogen attached doubly bonded carbon.

Addition of water: (Hydration of alkenes)
Normally, water does not react with alkenes. In the presence of concentrated sulphuric acid, alkenes react with water to form alcohols. This reaction follows carbocation mechanism and Markovnikoff’s rule.

Question 45.
What happens when ethylene is passed ‘ through cold dilute alkaline potassium permanganate.
Answer:
CH₂ = CH + H₂O + (O) CH₂OH – CH₂OH
Ethylene                                                                Ethylene glycol

Question 46.
Write the structures of following alkanes.
1) 2, 3 – Dimethyl – 6 – (2 – methyl propyl) decane
2) 5 – (2 – Ethyl butyl ) – 3, 3, – dimethyldecane
3) 5 – (1, 2 – Dimethyl propyl) – 2 – methylnonane
Answer:
1) 2, 3 – Dimethyl – 6 – (2 – methyl propyl) decane

2) 5 – (2 – Ethyl butyl ) – 3, 3, – dimethyldecane

3) 5 – (1, 2 – Dimethyl propyl) – 2 – methylnonane

Question 47.
How will you prepare propane from a sodium salt of fatty acid?
Answer:

Question 48.

Identify A and B
Answer:
A)

b)

Question 49.
Complete the following :

i) 2 – butyne 

ii) CH₂ = CH₂

iii)

iv) CaC₂
Answer:
i) 2 – butyne

ii) CH₂ = CH₂

iii)

iv) CaC₂
CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂↑
Calcium Carbide                  Acetylene

Question 50.
How will distinguish 1 – butyne and 2 – butyne?
Answer:

1 – butyne reacts with ammoniacal AgNO₃ solution it forms white precipitate of silver acetylide but, 2 – butyne doesnot reacts with ammoniacal AgNO₃ solution.

11th Chemistry Guide Hydrocarbons Additional Questions and Answers

I. Choose the best answer:

Question 1.
The IUPAC name of neopentane is
a) 2 – methyl butane
b) 2, 2 – dimethyl propane
c) 2 – methyl propane
d) 2, 2- dimethyl butane
Answer:
b) 2, 2 – dimethyl propane

Question 2.
Alkanes are also known as
a) olefins
b) unsaturated aliphatic hydrocarbons
c) saturated aromatic hydrocarbon
d) paraffins
Answer:
d) paraffins

Question 3.
The compressed gas available in cooking gas cylinders is a mixture of:
a) C₆H₆ + C₆H₅CH₃
b) C₂H₄ + C₂H₂
c) C₂H₄ + CH₄
d) C₄H₁₀ + C₃H₈
Answer:
d) C₄H₁₀ + C₃H₈

Question 4.
The gas supplied in cylinders for cooking is
a) marsh gas
b) LPG
c) mixture CH₄ and C₂H₆
d) mixture of ethane and propane
Answer:
d) mixture of ethane and propane

Question 5.
Adam’s catalyst is:
a) platinum metal
b) palladium
c) nickel metal
d) PtO₂
Answer:
d) PtO₂

Question 6.
Soda lime is
a) NaOH
b) NaOH + CaO
c) CaO
d) Na₂CO₃
Answer:
b) NaOH + CaO

Question 7.
Methyl bromide is converted into ethane by heating it in ether medium with
a) Al
b) Mg
c) Na
d) Cu
Answer:
c) Na

Question 8.
Hydrocarbon which is liquid at room temperature is
a) Pentane
b) Butane
c) Propane
d) Ethane
Answer:
a) Pentane

Question 9.
Pyrolysis of Methane and respectively are
a) Exothermic & Endothermic
b) Endothermic & Exothermic
c) Both are endothermic
d) Both are exothermic
Answer:
c) Both are endothermic

Question 10.
Select the correct statement about alkanes
a) they are polar in nature
b) they are soluble in water
c) they are non – combustible
d) their dipole moment is zero
Answer:
d) their dipole moment is zero

Question 11.
Final products of complete oxidation of hydrocarbon is
a) Acid
b) Dihydric alcohol
c) Aldehyde
d) H₂O + CO₂
Answer:
d) H₂O + CO₂

Question 12.
Isomerisation in alkane can be brought by using
a) Al₂O₃
b) Fe₂O₃
c) Anh.AlCl₃/ HCl at 200°C
d) Cone. H₂SO₄
Answer:
c) Anh.AlCl₃/ HCl at 200°C

Question 13.
In aromatization of n – hexane, the catalyst used is
a) Cr₂O₃
b) V₂O₅
c) Mo₂O₃
d) All
Answer:
d) All

Question 14.
The most oxidized form of ethane is
a) CO₂
b) HCHO
c) HCOOH
d) CH₃COOH
Answer:
a) CO₂

Question 15.
The following substance is used as anti knocking compound
a) TEL
b) Lead tetrachioride
c) Lead acetate
d) C₂H₂PbCl
Answer:
a) TEL

Question 16.
Conformational isomers are due to
a) Free rotation about C – C single bond
b) Frozen rotation about C – C single bond
e) Frozen rotation about C – C double bond
d) Restricted rotation about C – C single bond
Answer:
a) Free rotation about C – C single bond

Question 17.
The most stable conformation of ethane is
a) Eclipsed
b) Skew
c) Staggered
d) All are equally stable
Answer:
c) Staggered

Question 18.
IUPAC name of the following compound

a) 3 – methyl hexane
b) 3 – Ethyl pentane
c) 2, 3 – dimethyl pentane
d) 2, 2 – dimethyl pentane
Answer:
a) 3 – methyl hexane

Question 19.
The number of sigma bonds formed in ethane by the overlapping of sp3 – sp3 orbitals
a) 7
b) 5
c) 1
d) 4
Answer:
c) 1

Question 20.
How many types of carbon atoms are present in 2, 2, 3 – trimethyl pentane
a) one
b) Two
c) Three
d) Four
Answer:
d) Four

Question 21.
The correct IUPAC name of the following alkane is

a) 3, 6 – diethyl – 2- methyloctane
b) 5 – isopropyl – 3- ethyloctane
c) 3 – ethyl – 5- isopropyloctane
d) 3 – isopropyl – 6 – ethyloctane
Answer:
a) 3, 6 – diethyl – 2- methyloctane

Question 22.
In Wurtz reaction, n – hexane is obtained from
a) n – propyl chloride
b) n – butyl chloride
c) Ethyl chloride
d) isopropyl chloride
Answer:
a) n – propyl chloride

Question 23.
When sodium acetate is heated with sodalime the reaction is called
a) Dehydration
b) Decarboxylation
c) Dehydrogenation
d) Dehydrohalogenation
Answer:
b) Decarboxylation

Question 24.
The following substance reacts with water to give ethane
a) CH₄
b) C₂H₅MgBr
c) C₂H₄OH
d) C₂H₅OC₂H₅
Answer:
b) C₂H₅MgBr

Question 25.
Reaction of ROH with R’ MgX produces
a) RH
b) R’H
c) R – R
d) R’ – R”
Answer:
b) R’H

Question 26.
The solvent used in Wurtz reacton is
a) C₂H₅OH(aq)
b) CH₃COOH
c) H₂O
d) C₂H₅OC₂H₅(dry)
Answer:
d) C₂H₅OC₂H₅(dry)

Question 27.
Arrange the following in the decreasing order of their boiling points
i) n – butane
ii) 2 – methylbutane
iii) n – pentane
iv) 2 – methylbutane
a) i > ii > iii > iv
b) ii > iii > iv > i
c) iv > iii > ii > i
d) iii > ii > iv > i
Answer:
d) iii > ii > iv > i

Question 28.
The compound with the highest boiling point is
a) n – Hexane
b) n – Pentane
c) 2, 2 – dimethyl propane
d) 2 – methyl butane
Answer:
a) n – Hexane

Question 29.
The increasing order of reduction of alkyl halides with zinc and dilute HCl is
a) R – Cl < R – I < R – Br
b) R – Cl < R – Br < R – I
c) R – I < R – Br < R – Cl
d) R – Br < R – I < R – Cl
Answer:
b) R – Cl < R – Br < R – I

Question 30.
The volume of oxygen required for the complete combustion of 4 lit of ethane is
a) 4 lit
b) 8 lit
c) 12 lit
d) 14 lit
Answer:
d) 14 lit

Question 31.
The dihedral angle between the hydrogen atoms of 2 methyl groups in staggered conformation of ethane is
a) 0°
b) 60°
c) 120°
d) 240°
Answer:
b) 60°

Question 32.
The distances between the hydrogen nuclei in staggered and eclipsed form in ethane respectively are
a) 2.55 Å & 2.29 Å
b) 1.54 Å & 1.34 Å
c) 3.5 Å & 2.5 Å
d) 2.29 Å & 2.55 Å
Answer:
a) 2.55 Å & 2.29 Å

Question 33.
Energy barrier between staggered and eclipsed form in ethane is
a) 0.6 kcal / mole
b) 2.9 kcal / mole
c) 12 kcal / mole
d) 14 cal / mole
Answer:
b) 2.9 kcal / mole

Question 34.
IUPAC name of the following compound

a) 3 – Ethyl, 5 – methyl heptane
b) 5 – Ethyl, 3 – methyl heptane
c) 2 – Ethyl, 5 – methyl heptane
d) 4 – Ethyl, 5 – methyl heptane
Answer:
a) 3 – Ethyl, 5 – methyl heptane

Question 35.
Ethylene is converted to ethane in the presence of Ni at 300°C. In this reaction the hybridization of carbon changes from
a) sp to sp²
b) sp² to sp³
c) sp³ to sp
d) sp to sp³
Answer:
b) sp² to sp³

Question 36.
In which of the following reactions in the preparation of ethane a new C – C bond is formed
a) Sabatier – Senderen’s reaction
b) Reduction of ethyl iodide
c) Decarboxylation
d) Kolbe’s electrolysis
Answer:
d) Kolbe’s electrolysis

Question 37.
Select the correct statements
a) eclipsed and staggered ethanes give different products on reaction with chlorine in presence of light
b) the conformational isomers can be isolated at room temperature
c) torsional strain is minimum in ethane at dihedral angles 60°, 180° and 300°
d) steric strain is minimum in gauche form of n – butane
Answer:
c) torsional strain is minimum in ethane at dihedral angles 60°, 180° and 300°

Question 38.
The fully eclipsed conformation of n – butane is least stable due to the presence of
a) bond opposition strain only
b) steric strain only
c) bond opposition strain as well as steric strain
d) no strain is present in the molecule
Answer:
c) bond opposition strain as well as steric strain

Question 39.
Vinyl group among the following is
a) (CH₃)₂ CH –
b) HC ≡ C –
c) H₂C = CH – CH₂ –
d) CH₂ = CH –
Answer:
d) CH₂ = CH –

Question 40.
The alkene that exhibits geometrical isomerism is
a) propene
b) 2 – methyl propene
c) 2 – butene
d) 2 – methyl – 2 – butene
Answer:
c) 2 – butene

Question 41.

a) 5 – methylocta – 1, 3, 5, 7 – tetraene
b) 4 – methylocta – 1, 3, 5, 7 – tetraene
c) 4 – butenylocta -1, 3- diene
d) octa – 1, 5 – diene
Answer:
b) 4 – methylocta – 1, 3, 5, 7 – tetraene

Question 42.
CH₂ = C (CH₂CH₂CH₃)₂
a) 2 – Propyl pent – 1 – ene
b) 2 – Propyl pent – 2- ene
c) 2 – Propyl pent – 3 – ene
d) 3 – Propyl pent – 1- ene
Answer:
a) 2 – Propyl pent – 1 – ene

Question 43.
The number of sigma (σ) and pi (π) bonds in the following structure are
a) σ bonds – 33 π bonds – 2
b) σ bonds – 22 π bonds – 2
c) σ bonds – 42 π bonds – 2
d) σ bonds – 40 π bonds – 3
Answer:
a) σ bonds – 33 π bonds – 2

Question 44.
In dehydrohalogenation, hydrogen and halogen are removed from
a) the same carbon atom
b) from adjacent carbon atoms
c) from isolate carbon atoms
d) from any two carbon atoms
Answer:
b) from adjacent carbon atoms

Question 45.
Ethylene readily undergoes the following type of reaction.
a) Elimination
b) Addition
c) Rearrangement
d) Substitution
Answer:
b) Addition

Question 46.
Baeyer’s reagent is
a) Aqueous bromine solution
b) Neutral permanganate solution
c) Acidified permanganate solution
d) Alkaline potassium permanganate solution
Answer:
d) Alkaline potassium permanganate solution

Question 47.
Baeyer’s reagent oxidizes ethylene to
a) Ethylene chlorohydrin
b) Ethyl alcohol
c) CO₂ and H₂O
d) Ethane – 1, 2 – diol
Answer:
d) Ethane – 1, 2 – diol

Question 48.
On reductive ozonolysis ethylene gives
a) Aldehyde
b) Ketone
c) Carboxylic acid
d) Ether
Answer:
a) Aldehyde

Question 49.
Polythene is obtained by the polymerization of
a) Styrene
b) A mixture of ethylene and styrene
c) Acetylene
d) Ethene
Answer:
c) Acetylene

Question 50.
Polytetrafluoroethylene is commercially known as
a) Teflon
b) Freon
c) Lewisite
d) Westron
Answer:
a) Teflon

Question 51.
Polythens is
a) (- H₂C = CH₂ -)_n
b) (- HC = CH – )_n
c) (- H₃C – CH₃ – )_n
d) (- H₂C – CH₂ -)_n
Answer:
d) (- H₂C – CH₂ -)_n

Question 52.
When ethanol vapours are passed over alumina heated at 350°C, the main product obtained is
a) C₂H₆
b) C₂H₄
c) C₂H₂
d) C₂H₅OC₂H₅
Answer:
b) C₂H₄

Question 53.
Dehydrohalogenation of ethyl chloride in presence of ale. KOH produces the following
a) HC ≡ CH + KCl + H₂O
b) CH₄ + KCl + H₂O
c) CH₂ = CH₂ + KCl + H₂O
d) C₂H₄ + HCl
Answer:
c) CH₂ = CH₂ + KCl + H₂O

Question 54.
Ethylene is prepared by
a) Dehalogenation of chloroform
b) Pyrolysis of ethane at 450°C
c) Dehydration of methanol with Al₂O₃ / 350°C
d) Methyl chloride on reduction
Answer:
b) Pyrolysis of ethane at 450°C

Question 55.
The peroxide effect involves
a) Ionic mechanism
b) Free – radical mechanism
c) Heterolytic fission of double bond
d) Homolytic fission of double bond
Answer:
b) Free – radical mechanism

Question 56.
In which of the following will Kharasch effect operate?
a) CH₃ – CH₂ – CH = CH₂ + HCl
b) CH₃ – CH₂ – CH = CH₂ + HBr
c) CH₃ – CH = CH – CH₃ + HBr
d) CH₃ – CH₂ – CH = CH₂ + HI
Answer:
b) CH₃ – CH₂ – CH = CH₂ + HBr

Question 57.
Anti Markownikoff addition of HBr is not observed in
a) Propene
b) Butene – 1
c) Butene – 2
d) pentene – 2
Answer:
c) Butene – 2

Question 58.
Conditions used for the formation of ethylene glycol from ethylene
a) bromine water
b) cold alkaline KMnO₄
c) dil H₂SO₄, 60°C
d) Ag / 200°C
Answer:
b) cold alkaline KMnO₄

Question 59.
The olefin which on ozonolysis gives CH₃CH₂CHO and CH₃CHO is
a) 1 – butene
b) 2 – butene
c) 1 – pentene
d) 2 – pentene
Answer:
d) 2 – pentene

Question 60.
In the following reaction, A and B respectively are,

a) C₂H₄ and alcoholic KOH / ∆
b) C₂H₅Cl and aqueous KOH / ∆
c) C₂H₅OH and aq KOH / ∆
d) C₂H₂ and Br₂
Answer:
a) C₂H₄ and alcoholic KOH / ∆

Question 61.
The number of possible alkynes with molecular formula C₅H₈ is
a) 3
b) 4
c) 5
d) 6
Answer:
a) 3

Question 62.
The number of open chain structural isomers possible with molecular formula C5H8 is
a) 7
b) 6
c) 5
d) 4
Answer:
a) 7

Question 63.
Alkynes exhibit.
a) Chain isomerism
b) Position isomerism
c) Functional isomerism
d) All the above
Answer:
d) All the above

Question 64.
The IUPAC name of the compound having the formula CH ≡ C – CH = CH₂
a) Butene – 2 – ye
b) But – 2- yne – 3 – ene
c) 3 – butane 1 – ene
d) But – 1 – ene – 3 – yne
Answer:
d) But – 1 – ene – 3 – yne

Question 65.
Acetylene can be obtained by the electrolysis of the following compound
a) Potassium fumerate
b) Potassium succinate
c) Potassium acetate
d) Potassium formate
Answer:
a) Potassium fumerate

Question 66.
The gas obtained when ethylene chloride reacts with alcoholic potash and sodamide is
a) C₂H₄
b) C₂H₆
c) C₂H₂
d) C₂H₅Cl
Answer:
c) C₂H₂

Question 67.
PVC is the polymer of the following
a) Ethyl chloride
b) Vinyl Chloride
c) Allyl Chloride
d) Ethynyl chloride
Answer:
b) Vinyl Chloride

Question 68.
Which of the following possess acidic hydrogen
a) C₂H₆
b) C₂H₄
c) C₂H₂
d) CH₄
Answer:
c) C₂H₂

Question 69.
Hydrocarbon which gives oxyacetylene flame
a) ethane
b) ethene
c) ethyne
d) ethanol
Answer:
c) ethyne

Question 70.
The isomer of propyne
a) Allene
b) Propene
c) Cyclo propane
d) Propane
Answer:
a) Allene

Question 71.
Bond angle between C – C in alkyne
a) 109°.28′
b) 120°
c) 180°
d) 60°
Answer:
c) 180°

Question 72.
The molecule having linear structure is
a) Methane
b) Ethylene
c) Acetylene
d) Water
Answer:
c) Acetylene

Question 73.
The C – C bond length is shortest in
a) C₂H₆
b) C₃H₈
c) C₆H₆
d) C₂H₄
Answer:
b) C₃H₈

Question 74.
The hydrolysis of Mg₂C₃ produces
a) acetylene
b) propyne
c) butyne
d) ethylene
Answer:
b) propyne

Question 75.
1 – pentyne and 2 – pentyne can be distinguished by
a) Silver mirror test
b) Iodoform test
c) Addition of H₂
d) Baeyers test
Answer:
a) Silver mirror test

Question 76.
Acetylene on reaction with silver nitrate shows
a) Oxidizing property
b) Reducing property
c) Basic nature
d) Acidic nature
Answer:
d) Acidic nature

Question 77.
The acidic nature of hydrogens in acetylene cannot be explained by the reaction with
a) Sodium metal
b) Ammonical cuprous chloride solution
c) Ammonical silver nitrate solution
d) HCN
Answer:
d) HCN

Question 78.
Westron is the solvent obtained by the reaction of chlorine with
a) Ethylene
b) Ethyne
c) Ethane
d) Methane
Answer:
b) Ethyne

Question 79.
CH ≡ CH is
a) CH₂ = CH – CH = CH₂
b) HC ≡ C – CH₃
c) CH₂ = CH – CH₃
d) CH₃ – CH₂ – CH₃
Answer:
b) HC ≡ C – CH₃

Question 80.
Hydration of ethyne to ethanal takes place through the formation of
a) CH₃CH(OH)₂
b) CH₂ = CHOH
c) CH₂ = CHO^–
d) CH ≡ C^–
Answer:
b) CH₂ = CHOH

Question 81.
B is
a) Acetylene
b) Acetaldehyde
c) Acetone
d) Acetic acid
Answer:
b) Acetaldehyde

Question 82.
is
a) Ethyl chloride
b) 1, 2 dichloro ethene
c) Vinyl chloride
d) Ethylidine chloride
Answer:
c) Vinyl chloride

Question 83.
The Polymer ‘B’ is
a) orlon
b) PVC
c) nylon
d) Teflon
Answer:
b) PVC

Question 84.
Benzene is ______ molecule.
a) Tetrahedral
b) Planar
c) Trigonal
d) Square planar
Answer:
b) Planar

Question 85.
Bond length of C – C in benzene.
a) 1.34 Å
b) 1.39 Å
c) 1.54 Å
d) 1.20 Å
Answer:
c) 1.54 Å

Question 86.
The resonance energy Benzene is
a) 36 kcal / mol
b) 85.8 kJ / mole
c) 150.48 kJ / mole
d) Both (a) and (c)
Answer:
d) Both (a) and (c)

Question 87.
In Huckel’s (4n + 2) π rule for aromaticity, ‘n’ represents
a) Number of carbon atoms
b) Number of rings
c) Whole number
d) Fractional number (or) integer (or) zero
Answer:
c) Whole number

Question 88.
Coal tar is obtained as a by product during
a) Destructive distillation of wood
b) Destructive distillation of coal
c) Destructive distillation of bones
d) steam distillation of light oil
Answer:
b) Destructive distillation of coal

Question 89.
Gammaxene is ________ isomer of benzene hexa chloride.
a) α
b) β
c) γ
d) δ
Answer:
c) γ

Question 90.
The empirical formula of benzene and acetylene is/are
a) CH₂, CH
b) CH₂, CH₂
c) CH, CH
d) CH₃, CH₃
Answer:
c) CH, CH

Question 91.
Chemical name of the insecticide gammaxene is
a) DDT
b) Benzene hexa chloride
c) Chloral
d) Hexa chloro ethane
Answer:
b) Benzene hexa chloride

Question 92.
Which is non benzenoidal aromatic compound?
a) Benzene
b) Pyridine
c) Toluene
d) Phenol
Answer:
b) Pyridine

Question 93.
Benzene is purified by
a) distillation
b) fractional distillation
c) Evaporation
d) sublimation
Answer:
b) fractional distillation

Question 94.
Preparation of benzene from phenol is
a) Reduction
b) Oxidation
c) Addition
d) Dehydrogenation
Answer:
a) Reduction

Question 95.
The true statement about benzene is
a) Because of unsaturation benzene easily undergoes addition reactions
b) There are two types C – C bonds in benzene molecule
c) There is a cyclic delocalization of pi – electrons in benzene
d) Mono substitution of benzene gives three isomeric products
Answer:
c) There is a cyclic delocalization of pi – electrons in benzene

Question 96.
– COOH group in electrophilic substitution directs the incoming group to
a) o – position
b) p – position
c) m – position
d) o – and p – position
Answer:
c) m – position

Question 97.
Which of the following is not meta directing group?
a) -SO₃H
b) – NO₂
c) – CN
d) – NH₂
Answer:
d) – NH₂

Question 98.
Which among the following is very strong o – , p – directing group?
a) – Cl
b) – OR
c) – NH₂
d) – NHR
Answer:
d) – NHR

Question 99.
Cyclo butadiene is said to be
a) Aromatic
b) Aliphatic
c) anti aromatic
d) heterocyclic
Answer:
c) anti aromatic

Question 100.
In the reaction
the attacking species is
a) Cl₂
b) Cl⁺
c) Cl^–
d) FeCl₄^–
Answer:
b) Cl⁺

Question 101.
The electrophile in Acetylation of Benzene

Answer:
b)

Question 102.
The ratio of sigma and pi bonds in benzene is
a) 4 : 1
b) 2 : 3
c) 6 : 1
d) 1 : 1
Answer:
a) 4 : 1

Question 103.
Benzene reacts with _______ to yield acetophenone.
a) CH₃COCl + AlCl₃
b) C₆H₅COCl + AlCl₃
c) RCOCl + AlCl₃
d) C₂H₅COCl + AlCl₃
Answer:
a) CH₃COCl + AlCl₃

Question 104.
The order of activites of the various O and P director is
a) – O^– > – OH > – OCOCH₃ > – COCH₃
b) – OH > – O^– > – OCOCH₃ > – COCH₃
c) – OH > – O^– > – COCH₃ > – OCOCH₃
d) -O^– > – COCH₃ > -OCOCH₃ > -OH
Answer:
a) – O^– > – OH > – OCOCH₃ > – COCH₃

II. Very short question and answers (2 Marks):

Question 1.
What are alkanes? Give example.
Answer:
Alkanes are saturated hydrocarbons represented by the general formula C_nH_{2n + 2} where ‘n’ is the number of carbon atoms in the molecule. Methane CH₄, is- the first member of alkane family. The successive members are ethane C₂H₆, propane C₃H₈,butane C₄H₁₀, pentane C₅H₁₂ and so on. It is evident that each member differs from its proceeding or succeeding member by a -CH₂ group.

Question 2.
Give the IUPAC name of the following alkane.
a)

b)
Answer:
a)

b)

Question 3.
Draw the structural formula for 4,5 – diethyl – 3, 4, 5 – trimethyl octane.
Answer:

Question 4.
How is methane prepared from sodium acetate?
Answer:
When a mixture of sodium salt of carboxylic acid and soda lime (sodium hydroxide + calcium oxide) is heated, alkane is formed. The alkane formed has one carbon atom less than carboxylic acid. This process of eliminating carboxylic
group is known as decarboxylation.
CH₃COONa + NaOH CH₄ + Na₂CO₃
Sodium acetate                            Methane

Question 5.
Write a short note on Kolbe’s Electrolytic method.
Answer:
When sodium or potassium salt of carboxylic acid is electrolyzed, a higher alkane is formed. The decarboxylative dimerization of two carboxylic acid occurs. This method is suitable for preparing symmetrical alkanes(R-R).

Question 6.
How will you convert chloro propane into propane?
Answer:
When chloro propane is reduced with Zn / HCl it gives propane.
Example:

Question 7.
Explain the combustion reaction of alkane with suitable example.
Answer:
A combustion reaction is a chemical reaction between a substances and oxygen with evolution of heat and light (usually as a flame). In the presence of sufficient oxygen, alkanes undergoes combustion when ignited and produces carbondioxide and water.

The combustion reaction is expressed as follows.
Example:
CH₄ + 2O₂ → CO₂ + 2H₂O
∆H° = -890.4 KJ

When alkanes burn in insufficient supply of oxygen, they form carbonmonoxide and carbon black.
2CH₄ + 3O₂ 2CO + 4H₂O
CH₄ + O₂ → C + 2H₂O

Question 8.
How are the following compound prepared by Aromatisation method?
(i) Benzene
(ii) Toluene
Answer:
(i) Benzene
n-Hexane passed over Cr₂O₃ supported on alumina at 873 k gives benzene.

(ii) Toluene

Question 9.
What happens when methane reacts with steam?
Answer:
Methane reacts with steam at 1273K in the presence of Nickel and decomposes to form carbon monoxide and hydrogen gas.
CH₄(g) + H₂O(g) CO(g) + 3H₂
Production of H₂ gas from methane is known as steam reforming process and it is a well-established industrial process for the production of H₂ gas from hydrocarbons.

Question 10.
Explain the Isomerisation reaction with suitable example.
Answer:
Isomerisation is a chemical process by which a compound is transformed into any its isomeric forms. Normal alkanes can be converted into branched alkanes in the presence of AlCl₃ and HCl at 298 k.

This process is of great industrial importance. The quality of gasoline is improved by isomerising its components.

Question 11.
What are alkenes? Give example.
Answer:
Alkenes are unsaturated hydrocarbons that contain carbon-carbon double bond. They are represented by the general formulae C_nH_2n where ‘n’ stands for number of carbon atoms in the molecule. Alkenes are also known as olefins (in Latin – oil maker) because the first member ethene combines with chlorine gas to form an oily liquid as a product.
Example:
Ethylene (C₂H₄)

Question 12.
Explain the Geometrical isomerism of alkene with suitable example.
Answer:
It is a type of stereoisomerism and it is also called cis-trans isomerism. Such type of isomerism results due to the restricted rotation of doubly bounded carbon atoms.
If the similar groups lie on the same side, then the geometrical isomers are called Cis-isomers. When the similar groups lie on the opposite side, it is called a Trans isomer.
Example:
The geometrical isomers of 2-Butene is expressed as follows

Question 13.
Write the test for Alkene.
Answer:
Bromine in water is reddish brown colour. When small about of bromine water is added to an alkene, the solution is decolourised as it forms dibromo compound. So, this is the characteristic test for unsaturated compounds.
Example:

Question 14.
Mention uses of Alkenes.
Answer:

• Alkenes find many diverse applications in industry. They are used as starting materials in the synthesis of alcohols, plastics, liquors, detergents and fuels
• Ethene is the most important organic feed stock in the polymer industry. E.g,’ PVC, Sarans and polyethylene. These polymer are used in the manufacture of floor tiles, shoe soles, synthetic fibres,raincoats, pipes etc.

Question 15.
How is propyne prepared from propylidine chloride?
Answer:

Question 16.
How is ethyne prepared from CaC₂?
Answer:
Ethyne can be manufactured in large scale
by action of calcium carbide with water.

Calcium carbide needed for this reaction is prepared by heating quick lime and coke in an electric furance at 3273 K
CaO + 3C CaC₂ + CO

Question 17.
Write the reaction of propyne using Br₂.
Answer:

When Br₂ in CCl₄ (Reddishbrown) is added to an aikyne, the colour is decolounsed. This is the test for unsaturation.

Question 18.
Mention the uses of alkynes.
Answer:

1. Acetylene is used in oxy acetylene torch used for welding and cutting metals.
2. It is used for manufacture of PVC, polyvinyl acetate, polyvinyl ether, orlon and neoprene rubbers.

III. Short question and answers (3 Marks):

Question 1.
How are the following conversions carried out?
(i) propene → propane
(ii) ethene → ethane
(iii) prop – 1 – yne → propane
Answer:
(i) propene → propane
CH₃ – CH = CH₂ + H₂ CH₃ – CH₂ – CH₃
propene                                     propane

(ii) ethene → ethane
CH₂ = CH₂ + H₂ CH₃ – CH₃
ethene                               ethane

(iii) prop – 1 – yne → propane
CH₃ – C ≡ CH + 2H₂ CH₃ – CH₂ – CH₃
prop – 1 – yne                            propane

Question 2.
write the IUPAC name of the following compounds.

Answer:

Question 3.
Write the structural formula for the following compounds.
(i) 3 – Ethyl – 4, 5 – dipropyl octane
(ii) 2, 3 – Dimethyl pentane
(iii) 4 – Ethyl – 2,7 – Dimethyl octane
Answer:
(i) 3 – Ethyl – 4, 5 – dipropyl octane

(ii) 2, 3 – Dimethyl pentane

(iii) 4 – Ethyl – 2,7 – Dimethyl octane

Question 4.
Write a short note on
(i) Wurtz reaction
(ii) Corey – House Mechanism
Answer:
(i) Wurtz reaction:
When a solution of halo alkanes in dry ether is treated with sodium metal, higher alkanes are produced. This reaction is used to prepare higher alkanes with even number of carbon atoms.
Example:
CH₃ – Br + 2Na + Br – CH₃ CH₃ – CH₃ + NaBr
methyl bromide                                        ethane

(ii)Corey-House Mechanism:
An alkyl halide and lithium di alkyl cuprate are reacted to give higher alkane.
Example:
CH₃CH₂Br + (CH₃)₂LiCu → CH₃CH₂CH₃ + CH₃Cu + LiBr
Ethyl bromide

Question 5.
How is methane prepared from Grignard reagent?
Answer:
Methyl chloride reacts with magnesium in presence of dry ether gives methyl magnesium chloride. Then methyl magnesium chloride reacts with water to give methane.
CH₃ – Cl + Mg CH₃MgCl
chloromethane                 methyl magnesium chloride

CH₃MgCl + H₂O → CH₄ + Mg(OH)Cl
methane

Question 6.
What is meant by pyrolysis? Explain the pyrolysis reaction of Ethane and propane.
Answer:
Pyrolysis is defined as the thermal decomposition of organic compound into smaller fragments in the absence of air through the application of heat. ‘Pyro’ means ‘fire’ and ‘lysis’ means ‘separating’. Pyrolysis of alkanes also named as cracking.

In the absence of air, when alkane vapours are passed through red-hot metal it breaks down into simpler hydrocarbons.

1)

2) 2CH₃ – CH₃   CH₂ = CH₂ + 2CH₄
Ethane                                 Ethylene

Question 7.
Mention the uses of alkanes.
Answer:
The exothermic nature of alkane combustion reaction explains the extensive use of alkanes as fuels. Methane present in natural gas is used in home heating. Mixture of propane and butane are known as LPG gas which is used for domestic cooking purpose. GASOLINE is a complex mixture of many hydrocarbons used as a fuel for internal combustion engines.

Carbon black is used in the manufacture of ink, printer ink and black pigments. It is also used s fillers.

Question 8.
Write all possible structural isomers with the molecular formula C₄H₁₀ and name them.
Answer:
(i) CH₃ – CH = CH – CH₃ 2 – butene
(ii) CH₂ = CH – CH₂ – CH₃ 1 – butene
(iii) 2 – mehyl – 1 – propene
structures (i) 8s (ii) are position isomers, structures (i) & (iii), (ii) 8s (iii) are chain isomers.

Question 9.
How is ethene prepared by Kolbe’s electrolytic method?
Answer:
When an aqueous solution of potassium succinate is electrolyzed between two platinum electrodes, ethene is produced at the anode.

Question 10.
How are the following compounds prepared by ozonolysis method?
(i) Formaldehyde
(ii) Acetaldehyde
Answer:
(i) Formaldehyde:

(ii) Acetaldehyde:

Question 11.
How ozone reacts with 2 – methyl propene?
Answer:

When 2 – methyl propene reacts with ozone to give ozonoid. Ozonide is treated with Zn/H₂O gives acetone.

Question 12.
How is acetylene prepared from ethylene?
Answer:
This process involves two steps:
(i) Halogenation of alkenes to form vicinal dihalides
(ii) Dehalogenation of vicinal dihalides to form alkynes.

Question 13.
How is acetylene prepared by Kolbe’s electrolytic method?
Answer:
Electrolysis of sodium or potassium salt of maleic or fumaric acid yields alkynes.

Question 14.
Write Ozonolysis reaction of Propyne?
Answer:

Question 15.
How is BHC prepared? Give its uses.
Answer:
Chlorination of Benzene:
Benzene reacts with three molecules of Cl₂ in the presence of sun light or UV light to yield Benzene Hexa Chloride (BHC) C₆H₆Cl₆. This is known as gammaxane or Lindane which is a powerful insecticide.

Question 16.
How propane is prepared form 1, 2 – dichloro propane?
Answer:

Question 17.
Explain the polymerization reaction of alkenes.
Answer:
A polymer is a large molecule formed by the combination of larger number of small molecules. The process is known as polymensation. Alkenes undergo polymerisation at high temperature and pressure, in the presence of a catalyst.
Example:
red hot

Question 18.
Write a note on acidic nature of Alkynes.
Answer:
An alkyne shows acidic nature only if it contains terminal hydrogen. This can be explained by considering sp hybrid orbitals of carbon atom in alkynes. The percentage of S-character of sp hybrid orbital (50%) is more than sp² hybrid orbital of alkene (33%) and sp³ hybrid orbital of alkane (25%). Because of this, Carbon becomes more electronegative facilitating donation of H+ ions to bases. So hydrogen attached to triply bonded carbon atoms is acidic but not the others.

Question 19.
Write a short note on
(i) Wurtz – Fittig reactions
(ii) Friedel Craft’s reaction
Answer:
(i) Wurtz – Fittig reactions:
When a solution of bromo benzene and iodo methane in dry ether is treated with metallic sodium, toluene is formed.

(ii) Friedel Craft’s reaction:
When benzene is treated with methyl chloride in the presence of anhydrous aluminium chloride, toluene is formed.

IV. Long Question and answers (5 Marks):

Question 1.
How to draw structural formula for given IUPAC name with suitable example.
Answer:
After you learn the rules for naming alkanes, it is relatively easy to reverse the procedure and translate the name of an alkane into a structural formula. The example below show how this is done.
Let us draw the structural formula for
3 – ethyl – 2, 3 – dimethyl pentane
Step 1:
The parent hydrocarbon is pentane. Draw the chain of five carbon atoms and number it. .

Step 2:
Complete the carbon skeleton by attaching the alkyl group as they are specified in the name. An ethyl group is attached to carbon 3 and two methyl groups are attached to carbon 2 and 3.

Step 3:
Add hydrogen atoms to the carbon skeleton so that each carbon atoms has four bonds.

Question 2.
Explain the conformations of ethane.
Answer:
The two tetrahedral methyl groups can rotate about the carbon – carbon bond axis yielding several arrangements called conformers. The extreme conformations are staggered and eclipsed conformation. There can be number of other arrangements between staggered and eclipsed forms and their arrangements are known as skew forms.
Eclipsed conformation:

In this conformation, the hydrogen’s of one carbon are directly behind those of the other. The repulsion between the atoms is maximum and it is the least stable conformer.

Staggered conformation:

In this conformation, the hydrogen’s of both the carbon atoms are far apart from each other. The repulsion between the atoms is minimum and it is the most stable conformation.

Skew conformation:

The infinite numbers of possible intermediate conformations between the two extreme conformations are referred as skew conformations. The stabilities of various conformations of ethane are:
Staggered > Skew > Eclipsed
The potential energy difference between the staggered and eclipsed conformation of ethane is around 12.5 kJmol^-1. The various conformations can be represented by new man projection formula.

Eclipsed Skew Staggered newmann projection formula for Ethane.

Question 3.
Explain the steps involved in the mechanism of halogenations of alkane.
Halogenation:
A Halogenation reaction is the chemical reaction between an alkane and halogen in which one or more hydrogen atoms are substituted by the halogens.

Chlorination and Bromination are two widely used halogenation reactions. Fluorination is too quick and iodination too slow. Methane reacts with chlorine in the presence of light or when heated as follows.

Mechanism:
The reaction proceeds through the free radical chain mechanism. This mechanism is characterized by three steps initiation, propagation and termination.

(i) Chain Initiation:
The chain is initiated by UV light leading to homolytic fission of chlorine molecules into free radicals (chlorine atoms).

Here we choose Cl – Cl bond for fission because C – C & C – H bonds are stronger than Cl – Cl.

ii) Propagation:
It proceeds as follows
a) Chlorine free radial attacks the methane molecule and breaks the C – H bond resulting in the generation of methyl free radical

b) The methyl free radical thus obtained attacks the second molecule of chlorine to give chloromethane (CH₃Cl) and a chlorine free radical as follows.

c) This chlorine free radical then cycles back to step a) and both step a) and b) are repeated many times and thus chain of reaction is set up.

iii) Chain termination:
After sometimes, the reactions stops due to consumption of reactant and the chain is terminated by the combination of free radicals.

Question 4.
Write the IUPAC name of the following compounds.
1) CH₃ – CH = CH₂
2) CH₃ – CH = CH – CH₃
3)
4)
Answer:

Question 5.
Write the IUPAC name of the following compounds.

Answer:
1)

2)

3)

4)

Question 6.
Draw the structures for the following alkenes.
(i) 6 – Bromo – 2, 3 – dimethyl – 2 – hexene
(ii) 5 – Bromo – 4 – chloro – 1 -heptene
(iii) 2, 5 – dimethyl – 4 – octene
(iv) 4 – Methyl – 2 – pentene
Answer:
(i) 6- Bromo – 2, 3-dimethyl – 2 -hexene

(ii) 5 – Bromo – 4 – chloro – 1 -heptene

(iii) 2, 5 – dimethyl – 4 – octene

(iv) 4 – Methyl – 2 – pentene

Question 7.
Draw the structure and write down the IUPAC name for the isomerism exhibited by the molecular formulae:
(i) C₅H₁₂ – Pentene (3 isomers)
(ii) C₆H₁₄ – Hexene (5 isomers)
(iii) C₅H₁₂ – Pentene (3 isomers)
Answer:
(i) C₅H₁₂ – Pentene
a) CH₃ – CH₂ – CH₂ – CH = CH₂
1 – Pentene

b)
2 – methyl – 2 – butene

c) CH₃CH = CH – CH₂CH₃
2 – pentene

(ii) C₆H₁₄ – Hexene
a) CH₃ – CH₂ – CH₂ – CH₂ – CH = CH₂
1 – hexane

b) CH₃ – CH₂ – CH₂ – CH = CH – CH₃
2 – hexane

c) CH₃ – CH₂ – CH = CH – CH₃ – CH₂
3 – hexane

d)

e)

Question 8.
How are the following conversions carried out?
(i) ethanol → ethene
(ii) 2- butyne cis → 2 – butene and trans – 2 – butane
(iii) 1 – bromopropane → prop – 1 – ene
(iv) 1 – 2 – dibromoethane – ethene
Answer:
1) ethanol → ethene
C₂H₅OH H₂C = H₂C
ethanol ethane

(ii) 2 – butyne → cis – 2 – butene
H₃C – C ≡ C – CH₃ + H₂

2 – butane → trans – 2 – butane

(iii) 1 – bromopropane → prop – 1 – ene
H₃C – CH₂ – CH₂ – Br H₃C – CH = CH₂ + KBr + H₂O
1 – bromopropane → prop – 1 – ene

(iv) 1 – 2 – dibromoethane – ethene

1 – 2 – dibromoethane – ethene

Question 9.
Write the mechanism involved in the addition of HBr to alkene in the presence of organic peroxide.
Answer:
Anti-Markovnikoff’s Rule (Or) Peroxide Effect (Or) KharaschAddition:
The addition of HBr to an alkene in the presence of organic peroxide takes place in the direction opposite to that predicted by Markovnikoff’s rule.
CH₃ – CH = CH₂ + HBr CH₃ – CH₂ – CH₃ – CH₂ – CH₂ – Br
prop – 1 – ene                                                          1 – bromopropane

Mechanism:
The reaction proceeds via free radical mechanism.

Step 1:
The week O – O single bond linkages of peroxides undergoes homolytic cleavage to generate free radical.

Step 2:
The radicals abstract H from HBr thus generating bromine radical.

Step 3:
The Bromine radical adds to the double bond in the way to form more stable alkyl free radical.

Step 4:
Addition of HBr to secondary free radical

Step 5:
Addition of HBr to primary free radical

Question 10.
How are the following conversions carried out?
Answer:
(i) Propene → 2 – Propanol
(ii) ethene → ethylene glycol
(iii) 2 – butene → Acetic acid
(iv) 2 – methyl – 1 – propene → Acetone
Answer:
(i) Propene → 2 – Propanol

(ii) ethene → ethylene glycol

(iii) 2 – butene → Acetic acid

(iv) 2 – methyl – 1 – propene → Acetone

Question 11.
An organic compound (A) C₂H₄ decolourises bromine water. (A) on reaction with chlorine gives (B) A reacts with HBr to give (C). Identity (A), (B), (C). Explain th. reactions.
Answer:

Result:
(A) – ethylene
(B) – 1, 2 – dichloroethane
(C) – ethyl bromide

Question 12.
How are the following conversions carried out?
(i) 2 – butyne → 2, 2 – dichlorobutane
(ii) 1 – butyne → 2, 2 – dibromobutane
(iii) ethyne → acetaldehyde
(iv) Propyne → propan – 2 – one
Answer:
(i) 2 – butyne → 2, 2 – dichlorobutane

(ii) 1 – butyne → 2, 2 – dibromobutane

(iii) ethyne → acetaldehyde

(iv) Propyne → propan – 2 – one

Question 13.
How are the following compounds prepared from ethyne?
(i) Formic acid
(ii) Vinyl ethylene
(iii) Benzene
Answer:
(i) Formic acid

(ii) Vinyl ethylene
2CH ≡ CH CH₂ = CH – C ≡ CH (Vinyl ethylene)

(iii) Benzene

Question 14.
Explain the Huckel’s rule of Aromaticity.
Answer:
Huckel proposed that aromaticity is a function of electronic structure. A compound may be aromatic, if it obeys the following rules (Huckel’s rule)
i) The molecule must be co-planar
ii) Complete delocalization of n electron in the ring
iii) Presence of (4n+2) n electrons in the ring where n is an integer (n = 0,1,2….)
This is known as Huckle’s rule.
Some of the examples which obey Huckel rule.

1. The benzene ring is planar with delocalized π electrons (6)
It obeys Huckel’s rule because 4n + 2 = (4 × 1) + 2 = 6π electrons.
Hence, it is an aromatic compound

2. It has planar ring structure with delocalized π electrons (10).
Applying Huckle’s rule (4 × 2) + 2 = 10π electrons.
Hence it is an aromatic compound

Naphthalene

3. It has a planar ring structure with delocalized π electrons(14).
Applying Huckle’s rule (4 × 3) + 2 = 14π electrons.

4. It has planar ring structure but the π electrons are not delocalized.
Applying Huckle’s rule (4 × 1) + 2 = 6π electrons.
But it has only 4electrons. So it is not an aromatic compound

5. It has a tub shaped ring structure. It does not obey Huckel’s rule.
Applying Huckle’s rule 4n + 2 = 8π electrons if n = 2
So it is not an aromatic compound.

Question 15.
Explain the Kekule’s structure of benzene.
Answer:
In 1865, August Kekule suggested that benzene consists of a cyclic planar structure of six carbon with alternate single and double bonds.
There were two objections:
(i) Benzene forms only one orthodisubstituted products whereas the Kekule’s structure predicts two o-di substituted products as shown below.

Presence of double bond between the substituents

Presence of single bond between the substituents

(ii) Kekule’s structure failed to explain why benzene with three double bonds did not give addition reactions like other alkenes.To overcome this objection, Kekule suggested that benzene was mixture of two forms (1 and 2) in rapid equilibrium.

Question 16.
Explain the resonance in benzene.
Answer:
The phenomenon in which two or more structures can be written for a substance which has identical portions of atoms in called resonance. The actual structure of the molecule is said to be resonance hybrid of various possible alter nature structures. In benzene, Kekule’s structures I & II represented the resonance structure, and structure III is the resonance hybrid of structure I & II.

The structures 1 and 2 exist only in theory. The actual structure of benzene is the hybrid of two hypothetical resonance structures.

Question 17.
Write the industrial preparation of benzene from coal tar.
Answer:
Coal tar is a viscous liquid obtained by the pyrolysis of coal. During fractional distillation, coal tar is heated and distills away its volatile compounds namely benzene, toluene, xylene in the temperature range of 350 to 443 K. These vapours are collected at the upper part of the fractionating column

Question 18.
How is benzene prepared from
(i) Acetylene
(ii) Decarboxylation
(iii) Phenol
Answer:
(i) From acetylene
Acetylene on passing through a red -hot tube trimerises to give benzene. We havealready studied this concept in polymerization of alkynes.

(ii) Decarboxylation of aromatic acid.
When sodium benzonate is heated with sodalime, benzene vapours distil over.
C₆H₅COONa + NaOH C₆H₆ + Na₂CO₃

(iii) Preparation of benzene from Phenol
When phenol vapours are passed over zinc dust, then it is reduced to benzene.
C₆H₆OH + Zn  C₆H₆ + ZnO

Question 19.
Explain Electrophilic substitution reaction of benzene.
Answer:
(i) nitration:
When benzene is heated at 330K with a nitrating mixture (Con. HNO₃ + Con. H₂SO₄), nitro benzene is formed by replacing of hydrogen atom by nitronium ion NO₂⁺ (electrophile).

Concentrated H₂SO₄ is added to produce nitronium ion NO₂⁺.

(ii) Halogenation:
Benzene reacts with halogens (X₂ = Cl₂, Br₂,) in the presence of Lewis acid such as FeCl₃, FeBr₃ orAlCl₃ and give corresponding halo benzene.

(iii) Sulphonation:
Benzene reacts with fuming sulphuric acid (Con. H₂SO₄ + SO₃) and gives benzene sulphonic acid. The electrophile SO₃ is a molecule.

(iv) Friedel craft’s alkylation: (methylation)
When benzene is treated with a alkyl halide in the presence of only AlCl₃, alkyl benzene is formed.

(v) Friedel craft’s acylatlon: (Acetylation)
When benzene is treated with acetyichioride in the presence of AlCl₃, acyl benzene is formed.

Question 20.
How is benzene converted into
a) Cyclo hezane
b) maleic anhydride
c) 1, 4 cyclo hexadiene
Answer:
a) Cyclo hexane:
Benzene reacts with hydrogen in the presence of Platinum or Palladium to yield Cyclohexane. This is known as hydrogenation.

b) maleic anhydride:
Although benzene is very stable to strong oxidizing agents, it quickly undergoes vapour phase oxidation by passing its vapour mixed with oxygen over V₂O₅ at 773k. The ring breaks to give maleic anhydride.

c) 1, 4 cyclo hexadiene:
Benzene can be reduced to non- conjugated dienes 1, 4 – cyclohexadiene by treatment with Na or Li in a mixture of liquid ammonia and alcohol. It is the convenient method to prepare cyclicdienes.

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Samacheer Kalvi 11th Computer Science Book Back Answers

Unit 1 Fundamentals of Computer and Working with a Typical Operating Systems (Windows & Linux)

• Chapter 1 Introduction to Computers
• Chapter 2 Number Systems (Part 1)
• Chapter 2 Boolean Algebra (Part 2)
• Chapter 3 Computer Organization
• Chapter 4 Theoretical Concepts of Operating System
• Chapter 5 Working with Typical Operating System (Windows & Linux)

Unit 2 Algorithmic Problem Solving

• Chapter 6 Specification and Abstraction
• Chapter 7 Composition and Decomposition
• Chapter 8 Iteration and Recursion

Unit 3 Introduction to C++

• Chapter 9 Introduction to C++
• Chapter 10 Flow of Control
• Chapter 11 Functions
• Chapter 12 Arrays and Structures

Unit 4 Object Oriented Programming with C++

• Chapter 13 Introduction to Object-Oriented Programming Techniques
• Chapter 14 Classes and Objects
• Chapter 15 Polymorphism
• Chapter 16 Inheritance

Unit 5  Computer Ethics and Cyber Security

• Chapter 17 Computer Ethics and Cyber Security
• Chapter 18 Tamil Computing

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Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Zoology Guide Pdf Chapter 11 Chemical Coordination and Integration Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Zoology Guide Chapter Chapter 11 Chemical Coordination and Integration

11th Bio Zoology Guide Chemical Coordination and Integration Text Book Back Questions and Answers

Part I

Question 1.
The maintenance of a constant internal environment is referred as
a) Regulation
b) homeostasis
c) Co-ordination
d) hormonal control
Answer:
b) homeostasis

Question 2.
Which of the following are exclusive endocrine glands?
a) Thymus and testis
b) adrenal and ovary
c) parathyroid and adrenal
d) pancreas and parathyroid
Answer:
c) parathyroid and adrenal

Question 3.
Which of the following hormone is not secreted under the influence of the pituitary gland?
a) thyroxine
b) insulin
c) oestrogen
d) glucocorticoids
Answer:
b) insulin

Question 4.
Spermatogenesis in mammalian testes is controlled by
a) Luteinising hormone
b) Follicle-stimulating Hormone
c) FSH and prolactin
d) GH and prolactin
Answer:
b) Follicle-stimulating Hormone

Question 5.
Serum calcium level is regulated by
a) Thyroxine
b) FSH
c) Pancreas
d) Thyroid and parathyroid
Answer:
d) Thyroid and parathyroid

Question 6.
Iodised salt is essential to prevent
a) rickets
b) scurvy
c) goiter
d) acromegaly
Answer:
c) goiter

Question 7.
Which of the following gland is related to immunity?
a) Pineal gland
b) adrenal gland
c) thymus
d) parathyroid gland
Answer:
c) thymus

Question 8.
Which of the following statement about sex hormones is correct?
a) Testosterone is produced by Leydig ceils under the influence of the luteinizing hormone
b) Progesterone is secreted by corpus luteum and softens pelvic ligaments during childbirth
c) Oestrogen is secreted by both sertoli cells and corpus luteum
d) Progesterone produced by corpus luteum is biologically different from the one produced by the placenta.
Answer:
a) Testosterone is produced by Leydig cells under the influence of luteinizing hormone

Question 9.
Hypersecretion of GH in children leads to
a) Cretinism
b) Gigantism
c) Graves disease
d) Tetany
Answer:
b) Gigantism

Question 10.
A pregnant female delivers a baby who suffers from stunted growth, mental retardation, low intelligence quotient, and abnormal skin. This is the result of
a) Low secretion of growth hormone
b) Cancer of the thyroid gland
c) Over secretion of pars distalis
d) Deficiency of iodine in the diet
Answer:
a) Low secretion of growth hormone

Question 11.
The structure which connects the hypothalamus with the anterior lobe of the pituitary gland is the
a) Dendrites of the neurohypophysis
b) Axons of neuro hypophysis
c) Bands of white fibers from the cerebellar region
d) Hypophysial portal system
Answer:
d) Hypophysial portal system

Question 12.
Comment on homeostasis.
Answer:

• Maintenance of constant internal environment of the body by the different co-ordinating system.
• The maintenance of the constant internal environment of the body is due to the functioning of the endocrine system and nervous system.
  Endocrine gland.

1. a) If the calcium level in the blood decreases the parathyroid gland secretes parathyroid hormones and increases the calcium level in the blood.
b) If there is more calcium in the blood the other hormone secreted by the parathyroid gland called calcitonin acts against the parathormone and reduces calcium level.

2. a) The adrenalin secreted by the adrenal gland in emergency increases heartbeat rate and blood pressure.
b) The other hormone secreted by the adrenal is nor-adrenalin which reduces heartbeat rate and blood pressure.

Nervous system:
1. a) The sympathetic nervous system at the time of shock induces tear glands to secrete tears,
b) The parasympathetic nerve at the time of shock and emotion reduces the tear secretion.

Question 13.
Which one of the following statement is correct
a) Calcitonin and thymosin are thyroid hormones
b) Pepsin and prolactin are secreted in the stomach
c) Secretin and rhodopsin are polypeptide hormones
d) Cortisol and aldosterone are steroid hormones
Answer:
d) Cortisol and aldosterone are steroid hormones

Question 14.
Which of the given option shows all wrong statements for thyroid gland Statements?
i) It inhibits the process of RBC formation
ii) It helps in the maintenance of water and electrolytes
iii) It’s more secretion can reduce blood pressure
iv) It stimulates osteoblast
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (i) and (iii)
Answer:
(d) (i) and (iii)

Question 15.
Hormones are known as a chemical messengers. Justify.
Answer:
Hormones are released into the bloodstream and circulated as chemical signals. These act specifically on certain organs or tissues called target organs or tissues. These speed up or slow down or alter the activity of target tissues or organs. Hence they are known as chemical messengers.

Question 16.
Write the role of t-oestrogen in ovulation.
Answer:

• Oestrogen hormones promote the growth of the ovarian follicle
• While the follicles are growing it secretes the hormone oestrogen which in turn promotes the ovum to develop.
• The shedding up of ovum at the Luteal phase takes place by the influence of the Luteinizing hormone.

Question 17.
Comment on Acini of the thyroid gland.
Answer:
The thyroid gland is a bilobed endocrine gland. Each lobe is made up of many lobules. The lobules consist of follicles called acini. Each acinus is lined with glandular, cuboidal, or squamous epithelial cells. The lumen of the acinus is filled with colloid, a thick glycoprotein mixture consisting of thyroglobulin molecules.

Question 18.
Write the causes for diabetes mellitus and diabetes insipidus.
Answer:

• Diabetes emeritus: If the insulin is not secreted sufficiently the liver and muscles are unable to convert the glucose into glycogen. As a result, more glucose enters into the bloodstream raising the blood sugar level leads to diabetes mellitus.
• Diabetes Insipidus: The hormone antidiuretic hormone is secreted by the neurohypophysis, which promotes reabsorption of water and thus reduces the loss of water through urine ADH deficiency induces the production of large amounts of urine leads to diabetes insipidus.

Question 19.
Specify the symptoms of acromegaly.
Answer:
Acromegaly is caused due to excessive secretion of growth hormone in adults. The symptoms of acromegaly are an overgrowth of hand bones, feet bones, jawbones malfunctioning of gonads. enlargement of viscera, tongue, lungs, heart, liver, spleen, and endocrine glands like thyroid, or adrenal glands.

Question 20.
Write the symptoms of cretinism.
Answer:
Decreased secretion of the thyroid (Hypothyroidism) causes cretinism. The cretins show retarded skeletal growth, absence of sexual maturity retarded mental ability thick wrinkled skin, protruded enlarged tongue bloated face, thick and short limbs occurs. The other symptoms are low BMR slow pulse rate, subnormal body temperature, and elevated blood cholesterol level.

Question 21.
Briefly explain the structure of the thyroid gland.
Answer:
The thyroid gland is butterfly-shaped, bilobed situated below the larynx on each side of the upper trachea. The two lobes are connected by a median tissue mass called isthmus. Each lobe is made up of many lobules. The lobules consist of follicles called acini. Each acinus is lined with glandular, cuboidal, or squamous epithelial cells.

The lumen of acini is filled with colloid, a thick glycoprotein mixture consisting of thyroglobulin molecules. The thyroid gland secretes Tri-iodothyronine (T,) and tetra-iodothyronine (T4) or thyroxine hormones. These are concerned with metabolism.

Question 22.
Name the layers of adrenal cortex and mention their secretions.
Answer:

• The adrenal cortex has three layers namely Zona glomerulosa, Zona fasciculate and Zona reticulate. Zona glomerulosa which constitutes 15% of cortex is a thin outer layer secretes minerals corticoids
• Zona fasciculate the middle widest layer constitutes 75% cortex and secretes gluco corticosteroids such as cortisol, corticosterone and small amount of adrenal androgen and oestrogen.
• Zona reticulata an inner layer of adrenal cortex constitute about 19% of cortex and secretes adrenal androgen and small amount of estrogen and glucocorticoids.

Question 23.
Differentiate hyperglycemia from hypoglycemia.
Answer:
Hyper glycemia:
Hyperglycemia is condition in which there is increased blood glucose level, it may be due to the reduced secretion of insulin.

Hypo glycemia:
Hypoglycemia is a condition in which the blood glucose level decreases. It may be due to increased secretion of insulin there by reducing blood glucose level.

Question 24.
Write the functions of (CCK)- Cholecystokinin.
Answer:
CholecystokininCholecystokinin is secreted by duodenum in response to the presence of fat and acid in the diet. It acts on the gall bladder to release bile into duodenum and stimulates the secretion of pancreatic enzymes and its discharge.

Question 25.
Growth hormone is important for normal growth. Justify the statement.
Answer:
Growth hormone promotes growth of all the tissues and metabolic process of the cell. The growth hormone stimulates the growth in the following ways

• It influences the metabolism of carbohydrate proteins and lipids.
• It increases the rate of protein biosynthesis.
• It stimulates cartilage formation of condrogenesis.
• It stimulates bone formation osteogenesis.
• It helps in the retention of minerals like nitrogen, potassium, phosphorous sodium in the body.
• It increases the release of fatty acid from adipose tissue.
• It decreases the rate of glucose utilization for energy by the cell, by which it conserves glucose for glucose dependent tissues such as the brain.

Question 26.
Pineal gland is an endocrine gland, write its role.
Answer:
The pineal gland or epiphysis cerebri or conarium is located behind the third ventricle of brain. It is formed of paranchymal cells and interstitial cells. It secretes the hormone, melatonin.

It plays a central role in the regulation of circadian rhythm of our body and maintains normal sleep-wake cycle. It also regulates the timing of sexual maturation of gonads. It also influences metabolism, pigmentation, menstrual cycle and defence mechanism of our body.

Question 27.
Comment on the functions of adrenalin.
Answer:

• Adrenalin increases liver glycogen breakdown into glucose and increases the release of fatty acids from fat cells.
• During emergency it increases heart beat rate and blood pressure.
• It stimulates the smooth muscles of cutaneous and visceral arteries to decrease blood flow.
• It increases blood flow to the skeletal muscles there by increases the metabolic rate of skeletal muscles cardiac muscles and nervous tissues.

Question 28.
Predict the effects of removal of Pancreas from the human body.
Answer:
Pancreas is both exocrine and endocrine gland. It is located just below the stomach as a leaf like structure. It secretes digestive enzymes and hormones like insulin and glucogon.

The digestive enzymes digest carbohydrates, proteins and fats. Insulin and glucose regulate blood sugar level. If pancreas is removed from the body, digestion and main’taince of blood sugar level gets afftected.

Question 29.
Enumerate the role of kidney as an endocrine gland.
Answer:

• Kidney is a partial endocrine gland. Kidney secretes hormones such as renin, erythropoietin and calcitriol.
• Renin is secreted by Juxta glomerular cells (JG) which increase blood pressure when angiotensin is formed in blood.
• Erythropoietin is also secreted by JGA cells of the kidney and stimulates the formation of RBC in bone marrow known as erythropoiesis.
• Calcitriol is secreated by proximal tubules of nephron, it is an active form of vitamin D3 which promotes calcium and phosphorus absorption from intestine and accelerates bone formation.

Part – II.

11th Bio Zoology Guide Chemical Coordination and Integration Additional Important Questions and Answers

I. Choose The Correct Answer

Question 1.
Where is hormones released ifito?
a) Mouth
b) Blood
c) Digestive system
d) Kidney
Answer:
b) Blood

Question 2.
Find out the endocrine glands from the following.
a) Sebaceous gland
b) Sweat glands
c) Salivary glands
d) Thyroid gland
Answer:
d) Thyroid gland

Question 3.
Which is called as master endocrine glands?
a) Hypothalamus
b) Pituitary gland
c) Thyroid gland
d) Thymus
Answer:
b) Pituitary gland

Question 4.
Where is pituitary situated?
a) On the ethmoid bone
b) On sella turcica
c) On the foramen of Monro
d) On the Rathkes packet
Answer:
b) On sella turcica

Question 5.
The retention of nitrogen is due to this hormone.
a) TSH
b) GH
c) FSH
d) ACTH
Answer:
b) GH

Question 6.
Find out the wrong statement related with growth hormone.
1. a) It stimulates cartilage formation
2. b) It releases the fattyacid from adipose tissue
3. c) It increases the glucose utilization in the cells
4. d) It stimulates the carbohydrate synthesis
Answer:
4. d) It stimulates the carbohydrate synthesis

Question 7.
A male child is born to a parents as he grown if FSH and LH is not properly secreted what happens to the male child.
a) He grows as a normal male child
b) He grows and he shows stunted growth
c) Secondary sexual characters are not developed properly
d) He grows as a mentally depressed male
Answer:
c) Secondary sexual characters are not developed properly

Question 8.
These hormones are collectively known as Gonodotropins?
a) Oxytocin and ADH
b) Oestrogen and Progestron
c) Testosteron and androgens
d) FSH and LH
Answer:
d) FSH and LH

Question 9.
The day and night rhythm is controlled by this hormone.
a) Melonocytes
b) Melanin
c) Melotonin
d) Thyroxine
Answer:
c) Melotonin

Question 10.
Prabhu is working in a MNC Company. He has to do night shift once in every fifteen days.
Aftern a few years he is suffering from sleeplessness (in somnia) What may be the cause of his problem.
a) It may be becauses of his nature of work
b) More work pressure
c) The sleepwake cycle is disturbed due to the irregular synthesis of melotonin hormone
d) Due to the metabolic disturbances
Answer:
c) The sleepwake cycle is disturbed due to the irregular synthesis of melotonin hormone

Question 11.
Name the structure that connects the lobes of thyroid gland?
a) Acinus
b) Ischium
c) Isthmus
d) bridge tissue
Answer:
c) Isthmus

Question 12.
Name the element helps in the synthesis of thyroxine.
a) Iron
b) Calcium
c) Iodine
d) Sodium
Answer:
c) Iodine

Question 13.
Assertion: The Oxyphil cells of parathyroid secrete parathormone
Reason: The chief cells of parathyroid regulates the synthesis of parathormone
a) Assertion and Reason are correct
b) Assertion incorrect and reason is wrong
c) The assertion is true. The reason is false
d) Both the assertion and reason are false.
Answer:
d) Both the assertion and reason are false.

Question 14.
Which of the functional features of hormone is not correctly matched with its description?
a) Thyroid gland hormones often called the major metabolic hormones.
b) Thyro calcitonin increases the blood calcium level
c) The adrenalin is the emergency hormone.
d) The functions of oxyphil cells are not known.
Answer:
b) Thyro calcitonin increases the blood calcium level

Question 15.
Which of the following option shows the with its action matched hormones
(given in column I) (given in column II)

Column I	Column II
A Pituitary	i) Partial endocrine gland
B Thyroid	ii) Secretes steroid hormone oestrogen
C Ovary	iii) Thyroxine regulates basal metabolic rate
D Thymus	iv) Anterior lobe of pituitary originate from Rathke’s pouch

a) A – ii; B – iv; C – i; D – iii
b) A – iv ; B – iii; C – ii; D – i
c) A – iii; B – ii; C – iv; D – i
d) A – iv; B – i; C – iii; D – ii
Answer:
b) A – iv ; B – iii; C – ii; D – i

Question 16.
These are known as supra-renal glands.
a) Thymus gland
b) Pancreas
c) Adrenal gland
d) Ovary
Answer:
c) Adrenal gland

Question 17.
Find out the hormone which are catecholamines.
a) Thyroxine
b) Insulin
c) Adrenalin
d) Glucagon
Answer:
c) Adrenalin

Question 18.
Why there is an accumulation of ketone bodies in blood of diabetic melitus patients?
a) due to the excessive consumption of liquids
b) break down of fat in to glucose
c) conversion of glucose from protein
c) due to excessive in take of food
Answer:
b) break down of fat in to glucose

Question 19.
This hormone promotes the activation of Vitamin D thus by absorbing calcium?
a) Calcitonin
b) Thymosin
c) Parathormone
d) Thyroxine
Answer:
c) Parathormone

Question 20.
Which part of pancreas is act as a exocrine gland?
a) Globules
b) islets of Langerhans
c) Acinus
d) Globlets
Answer:
c) Acinus

Question 21.
Name the cells that secrete somatostatin
a) a cells
b) b cells
c) Lampda cells
d) delta cells
Answer:
d) delta cells

Question 22.
Why is insulin tablet not advisable for chronic diabetic mellitus patients?
a) It takes more time to act
b) The insulin find it difficult to reach the substrate
c) Insulin is easily digested by the digestive enzymes
d) The insulin is not a effective one.
Answer:
c) Insulin is easily digested by the digestive enzymes

Question 23.
This hormone is involved in the cyclic changes of menstruation.
a) Testosterone
b) Pitocin
c) Oestrogen
d) Progesterone
Answer:
c) Oestrogen

Question 24.
Contraction of uterus leads to miscarriages in a pregnant womens.
What would be administered to evacuate the embryo?
a) ADH
b) Vasopressin
c) Androgen
d) Oxytocin
Answer:
d) Oxytocin

Question 25.
In the case of thyrotecdomic patients what is advisable to given along with the thyroxine?
a) Insulin
b) Thyroglobulin
c) Parathormone
d) Adrenalin
Answer:
c) Parathormone

Question 26.
If a doctor finds a high level of atrial natriuretic factor in the blood of a patient what he will suspect?
a) A patient is suffering from in sufficient oxygen supply
b) A patient will have a heart attack due to high blood pressure
c) Suspecting depression problem
d) Many develop thrombosis
Answer:
b) A patient will have a heart attack due to high blood pressure

Question 27.
Name the hormone that stimulates the synthesis of HCl.
a) Enterokinase
b) Pepsinogen
c) Gastrin
d) Secretin
Answer:
c) Gastrin

Question 28.
What is the other name for type I diabetes?
a) Insulin dependent diabetes
b) Non-insulin dependent diabetes
c) Sensitive diabetes
d) Dependent types
Answer:
a) Insulin dependent diabetes

Question 29.
Which is called as second messenger.
a) Receptor cells
b) CAMP
c) Adenylate
d) Substrate
Answer:
b) CAMP

Question 30.
In the following diagram what are the parts A, B, C and D representing?

I) A) Pineal body B) Anterior tube C) Capillary bed D) Infundibulum
II) A) Hypophyseal vein B) Optic chiasma C) Endocrine cells D) Artery
III) A) Infundibuim B) Posterior C) Hypophyseal vein D) Endocrine cells
IV) A) Endocrine cells B) Infundibulum C) Paradisaical D) Pineal body
Answer:
III) A) Infundibuim B) Posterior C) Hypophyseal vein D) Endocrine cells

Question 31.
Find out the true and false statements from the following and on that basis find the correct answer.
i) ADH causes blood vessels to dialate
ii) The ‘c’ cells of thyroid gland secretes calcitonin
iii) Zona fasciculate secretes cortisol
iv) Minerals corticoids regulate water balance
i) a) True b) False c) True
ii) a) False b) True c) False
iii) a) False b) True c) False
iv) a) False b) False c) True
Answer:
iv) a) False b) False c) True

Question 32.
Which part interlinks both the nervous system and endocrine system?
a) Receptor molecules
b) Target tissue
c) Hypothalamus
d) Infundibulum
Answer:
c) Hypothalamus

Question 33.
Which of the following disease is not caused by iodine or thyroxine deficiency?
a) Sporodic goitre
b) Exophthalmic goitre
c) Simple goitre
d) Myxodema
Answer:
a) Sporodic goitre

Question 34.
Which is the correct location of the receptors of the hormones?
a) Extracellular matrix
b) Blood
c) Plasma membrane
d) Nucleus
Answer:
c) Plasma membrane

Question 35.
The primary target of the hormones of hypothalamus is
a) pineal gland
b) thymus
c) testis
d) pituitary
Answer:
d) pituitary

Question 36.
Functionally the adenohypophysis of pituitary gland includes
a) anterior lobe
b) Posterior lobe
c) intermediate lobe
d) both (a) and (c)
Answer:
d) both (a) and (c)

Question 37.
An outgrowth of hypothalamus from the base of the brain develops into
a) pars nervosa
b) pars intermedia
c) pars distalis
d) pars intermedia
Answer:
a) pars nervosa

Question 38.
The hormone secreted by neurohypophysis is
a) ACTH
b) ADH
c) GH
d) TSH
Answer:
b) ADH

Question 39.
Among the following hormones which is the peptide hormone.
a) GH
b) TSH
c) FSH
d) LH
Answer:
a) GH

Question 40.
Among the following which is not a glycoprotein hormone.
a) TSH
b) LTH
c) LH
d) FSH
Answer:
b) LTH

Question 41.
Find out the protein hormone from the following.
a) LTH
b) FSH
c) TSH
d) ACTH
Answer:
a) LTH

Question 42.
Which is the pituitary hormone that is present in other vertebrates?
a) MSH
b) ACTH
c) TSH
d) GH
Answer:
a) MSH

Question 43.
Find out the wrong statement about vasopressin or ADH
a) It promotes re-absorption of water and electrolytes by distal tubules of nephron.
b) Causes constriction of blood vessels
c) It stimulates vigorous contraction of smooth muscles of uterus during child birth
d) It is a peptide hormone
Answer:
c) It stimulates vigorous contraction of smooth muscles of uterus during child birth

Question 44.
The growth hormone releasing hormone stimulates the
a) Thymus to release the hormone
b) Pituitary for synthesis and release of growth hormone
c) Testis to release gonadotropin
d) Adrenal to release growth hormone
Answer:
b) Pituitary for synthesis and release of growth hormone

Question 45.
Posterior pituitary secretion is controlled by
a) hypothalamic hypophyseal portal blood vessel
b) neuro endocrine gland
c) hypophysis
d) hypothalamic hypophyseal axis
Answer:
d) hypothalamic hypophyseal axis

Assertion and Reason:- Directions: In the following questions a statement of Assertion is followed by a statement of reason. Mark the correct choice as;
a) If both Assertion and reason are true and reason is the correct explanation of assertion
b) If both Assertion and reason and true but reason is not the correct explanation of Assertion.
c) If assertion is true but reason is false
d) If both Assertion and reason are false

Question 46.
Assertion: Adrenalin nor-adrenalin, melatonin and thyroid hormones are proteins
Reason: Derived from cholesterol mostly water soluble
Answer:
d) If both Assertion and reason are false

Question 47.
Assertion: Growth hormone stimulates chondrogenesis and osteogenesis
Reason: Growth hormones promote growth of all tissues and metabolic process of the body.
Answer:
a) If both Assertion and reason are true and reason is the correct explanation of assertion

Question 48.
Assertion: Adrenal medulla hormones are referred as 3F hormones fight, flight and hormones.
Reason: During emergency it increases heart beat rate and blood pressure
Answer:
a) If both Assertion and reason are true and reason is the correct explanation of assertion

Question 49.
Assertion: The effects of aldosterone, oestrogen FSH are long lived as they alter the amount of m- RNA and protein in a cell
Reason: The action of cAMP are terminated by phosphodiesterases
Answer:
b) If both Assertion and reason and true but reason is not the correct explanation of Assertion.

Question 50.
Assertion: The immunity of old age people, becomes week and causes sickness.
Reason: Due to degeneration of pineal gland thymosin level decreases
Answer:
c) If assertion is true but reason is false

Question 51.
Assertion: JGA cells of the kidney stimulates erythropoiesis or formation of RBC
Reason: JGA cells also secrete Erythropoietin
Answer:
a) If both Assertion and reason are true and reason is the correct explanation of assertion

Question 52.
Assertion: Diabetes inspidus is marked by production of large amount of urine.
Reason: Hypo secretion of ADH leads to a condition of reduced water absorption. Thus the urine becomes diluted without sugar or glucose
Answer:
a) If both Assertion and reason are true and reason is the correct explanation of assertion

Question 53.
The Luteinizing hormone in males is
a) Testosterone
b) ICSH
c) FSH
d) LTH
Answer:
b) ICSH

Question 54.
The cells that secrete parathyroid hormone is knows as
a) chief cells
b) oxyphil cells
c) goblet
d) both b and c cells
Answer:
a) chief cells

Question 55.
Find out the correct statement about pineal gland.
a) Stimulates the production and release of sperms.
b) Increases blood pressure.
c) It plays a central role and the regulation of circadian rhythm of our body and maintains the normal sleep wake cycle.
d) It is about 1cm in diameter and 0.5gm.
Answer:
c) It plays a central role and the regulation of circadian rhythm of our body and maintains the normal sleep wake cycle.

Question 56.
The BMR is regulated by
a) Parathormone
b) Thyrocalcitonin
c) Adrenalin
d) Thyroxine
Answer:
d) Thyroxine

Question 57.
The primary function of thymus gland is
a) regulation of body temperature
b) regulation of body growth
c) immunological functions
d) Secretion of thyrotropin
Answer:
c) immunological functions

Question 58.
A hormone secreted by adrenal gland and called life-saving hormone is
a) adrenaline
b) cortisone
c) aldosterone
d) Cortisol
Answer:
d) Cortisol

Question 59.
Which of the following condition is not linked to a deficiency of thyroid hormone?
a) cretinism
b) goitre
c) Myxoedema
d) Exophthalmia
Answer:
d) Exophthalmia

Question 60.
Androgens are sex corticoids secreted from
a) Zona reticulate
b) Adrenal medulla
c) Zona glomerulosa
d) Acini
Answer:
a) Zona reticulate

Question 61.
A gland which is well developed in newborn child and produce lymphocytes
a) Thyroid gland
b) Thymus
c) Parathyroid gland
d) Pineal gland
Answer:
b) Thymus

Question 62.
Which one reduces the blood calcium level and shows an opposite effect to parathormone?
a) ADH
b) Insulin
c) Thyrocalcitonin
d) Thyroxine
Answer:
c) Thyrocalcitonin

Question 63.
Secretion of HCl and pepsinogen is controlled by
a) Cholecystokinin
b) Gastrin
c) Calcitriol
d) Renin
Answer:
b) Gastrin

Question 64.
A man has an IQ equivalent to that of a boy 5 years old this is due to the deficiency of which hormone?
a) Thyroxine
b) Adrenaline
c) Aldosterone
d) Somatotropin
Answer:
a) Thyroxine

Question 65.
Which of the following option shows the correct matching of disorder’s and causes.
A) Addison’s disease -(i) Hypo secretion of thyroid
B) Cushing’s syndrome – (ii) Hyper secretion of parathyroid hormone
C) Softening of bone – (iii) Hypo secretion of gluco corticoids
D) Gull’s disease (in adults) – (iv) Excess secretion of cortisol
Codes:
a) A – (ii); B – (i); C – (iii); D – (iv)
b) A – (iii); B – (iv); C – (ii); D – (i)
c) A – (iii); B – (ii); C – (i); D – (iv)
d) A – (iv); B – (iii); C – (iv); D – (ii)
Answer:
b) A – (iii); B – (iv); C – (ii); D – (i)

Question 66.
A person is having problems with calcium and phosphorous metabolism in his body.
Which one of the following glands may not be functioning.
a) Parathyroid
c) Pancreas
b) Parotid
d) Thyroid
Answer:
a) Parathyroid

Question 67.
Presence of fat and acid in the diet induces the secretion of
a) Gastrin
b) Secretion
c) Cholecystokinin
d) Calcitrol
Answer:
c) Cholecystokinin

Question 68.
Which is an amino acid derivative hormone?
a) Epinephrine
c) Progesterone
b) Oestrogen
d) Relaxin
Answer:
a) Epinephrine

Question 69.
Which of the following is a mineralococticoid?
a) Testosterone
b) Cortisol
c) Adrenalin
d) Aldosterone
Answer:
d) Aldosterone

Question 70.
Which hormone increases the rate of protein biosynthesis chondrogenesis and osteogenesis and helps in the retention of minerals?
a) Prolactin
b) Somatotrophic hormone
c) Thyrotropin
d) Glucagon
Answer:
b) Somatotrophic hormone

Question 71.
The male sex hormones are secreted by
a) Zona glomerulosa
b) Fat cells
c) Lay-dig cells
d) Acini
Answer:
c) Lay-dig cells

Question 72.
Which of the following pituitary hormone is secreted without the involvement of a releasing hormone?
a) Thyrotropin
b) Follicle stimulating hormone
c) Oxytocin
d) Prolactin
Answer:
c) Oxytocin

Question 73.
Match the following columns.

Column I	Column II
A Melatonin	1. T-lymphocyte formation
B Thymus	2. Formation of RBC
C Insulin	3. Sleep wake cycle
D Trythropoietin	4. Hypoglycemic hormone

Code:

Answer:
b) A -3,B-1,C-4,D-2

Question 74.
Which hormones can easily pass through the cell membrane and bind to their receptors and alter gene function?
a) Peptide hormones
b) Amino acid derived hormones
c) Neuro hormones
d) Steroid hormones
Answer:
d) Steroid hormones

Question 75.
The hormone which helps to find out conception is
a) FSH
b) Oestrogen
c) HCG
d) LH
Answer:
c) HCG

Question 76.
Gigantism and Acromegaly are due to
a) Hypothyroidism
b) Hyperthyroidism
c) Hypopituitarism
d) Hyper pitituitarism
Answer:
d) Hyper pitituitarism

Question 77.
After performing the functions in the target organs how hormones are inactivated and excreted?
a) By intestine
b) By lungs and skin
c) By liver and Kidney
d) Both a and b
Answer:
c) By liver and Kidney

Question 78.
The half life period of insulin is
a) 6 minutes
b) 8 minutes
c) 15 minutes
d) 7 minutes
Answer:
a) 6 minutes

Question 79.
The time taken by insulin to be cleared from circulation is
a) 10 -20 minutes
b) 10-15 minutes
c) 5 – 10 minutes
d) 2-10 minutes
Answer:
b) 10-15 minutes

(2 Marks)

II. Very Short Answer.

Question 1.
What is the causes of bone cyst formation?
Answer:
Hyper para thyrodism causes demineralisation of bone causes bone cyst makes the bone fragile and soft.

Question 2.
Why is the hypothalamus considered a neuroendocrine gland?
Answer:
The hypothalamus alone with its neural function produces hormones. Hence it is considered a neuroendocrine gland.

Question 3.
What is the meaning of the word hormone?
Answer:
Hormone means to excite.

Question 4.
Write on the origin of the pituitary gland?
Answer:
The anterior lobe of the pituitary gland originates from the embryonic invagination of the pharyngeal epithelium called Rathke’s pouch. The posterior lobe originates from the base of the brain as an outgrowth of the hypothalamus.

Question 5.
What is meant by Homeostasis?
Answer:
Maintenance of constant internal environment of the body by the different co-ordinating system is homeostasis.

Question 6.
What is Pars nervosa?
Answer:
The neurohypophysis of the pituitary gland is known as pars nervosa.

Question 7.
Give example for partial endocrine glands.
Answer:
Pancreas, gastrointestinal tract epithelium kidney, heart gonads and placenta.

Question 8.
Write a paragraph on the Growth Hormone?
Answer:
Growth hormone (GH):
It is also known as somatotropic hormone (STH) or Somatotropin. It is a peptide hormone Growth hormone promotes the growth of all the tissues and metabolic processes of the body. It influences the metabolism of carbohydrates, proteins, and lipids and increases the rate of protein biosynthesis in the cells.

It stimulates chondrogenesis (cartilage formation), osteogenesis (bone formation) and helps in the retention of minerals like nitrogen, potassium, phosphorus, sodium, etc., in the body. GH increases the release of fatty acid from adipose tissue and decreases the rate of glucose utilization for energy by the cells. Thus it conserves glucose for glucose-dependent tissues, such as the brain.

Question 9.
Name the hormone of peptide nature?
Answer:
Insulin, glucagon and pituitary hormone which are water soluble.

Question 10.
What are steroid hormones.
Answer:
They are derived from cholesterol and are lipid soluble.
Ex. Cortisol aldosterone testosterone oestrogen progesterone.

Question 11.
What is the role of Follicle stimulating hormone in man?
Answer:
In male FSH acts on the germinal epithelium of semi niferous tubules and stimulates the production and release of sperms.

Question 12.
What is the function of LH in female?
Answer:
LH induces ovulation maintains the corpus luteum and promotes the synthesis and release of ovarian hormones.

Question 13.
Why there is a short life span for hormone-like insulin?
Answer:
Insulin hormone is usually short lived as it has to work through second messenger (cAMP) system.

Question 14.
Why the hormones steroid may be long-lived?
Answer:
The effect of steroid hormones are long lived as they alter the amount of mRNA and protein in a cell.
Ex. Aldosterone oestrogen FSH.

Question 15.
How do the hormones reach and act on the specific target organs?
Answer:

• The hormones are released into the blood and circulated as chemical signals
• The target organs contain receptor molecules either on the surface or within the cell.
• The cells that contain the receptor molecules specific for the hormone are physiologically activated.
• Where as other hormones that come in contact can not be activated.

Question 16.
Name the three zones which are present in the Adrenal gland.
Answer:

1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis

Question 17.
Differentiate amines and steroid hormones
Answer:

Amines	Steroids
A. Small water soluble	1. Mostly lipid soluble
B. Derived from tyrosine or tryptophan	2. Derived from Cholesterol
C. Examples are Adrenalin Nor adrenalin, Melatonin and thyroid hormone	3. Examples are cortisol, aldosterone, testosterone, oestrogen and progesterone

Question 18.
Differentiate exocrine glands from endocrine glands.
Answer:

Exocrine glands	Endocrine glands
1. They have ducts to carry their substances to the membrane surfaces	1. These lack ducts and so release their hormone to the surrounding tissue fluid
2. They secrete enzymes, saliva and sweat	2. Their secretions are collectively termed as hormones.
3. Eg. Salivary gland, Sweat gland and Gastric glands	3. Eg. Pituitary, Thyroid Pineal, Adrenal Parathyroid

Question 19.
How endocrine glands be classified based on their secretary function?
Answer:

• Exclusive endocrine glands, e.g. Pituitary thyroid, Parathyroid, Pineal, Adrenal
• Neuro endocrine gland – Hypothalamus
• Partial endocrine glands, e.g. Pancreas, gastro intestinal tract epithelium, kidney, heart gonads and placenta – have endocrine tissues.

Question 20.
Pituitary gland is known as master endocrine glands. Justify the statement.
Answer:

• Pituitary gland is known as master endocrine gland, but it is in turn controlled by the hypothalamus and so the statement may not be totally applicable.
• The hypothalamus with its neuro secretary cells produces neuro transmitters which regulate the secretions of the pituitary.

Question 21.
Write about the location and dimension of pituitary gland.
Answer:

• The pituitary gland is located in the bony cavity of the sphenoid bone the sella tursica at the base of brain so is also called hypothalamus cerebri
• it is about one centimeter in diameter and 0.5gm in weight.

Question 22.
What is infundibulum?
Answer:
The pituitary gland is connected to the hypothalamic region of the brain by a stalk called infundibulum.

Question 23.
What is Rathke’s pouch?
Answer:
The anterior lobe of pituitary originates the embryonic invagination of pharyngeal epithelium called Rathke’s pouch.

Question 24.
Comment on MSH or Melanocyte stimulating hormone.
Answer:

• In mammals role of Pass intermedia is insignificant.
• In other vertebrates pass intermedia secretes melanocyte stimulating hormone or MSH.
• It induces pigmentation in the skin.

Question 25.
What are the functions of pineal gland?
Answer:
In human, the pineal gland or epiphysis cerebri or conarium is located behind the third ventricle of brain and is formed of parenchymal cells and interstitial cells.

It secretes the hormone, melatonin, which plays a central role in the regulation of circadian rhythm of our body and maintains the normal sleep-wake cycle. It also regulates the timing of sexual maturation of gonads. In addition, melatonin also influences metabolism, pigmentation, menstrual cycle and defence mechanism of our body.

Question 26.
What are the other names of Luteotropic hormone?
Answer:

1. Luteotropin
2. Lactogenic hormone
3. Proloctein
4. Mammotropin

Question 27.
Name the hormones that their secretions are regulated by negative feed back mechanisms?
Answer:

• Thyroid stimulating hormone TSH or Thyrotropin
• Adreno corticotropic hormone or ACTH

Question 28.
Give the meanings of the word pituitary oxytocin and Hormone?
Answer:

1. Pituitary means “to grow under”.
2. Oxytocin means “quick birth”.
3. Hormone means “to excite”.

Question 29.
Mention the importance of Luteotropic hormone in females?
Answer:
It stimulates milk secretion after the child birth.

Question 30.
Why prolactin is called luteotropic hormone?
Answer:

• High prolactin secretion during lactation
• Since it induces the corpus luteum hence named as luteotropic hormone.

Question 31.
Point out the role of oxytocin in females?
Answer:

• It stimulates vigorous contraction of the smooth muscles of uterus during child birth.
• Ejection of milk from the mammary glands after child birth.

Question 32.
Name the hormones that play a key role in milk secretion?
Answer:

• Prolactin or lactogenic hormone or mammotropin or luteotropic hormone.
• Oxytocin.

Question 33.
Name the hormone of pituitary that act on bloodvessels?
Answer:
The vasopressin causes constriction of blood vessels when released in large amount and in-creases blood pressure.

Question 34.
Which gland is located behind the third ventricle of brain?
Answer:
The pineal gland or epiphysis cerebri or conarium.

Question 35.
Which is the largest endocrine in the body and where it is located?
Answer:

• The thyroid gland is the largest gland.
• It is a bibbed gland located below the larynx on each side of upper trachea.

Question 36.
Name the hormones secreted by thyroid gland.
Answer:

• Tri-iodo thyronine or T3
• Tetra-iodo thyromne or T4 or Thyroxine
• Thyrocalcitonin

Question 37.
What are parafollicular cells or ‘C’ cells?
Answer:

• These are the cells in the thyroid gland.
• These cells secrete a hormone called thyrocalcitonin.

Question 38.
What element is important for synthesis of thyroid hormones? In what quantity it is essential?
Answer:

• Iodine is essential for the normal synthesis of thyroid hormones.
• About 1m. a week of Iodine is required.

Question 39.
Mention the normal glucose level in prepandial and postpandial test for glucose?
Answer:

1. Prepandial- 70-100 mg/dl (Fasting)
2. Post pandial (About 2 hours after food) – 110 – 140mg/ dl.

Question 40.
Is it advisable to take alcohol frequently? What ill effects does it cause over the body?
Answer:

• Alcohol consumption has widespread effect on endocrine system.
• It impairs the regulation of blood glucose level.
• More over it reduces the testosterone level
• Increases the risk of osteoporosis.

Question 41.
What is the injection administered to diabetic patients? Why is it given as injection and not as oral pills?
Answer:

• Humiline-N is administered to diabetic patients.
• Human insulin is administered as injection and not by oral consumption.
• The reason is if it is administered by oral consumption it may be digested by digestive enzymes.

Question 42.
What is sporadic goiter?
Answer:

• It is a genetic disease
• It is not caused by iodine or thyroxine deficiency.

Question 43.
Why laughing is good for health?
Answer:
It reduces the secretion of stress hormone, adrenalin and makes us to relax.

Question 44.
Define circadian rhythm.
Answer:
It is the 24-hour cycle of biological activities associated with natural periods of light and darkness.
Eg. Sleep wake cycle, body temperature, appetite etc.

(3 Marks)

III. Short Answer

Question 1.
What is simple goiter? What are its symptoms?
Answer:

• Simple goitre is otherwise known as endemic goitre.
• It is due to the hypo secretion of thyroxine.
• The symptoms are Enlargement of thyroid gland, Fall in serum thyroxine level, Increased TSH secretion.

Question 2.
What is tetany?
Answer:

• The hyposecretion of parathyroid hormones leads to a decrease in calcium level and increase in phosphate level, it causes.
• convulsion in muscle, locking of jaws, increased heart beat rate increased body temperature muscular spasm lead to tetany.

Question 3.
What is cushing’s syndrome? What are its symptoms?
Answer:
The excess secretion of cortisol causes cushing’s syndrome. The symptoms are obesity of the face and trunk.

1. Redness of face hand and feet.
2. Thick skin.
3. Excessive hair growth
4. Loss of mineral from bone
5. Systolic hypertension

Question 4.
What is the cause of dwarfism?
Answer:
It is due to the hypo-secretion of growth hormone in children in which skeletal growth and sexual maturity is arrested. They attain a maximum height of 4 feet only.

Question 5.
What is Gigantism?
Answer:

• Due to the hyper-secretion of growth hormone in children there is a over growth of skeletal
• structure may occur up to 8 feet height. The visceral growth is not appropriate with that of limbs.

Question 6.
You are walking on the road, suddenly a man with a knife in his hand comes in front of you. What would be your reaction?
Answer:
I will get bimple goose due to the Surge of vasodielation on the arector pili muscle and though, i am very much frightened, i will fight with that man. i will get that energy by the action of the hormone adrenalin.

Question 7.
Why oxytocin is considered as quick or rapid birth?
Answer:
Oxytocin stimulates the contraction of the smooth muscles of uterus during child birth which helps in the expulsion of foetus, hence it is called as quick birth.

Question 8.
Why thymus is considered as a lymphoid organ?
Answer:
Thy lymphocytes that comes to thymus is educated to become immuno competent T lymphocytes and provides cell mediated immunity. Hence thymus is a lymphoid organ.

Question 9.
Why is gluco corticoids considered in the life saving activity?
Answer:
During the period of emergency the gluco corticoids stimulate the synthesis of glucose from lipid and protein by lipolysis and proteolysis and releases energy to meet that emergency situation.

Question 10.
Why cortisol works as a stress combat hormone?
Answer:

• Cortisone involved in maintaining cardio vascular and kidney functions. It produces anti inflammatory reactions and suppresses the immune response, it stimulates the RBC production.
• Hence it is known as stress combat hormone.

Question 11.
How do the hormones act in the target tissue?
Answer:

• The hormones are released into the blood and circulated as chemical signals and act on specific target organs.
• Hormones may speed up or slow down or alter the activity of the target organs.
• The hormones secreted do not remain permanently in the blood.
• They are converted by the liver into inactive compound and excreted by kidneys.

Question 12.
What is a limbic system?
Answer:

• It is a collection of special structures located in the middle of the brain.
• It is also known as paleo mammalian brain.
• It controls emotions, behavior, motivation of long term memory and olfaction.

Question 13.
What are exocrine glands? Give examples
Answer:

• The exocrine glands have ducts to carry their secretion to the membrane surfaces.
• They secrete enzymes, saliva arid sweat.
• Examples are salivary gland, gastric gland.

Question 14.
Write down the functions of hypothalamus.
Answer:

1. Hypothalamic hormones control anterior pituitary secretion through hypothalamic hypophyseal portal blood vessel.
2. The nerve signal produced by the hypothalamic hypophyseal axis control the posterior pituitary secretion.
3. Hypothalamus maintains homeostasis.
4. Blood pressure
5. Body temperature.
6. Cardio and fluid electrolyte balance of the
7. As the part of limbic system it influences various emotional responses.

Question 15.
Draw the diagram of the hypothalamus and pituitary gland and label the following parts.
Answer:
A. Anterior lobe
B. Posterior lobe
C. Hypothalamus
D. Interior Hypophyseal artery
E. Endocrine cells
F. Hypophyseal vein

Question 16.
Draw the diagram of thyroid gland and label the following parts
Answer:
A Thyroid cartilage
B. Thyroid gland
C. Trachea
D.Isthumus

Question 17.
Draw the diagram of thyroid gland and label the following parts
A. Capsule
B. Cortex
C. Medulla
D. Blood Vessels

Question 18.
Explain the role of leuteinizing hormone (LH) in male and females.
Answer:

• It is a glycoprotein hormone
• It is also known as Interstitial cell stimulating hormone (ICSH) in males.
• The ICSH hormones acts on the interstitial cells of testis to produce the male sex hormone testosterone.
• In females along with FSH matures the ovarian follicles.
• LH independently induces ovulation, maintains the corpus luteum and promotes synthesis and release of ovarian.
• FSH and LH secretion starts only during pre pubertal period.
• FSH and LH are collectively referred as gonadotropins.

Question 19.
Compare the structural difference of vasopressin and oxytocin. Vasopressin Oxytocin
Answer:

Exocrine glands	Endocrine glands
1. Composed of a amino acids	1. Composed of a amino acids
2. Amino acid sequence is cysteine – tyrosine – Phenyl alanine – glutamine arspargine – cysteine – proline – argirune – glycine.	2. Amino acid sequence is – cysteine – tyrosine – Isoleucine – Glutamine – aspargine – cysteine – proline – leucine – glycine.

Question 20.
How does the posterior lobe of the pituitary help in osmoregulation?
Answer:

• ADH is a peptide hormone
• It promotes absorption of water and electrolytes by distal tubules of nephron and there by reduces loss of water through urine.
• Hence it is called as anti diuretic hormone.
• ADH deficiency causes Diabetes insipidus which induces the production of large amount of urine.
• This is how it helps in osmoregulation.
• ADH when released in large amount causes constriction of blood vessels and increases blood pressure.

Question 21.
Explain the role of melatonin in our body.
Answer:

• It is secreted by pineal gland.
• It plays a central role in the regulation of circadium rhythm of our body
• Maintains the normal sleep wake cycle.
• It also regulates the timing of sexual maturation of gonads.
• In addition it also influences metabolism, pigmentation, menstrual cycle and defence mechanism of our body.

Question 22.
List out the role of thyroxine or tetra iodo thyronine (T4) in our body.
Answer:

• It regulates the Basal Metabolic Rate (BMR) and body heat production.
• It stimulates protein synthesis and promotes growth
• It is essential for the development of skeletal and nervous system.
• It plays an important role in maintaining blood pressure
• It reduces serum cholesterol levels.
• Optimum levels of thyroxine in the blood are necessary for gonadial functions.

Question 23.
Which hormone is called hypercalcemic hormone? Explain its role.
Answer:

• The parathyroid hormone (PTH) is the hypercalcemic hormone.
• It is a peptide hormone.
• It involves in controlling the calcium and phosphate homeostasis.
• The secretes or PTH is controlled by calcium level in the blood.
• It increases the blood calcium level by stimulating osteoclasts to dissolve the bone matrix.
• As a result calcium and phosphate are released into the blood.
• PTH enhances the re-absorption of calcium and exertion of phosphates by the renal tubules.
• It promotes activation of vitamin D to increase calcium absorption by intestinal mucosal cells.

Question 24.
Explain the role of heart as a partial endocrine gland.
Answer:
1. In the heart, cardiocytes on the atrial walls secretes an important peptide hormone called Atrial Natriuretic Factor (ANF)
2. When blood pressure is increased ANF is secreted and causes dilation of the blood vessels to reduce the blood pressure.

Question 25.
Is it good to take synthetic soft drinks? Why?
Answer:

• It is not good to take synthetic soft drinks.
• The branded soft drinks damage our endocrine system.
• While consuming soft drinks the sugar level increases in blood. Which leads to elevated insulin secretion
  to reduce the blood glucose level.
• The elevated insulin level diminishes immunity.
• It causes obesity, cardio-vascular disorders etc.

Question 26.
The doctors avoid prescribing steroid tablets most often. Why?
Answer:
The abuse of steroids can cause serious health problems such as.

• HighB.P.
• Heart diseases.
• Liver damage
• Cancer
• Stroke
• Blood clotsa

Side effects such as

1. Nausea
2. V omiting
3. Ligament and tendon injuries
4. Head ache
5. JointPain
6. Muscle cramps
7. Diarrhoea
8. Sleep problem

Question 27.
if para-thyroid gland shows hyper-secretion. What will be the symptoms of this disorder?
Answer:

• The excess secretion of parathyroid gland is known as hyperparathyroidism
• Symptoms are Demineralisation of bone.
• Cyst formation
• Softening of bone
• Loss of muscletone
• General weakness
• Renal disorders.

Question 28.
Differentiate Glycogenolysis from gluconeogenesis.
Answer:

• Glycogenolysis is breakdown of glycogen to glucose
• This process is carried out in the liver by the Glucagon hormone.
• Glucagon thus releases glucose from the liver cells increasing Gluconeogenesis.
• it is the synthesis of glucose from lactic acid and from non-carbohvdrate molecules is called Gluconeogenesis. this increases the blood glucose levels.

Question 29.
Mention the symptoms of diabetes mellitus.
Answer:

• Poly urea – Excessive urination
• Polyphagia – Excessive intake of food
• Polydipsia – Excessive consumption of liquids due to thirst.
• Ketosis – Breakdown of fat into glucose results in accumulation of ketone bodies.

Question 30.
Give a short account on hypothalamus.
Answer:

• Hypothalamus is a small cone shaped structure that projects downward from the brain ending into the pituitary stalk.
• It interlinks both the nervous system and endocrine system.
• Pituitary gland is controlled by the hypothalamus.
• It produces neuro transmitters which act either as a releasing hormone or as an inhibitory hormone.
• Hypothalamus contains groups of neuro secretory cells which produces neuro transmitters which regulate the secretions of the pituitary gland.

Question 31.
Comment on pineal gland.
Answer:

• It is located behind the third ventricle of brain.
• In human it is called epiphysis cerebri conarium.
• It is formed of parenchymal cells and interstitial cells.
• It secretes the hormone melatonin.
• It plays a central role in the regulation of circadian rhythm of our body and maintains the normal sleep wake cycle.

Question 32.
Write down the functions of thyrocalcitonin.
Answer:

1. It is a polypeptide hormone.
2. It regulates the blood calcium and phosphate levels.
3. It reduces the blood calcium level and oppose the effects of parathyroid hormone.

Question 33.
Give a brief account on parathyroid gland.
Answer:

• In man, four tiny parathyroid glands are found in the posterior wall of the thyroid glands.
• It composed of two types of cells. The chief cells and oxyphil cells.
• The chief cells secrete parathyroid hormone.
• The functions of oxyphil cells are not known.

Question 34.
Write short notes on thymus gland.
Answer:

• Thymus gland is partially an endocrine and partially a lymphoid gland.
• It is a bi-lobed structure located just above the heart and aorta behind the sternum.
• It is covered by a fibrous capsule.
• Anatomically it is divisible into an outer cortex and an inner medulla.
• It secretes four hormones such as thymulin, thymosin, thymopoietin and thymic humoral factor (THF).
• The primary function is the production of immuno competent T lymphocytes which provides cell mediated immunity.

Question 35.
Write about Acromegaly.
Answer:
Acromegaly is due to excessive secretion of growth hormone in adults.
Symptoms:-

• Over growth of hand bones, feet bones, jaw bones
• Malfunctioning of gonads
• Enlargement of viscera, tongue, lungs, heart, liver, spleen and endocrine gland like thyroid adrenal.

Question 36.
What is hyperparathyroidism? Write down its symptoms.
Answer:
1. Hyperparathyroidism is caused due to excess parathyroid hormone in blood.
Symptoms:-

• Demineralisation of bones
• Cyst formation, softening of bone.
• Loss of muscle tone
• General weakness
• Renal disorders.

Question 37.
Comment on Addison’s disease.
Answer:
Addison’s disease is caused due to hyposecretion of glucocorticoids and mineralocorticoids from the adrenal cortex.
Symptoms:-

• Muscular weakness, Low BP
• Loss of appetite, vomiting
• Hyper pigmentation of the skin
• Low metabolic rate, subnormal temperature.
• Weight loss reduced blood volume.
• Low aldosterone level increases urinary excretion of NaCl and water and decreases potassium excretion leading to dehydration.

Question 38.
Give reasons for Diabetes insipidus and point out its symptoms.
Answer:
Diabetes insipidus is caused due to hypo secretion of vasopressin.
Symptoms:-

• Polyurea-frequent urination
• Polydipsia – excessive consumption of liquids due to thirst.

Question 39.
Define BMR.
Answer:
The amount of energy needed to keep the body at rest.

Question 40.
Write down the general function of adrenalin hormone and its nature of secretion?
Answer:
Function:- The general function of nor adrenalin is to mobilize the brain and body for action. Nature of secretion: Its secretion is less during sleep, more during wakefulness and reaches much higher levels during stress situations. This response is known as ‘fight or flight’ response.

Question 41.
Old age people are sick often why?
Answer:
Due to degeneration of thymus gland, thymosin level decreases as a result the immunity of old age people becomes weak and causes sickness.

Question 42.
What is the role of pass intermedia in mammals and in other vertebrates?
Answer:

• In mammals the role of pass intermedia is insignificant.
• In other vertebrates it secretes melanocyte stimulating hormone (MSH)
• It induces pigmentation in skin.

(5 Marks)

IV. Brief Answers

Question 1.
Describe the mechanism of peptide hormone action with a diagram.
Answer:

• Peptide hormones cannot cross the phospholipid cell membrane and bind to the receptors on the exterior cell surface.
• They are transported to the golgi which is the site of modification.
• It acts as a first messenger in the cell.
• Hormones generate a second messenger like cyclic AMP (cAMP) that regulates cellular metabolism. This cAMP is catalyzed by the adenylate cyclase ezyme.
• The interaction between the hormone surface and the effect of cAMP within the cell is known as a signaling cascade. There may be amplication at each step.
• One hormone molecule may bind to multiple receptor molecules before it is degraded.
• Each receptor activates to form more cAMP and produces more signals.

Question 2.
Describe the mechanism of action of steroid hormone.
Answer:

• Steroid hormones can easily cross the cell membrane and bind their receptors which may be intracellular or intercellular.
• Then they pair up with another receptor and form a receptor-hormone complex. This can bind to DNA and alter its transcription.
• As it changes the mRNA and protein the effect will be with stand for a long time. Eg. Estrogen

Question 3.
What is typical about Addison’s disease.
Answer:

• There is a hyper pigmentation of the skin. It is caused due to hypo secretion of glucocorticoids from the adrenal cortex.
• Muscular weakness low BP, loss of appetite vomiting, low metabolic rate subnormal temperature reduced blood volume and weight are the other symptoms of Addison’s disease.

Question 4.
What is the cause of cretinism? What are the symptoms?
Answer:

• Hypothyroidism is the cause of cretinism in infants. There is a retarded skeletal growth absence of sexual maturity, retarded mental ability, thick wrinkled skin protruded enlarged tongue bloated face thick and short limbs.
• There is low BMR, slow pulse rate subnormal body temperature and elevated blood cholesterol levels.

Question 5.
What are the hormones responsible for maintaining blood glucose levels?
Answer:
Insulin and glucagon are the hormones secreted by Islets of Langerhans of the pancreas:-
Insulin:
Insulin is a peptide hormone and plays an important role in glucose homeostasis. Its main effect is to lower blood glucose levels by increasing the uptake of glucose into the body cells, especially muscle and fat cells. Insulin also inhibits the breakdown of glycogen to glucose, the conversion of amino acids or fats to glucose, so insulin is rightly called a hypoglycemic hormone.

Glucagon:
Glucagon is a polypeptide hormone. It is a potent hyperglycaemic hormone that acts on the liver and promotes the breakdown of glycogen to glucose (Glycogenolysis), synthesis of glucose from lactic acid and from non-carbohydrate molecules (gluconeogenesis).

Releases glucose from the liver cells, increasing the blood glucose levels. Since glucagon reduces the cellular uptake and utilisation of glucose it is called a hyperglycemic hormone. Prolonged hyperglycemia leads to the disorder called diabetes mellitus.

Question 6.
What is an exophthalmic goiter? What are its symptoms?
Answer:
This disease is caused due to hyper secretion of the thyroid.
Symptoms:

• Enlargement of the thyroid gland
• Increased BMR.
• Elevated respiratory and excretory rates
• Increased heart beat
• High blood pressure
• Increased body temperature
• Protection of eye ball (Exophthalmic)
• The weakness of eye muscles
• Weight loss.

Question 7.
What is meant by negative feedback mechanism? Explain with an example.
Answer:
When the thyroxine level in the blood decreases it is sensed by the hypothalamus to release the thyroid releasing factor that induces the pituitary to secrete thyroid stimulating hormone that stimulates the thyroid to release thyroxine – when the thyroxine level in the blood increases TTH acts on both the pituitary and hypothalamus to inhibit TSH secretion. This is meant by negative feedback mechanism.

Question 8.
Why parathormone is considered as a hypercalcemic hormone.
Answer:

• It increases the blood calcium level by stimulating osteo clasts to dissolve the bone matrix.
• It enhances the reabsorption of calcium and also increases calcium adsorption by intestinal mucosal cells.
• By all these action it increases the blood calcium level. Hence it is known as hypercalcemic hormone.

Question 9.
Write on Hyperthyroidism and Hypothyroidism?
Answer:
In infants, hypothyroidism causes cretinism. A cretin shows retarded skeletal growth, absence of sexual maturity, retarded mental ability, thick wrinkled skin, protruded enlarged tongue, bloated face, thick and short limbs occurs. The other symptoms are low BMR, slow pulse rate, subnormal body temperature and elevated blood cholesterol level.

Hyposecretion of the thyroid in adults causes myxoedema. It is otherwise called Gull’s disease. This disease is characterised by decreased mental activity, memory loss, slowness of movement, speech, and general weakness of body, dry coarse skin, scarce hair, puffy appearance, disturbed sexual function, low BMR, poor appetite, and subnormal body temperature.

Grave’s disease also called thyrotoxicosis or exophthalmic goiter. This disease is caused due to hypersecretion of the thyroid. It is characterised by enlargement of the thyroid gland, increases BMR (50% -100%), elevated respiratory and excretory rates, increased heartbeat, high BP, increases body temperature, protrusion of eyeball, and weakness of eye muscles and weight loss.

Simple goitre is also known as Endemic goitre. It is caused due to hyposecretion of thyroxine. The symptoms include enlargement of thyroid gland, fall in serum thyroxine level, increases TSH secretion.

Question 10.
Give an account of the actions of insulin.
Answer:

• Insulin lowers the blood glucose level by increasing the uptake of glucose into the body cells.
• It inhibits the conversion of amino acids or fat to glucose.
• Insulin is called a hypoglycemic hormone.

Question 11.
Write on the disorders associated with parathryroid gland?
Answer:
Tetany is caused due to the hyposecretion of parathyroid hormone (PTH). Due to hyposecretion of PTH serum calcium level decreases (Hypocalcemia), as a result serum phosphate level increases. Calcium and phosphate excretion level decreses. Generalized convulsion, locking of jaws increased heart beat rate, increases body temperature, muscular spasm are the major symptoms of tetany. Hyperparathyroidism is caused due to excess PTH in blood. Demineralisation of bone, loss of muscle tone, general weakness, renal disorders are the symptoms of hyperparathyroidism.

Question 12.
a) What are the systems that regulate and co-ordinate the physiological functions of our body?
b) Give the meaning of the word “Hormone”.
c) What are the general characters of hormone?
Answer:
a) The systems that regulate and co-ordinate the physiological functions of our body are

• Nervous or neural system
• Endocrine system

b) The meaning of the word “Hormone”is “to excite”
c) General characters of hormones:

• The endocrine system influences the metabolic activities through the hormones
• These are chemical messengers released in to the blood and acts specifically on certain target organs or target tissues.
• Hormones may speed up or slow down or alter the activity of the target organs.
• Hormones secreted do not remain permanently in the blood.
• After their function they are converted by the liver into inactive compounds and excreted by the kidneys.

Question 13.
Write a paragraph on different types of diabetes mellitus?
Answer:
Hyperglycaemia is otherwise known as Diabetes mellitus. Is caused due to reduced secretion of insulin. As the result, the blood glucose level is elevated. Diabetes mellitus is of two types, Type! Diabetes and Type II Diabetes. Type I diabetes is also known as Insulin-dependent diabetes, caused by the lack of insulin secretion due to illness or viral infections. Type II diabetes is also known as Non-Insulin dependent diabetes, caused due to reduced sensitivity to insulin, often called insulin resistance.

Symptoms of diabetes include polyuria (excessive urination), polyphagia (excessive intake of food), polydipsia (excessive consumption of liquids due to thirst), ketosis (the breakdown of fat into glucose results in accumulation of ketone bodies) in blood. Gluconeogenesis (Conversion of non-carbohydrate) also occurs in diabetes.

Question 14.
Give a diagrammatic sketch of the glandular system.
Answer:

Question 15.
Tabulate the major hypothalamic hormones and their functions.
Answer:

Hormones	Functions
1. Thyrotropin-releasing hormone (TRH)	Stimulates the secretion of TSH
2. Gonadotropin-releasing hormone(GnJRH)	Stimulates the secretion of FSH
3. Corticotropin-releasing hormone (CRH)	Stimulates the secretion of ACTH
4. Growth hormone-releasing hormone (GHRH)	Stimulates the secretion of GH
5. Prolactin releasing hormone (PRH)	Stimulates the secretion of Prolactin
6. Luteinizing hormone-releasing hormone (LHRH)	Stimulates the secretion of LH
7. MSH releasing hormone	Stimulates the secretion of MSH
8.Growth hormone-inhibiting hormone(GHIH)	Inhibits the secretion of GH
9. Prolactin inhibiting hormone (PIEI)	Inhibits the secretion of Prolactin
10. MSH inhibiting hormone	Inhibits the secretion of MSH

Question 16.
Discuss the role of the hypothalamus and pituitary as a coordinated unit in maintaining the physiological process.
Answer:

• Hypothalamus is a small cone-shaped structure that projects downward from the brain ending into the pituitary stalk.
• It interlinks both the nervous system and endocrine system.
• Hypothalamus contains a group of neuro secretary cells and it produces neuro transmitters which regulate the secretions of the pituitary.
• The hormones produced by the hypothalamus act either as a releasing hormone or as an inhibitory hormone.
• Though the pituitary gland is known as the master endocrine glands really it is in turn controlled by the hypothalamus.
• The hypothalamus and pituitary gland are anatomically different they are interlinked and functioning as a co-ordinated unit in maintaining the physiological process. They can not functions as a separated unit.
• The hypothalamic hypophyseal portal blood vessel allows hypothalamic hormones to control the anterior pituitary.
• The nerve signal produced by the hypothalamic hypophyseal axis (nerve bundle) controls the posterior pituitary secretion.
• Hypothalamus maintains homeostasis.
• Maintains blood pressure, body temperature cardio, and fluid-electrolyte balance of the body it influences emotional responses.
• The pituitary gland through its hormones performs various functions.

Question 17.
Give the classification of hormones based on their chemical nature?
Answer:

Class	Chemical properties	Example
Amines	Small, water-soluble derived from tyrosine or tryptophan	Adrenalin, nor adrenalin, melatonin, and thyroid hormone
Protein/ Peptides	Water-soluble	Insulin, glucagon, and pituitary hormones
Steroids	Derived from cholesterol mostly lipid-soluble	Cortisol, aldosterone, testosterone, oestrogen, progesterone.

Question 18.
Explain the structure of Testis?
Answer:

• A pair of the testis is present in the scrotal sac of males.
• The testis functions as a sex organ and also as an endocrine gland.
• Testis composed of seminiferous tubules and Ley dig cells.
• Lay dig cells secrete several male sex hormones collectively called Androgens.
• The main male sex hormone is Testosterone.

Functions of Testosterone:

1. Under the influence of FSH and LH, testosterone initiates the maturation of the male reproductive organ.
2. The appearance of secondary sexual characters. Eg. Muscular growth, growth of facial and axillary hair, masculine voice, and male sexual behaviour.
3. It enhances the total bone matrix and stimulating the process of spermatogenesis.

Question 19.
Give a brief account of the ovary.
Answer:

• Females have a pair of ovaries located in the pelvic region of the abdomen.
• It is composed of ovarian follicles and stromal tissue.
• It produces the egg or ova.
• It secretes the steroid hormones oestrogen and progesterone.

Functions:

1. Oestrogen is responsible for the maturation of reproductive organs and the development of secondary sexual characters at puberty.
2. Along with progesterone, oestrogen promotes breast development and initiates the menstrual cycle.
3. Progesterone prepares the uterus for implantation of the fertilized ovum.
4. It decreases the uterine contraction during pregnancy and stimulates the development of mammary glands and milk secretion.
5. It is responsible for premenstrual changes in the uterus and for the formation of the placenta.

Question 20.
Explain the functions of hormones of the heart and kidney.
Answer:
Heart: The cardiocytes on the atrial walls secrete an important peptide hormone called atrial natriuretic factor (ANF)

Function: When blood pressure is increased ANF is secreted and causes dilation of the blood vessels to reduce the blood pressure.

Kidney: Three hormones are secreted by the kidneys. They are Renin, erythropoietin, and calcitriol.

Renin:

• It is secreted by Juxta glomerular Cells (JGA).
• It increases blood pressure when angiotensin is formed in the blood.

Erythropoietin:

• It is also secreted by JGA.
• Stimulates erythropoiesis ie formation of RBC in bone mawow.

Calcitriol:

• It is secreted by proximal tubules of the nephron.
• It is an active form of vitamin D3.
• It promotes calcium and phosphorus absorption from the intestine and accelerates bone formation.

Question 21.
If you happen to see a man/lady with short stature how will you identify him?
Differentiate and give a reason for that disorder.
Answer:
The person may be suffering from either cretinism or Dwarfism.
The following symptoms may be observed in cretinism. It is due to the hypo-secretion of Thyroxine.

• A cretin shows retarded skeletal growth.
• Absence of sexual maturity.
• Retarded mental ability.
• Thick wrinkled skin.
• Protruded enlarged tongue.
• Bloated face.
• Thick and short limb occur
• Low BMR
• Slow pulse rate.
• Subnormal body temperature
• Elevated blood cholesterol levels.

If the person shows the following symptom, he may have Dwarfism, it is due to hyposecretion of growth hormone.

1. Skeletal growth and sexual maturity is arrested.
2. They attain a maximum height of 4 feet only.

Question 22.
(i) Describe the structure of the pancreas.
(ii) Draw the diagram and marced it parts
(iii) How insulin controls blood sugar?
(iv) What is the role of glucagon in our body?
Answer:
i) Structure of pancreas:

• Pancreas is a composite gland which performs both endocrine and exocrine functions.
• It is located just below the stomach as a leaf-like structure.
• It is composed of two major tissues such as acme and islets of Langerhans
• Acme secretes digestive enzymes and the islets of Langerhans secretes hormones like insulin and glucagon.
• Human pancreas has 1 -2 million islets of Langerhans.
• In each islet about 60% cells are beta cells 25% cells are alpha cells and 10% are delta cells.
• The alpha cells secrete glucagon the beta cells secrete insulin and delta cells secrete somatostatin.

ii) Structure of Islets of Langerhans (pancreas)

iii) Insulin control-blood sugar:-

• Insulin is a peptide hormone and plays an important role in glucose homeostasis.
• Its main effect is to lower blood glucose levels by increasing the uptake of glucose into the body cells
• especially muscle and fat cells.
• Insulin also inhibits the breakdown of glycogen to glucose, the conversion of amino acids or fats to glucose.
• So insulin is rightly called a hypoglycemic hormone.
• Reduced secretion of insulin leads to diabetes mellitus. As a result glucose level is elevated.
• It is of two types. Type I. Diabetes and Type II Diabetes. Type I Diabetes is caused by lack of secretion of insulin due to illness or viral infection. Type II or Non-insulin-dependent diabetes caused due to reduced sensitivity to insulin.

iv) Role of Glucagon:

• Glucagon is a polypeptide hormone.
• It is a potent hyper glycemic hormone.
• It acts on the liver and promotes the break down of glycogen to glucose (glycogenolysis)
• It also promotes synthesis of glucose from lactic acid and from non-carbohydrate molecules is called Gluconeogenesis.
• Glucogon releases glucose from the liver cell increasing the blood glucose levels.
• Since glucagon reduces the cellular uptake and utilisation of glucose it is called a hyperglycemic hormone. Prolonged hyperglycemia leads to the disorder called diabetes mellitus.

Question 23.
Symptoms of diabetes
Answer:

• Polyurea – excessive urination
• Polyphagia – excessive intake of food
• Poly dispsia – excessive consumption of liquids due to thirst.
• Ketosis – breakdown of fat into glucose results in accumulation of ketone bodies in blood.
• Gluconeogenesis also occur ie conversion of the non-carbohydrate form like amino acids and fat into glucose.

Question 24.
a) Write down the location and dimension of the pituitary gland?
b) Explain the internal structure of the pituitary gland?
c) Draw the diagram of the pituitary gland and label the parts.
Answer:
a. Location of pituitary gland:-

• It is located in a depression called sella tursica a bony cavity of the sphenoid bone below the brain.
• The pituitary gland means “to grow under”.
• It is connected to the brain by a stalk called the infundibulum
• Dimension:- It is about 1cm in diameter and 0. 5gm in weight.

b. Internal structure:-

• The pituitary consists of two lobes, anterior glandular adenohypophysis and posterior neural neuro hypophysis.
• Anatomically the anterior lobe or adenohypophysis has three lebesor zones namely pass intermedia, pass distalis and pass tuberalis.
• The neurohypophysis is otherwise known as pars nervosa.
• Embryonic origin:- The anterior lobe originates from the Embryonic invagination of pharyngeal epithelia called Rathke’s pouch.
• The posterior lobe originates from the base of the brain as an outgrowth of the hypothalamus.

c. Hypothalamus and pituitary gland

Question 25.
Give a brief account of the hormones of the adenohypophysis.
Answer:
It secretes six hormones.
1. Growth Hormone:-

• It is also known as somatotropic hormone (STH) or somatotropin
• It is a peptide hormone.
• It promotes the growth of all the tissues and metabolic processes of the body.
• It influences the metabolism of carbohydrates, proteins, and lipids and increases the rate of biosynthesis in the cells.
• It stimulates chondrogenesis (cartilage formation), osteogenesis (bone formation).
• It helps in the retention of minerals like nitrogen and potassium, phosphorous, sodium, etc. in the body.

2. Thyroid Stimulating Hormone TSH or Thyrotropin:-

• It is a glycoprotein.
• It stimulates the thyroid gland to secrete Tri-iodothyronine (T3) and Thyroxine (T4).
• TSH secretion is regulated by a negative feedback mechanism.
• Its release from the anterior pituitary is induced by the thyrotropin-releasing hormone (TRH).
• When thyroxine level in the blood increases TRH acts on both the pituitary and hypothalamus to inhibit TSH secretion.

3. Adreno Corticotropic Hormone (ACTH):-

• It is a peptide hormone.
• It stimulates the adrenal cortex to secrete glucocorticoids and mineral corticoids.
• It stimulates melanin synthesis in melanocytes induces the release of fatty acids from adipose tissues and stimulates insulin secretion.
• its secretion is regulated by a negative feedback mechanism.

4. Follicle Stimulating Hormone (FSH):-

• It is a glycoprotein hormone.
• It regulates the functions of the gonads.
• In males, FSH along with androgens act on the germinal epithelium of seminiferous tubules and stimulates the production and release of sperms (Spermatogenesis).
• In females, it acts on the ovaries and brings about the development and maturation of graffian follicles.

5. Luteinizing hormone (LH):-

• It is a glycoprotein hormone.
• It is also known as interstitial cell-stimulating hormone.
• In females LH, along with FSH matures the ovarian follicles.
• LH independently induces ovulation, maintains the corpus luteum and promotes synthesis and release of ovarian hormones.
• In males, ICSH acts on interstitial cells of testes to produce the male sex hormone testosterone.

6. Luteo Tropic Hormone (LTH):-

• It is a protein hormone.
• It is also called luteotropin or lactogenic hormone or prolactin or mammotropin.
• It stimulates milk secretion after childbirth.
• Since it induces the corpus luteum hence named as a luteotropic hormone.

Question 26.
a) Name the hormones secreted by the neuro hypophysis?
b) Give a brief account of its functions?
Answer:
a. Neuro hypophysis secretes two hormones.

1. Vasopressin or anti-diuretic hormone
2. Oxytocin.

Vasopressin or Anti diuretic Hormone (ADH):-

• It is a peptide hormone.
• it promotes reabsorption of water and electrolytes by distal tubules of the nephron and thereby reduces the loss of water through urine.
• Hence it is called an anti-diuretic hormone.
• When released in large amounts it causes constriction of blood vessels and increases blood pressure.
• ADH deficiency causes Diabetes insipidus which induces the production of a large amount of urine.

Oxytocin:-

• It means quick birth.
• It is a peptide hormone.

3. It stimulates vigorous contraction of the smooth muscles of the uterus during childbirth.
4. And it also stimulates the ejection of milk from the mammary glands.

b. Chemical nature:

• The insulin hormone is a peptide hormone with 51 amino acids.
• The molecular weight of insulin hormone is 5734 Dalton.
• It consists of two chains A and B which are linked together by disulphide bridges formed between cystine residues.

Role of Insulin:

• It increases uptake of glucose into body cells especially muscle and fat cells.
• It inhibits the breakdown of glycogen to glucose, the conversion of amino acids or fats to glucose.
  Thus it decreases the blood glucose level and so insulin is rightly called as a hypoglycemic hormone.

c. How can this condition be reversed?

• maintenance of normal body weight through adoption of nutritional habits ie. balanced diet and physical exercise.
• Correction of over nutrition and obesity may reduce the risk of diabetes and its complications.
• Alcohol and smoking should be avoided.
• Control of high blood pressure elevated cholesterol and high triglyceride levels.

Question 27.
a) Why hormones are called chemical messengers?
b) Explain how the target organs are specifically fit for the action of hormones?
Answer:
a) Hormones are chemical messengers because they act as organic catalysts and co-enzymes to perform specific functions in the target organs.

b) Special features of target organs:

• The target organs contain receptor molecules either on the surface or within the cell.
• Although different hormones come in contact, only the cells that contain receptor molecules specific to the hormone are physiologically activated.
• A single hormone may have multiple effects on a single target tissue or on different target tissues.
• Many hormones exhibit long-term changes like growth, puberty, and pregnancy.
• Serious deficiency or excess secretion of hormones leads to disorders.
• Hormones coordinate different physiological mental activities and maintain homeostasis.

Question 28.
Draw the Endocrine gland is our body.
Answer:

Question 29.
Give an account on parathyroid hormones its hypo and hyper secretion deficiencies.
Answer:

• Four tiny parathyroid glands are found in the posterior wall of the thyroid gland.
• It is composed of Chief cells and oxyphil cell.
• The chief cells secrete parathyroid hormone and the function of oxyphill cell are not known

Functions

• It involves in calcium and phosphate.
• It promotes the activation of vitamin D to increase calcium absorption by intestine.

Hyper secretion

• Hyper parathyroidism causes demineral isation of calcium in bones.
• Thus increasing the calcium and phosphate level in the blood.
• PTH enhances the reabsorption of calcium and excretion of phosphate by the renal tubules.

Hypo secretion

• Due to the hyposecretion of PTH serum calcium level decreases and the serum phosphate level increases.
• Generalised convulsion occurs.

Question 30.
a. Give an account of position of adrenal gland and it’s internal structure, b. List out the function of adrenal hormone.
Answer:
a) Position
A pair of adrenal glands are located at the anterior end of the kidney. Hence called supra renal glands.
b) Structure
The adrenal gland is composed of the outer cortex and an inner medulla.
The cortex consists of

1. zona glomerulosa
2. zona fasciculata
3. zona reticularis.

1. zona glomerulosa
– secretes minerals corticoids

2. zona fasciculata
– secretes gluco corticoids

3. zona reticularis.
– secretes androgen and oestrogen.

b) Functions

• Gluco corticoids stimulate gluco neogenesis.
• Cortisolies involved in maintaining cardio vascular and kidney functions.
• Cortisol stimulates RBC production.
• Mineralocorticoids regulated the water and electrolyte balance of our body.
• Androgen plays a role in hair growth in the axial region pubis and face during Puberty.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Zoology Guide Pdf Chapter 10 Neural Control and Coordination Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Zoology Guide Chapter 10 Neural Control and Coordination

11th Bio Zoology Guide Neural Control and Coordination Text Book Back Questions and Answers

 

Part -I.

I. Choose The Best Options

Question 1.
Which structure in the ear converts pressure waves to action potentials?
a) Tympanic membrane
b) Organ of Corti
c) Oval window
d) Semicircular canal
Answer:
b) Organ of Corti

Question 2.
Which of the following pairings is correct
a) Sensory nerve – afferent
b) Motor nerve – afferent
c) Sensory nerve – ventral
d) Motor nerve – dorsal
Answer:
a) Sensory nerve – afferent

Question 3.
During synaptic transmission of nerve impulse, neurotransmitter (P) is released from synaptic vesicles by the action of ions
(Q). Choose the correct P and Q.
a) P = Acetylcholine, Q = Ca⁺⁺
b) P = Acetylcholine, Q = Na⁺
c) P = GABA, Q = Na⁺
d) P = Cholinesterase, Q = Ca⁺⁺
Answer:
a) P = Acetylcholine, Q = Ca⁺⁺

Question 4.
Examine the diagram of the two cell types A and B given below and select the correct option.
a) Cell – A is the rod cell found evenly all over retina
b) Cell – A is the cone cell more concentrated in the fovea centralis
c) Cell – B is concerned with colour vision in bright light
d) Cell – A is sensitive to bright light intensities

Answer:
c) Cell – B is concerned with colour vision in bright light

Question 5.
Assertion- The imbalance in concentration of Na⁺, K⁺ and proteins generates action potential.
Reason: To maintain the unequal distribution of Na⁺ and K⁺ , the neurons use electrical energy.
a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
b) Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.
c) Assertion is true, but Reason is false.
d) Both Assertion and Reason are false.
Answer:
a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.

Question 6.
Which part of the human brain is concerned with the regulation of body temperature?
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Hypothalamus
Answer:
d) Hypothalamus

Question 7.
The respiratory centre is present in the
a) Medulla oblongata
b) Hypothalamus
c) Cerebellum
d) Thalamus
Answer:
a) Medulla oblongata

Question 8.
Match the following human spinal nerves in column I with their respective number in column II and choose the correct option
Column I Column 11
(P) Cervical nerves
(Q) Thoracic nerve
(R) Lumbar nerve
(S) Coccygeal nerve
(i) 5 pairs
(ii) 1 pair
(iii) 12 pairs
(iv) 8 pairs
a) (P-iv), (Q-iii), (R-i), (S-ii)
b) (P-iii), (Q-i), (R-ii), (S-iv)
c) (P-iv), (Q-i), (R-ii), (S-iii)
d) (P-ii), (Q-iv), (R-i), (S-iii)
Answer:
a) (P-iv), (Q-iii), (R-i), (S-ii)

Question 9.
Which of the following cranial nerve controls the movement of eye ball?
a) Trochlear nerve
b) Optic nerve
c) Olfactory nerve
d) Vagus nerve
Answer:
a) Trochlear nerve

Question 10.
The abundant intracellular cation is
a) H⁺
b) K⁺
c) Na⁺
d) Ca⁺⁺
Answer:
b) K⁺

Question 11.
Which of the following statements is wrong regarding conduction of nerve impulse.
a) In a resting neuron, the axonal membrane is more permeable to K⁺ ions and nearly impermeable to Na⁺ ions.
b) Fluid outside the axon has a high concentration of Na⁺ ions and low concentration of K⁺, in a resting neuron.
c) Ionic gradient s are maintained by Na⁺ K⁺ pumps across the resting membrane, which transport 3 Na ions outwards for 2K⁺ into the cell.
d) A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.
Answer:
b) Fluid outside the axon has a high concentration of Na⁺ ions and low concentration of K⁺, in a resting neuron.

Question 12.
All of the following are associated with the myeline sheath except
a) Faster conduction of nerve impulses
b) Nodes of Ranvier forming gaps along the axon
c) Increased energy output for nerve impulse conduction
d) Saltatory conduction of action potential
Answer:
c) Increased energy output for nerve impulse conduction

Question 13.
Several statements are given here in reference to cone cells which of the following option indicates all correct statements for cone cells? Statements
(i) Cone cells are less sensitive in bright light than Rod cells
(ii) They are responsible for colour vision
(iii) Erythropsin is a photo pigment which is sensitive to red colour light
(iv) They are present in fovea of retina
a) (iii), (ii) and (i)
b) (ii), (iii) and (iv)
c) (i), (iii) and (iv)
d) (i), (ii) and (iv)
Answer:
c) (i), (iii) and (iv)

Question 14.
Which of the following statement concerning the somatic division of the peripheral neural system is incorrect?
a) Its pathways innervate skeletal muscles
b) Its pathways are usually voluntary
c) Some of its pathways are referred to as reflex arcs
d) Its pathways always involve four neurons
Answer:
d) Its pathways always involve four neurons

Question 15.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of
a) Depolarization
b)FIyperpo1ariation
c) Repolarization
d) Hypopolaiization
Answer:
c) Repolarization

Question 16.
Why is the blind spot called so?
Answer:
Slightly below the posterior pole of the eye, the optic nerve and the retinal blood vessels enter the eye. This region is devoid of rods and cones. Hence, this region is called blind spot.

Question 17.
Sam’s optometrist tells him that his intraocular pressure is high. What is this condition called and which fluid does it involve?
Answer:

• The increase in intraocular pressure leads to the disease called Glaucoma.
• Any block in the canal of Schlemm increases the intraocular pressure of aqueous humor and leads to ‘Glaucoma’ where the optic nerve and the retina are compressed due to pressure.

Question 18.
The action potential occurs in response to a threshold stimulus: but not at sub-threshold stimuli. what is the name of the principle involved?
Answer:
When we cry, the tears come out of the tear glands under the eyelids and drain through the tear duct that empties into the nose. It mixes with mucus there and the nose runs.

Question 19.
Pleasant smell of food urged Ravi to rush into the Kitchen. Name the parts of the brain involved in the identification of food and emotional responses to odour
Answer:
The hypothalamus contains a pair of small rounded body called mamillary bodies that are involved in olfactory reflexes and emotional responses to odour
This is also act as centre for appetite thirst and heat regulation.

Question 20.
Cornea transplant in humans is almost never rejected State the reason.
Answer:
The cornea does not have blood vessels. Hence there is no possibility of rejection when the cornea is transplanted from one person to another person.

Question 21.
At the end of repolarisation, the nerve membrane gets hyperpolarized Why?
Answer:
If repolarization becomes more negative than the resting potential – 70mV to about – 90mV it is called hyperpolarization.

Question 22.
Label the parts of the neuron.
Answer:

A- Nucleus with nucleolus
B- Axolemma
C- Dendrites
D- Myelin sheath, Nucleus
E- Axon (Direction of signal transmission)
F- Node of Ranvier.

Question 23.
The choroid plexus secretes cerebral spinal fluid List the function it.
Answer:
Cerebrospinal fluid provides buoyancy to the central nervous system.

1. It acts as a shock absorber for the brain and spinal cord.
2. It nourishes the brain cells by transporting food and oxygen.
3. It carries harmful metabolic wastes from the brain to the blood.
4. It maintains constant pressure inside the cranial vessels.

Question 24.
What is the ANS controlling center? Name the parts that are supplied by the ANS?
Answer:
Controlling center – autonomic neural system. Controlling organs.

1. Eyes
2. Salivary Glands
3. Heart
4. Lungs
5. Stomach
6. Liver
7. Kidney
8. Intestines
9. Bladder

Question 25.
Why the limbic system is called the emotional brain. Name the parts of it?
Answer:
The limbic system is a set of components located on both sides of the thalamus present in the inner part of the cerebral hemisphere. It includes the olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus and hypothalamus. The limbic system plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling, affection and memory. Hence it is called the emotional brain.

Question 26.
Classify receptors based on the type of stimuli.
Answer:

Receptors	Stimulus	Effector organs
Mechano receptors	Pressure and vibration	Mechano receptors are present in the cochlea of the inner ear and the semicircular canal and utriculus
Chemoreceptors	Chemicals	Taste buds in the tongue and nasal epithelium
Thermo receptors	Temperature	Skin
Photoreceptors	Light	Rod and cone cells of the retina in the eye.

Question 27.
Name the first five cranial nerves, their nature and their functions
Answer:

Cranial nerves	Nature of nerve	Function
I. Olfactory nerve	Sensory	Sense of smell
II.Optic nerves	Sensory	Sense of sight
III. Oculo motor nerves	Motor	Movement of the eye
IV. Trochlear nerve	Motor	Rotation of the eyeball
V.Trigeminal nerve	Sensory and motor mixed	The functioning of face ball

Question 28.
The sense of taste is considered to be the most pleasurable of all senses. Describe the structure of the receptor involved with a diagram.
Answer:

• The sense of taste is considered to be the most pleasurable of all senses.
• The tongue is provided with many small projections called papillae.
• Taste buds are located mainly on the papillae.
• Taste buds are flask-shaped.

There are two major types.

• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.

• Long microvilli called gustatory hairs project from the tip of the gustatory cells and extend through a taste pore to the surface of the epithelium.
• Gustatory hairs are the sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.

Question 29.
Describe the structures of olfactory receptors?
Answer:
The smell receptors are excited by air-borne chemicals that dissolve in fluids. The yellow coloured patches of olfactory epithelium form the olfactory organs that are located on the roof of the nasal cavity.

The olfactory epithelium is covered by a thin coat of mucus layer below and olfactory glands bounded connective tissues, above. It contains three types of cells: supporting cells, Basal cells and millions of pin-shaped olfactory receptor cells (which are unusual bipolar cells).

The olfactory glands and the supporting cells secrete the mucus. The unmyelinated axons of the olfactory receptor cells are gathered to form the filaments of olfactory nerve [cranial nerve-I] which synapse with cells of olfactory bulb.

The impulse, through the olfactory nerves, is transmitted to the frontal lobe of the brain for identification of smell and the limbic system for the emotional responses to odour.

Part-II.

11th Bio Zoology Guide Neural Control and Coordination Additional Important Questions and Answers

I. Choose The Correct Answer

Question 1.
What is the functional unit of the nervous system?
a) Neuroglial cells
b) Neuron
c) Nephron
d) Axon
Answer:
b) Neuron

Question 2.
Name the nutritive cells of neuron.
a) Axon
b) Neuroglia
c) Schwann’s cell
d) Epithelial cells.
Answer:
b) Neuroglia

Question 3.
Name the cell organelle which is not seen in the nerve cell.
a) Mitochondria
b) Golgi apparatus
c) Centrioles
d) Nucleus
Answer:
c) Centrioles

Question 4.
Name the plasma membrane which surrounds the neurons?
a) Neurilemma
b) Axolemma
c) Myalin membrane
d) Sarcolemma
Answer:
a) Neurilemma

Question 5.
Name the plasma membrane surrounds the axon?
a) Neurilemma
b) Myalin membrane
c) Sarcolemma
d) Axolemma
Answer:
d) Axolemma

Question 6.
Where is Nissl’s bodies seen in the nerve cell?
a) Cell body and dendrites
b) Cell body and axon
c) Cell body and myalin sheath
d) Cell body and end plate of axon.
Answer:
a) Cell body and dendrites

Question 7.
Name the cell organell which is not seen in the axons.
a) Mitochondria
b) Golgi apparatus
c) Centriole
d) Endoplasmic reticulum
Answer:
b) Golgi apparatus

Question 8.
Cell forms the myalin sheath ……………..
a) Schwaan’s cell
b) Neuroglial cells
c) Nephron
d) Epithelial cells
Answer:
a) Schwaan’s cell

Question 9.
Which part of the nerve cells do not contain myalin sheath.
a) Axon
b) Cell body
c) Dentrites
d) Axon end plate
Answer:
c) Dentrites

Question 10.
Which of the following does the work of phagocytosis of microbes during the infection of the brain
a) Schwann cells
b) Node of Ranvier
c) Neuroglial cells
d) Neurilemma
Answer:
c) Neuroglial cells

Question 11.
Find out the correct statement
a) The short nerve fibres are called as dentrites.
b) The membrane surrounds the neuron is axolemma.
c) The longest sciatic nerve runs from the base of the spine to the big toe of each foot
d) Schwann cell’s do not synthesize myalin sheath
Answer:
c) The longest sciatic nerve runs from the base of the spine to the big toe of each foot

Question 12.
Find out the wrong pair
a) Multi polar neuron: One axon and two or more dentrites.
b) Bi polar neurons: One axon and more than two dentrites.
c) Uni polar neurons: Short process axon.
d) Synaptic Knob: Neurotransmitters
Answer:
b) Bi polar neurons: One axon and more than two dentrites.

Question 13.
This substance is more in the tissue fluid of cytoplasm of axolemma?
a) Sodium chloride and bicarbonates.
b) Nutritious substances and oxygen.
c) Potassium and magnesium phosphate.
d) All the above.
Answer:
c) Potassium and magnesium phosphate.

Question 14.
Match the following and find the answer.

1. Leakage channels	a. Opens through the sensation of touch and pressure.
2. Ligand-gated channels	b. They are stable.
3. Voltage gated channels	c. Opens through chemical stimulation.
4. Charged particles	d. Ionic channels are always open.

Answer:
c) i- B,ii – D,iii – C,iv – A

Question 15.
Name the gaps in the myelin sheath between adjacent Schwann.
a) Nodes of Ranvier
b) Nodes of axon
c) Nodes of cyton
d) Nodes of dentrites
Answer:
a) Nodes of Ranvier

Question 16.
Where are bipolar neurons situated?
a) Cranial nerves
b) Olfactory lobes of brain
c) Spinal nerves
d) Skin
Answer:
b) Olfactory lobes of brain

Question 17.
Where are Bipolar neurons situated?
a) Spinal cord
b) Retina
c) Inner ear
d) Brain.
Answer:
a) Spinal cord

Question 18.
Find out the odd one.
a) Schwann cell – Myalin sheath
b) Synaptic knob – Synaptic vesicles
c) Bipolar neuron – Cranial nerves
d) Multipolar neuron – Spinal nerves.
Answer:
c) Bipolar neuron – Cranial nerves

Question 19.
Where is Bipolar neurons meet?
a) Synapses
b) Synaptic cleft
c) Synaptic vesicle
d) Synaptic Knob
Answer:
a) Synapses

Question 20.
Match and find the correct sequence.

I. Neuro junction	a. Neuron which receives a stimulus
II. Presynaptic neurons	b. Synaptic vesicles
III. Synaptic cleft	c. Synapses
IV. Neurotransmitter	d. Pre and post neuron junction

a) I-d II-a ¡II-c IV-d
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-c II-a III-d IV-b
Answer:
d) I-c II-a III-d IV-b

Question 21.
Central nervous system forms from this layer during embryonic development.
a) Endoderm
b) Ectoderm
c) Mesoderm
d) Middle layer.
Answer:
b) Ectoderm

Question 22.
Find out whether the following statements are true or false. Find out the correct sequence.
i. The thick outer covering of the brain is dura matter
ii. The space between pia matter and dura matter is subarachnoid space.
iii. The membrane that surrounds the brain is piamalter
iv. The space between arachnoid and pia mater is subarachnoid space
a) I – False; II – False; III – True; IV – True
b) I-True; II-False; III-True; IV-True
c) I – True; II – False; III – False; IV – True
d) I-True; II-False; III-True; IV-False
Answer:
b) I-True; II-False; III-True; IV-True

Question 23.
Which is considered as the seat of intelligence.
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Pons.
Answer:
b) Cerebrum

Question 24.
Find out whether the following statements are true or false.
a) At resting membrane potential the efflux of potassium is more than the influx of sodium from the outer surface of the neurilemma.
b) When the stimulus is sent from the cell body to the axon there is no creation of action potential.
c) The spike potential is +45mV.
d) The threshold potential is +55mV.
i) a) True b) True c) False d) False
ii) a) False b) True c) True d) True
iii) a) True b) False c) True d) True
iv) a) True b) False c) True d) False
Answer:
iv) a) True b) False c) True d) False

Question 25.
Find out the wrong pair
a) Synapses – The junction of two neurons
b) Neurotransmitter – Postsynaptic neuron
c) Synaptic vesicles – A small bag filled with chemicals
d) Piamatter – Membrane which closely adheres to the brain.
Answer:
b) Neurotransmitter – Postsynaptic neuron

Question 26.
………………. is the part of the fore-brain.
a) Cerebrum – Mesencephalon
b) Cerebrum – Prosencephalon
c) Cerebrum – Diencephalon
d) Cerebrum – Parietal lobe.
Answer:
c) Cerebrum – Diencephalon

Question 27.
…………………….. is useful in diagnosis of neurological and sleep disorders.
a) PET
b) CT
c) X – rays
d) EEG
Answer:
d) EEG

Question 28.
Name the structure which connects cerebral hemisphere
a) Choroid tissue
b) Corpus callosum
c) Neuroglia tissue
d) Pineal body
Answer:
b) Corpus callosum

Question 29.
Match and find out the correct sequence.

I. Frontal lobe	a. Reading
II. Parietal lobe	b. Hearing
III. Temporal lobe	c. Vision
IV. Occipital lobe	d. Memory

a) I-d II-a III-c IV-b
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-d II-a III-b IV-c
Answer:
d) I-d II-a III-b IV-c

Question 30.
Assertion: Statement A- The cortex of cerebrum consists of grey matter.
Statement B- The reason for the grey matter is due to the presence of non – myelinated sheath.
a) Statement A- True, Statement B – False
b) Statement A and B are true
c) Statement A- False the statement B- True.
d) Statement A and B are false.
Answer:
b) Statement A and B are true

Question 31.
Match and find the correct answer.
1. Broca area a. Perception of taste.
2. The pre-central gyrus b. Voluntary movements
3. The postcentral gyrus c. Aggression
4. Amygdala d. Speech function
a) I-a II-b III-c IV-d
b) I-d II-b III-c IV-a
c) I-d II-b Ill-a IV-c
d) I-a II-b III-c IV-d
Answer:
c) I-d II-b III-a IV-c

Question 32.
Assertion: Statement S – Brain controls emotions and feelings.
Statement T – There are no sensory neurons in the brain. Hence it cannot sense the pain.
a) Statement – S – True. Statement T – False
b) Statement – S – True Statement T – True
c) Statement – S – False Statement T – False
d) Statement S – False Statement T – True
Answer:
b) Statement – S – True Statement T – True

Question 33.
Which is considered as the relay centre for impulses
a) Medulla oblongata
b) Cerebrum
c) Hypothalamus
d) Thalamus
Answer:
d) Thalamus

Question 34.
Which indicates A, B, C and D in the following diagram

(a)
a) Temporal lobe
b) Frontal lobe
c) Parietal lobe
d) Cerebellum
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe
(c)
a) Cerebellum
b) Frontal lobe
c) Temporal lobe
d) Parietal lobe
(d)
a) Parietal lobe
b) Cerebellum
c) Frontal lobe
d) Temporal lobe
Answer:
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe

Question 35.
Find out the wrong statement.
a) The pre-central gyrus is called a motor strip.
b) The post-central gyrus is called a sensory strip.
c) The medulla oblongata controls respiration.
d) Wernicke area of the brain involved in the comprehension of speech.
Answer:
d) Wernicke area of the brain involved in the comprehension of speech.

Question 36.
The melatonin hormone which controls the sleep-wake cycle is secreted by
a) Pineal body
b) Thalamus
c) Hypothalamus
d) Medulla oblongata
Answer:
a) Pineal body

Question 37.
The lower portion of the midbrain consists of a pair of longitudinal nervous bands called
a) Emotional brain
b) Cerebral peduncles
c) Pons
d) Vermis
Answer:
b) Cerebral peduncles

Question 38.
The cauda equina presents in
a) Cerebrum
b) Thalamus
c) Hippo cambus
d) Spinal cord
Answer:
d) Spinal cord

Question 39.
Match and find the correct answer.
i) Thalamus – A) Respiration Gastric Pits.
ii) Hypothalamus – B) Vision Hearing
iii) Mid brain – C) Satiety centre
iv) Medulla oblongata – D) Learning memory

Answer:
a) i- D,ii – C,iii – B,iv – A

Question 40.
The cluster of nerve tissue in the cell body of neurons are called as
a) Gyri
b) Sulci
c) Vermis
d) Nerve ganglion.
Answer:
d) Nerve ganglion.

Question 41.
Find out the wrong pair
a) Cervical nerve – 8 pairs
b) Thoracic nerve – 12 pairs
c) Sacrum nerve – 4 pairs
d) Coccyx nerve – 1 pair
Answer:
c) Sacrum nerve – 4 pairs

Question 42.
What is the amount of cerebrospinal fluid secreted in an adult?
a) 500 ml
b) 150 ml
c) 400 ml
d) 250 ml
Answer:
b) 150 ml

Question 43.
The dissolved nicotene and alcohol in …………………… and ………………… minutes reach the brain.
a) 7 and 8 minutes
b) 6 and 7 minutes
c) 7 seconds and 6 minutes
d) 7 and 5 minutes.
Answer:
c) 7 seconds and 6 minutes

Question 44.
Name the structure that regulates homeostasis.
a) Mammillary body
b) Pineal body
c) Hypothalamus
d) Pituitary.
Answer:
a) Mammillary body

Question 45.
What is brain stem.
a) The structure seen in between spinal cord and cerebellum.
b) The region between Diencephalon and spinal cord
c) The region between medulla oblongata and cerebrum.
d) The region between medulla oblongata and mid-brain.
Answer:
b) The region between Diencephalon and spinal cord

Question 46.
What is the function of corpora quadri gemina?
a) Vision and hearing
b) Vision and homeostasis
c) Hearing and sense of touch
d) Hearing and vomiting.
Answer:
a) Vision and hearing

Question 47.
The region seen in the mid of cerebellum.
a) Corpus callosum
b) Pineal body
c) Pituitary
d) Vermis.
Answer:
d) Vermis.

Question 48.
What is the function of the interneuron?
a) Impulses from afferent and efferent neurons.
b) Impulses transmitted from efferent neurons to afferent neurons.
c) Impulses transmitted from central nervous system to receptor organs
d) From nerve transmitters to the spinal cord
Answer:
a) Impulses from afferent and efferent neurons.

Question 49.
Which part of the brain controls the unconditioned reflux?
a) The cortex of cerebrum
b) The medulla of brain
c) Cerebellum
d) pons.
Answer:
a) The cortex of cerebrum

Question 50.
……………………..pair of nerves from cranium and
…………………….. pair of nerves from spinal cord
a) 10 and 31
b) 12 and 31
c) 31 and 12
d) 31 and 10.
Answer:
b) 12 and 31

Question 51.
How much cerebrospinal fluid is synthesized in adults?
a) 200ml
b) 300ml
c) 150ml
d) 100ml.
Answer:
c) 150ml

Question 52.
What is the function of vagus nerve?
a) It regulates the function of abdominal structure
b) It regulates the speech and swallowing
c) It regulates the homeostasis of the body
d) Taste perception
Answer:
a) It regulates the function of abdominal structure

Question 53.
Name the neural system which is auto functioning and self-governed.
a) Somatic neural system
b) Automatic neural system
c) Peripheral neural system
d) Limbic system.
Answer:
b) Automatic neural system

Question 54.
Name the structure that regulates the autonomic neural system.
a) Cerebrum
b) Cerebellum
c) Hypothalamus
d) Pons.
Answer:
c) Hypothalamus

Question 55.
Name the lubricating fluid which is secreted from the gland present at the base of the eyelashes.
a) Lacrymal gland
b) Cerebro-spinal fluid
c) Thymus gland
d) Sebaceous glands.
Answer:
d) Sebaceous glands.

Question 56.
Find the ABC and D in the diagram

a) a) Tear duct b) Sciera c) Iris d) Tear gland
b) a) Sciera b) Iris c) Tear gland d)Tear duct
c) a) Tear duct b) Iris c) Sclerad d)lTear duct
d) a) Tear gland b) Sclera c) Tear duct d) Iris.
Answer:
d) a) Tear gland b) Sclera c) Tear duct d) Iris.

Question 57.
Name the tissue which forms the non-vascular transparent coat cornea
a) Stratified squamous epithelium
b) Squamous epithelium
c) Canal of schlemm
d) All the above.
Answer:
a) Stratified squamous epithelium

Question 58.
Assertion: In bright light the circular muscle in the iris contract so that the size of the pupil decreases and the light enter is regulated Reason: In dim light, the radial muscle contract the pupil size increases and less light enters the eye.
a) The assertion true: but reason wrong
b) The assertion and reason are true
c) The assertion is true but reason does not explain the assertion
d) The assertion and reason are wrong.
Answer:
a) The assertion true: but reason wrong

Question 59.
Name the yellow flat spot at the centre of the posterior region of the retina.
a) Blind spot
b) Scelera
c) Iris
d) Maculalutea
Answer:
d) Maculalutea

Question 60.
Which colour is perceived through chloropsin is sensitive to the medium wavelength of 530 mm
a) Red cones
b) Green cones
c) Blue cones
d) Red cells.
Answer:
b) Green cones

Question 61.
Name the glands that secrete tear.
a) Lacrymal gland
b) Sebaceous gland
c) Mandibular gland
d) Choroid plexues
Answer:
a) Lacrymal gland

Question 62.
…………………… enzyme is present in the tear.
a) Ptyalin
b) Lysozyme
c) Lipase
d) Erypsin.
Answer:
b) Lysozyme

Question 63.
Name the structure where more cones present.
a) Foveacenlralis
b) Maculalutea
c) Retina
d) Blind spot.
Answer:
a) Foveacenlralis

Question 64.
……………………………….. people can see the nearby object but cannot see the distant object.
a) Astigmatism
b) Presbiopia
c) Hypermetropia
d) Myopia
Answer:
d) Myopia

Question 65.
The concave lens helps in correct ………………. defect
a) Myopia
b) Hyper metropia
c) Astigmatism
d) Presbiopia
Answer:
a) Myopia

Question 66.
Which of the defect is depicted in the following diagram:

a) Emmetropia
b) Myopia
c) Hypermetropia
d) Astigmatism.
Answer:
b) Myopia

Question 67.
Match and find the correct sequence.

I. Concave	Surgery
II. Convex	Hypermetropia
III. Cataract	Astigmatism
IV. Cylindrical lens	Myopia

a) 1 -a 2-b 3-c 4-c
b) 1 -d 2-b 3-a 4-c
c) 1-d 2-a 3-a 4-b
d) 1-d 2-c 3-b 4-c
Answer:
b) 1 -d 2-b 3-a 4-c

Question 68.
Name the organ which regulates vision perception and homeostasis.
a) Ear
b) Eye
c) Cerebrum
d) Cerebellum.
Answer:
a) Ear

Question 69.
Find out the wrong pair.
a) Pinna – Eardrum
b) Oval window – Round window
c) Cochlea – Malleus
d) Perilymph – Endolymph
Answer:
c) Cochlea – Malleus

Question 70.
Indicate ABC and D in the Diagram.

a)
a) lncus
b) Eardrum
c) Organ of Corti
d) Tactoreal membrane.
b)
a) Organ of cortri
b) Incus
c) Tectoreal membrane
d)Eardrum
c)
a) Eardrum
b) Incus
c) Organ of Corti
d) Tectoreal membrane
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti
Answer:
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti

Question 71.
Find out the wrong statement.
a) The equilibrium receptor regions called maculae are involved in detecting the linear movement of the head.
b) The otoliths are made up of calcium
c) The crista ampullaris is to detect rotational movement of the head
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.
(The 90db will affect the hearing).
Answer:
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.

Question 72.
A person on his way to a village in a car for weekend holidays after finishing the office work. As he is very tired he begins to feel drowsy. He turns up the car stereo volume opens the car window and has sips ice-cold water.
How do these actions keep him awake? The increase in the number of sensory stimuli he received is relayed to the cerebral cortex which gets activated and prevents sleeping,
a) Spinal cord
b) Cerebrum
c) Medulla oblongata
d) Cerebellum.
Answer:
c) Medulla oblongata

Question 73.
Name the structure that connects the middle ear and pharynx.
a) Eustachian tube
b) Middle ear
c) Oval window
d) Organ of the cortii.
Answer:
a) Eustachian tube

Question 74.
Which part of the ear have bony labyrinth and membranous labyrinth?
a) External ear
b) Inner ear
c) Middle ear
d) None of the above.
Answer:
b) Inner ear

Question 75.
Name the structure present in the bony labyrinth.
a) Cochlea, vestibule, maleus
b) Cochlea, vestibule Incus
c) Cochlea semicircular canals, stapes
d) Cochlea, vestibule semicircular canals.
Answer:
d) Cochlea, vestibule semicircular canals.

Question 76.
Where is the stereo cilia cells present in the ear?
a) Scala media
b) Scala vestibuli
c) Scala tymnani
d) Middle ear.
Answer:
a) Scala media

Question 77.
Match and find the correct sequence.

I. Meissner’s corpuscles	a) continuous pressure
II. Pacinian corpuscles	b) hardness, pain
III. Ruffini endings	c) temperature
IV. Krause and bulbs	d) light pressure

a) I-d, II-a, III-c, IV-d
b) I-d, II-b, III-c, V-a
c) I-d, II-b, Ill-a, IV-c
d) I-a, II-b, III-c, IV-d
Answer:
c) I-d, II-b, Ill-a, IV-c

Question 78.
When a cockroach tries to enter into the ear of a sleeping person, which one of the following process will start?
a) Unconditioned reflex
b) Neuro muscular fatigue
c) Stimulation of negative feedback mechanism
d) conditioned reflex
Answer:
a) Unconditioned reflex

Question 79.
What is the number of nerve cells present in the brain
a) 90 million
b) 100 billion
c) 90 billion
d) 100 million
Answer:
b) 100 billion

(2 Marks)

II. Write Very Short Answer

Question 1.
What are the two branches of human nervous system?
Answer:

1. Central nervous system
2. Peripheral nervous system

Question 2.
What is meant by Neuroglia? What are its functions?
Answer:
The non-nervous special cells called neuroglia from the supporting cells of the nervous tissue.

1. Providing nourishment to the neurons
2. Repairing the injured tissues
3. It helps in dividing and regeneration
4. Acting as phagocyte cells to engulf the foreign particles at the time of any injury to the brain.

Question 3.
Differentiate the functions of myelinated and non-myelinated neurons.
Answer:

Myelinated neuron	Non-myelinated neuron
They conduct impulses rapidly	Conduct impulse slowly
Present in the medulla	Seen in the cortex of the cerebrum.

Question 4.
Give notes on (a) Synaptic Knob (b) Neurotransmitters (c) Inter neural space.
Answer:

• Synaptic Knob: Distant end of the axon terminates into a bulb
• Synaptic vesicles: Vesicles filled with neurotransmitters
• Inter neural space – The space between presynaptic and postsynaptic neurons.

Question 5.
What is meant by nerve impulses?
Answer:
A nerve impulse is a series of electrical impulses which travel along with the nerve fibre.

Question 6.
What is meant by resting potential?
Answer:
The electrical potential difference across the plasma membrane of a resting neuron is called the resting potential.

Question 7.
What is meant by threshold potential?
Answer:
During depolarization when enough Na⁺ ions enter the cell the action potential reaches a certain level called threshold potential. (-55 mV)

Question 8.
What is threshold stimulus?
Answer:
The particular stimulus which is able to bring the membrane potential to the threshold is called the threshold stimulus.

Question 9.
What is meant by all or none principle?
Answer:
The action potential occurs in response to a threshold stimulus but does not occur at sub-threshold stimuli. This is called the all or none principle.

Question 10.
What is the cause of brain tumours?
Answer:

• Glial cells: Nerve cells do not divide but glial cells do not lose the ability to undergo cell division.
• So most brain tumours of neural origin consist of glial cells.

Question 11.
What are meninges?
Answer:
The brain is covered by outer Duramater, the median Arachnoid mater and the inner Piamater. These membranes are called meninges.

Question 12.
What is meant by lazy gate?
Answer:
During hyper polarization the K⁺ion gates are more permeable to K⁺ even after reaching threshold level it closes slowly hence called lazy gates.

Question 13.
What is spike potential?
Answer:
Due to the rapid influx of Na⁺ ions the membrane potential shoots rapidly up +45 mV which is called the spike potential.

Question 14.
What is meant by repolarisation?
Answer:
When the membrane reaches the spike potential the potassium ions K⁺ efflux from the axolemma and hence form negative potential. This is called repolarisation.

Question 15.
What is Hyper polarisation?
Answer:
If repolarisation becomes more negative than the resting potential -70 mV to about -90 mV it is called hyper polarisation.

Question 16.
Which decides the speed of the conduction of a nerve impulse?
Answer:

• The conduction speed of a nerve impulse depends on the diameter of axon.
• The greater the axon’s diameter the faster is the conduction.

Question 17.
What is septum pellucidum?
Answer:
A thin membrane which separates the lateral ventricles I and II is called the septum pellucid

Question 18.
What is the difference between sub durai space and sub arachnoid space
Answer:

Sub durai space	Sub arachnoid space
A narrow sub dural space present in between arachnoid and durameter	The space between arachnoid membrane and piameter.

Question 19.
What is meant by sulcus and gyrus? What is its functions.
Answer:

• Gyri – The convolution seen in the cerebrum.
• Sulci – The shallow grooves increase the surface area of the cerebral cortex.

Question 20.
Name the lobes of cerebrum?
Answer:

1. Pair of frontal
2. Pair of parietal
3. Pair of temporal
4. Occipital

Question 21.
What is the function of proca?
Answer:
It involves in speech function.

Question 22.
What is meant by a blood brain barrier.
Answer:
It protects the brain by preventing many foreign substances in our vascular system from reaching the brain.

Question 23.
Which part of the cerebrum is called as sheet of emotions?
Answer:
The cortex of parietal occipital and temporal.

Question 24.
What is meant by motor area?
Answer:

• The area which controls the voluntary muscular movements lies in the posterior part of the frontal lobes.
• Functions They receive and interpret the sensory impulses.

Question 25.
What is the function of association area?
Answer:
They deal with memory communications learning and reasoning.

Question 26.
Where is pineal body situated? What is its functions?
Answer:

It is situated behind the choroid plexus the epithalamus forms short stalk
Functions
The melotoxin secreted by the pineal body regulates sleep wake cycle.

Question 27.
For a man to live all parts of the brain is important. How is brain divided into?
Answer:

• Cerebrum
• Thalamus
• Hypothalamus
• Pons
• Cerebellum
• Medulla oblongata

Question 28.
What is meant by corpus callosum?
Answer:
The two hemispheres of cerebrum is connected with the nerve band known as corpus callosum.

Question 29.
What is meant by brain stem? What are its parts?
Answer:
The region between spinal cord and diencephalon.

1. Mid-brain
2. Pons varoli
3. Medulla oblongata

Question 30.
What is meant by corpora quadri gemina? What are its functions.
Answer:

• The four papillae seen on the dorsal side of mid brain.
• Perception of vision and hearing

Question 31.
What is meant by reflex arc?
Answer:

• It is a fast involuntary unplanned sequence of actions that occurs in response to a particular stimulus.
• The nervous elements that involved in carrying out reflex action constitute reflex arc.

Question 32.
What are the functions of cerebellum?
Answer:
The cerebellum controls and co-ordinates muscular movements and body equilibrium.

Question 33.
What is meant by receptors?
Answer:
The organ which made us aware of changes occur in our surrounding is called receptors.

Question 34.
What is meant by voluntary neural system?
Answer:
It is the part of the peripheral neural system associated with the voluntary control of body movements via skeletal muscles

Question 35.
Name the bacteriocidal substance present in the tears? Where is it seen? Name its secretion?
Answer:

• Lysosome enzyme
• Seen in tears.
• Lacrymal glands. 1ml is secreted in a day.

Question 36.
What are mammillary bodies? What are its functions?
Answer:

• The hypothalamus contains a pair of small rounded body called mammillary bodies.
• Functions: It is involved in olfactory reflexes and emotional responses to odour.

Question 37.
What are cerebral peduncles?
Answer:
The region between diencephalon and the pons is called midbrain. It consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.

Question 38.
What is brain stem? What are its parts?
Answer:
It is the part of the brain between the spinal cord and the diencephalon.
Organs: Mid-brain, Pons, Medulla oblongata

Question 39.
What is caudo equina?
Answer:

• After the 2nd lumbar vertebra the spinal nerves are greatly elongated
• The thick bundle of elongated nerve roots appears as a horse’s tail called as cauda equina.

Question 40.
Where is enlargement region seen in the spinal cord?
Answer:

• Cervical enlargement
• Lumbar enlargement.

Question 41.
What is meant by reflex action?
Answer:

• When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect.
• This rapid action by spinal cord is called reflex action.

Question 42.
What is meant by peripheral nervous system?
Answer:
All nervous tissue outside the CNS is the nervous system.

Question 43.
What is meant by mixed nerve?
Answer:
Each spinal nerve is a mixed nerve containing both afferent (sensory) and efferent (motor) fibers.

Question 44.
What is meant by pre ganglionic neuron?
Answer:
Its cell body is in the brain or spinal card. Its myelinated axon exits the CNS as part of cranial or spinal nerve and end in an autonomic ganglion.

Question 45.
What is autonomic ganglion?
Answer:
The axons of pre ganglionic neuron and cell bodies of post ganglionic neuron includes autonomic ganglion.

Question 46.
What is post ganglionic neuron?
Answer:
It conveys nerve impulses from autonomic ganglia to visceral effector organs.

Question 47.
What are the two branches of autonomous nervous system?
Answer:

1. Sympathetic neural system
2. Parasympathetic neural system.
3. varying distances is called accommodation.

Question 48.
Give short notes on Lacrymal glands?
Answer:

• The tear secreting glands are known as Lacrymal glands.
• 1ml of tear is secreted in a day.
• Tear salts, mucous and lysozyme enzyme to destroy bacteria.

Question 49.
What is conjunctiva?
Answer:
It is a thin protective mucous membrane found lining the outer surface of the eye ball.

Question 50.
Dilation and congestion of the blood vessels due to local irritation or infections. What is the disease? When will it occur?
Answer:

• Conjunctivitis or madras eye.
• Irritation or infection are the cause of blood shot eye.

Question 51.
What is sty?
Answer:
Infection of ciliary glands by bacteria causes a painful pus filled swelling called a sty.

Question 52.
What are the three types of cell present on the neural retina?
Answer:

• Photo receptor cell
• Cones
• Rods
• Bipolar and ganglion cells.

Question 53.
What is cataract?
Answer:
Due to the changes in nature of protein the lens become opaque called cataract.

Question 54.
What is aqueous humour and vitreous humour
Answer:

• Aqueous humour – The fluid filled in between the cornea and iris.
• Vitreous humour – Fluid filled in between lens and retina.

Question 55.
Give notes on lens fibres?
Answer:
Eye lens is transparent and biconvex made up of long columnar epithelial cells called lens fibre, these cells are formed of crystalline protein.

Question 56.
What are the three layers of eye ball?
Answer:

1. Sclera – Outer coat
2. Choroid – Pigmented middle layer
3. Retina – Inner most layer

Question 58.
What is meant by maculae lutea?
Answer:
The yellow flat spot at the centre of the posterior region of the retina is called macula lutea. It is responsible for sharp detailed vision.

Question 59.
What is fovea centralis?
Answer:
A small depression present in the centre of the yellow spot is called fovea centralis which contains only cones.

Question 60.
What is blind spot?
Answer:
The optic nerves and the retinal blood vessels enter the eye slightly below the posterior pole whichis devoid of photoreceptors is called blind spot.

Question 61.
Why there is no cornea rejection during cornea transplantation?
Answer:

• There is little or no possibility of cornea rejection.
• This is because cornea does not have blood vessels.

Question 62.
What are the three ear ossicles?
Answer:

1. Malleus – hammer bone
2. Incus – anvil bone
3. Stapes – stirrup bone

Question 63.
What are the three chambers of cochlea?
Answer:

1. Scala vestibule
2. Scala tympani
3. Scala media

Question 64.
What is tectorial membrane?
Answer:
A roof like structure over hanging the organ of corti through out its length with the stiff gel membrane called tectorial membrane.

Question 65.
Name the receptors which are excited by airborne chemicals that dissolve in fluids?
Answer:
The receptors for taste and smell are the chemo receptors

Question 66.
What is tactile merkel disc?
Answer:
It is the light touch receptor lying in the deeper layer of epidermis.

Question 67.
What are the structures present in the membranous labyrinth?
Answer:

• Cochlea
• Vestibule
• Semi circular canals

Question 68.
What are the three chambers of cochlea? Name the membrane which separates these chambers?
Answer:

1. Scala vestibuli
2. Scala tympanii
3. Scala media

Separating membranes
Reisner’s membrane. It separates scala vestibuli from scala media
Basilar membrane. It separates scala media from scala tympani.

Question 69.
What is meant by stereo cilia?
Answer:

• The organ of corti contains numerous hair cells on the basilar membrane.
• Protruding from the apical part of each hair cell is hair like structures called stereo cilia.

Question 70.
What is proprioception?
Answer:
The ability to provide information about position and movements of the body is proprioception.

Question 71.
What is meant by vestibular system?
Answer:
This is the organ of balance this system is composed of fluid filled sacs and tubules.

Question 72.
Give notes on utriculus and sacculus?
Answer:
The utricle and saccule contain equilibrium receptor regions called maculae that are involved in detecting the linear movement of the head.

Question 73.
What is otolith?
Answer:

• Maculae contains hair cells. These hair cells contain calcareous particles called otoliths.
• It increases the inertia.

Question 74.
What are ampullae?
Answer:
At one end of each semicircular canal at its lower end has a swollen area called ampulla Each ampulla has sensory hair cells and supporting cells called crista ampullaris. The function is to detect rotational movement of the head.

Question 75.
Give the name of balancing structures which perform the following action.
a) Linear movement of the head
b) Changes occurring in body position.
c) Rotational movement of the head
Answer:

• Maculae
• Vestibular system
• Crista ampularis

Question 76.
What is the unit of sound? Give notes on our ability of sound perception?
Answer:

• The intensity of sound is measured in decibels. (dB)
• 0-50 dB is the threshold of hearing for normal ear.
• Prolonged exposure to sound with intensities greater than 90dB causes hearing loss.

Question 77.
What are chemo receptors?
Answer:

• The receptors for taste and smell are the chemo receptors
• The smell receptors are excited by air borne chemicals that dissolve in fluids.

Question 78.
What are olfactory organs? Where are they situated?
Answer:

• The yellow coloured patches of olfactory epithelium form the olfactory organs.
• They are located on the roof of the nasal cavity.

Question 79.
What are papillae?
Answer:
The tongue is provided with many small projection called papillae which is responsible for taste.

Question 80.
Give notes on taste buds.
Answer:

• The taste bud cells are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These are the most dynamic cells in the body and replaced every seven to ten days.

 

(3 Marks)

III. Short Answers

Question 1.
What are the three main functions of nervous system.
Answer:

• Sensory functions: It receives sensory input from internal and external environment.
  Motor functions: It transmits motor commands from the brain to the skeletal and muscular system.
• Autonomic functions: Reflex actions.

Question 2.
How do we classify neurons on the basis of its functions.
Answer:

• Afferent neurons – That take sensory impulses to the central nervous system from the sensory organs.
• Efferent neurons – That carry motor impulses from CNS to the effector organ.
• Inter neurons – That lie entirely within the CNS between the afferent and efferent neurons.

Question 3.
What is meant by depolarisation?
Answer:

• The inside of the axolemma becomes positively charged and negatively charged outside.
  This reversal of electrical charge is called depolarisation.

Question 4.
How is nerve impulses transmitted?
Answer:

• Inner to the axolemma the cytoplasm contains the infra cellular fluid with large amounts of potassium and magnesium phosphate with negatively charged proteins and other organic molecules.
• Outside the axolemma contains large amounts of sodium chloride bicarbonates CO² andmetabolic wastes
• Due to the charged particles present in the inner and outside of the axolemma are responsible for the conduction of nervous impulses.

Question 5.
What is meant by repolarisation?
Answer:

• When the axolemma reaches the spike potential the sodium voltage – gate closes and potassium – voltage gate opens.
• It checks influx of Na⁺ ions and initiation the efflux of K ions which lowers the number of positive ions within the cell. Thus the potential falls back towards the resting potential.

• The reversal of membrane potential inside the axolemma to negative occurs clue to efflux of K⁺ ions. This is called repolarisation.

Question 6.
What is meant by hyper polarisation.
Answer:

• If repolarisation becomes more negative than the resting potential -70 mV to about -90 mV.
  • It is called hyper polarisation. During this K⁺ ion gate are more permeable to K⁺ even after reaching the threshold level as it closes slowly hence called lazy gates.

• The membrane potential return to its original resting state when K⁺ ion channel close completely.
• During hyper polarization the Na⁺ voltage gate remains closed.

Question 7.
Give an account of the conduction speed of a nerve impulse.
Answer:

• If the axon’s diameter is greater the conduction will be faster.
• The myelinated axon conducts the impulse faster than the non – myelinated axon.

Question 8.
What is meant by saltatory conduction?
Answer:
The myelinated axon conduction the impulse faster than the non – myelinated axon.
The voltage gated Na⁺ and K⁺ channels are concentrated at the nodes of Ranvier as a result the impulse jumps node to node. This is called saltatory conduction.

Question 9.
Give an account of the membranes (meninges) of brain?
Answer:
Brain is covered by three cranial meninges.

1. The outer thicker layer is duramater which lines the inner surface of the cranial cavity.
2. The inner most layer which is adhered to the brain is piameter.
3. The median thin layer is arachnoid mater by a narrow subdural space.
4. The piameter is separated from the arachnoid mater by the subarachnoid space.

Question 10.
List out the functions of brain lobes?
Answer:

Structure	Function
Frontal	Behaviour intelligence memory movement
Parietal	Language reading sensation
Temporal	Speech hearing memory
Occipital	Visual processing

Question 11.
Why is thalamus considered as a important relay centre for impulse?
Answer:

• It serves as a relay centre for impulses between the spinal and brain and cerebrum.
• Information is sorted and edited.
• It plays a key role in learning and memory.
• It is a co-ordinating centre for sensory and motor signaling.

Question 12.
Why there may be a death due to the affectation of medulla oblongata?
Answer:

• Medulla controls cardio-vascular reflexes respiration and gastric secretions.
• If medulla is getting affected the circulation and respiration is affected.
• That may cause a death of a person.

Question 13.
Give notes on mid brain?
Answer:

• The midbrain is located between the diencephalon and the pons.
• The lower portion of the mid-brain consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.
• This relay impulses back and forth between cerebrum cerebellum pons and medulla.
• The dorsal position of the mid Brain consist of four rounded bodies called corpora quadrigemina which acts as a reflex center for vision and hearing.

Question 14.
What are the features we develop when there is a functional deficiency of serotonin and nor epinephrine?
Answer:
Features:

• negative mood
• loss of interest
• an in ability to experience pleasure
• suicidal tendencies.

Drugs:
Anti depressant drug can treat all this features.

Question 15.
Give notes on cerebro spinal fluid?
Answer:

• 150ml of cerebro spinal fluid is secreted in an adult.
• 500ml of cerebro spinal fluid is secreted in a day.
• Every 8 hours this fluid is rejuvenated.
• Choroid plexux carries harmful metabolic wastes from the brain to the blood.

Question 16.
Based on their position how the receptors are classified?
Answer:
1. Exteroceptors – They are located at the surface of the body.
These senses the hearing vision touch taste and smell.

2. Introceptors: They are located in the visceral organs and blood vessels.
They are sensitive to internal stimuli.

3. Prerprioceptors:
They provide information about position and movements of the body.

Question 17.
Your friend is returning home after his visit to USA. All at home are waiting for his arrival.
How would you feel? State the division of ANS that predominates and mention few changes take place in your body?
Answer:

• The sympathetic and parasympathetic neural system are is mainly involved.
• On seeing his friend out of the happiness his autonomic nervous system is stimulated and he gets tears in his eyes.
• After sometime the parasympathetic stops the secretion of tears.

Question 18.
What is meant by depression? What are its symptoms?
Answer:

• Depression is a functional deficiency of serotonin and nor epinephrine.
• This disorder is characterized by a pervasive negative mood, loss of interest an inability to experience pleasure and suicidal tendencies.

Question 19.
When dust falls on our eyes like eyelids close immediately not waiting for our willingness, on touching a hot pan the hand is with drawn rapidly. Do you know how this happens?
Answer:
Reflex axon.
When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect it is due to fast action of spinal cord.

Question 20.
What are the differences between conditioned and unconditioned reflex.
Answer:

Unconditioned reflex	Conditioned reflex
In born reflex for an unconditioned stimulus.	It’s response to a stimulus acquired by learning.
It does not need any past experience or training	Does not naturally exists in animals.
Eg: Blinking of an eye when a dust particle about to fall in it	Eg: Excitement of salivary gland on seeing a food

Question 21.
What is the difference between exteroceptors and interoceptors.
Answer:

Exteroceptors	Interoceptors
Located at or near the surface of the body	They are located in the visceral organs and blood vessels.
These receive impulses from hearing vision touch taste and smell.	They are sensitive to internal stimuli.

Question 22.
Where are lens fiber seen? What is the substance that fills it?
Answer:

• The lens is a transparent biconvex structure made up of slender columnar epithelial cells.
• These cells are called as lens fibre.
• These cells are formed of crystaline protein.

Question 23.
What is meant by accommodation of eye? List the structures that are involved in this process?
Answer:

• The ability of the eyes to focus objects at varying distances is called accommodation.
• This is achieved by suspensory ligament ciliary muscle and ciliary body

Question 24.
Name the structures that helps in fixing eyes in the eye ball?
Answer:
Eye is held in its position with the help of six extrinsic muscles.
They are
Superior
Interior
Lateral
Median rectus muscle
Superior oblique
Inferior oblique

Question 25.
Name the accessory structure which protects eye?
Answer:

• Eye lashes and the eye brows
• They help to protect the eyeballs from foreign objects, perspiration and from direct sunrays.
• Sebaceous glands or ciliary glands.
• They secrete a lubricating fluid.
• Lacrymal glands.
• Secrete tears.
• Tears contain salts mucus and lysozyme enzyme to destroy bacteria.

Question 26.
Give an account of aqueous humour?
Answer:

• It supplies nutrients and oxygen to the lens cornea and retinal cells.
• It is produced and drained at same rate.
• It maintains a constant infra ocular pressure of about 16 mmHg.

Question 27.
Give short notes on glaucoma.
Answer:
Any block in the canal of Schlemm increases the intra ocular pressure of aqueous humour and leads to “glaucoma when the optic nerve and the retina are compressed due to pressure.

Question 28.
Name the detects of detraction.
Answer:

• Myopia
• Hyper metropia
• Astigmatism
• Cataract

Question 29.
Give notes on pigments of colour vision
Answer:

• Redcones. It contains visual pigment erythropsin which is sensitive to long wavelength close to 560 nm.
• Green cones – It has a pigment chloropsin which is sensitive to medium wavelength of 530 nm.
• Blue cones – It has a pigment which is sensitive to short wavelength of 420 nm.

Question 30.
What is the difference between conducting hearing loss and neuro sensory hearing loss.
Answer:

Conducting Hearing loss	Neuro sensory
This defect is due to the blockage of ear canal with ear wax	The defect may be in the organ of cortii
Rupture of ear	The auditory nerve
Middle ear infection with fluid accumulation restriction of ossicular movement	In the ascending auditory pathways or auditory cortex

Question 31.
Give short notes on melanin.
Answer:

• Melanocytes synthesize melanin.
• It gives colour to skin and protects it from the sun.
• Vitiligo is a condition in which the melanin pigment is lost from the areas of the skin causing white patches.
• The leukoderma appears when melanocytes fails to synthesis melanin pigment.

Question 32.
What is meant by the proprioception?
Answer:

• Balance is part of a sense called proprioception.
• It is the ability to sense the position orientation and movement of the body.

Question 33.
Which is the fastest renewable cells in the body? How is it affected?
Answer:
Taste buds

• Taste buds are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These cells are replaced every 7-10 days.

Question 34.
Name the disease which can affect people of any age gender or ethnic group. This is not the contagious disease?
Answer:
Leucoderma is a condition in which the melanin pigment is lost from areas of the skin causing white patches.

Question 35.
What are meissner’s corpuscles?
Answer:

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hairless skin areas such as finger tips and soles of the feat.

(5 Marks)

IV. Brief Answers

Question 1.
Describe structure of a neuron.
Answer:
Neuron is composed of three region.

1. Cell body
2. Dendrites
3. axon.

Cell body:
The cell body is spherical. There is no centriole.
The plasma membrane covering the neuron is called neurilemma and axon is axolemma.

Dendrites:
The repeatedly branched short fibres coming out of the cell bod dendrites which transmit impulses towards the cell body in it’s cytoplasm Nissl’s granules are present.

Axon:
It is a long fibre that arises from a cone shaped area of the cell body. There is no golgi bodies and Nissis granules in its cytoplasm.
The axon of peripheral nerves is surrounded by Schwann’s cells to form myelin sheath. The myelin sheath is not continuous. There are gaps in the myelin sheath between an adjacent Schwann cells called nodes of Ranvier.
Each branch at the distal end of the axon terminates into a knob like structure called synaptic knob which possesses synaptic vesicles filled with transmitters. The axon transmits nerve impulses away from the body to neuro muscular junction. The myelinated nerve cell transmits impulses faster than non – myelinated nerve cells.

Question 2.
Describe about the different types of neuron with diagram?
Answer:
1. Multi polar neurons:
They have many processes with one axon and two or more dendrites.

2. Bipolar neurons:
They have two processes with one axon and one dendrites.
These are found in the retina of the eye, inner ear and the olfactory area of the brain.

3. Unipolar neurons:
They have a single short process and one axon.

Question 3.
Give an account of Ionic channels in the axolemma?
Answer:
Ionic channels:

1. Leakage channels
2.  Ligand – gated channels
3. Voltage-gated channels.

1. Leakage channels:

• • These channels are always remain open.
  • K⁺ leakage channels are more in number than the Na⁺ leakage channels.
  • Sarco lemma has greater permeability to k⁺ icons than Na⁺ icons
  • These icons keep moving continuously to maintain the potential continuously to maintain the
  • potential difference across the axo lemma.

2. Ligand – gated channels:
These are chemic called gated channels which open or close in response to a chemical stimuli.

• They are located between the pre synaptic membrane of the first axon and post synaptic membrane of the second.
• The neurotransmitter acetylcholine opens ligand channels that allow Na⁺ and Ca⁺⁺ ions diffuse inward and K⁺ icon diffuse outward.

Voltage-gated channels:
Answer:
This channels open in response to a physical stimulus in the form of vibration such as touch and pressure.

• Sodium Voltage gated channels.
• Potassium Voltage gated channels.

Question 4.
Give an account of resting potential?
Answer:

• The electrical potential difference across the plasma membrane of a resting neuron is called the resting potential.
• More potassium is getting out of the neurilemma rather than sodium which is getting into.
• Hence the interior of the cell becomes negative.
• In resting condition the axon membrane is more permeable to K⁺ and less permeable to Na⁺ cons whereas it remains impermeable to negatively charged protein icons.
• In the outer side of axon there is low concentration of K⁺ and high concentration of Na⁺ ions.
• This difference can be maintained by ATP – driven sodium – potassium pump. This exchange 3 Na⁺ outwards for 2K⁺ in the cells.
• In neuron the resting membrane potential ranges from 40mv to 90mv.
• And its normal value is 70mv.

Question 5.
a) What is meant by action – membrane potential?
b) What is Depolarisation?
Answer:
a) An action potential occurs when a neuron sends information down an axon away from the cell body.
b) When a nerve fibre is stimulated sodium voltage gate opens and makes the axo lemma permeable to Na⁺⁺ and the potassium voltage gate closes and potassium is getting out of the axo lemma. The concentration reduces

• The axo lemma becomes positively charged inside and negatively charged outside.
• This reversal of electrical charge is called depolarisation potential reaches level called threshold potential (-55mV)
• The stimulus which bring this threshold potential is called threshold stimulus.
• The action potential occur in response to a threshold stimulus but does not occur at subthreshold stimuli. This is called all or none principle.
• Due to the rapid influx of Na⁺ ions the membrane potential shoots rapidly up to +45mV which is called the spike potential.

Question 6.
What is synapsis?
Answer:

• The junction between two neurons is called a synapses through which a nerve impulse is transmitted,
• The first neuron involved in the synapse forms the pre synaptic neuron and the second neuron is the post – synaptic neuron
• A small gap between the two neuron is synaptic cleft.
• The axon terminals contain synaptic vesicles filled with neurotransmitters.
• When an impulse arrives at the axon terminals it depolorizes the pre – synaptic membrane opening the voltage gated calcium channels.
• Influx of calcium ions stimulates the synaptic vesicles toward the pre – synaptic membrane and fuse with it.
• In the neurilemma the vesicles release their neurotransmitters into the synaptic cleft by exocytosis.
• The released neurotransmitters bind to their specific receptors.
• The entry of the ions can generate a new potential in the post synaptic neuron.
• This excitatory post – synaptic potential causes depolarisation and in inhibitory post – synaptic potential causes hyperpolarisation.

Question 7.
In the following diagram indicate
Answer:
(A) – Frontal
(B) – parietal
(C) – occipital
(D) – temporal lobe

Question 8.
Describe the structure of human brain with a diagram?
Answer:

• The brain is located in the cranial cavity and it is covered by three cranial membranes.
• The outer layer — durameter the inner most layer piameter and the median thin layer arachnoid. The brain is divided into three major regions. Fore brain, Mid-brain, Hind

• It comprises of cerebrum and diencephalon.
• Tire cerebral cortex is composed of grey and unmyelinated nerve cells.
• The medulla is composed of white mater.
• The surface of the cerebrum shows many convolutions and grooves. The folds are called gyri and the shallow groove is sulci.

There are eight lobes in cerebrum.
A pair of frontals, parietals temporals and occipital lobes.
The longitudinal fissure divides the cerebrum | longitudinally into two hemispheres The hemispheres are connected by a tract of nerve fibres called corpus callosum.
Cerebral cortex has three functional areas

Sensory areas :
It occurs in the parietal temporal and occipital lobes of the cortex.

Motor areas :
This controls voluntary muscular movement which lies in the posterior part of the frontal iobes.

Association area :
It lies in between cortex and diencephalan This involves in memory communication learning and reasoning.

Question 9.
Describe the structure of hind brain?
Answer:
Rhombencephalon forms the hind brain.
It comprises of cerebellum pons varolii and medulla oblongata.

Cerebellum:
It is the second largest part of the brain. It consists of two cerebellar hemisphere and central worm shaped part the vermis.

Function:
It controls and coordinates muscular movements and body equilibrium.
Any damage to cerebellum results in unco-ordinated voluntary muscle movements.

Pons varoli:
It lies in between the midbrain and the medulla oblongata.
This form a bridge between the two cerebellar hemisphere and connect the medulla oblongata with the other region of the brain.

Medulla oblongata:
This forms the posterior most part of the brain. It connects the spinal cord with various parts of the brain.
It receives and integrates signals from spinal cord and sends it to the cerebellum and thalamus.

Function:
It controls cardiovascular reflexes respiration and gastric secretions.

Question 10.
Describe the structures of diencephalon?
Answer:
Epithalamus

• It is a non – nervous tissue.
• The anterior part of epithalamus is vascular and folded to form the anterior choroid plexus.
• The epithalamus forms a short stalk which ends in a rounded body called pineal body.
• This secretes the hormone melotonin which regulates sleep and wake cycle.

Thalamus

• It is formed of grey matter
• It serves as a relay centre for impulses between the spinal cord brain stem and cerebrum.
• It plays a key role in learning and memory.
• It is a major co-ordinating centre for sensory and motor signalling.

Hypothalamus

• It forms the floor of the diencephalon.
• It has a pair of small rounded body called mammillary bodies
• It involves in olfactory reflexes and emotional responses to odour.
• It maintains homeostasis.
• It controls the body temperature.
• Urge for eating and drinking.
• It also contains a group of neuro secretory cells which secrete the hypothalamic hormones.
• It also acts as the satiety centre.

Question 11.
Give an account of ventricles of the brain.
Answer:

• The brain has four hollow fluid filled spaces.
• The c – shaped space found inside each cerebral hemisphere forms the lateral ventricles I and II which are separated by a thin membrane called the septum pellucidum. Each lateral ventricle communicates with the III ventricle through opening called foramen of mortro.
• The III ventricle opens in to the IV th ventricle through a canal called aqueduct of sylvius. Choroid plexus is a network of blood capillaries found in the root of the ventricles and forms cerebro spinal fluid.

Functions

• CSF provides buoyancy to the CNS.
• It acts as a shock absorber.
• It nourishes the brain by supplying food and oxygen.
• It carries harmful metabolic wastes from the brain to the blood.
• It maintains a constant pressure inside the cranial vessels

Question 12.
Differentiate the conditioned stimulus from unconditioned stimulus.
Answer:

Conditioned	Unconditioned
1. Not through learning	Acquired by learning
2. In born reflex	It is not an in born reflex
3. It does not need any past experience	Experience makes it a part of the behaviour
4. Eg: Blinking of an eye when a dust fall in to it.	Eg: Secretion of salivary gland on seeing the food

Question 13.
Tabulate the nerves and functions and its nature of 6-12th cranial nerves.
Answer:

Cranial nerves	Nature of nerve	Function
I Olfactory nerve	Sensory	Sense of smell
II Optic nerve	Sensory	Sense of sight
III Oculomotor nerve	Motor	Movement of the eye
IV Trochlear nerve	Motor	Rotation of the eye ball
V Trigeminal nerve	Sensory and motor (mixed)	Functioning of facial parts
VI Abducens nerve	Motor	Rotation of the eye ball
VII Facial nerve	Mixed	Functioning of facial parts
VIII Auditory/ Vestibulocochlear nerve	Sensory	Maintains the equilibrium of the body/ Auditory function
IX Glossopharyngeal nerve	Mixed	Taste and touch
X Vagus	Mixed	Regulation of the visceral organs
XI Spinal accessory	Motor	Muscular movement of pharynx, larynx, neck and shoulder
XII Hypoglossal	Motor	Speech and swallowing

Question 14.
Tabulate the functions of sympathetic and para sympathetic nerve.
Answer:

Sympathetic nervous system	Para sympathetic nervous system
1. It dialates pupil	It constricts pupil of the eye
2. It inhibits the secretion of saliva	It stimulates saliva secretion
3. It increases the heart beat	It reduces the heart beat
4. It dialates bronches	It constricts the bronchus
5. It inhibits digestion	It stimulates digestion
6. It increases the glucose release	It stimulates bile release
7. Stimulates epinephrine and nor epinephrine release	It reduces the epinephrine and nor epinephrine release
8. Inhibits peristalsis and secretion	Stimulates peristalsis and secretion
9. Reflexes bladder	Contracts bladder

Question 15.
Describe the structure of cross section of spinal cord.
Answer:

• There are two indentations the posterior median sulcus and the anterior median fissure.
• In the spinal cord the grey matter forms an inner butterfly shaped region surrounded by the outer white matter.
• The grey matter consists of dendrites inter neurons and guai cells.
• White matter consists of bundles of nerve fibres.
• Each half of the grey matter is divided into a
• Dorsal horn – Cell bodies of inter neurons.
• Ventral horn – Efferent motor neurons supplying the skeletal muscle.
• Lateral horn – Nerves supply to heart smooth muscles exocrine glands. Originate from the cell bodies.
• Ascending tract – This carry sensory impulses to the brain.
• Descending tract – This carry motor impulses to brain.

Question 16.
Give an account of the functional components of a reflex arc.
Answer:
Sensory receptor – It is a sensory structure that responds to specific stimulus.
Sensory neuron – This neuron takes the sensory impulse to the grey (afferent) matter of the
spinal cord through the dorsal root of the spinal cord.
Inter neuron – It may serve to transmit the impulses from the sensory neuron to the motor neuron.
Motor neuron – It transmits impulse from CNS to the effector organ
Effector neuron – It may be a muscle or gland which responds to the impulse received.

• Lacrymal glands located in the upper lateral region of each orbit secrete tears.
• Tears are secreted at the rate of 1 ml/day.
• Tears contain salt mucus and lysozyme enzyme to destroy bacteria.
• The protective mucus membrane present in the outer surface of the eye ball.
• The eye has two compartments anterior and posterior compartments filled with aqueous humour and vitreous humour respectively.
• The eye ball is consists of three layers sclera, vascular choroid and sensory retina.

Sclera

• It consists of anterior cornea and the posterior sclera.
• Cornea is composed of stratified squamous epithelium. Sclera forms the white of the eye and protects the eyeball.
• At the junction of the sclera and the cornea is a channel called canal of schlemm which continuously drains out the excess of aqueous humour.

Choroid layer
It is highly vascularised pigmented layer.

Question 17.
Tabulate the differences between sympathetic and parasympathetic neural system.
Answer:

Sympathetic Neural System (SNS)	Parasympathetic Neural System (PNS)
SNS originates in the thoracic and lumbar region of the spinal cord.	PNS originates in the cranial region of the brain and the sacral region of the spinal cord.
Sympathetic ganglia are linked up to form a chain.	Its ganglia remain isolated
Preganglionic fibres are short and the postganglionic fibres are long.	Preganglionic fibres are long and the postganglionic fibres are short.
Noradrenaline is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is adrenergic.	Acetylcholine is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is cholinergic.
Active during stressful conditions preparing the body to face them.	Active during relaxing times restoring normal activity after a stress.
The overall effect is excitatory and stimulating.	The overall effect is inhibitory.
It is considered as the flight or fight system.	It is considered as “The rest and Digest System” or “The Feed and Breed System”.

Question 18.
Give an account of peripheral nervous system.
Answer:

• All nervous tissue outside the central nervous system is the peripheral neural system.
• It includes nerves ganglia enteric plexuses and sensory receptors.
• Ganglia are sinai! masses of nervous tissue.
• The neurons of these plexuses help in regulating the digestive system.
• The specialised structure that helps to respond to changes in the environment are called sensory receptor.
• This triggers nerve impulses along the afferent fibres to CNS.
• PNS comprises of 12 pairs of cranial nerves and 31 pairs of spinal nerve.
• The neural retina layer consists of cones and rods.
• The yellow flat spot at the centre of the posterior region of the retina is called macula lutea.
• A small depression present in the centre of the

Question 19.
Describe the structure of an eye.
Answer:

• Eye is located in the orbit of the skull and held in its position with the help of six-extrinsic muscles.
• Eye lashes and the eye brows help to protect the eyeballs.
• Anteriorly the choroid thickens to form the ciliary body and coloured portion of the iris.
• The aperture at the centre of the iris is the pupil through which the light enters.
• The ability of the eyes to focus objects at varying distances is called accommodation which is achieved by suspensory ligament ciliary muscle and ciliary body.

Retina

• It contains two region.
• A sheet of non visual pigmented part neural visual region.
• yellow spot is called fovea centralis which contains only cones.
• The optic nerves and the retinal blood vessels enter the eye slightly below the posterior pole which is devoid of photo receptors called blind spot.

Question 20.
Draw the diagram of cross section of the eye.
Answer:

Question 21.
Describe about the mechanism of vision.
Answer:

• When light enters the eye it gets refracted by the cornea, aqueous humor and lens and it is focused on the retina and excites the rod and cone cells.
• The rods and cones contain the retinal a derivative of vitamin A and the photo pigment opsin.
• Light induces dissociation of retinal from opsin and causes the structural changes in opsin.
• This generates an action potential in the photo receptor cells.
• It is transmitted by the optic nerves to the visual cortex of the brain via the optic nerves for the perception of vision.

Question 22.
List the refractive errors of eye.
Answer:
Myopia

• The affected person cannot see distant objects.
• As the eyeball is elongated or thickened lens the image of distant object is formed in front of the yellow spot.
• This error can be corrected using concave lens.

Hyper metropia

• Affected person cannot see the nearby objects.
• This is due to a shortened eyeball and thin lens. So the image of closest object is converged behind the retina.
• This defect can be corrected by using convex lens.

Presbyopia

• Due to aging the lens loses elasticity and power of accommodation.
• Convex lenses are used to correct this defect.

Astigmatism

• It is due to the rough curvature of cornea or lens.
• Cylindrical glasses are used to correct this error.

Question 23.
Describe the structure of an ear?
Answer:
Anatomically the ear is divided into three regions external ear middle ear and inner ear.
External ear:-

• It consists of pinna external auditory meatus and ear drum.
• The pinna collects the sound waves.
• The external auditory meatus extends up to the tympanic membrane.
• The tympanic membrane is covered with skin outside and with mucus membrane inside.

Middle ea:-

• It is a air filled cavity in the temporal bone.
• The middle ear contains three ossicles malleus incus and stapes.
• The malleus is attached to the tympanic membrane and its head articulates with the incus.
• The stapes is attached to the oval window in the inner ear.
• The Eustachian tube connects the middle ear cavity with the pharynx

Inner ear:-

• It is the fluid filled cavity consisting of two parts the bony labyrinth and the membranous labyrinths.
• The bony labyrinth consists of three areas, cochlea, vestibule and semicircular canals.

a Cochlea is a coiled portion consist of 3 chambers namely.

1. Scala vestibule
2. Scala media
3. Scala tympanii.

Scala vestibule and scala tympani are filled with peri lymph.
The scala media is filled with endo lymph.

Question 24.
Describe the structure and functions of organ of cortii.
Answer:

• Organ of corti is a sensory ridge located on the top of the basilar membrane.
• Basilar membrane contains numerous hair cells that are arranged in four rows.
• Protruding from the apical part of each hair cell is hair like structures known as stereocilia.
• On the organ of cortii a stiff gel membrane called tectorial membrane is situated.
• During the conduction of sound wave sterocilia makes contact with tectorial membrane.

Question 25.
Give an account of mechanism of sound?
Answer:

• Sound waves entering the external auditory meatus fall on the tympanic membrane and gets vibrated.
• These vibrations are transmitted to the oval window through the three ear ossicles.
• Since tympani membrane is 17-20 times larger than the oval windows. This pressure exerted on the oval window is about 20 times more than that on the tympanic membrane.
• This pressure causes the round window to alternately bulge outward and inward mean while the basilar membrane along with the organ of corti move up and down.
• These movements of hair alternately open and close the mechanically gated ion channel causes action potential.
• This is propagated to the brain as sound sensation through cochlear nerve.

Question 26.
Differentiate the rods from cones.
Answer:

Rods	Cones
1. Helps in seeing in dim light	Colour perception in bright light
2. Contains Rhodopsin pigment	Contains photopsin
3. The protein retinol and vitamins aldehyde combine to form scotoptin called Rhodopsin	The protein opsin and retinol combines to form photopsin.
4. There are 120 million rods are seen on the retina	6-7 million cone cells are seen on the retina
5. Rods are seen richly over the surface of the foveal region.	Cones are richly present on the foveal region.

Question 27.
A man is chating with his family in this time a house fly sits on his back at once he lifts the hand and strikes the fly. How can he know that? What are the structures involved in this perception?
Answer:

• The skin senses this skin is the largest sense organ.
• All over the skin sensory receptors of pressure heat cold and pain.
• Following are the sensory receptors of skin.

Tactile merkel disc

• It is a light touch receptor lying in the deeper layer of epdidermis.
• Hair follicle receptors. These are light touch receptors lying around the hair follicles.

Meissner’s corpuscles

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hair less skin areas such as finger tips and soles of the feet.

Pacinian corpuscles

• These are the large egg shaped receptors found scattered in the dermis.
• It detects different textures temperature hardness and pain.

Ruffini endings
This lie in the dermis responds to continuous pressure Krause end bulbs are thermo receptors that sense temperature.

Question 28.
Give notes on Defects of ear.
Answer:

• Deafness may be temporary or permanent
• Conductive deafness
• Possible causes
• The blockage of ear canal with ear wax.
• Rupture of ear drum.
• Middle ear infection with fluid accumulation,
• Restriction of ossicular movement.
• Sensory-neural deafness
• The defect may be in the organ of cortii or the auditory nerve or in the ascending auditory pathways or auditory cortex.

Question 29.
a) What is meant by proprioception?
b) Give an account of organs of equilibrium?
Answer:
The ability to sense the position orientation and movement of the body is called proprioception.
1. Vestibular system: This is the organ of balance.
It is composed of a series of fluid filled sacs contain endolymph and are kept in the surrounding peri lymph.

Semicircular canals

• The canals that lie posterior and lateral to the vestibule are semi circular canals.
• At each end of semi circular canal has a swollen area called ampulla.
• Each ampulla has a sensory area known as crista ampullaris.
• It detects the rotational movement of the head.

Question 30.
Give notes on Gustatory receptors?
Answer:

• The sense of taste is considered to be the most pleasurable of all senses.
• The tongue is provided with many small projections called papillae which gives the tongue an abrasive feel.
• Most taste buds are located on the tongue few are scattered on the soft palate inner surface of the cheeks.

Structure
Taste buds are flask shaped and consists of 50 -100 epithelial cells of two major types.

1. ustatory epithelial cells: Taste cells.
2. Basal epithelial cells

Gustatory epithelial cells:

• Long gustatory hairs project from the tip of the gustatory cells and extends through a taste pore senses the taste.
• The sensory dendrites send signal to the brain and senses the taste.
• The basal cells differentiates in to new gustatory cells.

Question 31.
Describe the structure of the receptor involved with a diagram.
Answer:

• Taste buds are flask shaped. There are two major types.
• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.
• Long micro villi called gustatory hairs project from the tip of the gustatory cells and extends through a taste pore to the surface of the epithelium.
• Gustatory hairs are tire sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 12 Basic Concepts of Organic Reactions Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 12 Basic Concepts of Organic Reactions

11th Chemistry Guide Basic Concepts of Organic Reactions Text Book Back Questions and Answers

Textbook Evaluation:

I. Choose the best answer:

Question 1.
For the following reactions
(A) CH₃CH₂CH₂Br + KOH → CH₃ – CH = CH₂ + KBr + H₂O

(B) (CH₃)₃CBr + KOH → (CH₃)₃COH + KBr

(C)
Which of the following statement is correct?
a) (A) is elimination, (B) and (C) are substitution
b) (A) is substitution, (B) and (C) are elimination
c) (A) and (B) are elimination and (C) is addition reaction
d) (A) is elimination, (B) is substitution and (C) is addition reaction
Answer:
d) (A) is elimination, (B) is substitution and (C) is addition reaction

Question 2.
What is the hybridisation state of benzyl carbonium ion?
a) sp²
b) spd²
c) sp³
d) sp²d
Answer:
a) sp²

Question 3.
Decreasing order of nucleophilicity is
a) OH^– > NH₂^– > -OCH₃ > RNH₂
b) NH₂^– > OH^– > -OCH3 > RNH₂
c) NH₂^– > CH₃O^– > OH^– > RNH₂
d) CH₃O^– > NH₂^– > OH^– > RNH₂
Answer:
b) NH₂^– > OH^– > -OCH3 > RNH₂

Question 4.
Which of the following species is not electrophilic in nature?
a) Cl⁺
b) BH₃
c) H₃O⁺
d) ⁺NO₂
Answer:
c) H₃O⁺

Question 5.
Homolytic fission of covalent bond leads to the formation of
a) electrophile
b) nucleophile
c) carbocation
d) free radical
Answer:
d) free radical

Question 6.
Hyper conjucation is also known as
a) no bond resonance
b) Baker – nathan effect
c) both (a) and (b)
d) none of these
Answer:
c) both (a) and (b)

Question 7.
Which of the group has highest + I effect?
a) CH₃–
b) CH₃ – CH₂ –
c) (CH₃)₂ – CH-
d) (CH₃)₃ – C –
Answer:
d) (CH₃)₃ – C –

Question 8.
Which of the following species does not exert a resonance effect?
a) C₆H₅OH
b) C₆H₅Cl
c) C₆H₅NH₂
d) C₆H₅NH₃
Answer:
d) C₆H₅NH₃

Question 9.
– I effect is shown by
a) – Cl
b) – Br
c) both (a) and (b)
d) – CH₃
Answer:
c) both (a) and (b)

Question 10.
Which of the following carbocation will be most stable?
a) Ph₃⁺C –
b) CH₃ – ⁺CH₂ –
c) (CH₃)₂ – ⁺CH
d) CH₂ = CH – ⁺CH₂
Answer:
d) CH₂ = CH – ⁺CH₂

Question 11.
Assertion:
Tertiary Carbocations are generally formed more easily than primary Carbocations ions.
Reason:
Hyper conjucation as well as inductive effect due to additional alkyl group stabilize tertiary carbonium ions.
a) both assertion and reason are true and reason is the correct explanation of assertion.
b) both assertion and reason are true but reason is not the correct explanation of assertion.
c) assertion is true but reason is false.
d) both assertion and reason are false.
Answer:
a) both assertion and reason are true and reason is the correct explanation of assertion.

Question 12.
Heterolytic fission of C – Br bond results in the formation of
a) free radical
b) Carbanion
c) Carbocation
d) Carbanion and Carbocation
Answer:
d) Carbanion and Carbocation

Question 13.
Which of the following represent a set of nucleophiles?
a) BF₃, H₂O, NH^2-
b) AlCl₃, BF₃, NH₃
c) CN, RCH₂^–, ROH
d) H⁺, RNH₃⁺, :CCl₂
Answer:
c) CN, RCH₂^–, ROH

Question 14.
Which of the following species does not acts as a nucleophile?
a) ROH
b) ROR
c) PCl₃
d) BF₃
Answer:
d) BF₃

Question 15.
The geometrical shape of carbocation is
a) Linear
b) tetrahedral
c) Planar
d) Pyramidal
Answer:
c) Planar

II. Write brief answer to the following questions:

Question 16.
Write short notes on
a) Resonance
b) Hyper Conjucation
Answer:
a) Resonance (or) Mesomeric effect:
The resonance is a chemical phenomenon which is observed in certain organic compounds possessing double bonds at a suitable position. Certain organic compounds can be represented by more than one structure and they differ only in the position of bonding and lone pair of electrons. Such structures are called resonance structures (canonical structures) and this phenomenon is called resonance. This phenomenon is also called mesomerism or mesomeric effect.

For example, the structure of aromatic compounds such as benzene and conjugated systems like 1,3 – butadiene cannot be represented by a single structure, and their, observed properties can be explained on the basis of a resonance hybrid.

In 1,3 butadiene, it is expected that the bond between C¹ – C² and C³ – C⁴ should be shorter than that of C² – C³, but the observed bond lengths are of same. This property cannot be explained by a simple structure in which two n bonds localised between C¹ – C² and C³ – C⁴. Actually the n electrons are delocalised as shown below.

The resonating structures are called canonical forms and the actual structure lies between these three resonating structures, and is called a resonance hybrid. The resonance hybrid is represented as below.

Similar to the other electron displacement effect, mesomeric effect is also classified into positive mesomeric effect (+M or +R) and negative mesomeric effect (-M or -R) based on the nature of the functional group present adjacent to the multiple bond.

b) Hyper Conjucation:
The delocalisation of electrons of a bond is called as hyper conjugation. It is a special stabilising effect that results due to the interaction of electrons of a σ -bond (usually C – H or C – C) with the adjacent, empty non-bonding p-orbital or an anti¬bonding σ* or π*-orbitals resulting in an extended molecular orbital. Unlike electromeric effect, hyper conjugation is a permanent effect.

It requires an α-CH group or a lone pair on atom like N, O adjacent to a π bond (sp² hybrid carbon). It occurs by the overlapping of the σ-bonding orbitai or the orbital containing a lone pair with the adjacent π-orbital or p-orbital.

Example:
In propene, the σ -electrons of C-H bond of methyl group can be delocalised into the π -orbital of doubly bonded carbonas represented below.

In the above structure the sigma bond is involved in resonance and breaks in order to supply electrons for delocalization giving rise to 3 new canonical forms. In the contributing canonical structures: (Il), (III) & (IV) of propene, there is no bond between an α-carbon and one of the hydrogen atoms. Hence the hyper conjugation is also known as “no bond resonance” or “Baker Nathan effect”. The structures (II), (III) & (IV) are polar in nature.

Question 17.
What are electrophiles and nucleophiles? Give suitable examples for each.
Answer:
Nucleophiles are reagents that has high affinity for electron positive centers. They possess an atom has an unshared
pair of electrons, and hence it is in search for an electro positive centre where it can have an opportunity to share its electrons to form a covalent bond, and gets stabilised. They are usually negatively charged ions or electron rich neutral molecules (contains one or more lone pair of electrons). All Lewis bases act as nucleophiles.
Example :
Ammonia(NH₃) and amines (RNH₂), water (H₂O), alcohols (ROH) and ethers ((R-O-R)

Electrophiles:
Electrophiles are reagents that are attracted towards negative charge or electron rich center. They are either positively charged ions or electron deficient neutral molecules. All Lewis acids acts as electrophiles. Neutral molecules like SnCl4 can also act as an electrophile, as it has vacant d – orbitals which can accommodate the electrons from others.
Example:
Carbon dioxide (CO₂), dichlorocarbene (: CCl₂), Aluminium chloride (AlCl₃), boron trifluoride (BF₃) and Ferric Chloride (FeCl₃)

Question 18.
Show the heterolysis of covalent bond by using curved arrow notation and complete the following equations. Identify the nucelophile in each case.
i) CH₃ – Br + KOH →
ii) CH₃ – O – CH₃ + HI →
Answer:
(i) CH₃ – Br + KOH →
CH₃ – Br + KQH → CH₃OH + KBr
Nucleophile is : OH^–

ii) CH₃ – O – CH₃ + HI →
H            I
CH₃ – O – CH₃ + HI → CH₃OH + CH₃ I
Nucleophile is : I^–

Question 19.
Explain inductive effect with suitable example.
Answer:
Inductive effect is defined as the change in the polarisation of a covalent bond due to the presence of adjacent bonds, atoms or groups in the molecule. This is a permanent phenomenon.

Let us explain the inductive effect by considering ethane and ethylchloride as examples. The C-C bond in ethane is non polar while the C-C bond in ethyl chloride is polar. We know that chlorine is more electronegative than carbon, and hence it attracts the shared pair of electron between C-Cl in ethyl chloride towards itself. This develops a slight negative charge on chlorine and a slight positive charge on carbon to which chlorine is attached.

To compensate it, the C₁ draws the shared pair of electron between itself and C₂ This polarisation effect is called inductive effect. This effect is greatest for the adjacent bonds, but they also be felt farther away. However, the magnitude of the charge separation decreases rapidly, as we move away from C₂ and is observed maximum for 2 carbons and almost insignificant after 4 bonds from the active group.

It is important to note that the inductive effect does not transfer electrons from one atom to another but the displacement effect is permanent. The inductive effect represents the ability of a particular atom or a group to either withdraw or donate electron density to the attached carbon. Based on this ability the substituents are classified as +I groups and -I groups. Their ability to release or withdraw the electron through sigma covalent bond is called +I effect and -I effect respectively.

Highly electronegative atoms and atoms of groups which are cany a positive charge are electron withdrawing or-I group.
Example :
-F , -Cl, -COOH, -NO₂ NH₂

Higher the electronegativity of the substituent, greater is the -I effect. The order of the -I effect of some groups are given below.
NH₃ > NO₂ > CN > SO₃H > CHO > CO > COOH > COCl > CONH₂ > F > Cl > Br > I > OH > OR > NH₂ > C₆H₅ > H

Highly electropositive atoms and atoms are groups which carry a negative charge are electron donating or +1 groups.
Example:
Alkali metals, alkyl groups such as methyl, ethyl, negatively charged groups such as CH₃O^–, C₂H₅O^–, COO^– etc.

Lesser the electronegativity of the elements, greater is the +1 effect. The relative order of +1 effect of some alkyl groups is given below.
-C(CH₃)₃ > -CH(CH₃)₂ > -CH₂CH₃ > -CH₃

Question 20.
Explain electromeric effect with suitable example.
Answer:
Electromeric is a temporary effect which operates in unsaturated compounds (containing > C = C <, > C = 0, etc…) in the presence of an attacking reagent.
Let us consider two different compounds.
(i) compounds containing carbonyl group ( > C = O)
(ii) unsaturated compounds such as alkenes ( > C = C < )

When a nucleophile approaches the carbonyl compound, the n electrons between C and O is instantaneously shifted to the more electronegative oxygen. This makes the carbon electron deficient and thus facilitating the formation of a new bond between the incoming nucleophile and the carbonyl carbon atom.

On the other hand when an electrophile such as H⁺ approaches an alkene molecule, the π electrons are instantaneously shifted to the electrophile and a new bond is formed between carbon and hydrogen. This makes the other carbon electron deficient and hence it acquires a positive charge.

The electrometric effect, is denoted as E effect. Like the inductive effect, the electrometric effect is also classified as + E and – E based on the direction in which the pair of electron is transferred to form a new bond with the attacking agent.

When the π electron is transferred towards the attacking reagent, it is called + E (positive electrometric) effect.

The addition of H+ to alkene as shown above is an example of +E effect.
When the n electron is transferred away from the attacking reagent, it is called, -E (negative electrometric) effect.

The attack of CN^– on a carbonyl carbon, as shown above, is an example of – E effect.

Question 21.
Give examples for the following types of organic reactions
(i) β – elimination
(ii) Electrophilic substitution
Answer:
(i) β – elimination:
In this reaction two substituents are eliminated from the molecule, and a new C – C double bond is formed between the carbon atoms to which the eliminated atoms/groups are previously attached. Elimination reaction is always accompanied with change in hybridisation.
Example:
n – Propyl bromide on reaction with alcoholic KOH gives propene. In this reaction hydrogen and Br are eliminated.

(ii) Electrophilic substitution:

Here, Y⁺ is an electrophile.
Example :
Nitration of Benzene

11th Chemistry Guide Basic Concepts of Organic Reactions Additional Questions and Answers

I. Choose the best answer:

Question 1.
In organic reactions the reactant is called as ______.
a) intermediate
b) product
c) substrate
d) by product
Answer:
c) substrate

Question 2.
Heterolysis of C – Cl bond produces
a) Two free radicals
b) Two carbonium ions
c) Two carbanions
d) One cation and one anion
Answer:
d) One cation and one anion

Question 3.
Heterolysis of propane gives
a) Methyl and ethyl free radicals
b) Methyl carbocation and ethyl free radicals
c) Methyl anion and ethyl carbocation
d) Methyl free radical and ethyl carbocation
Answer:
c) Methyl anion and ethyl carbocation

Question 4.
Removal of hydride ion from a methane molecule will give a
a) Methyl radical
b) Carbonium ion
c) Carbanion
d) Methyl group
Answer:
b) Carbonium ion

Question 5.
The shape of carbonium ion is
a) Planar
b) Linear
c) Pyramidal
d) Tetrahedral
Answer:
a) Planar

Question 6.
The shape of methyl free radicals is
a) Planar
b) Pyramidal
c) Tetrahedral
d) Linear
Answer:
a) Planar

Question 7.
The reaction, (CH₃)₃C – Br -» (CH₃)₃ C⁺ + Br is an example of
a) Homolytic fission
b) Heterolytic fission
c) Cracking
d) All the above
Answer:
b) Heterolytic fission

Question 8.
Which of the following contains only three pairs of electrons
a) Carbocation
b) Carbanion
c) Free radical
d) All of these
Answer:
a) Carbocation

Question 9.
Which of the following species is paramagnetic
a) A carbaonium ion
b) A free radical
c) A carbanion
d) All of these
Answer:
b) A free radical

Question 10.
In carbonium ion the carbon bearing the positive charge is
a) sp hybridized
b) sp² hybridized
c) sp³ hybridized
d) un hybridized
Answer:
b) sp² hybridized

Question 11.
Among the following the true property about
is
a) non – planar
b) C⁺ is sp² – hybridized
c) Electrophile can attack on C⁺
d) Does not undergo hydrolysis
Answer:
b) C⁺ is sp² – hybridized

Question 12.
The geometry of a methyl carbanion is likely to be
a) Pyramidal
b) Tetrahedral
c) Planar
d) Linear
Answer:
a) Pyramidal

Question 13.
Which of the following statements are correct for nucleophile?
a) All negatively charged species are nucleophiles
b) Nucleophiles are Lewis bases
c) Alkenes, alkynes, benzene and pyrrole are nucleophiles
d) All are correct
Answer:
d) All are correct

Question 14.
Which one of the following statement is not correct for electrophile?
a) Electron deficient species are electrophiles
b) Electrophiles are Lewis acids
c) All positively charged species are electrophiles
d) AlCl₃ and SO₃ are electrophiles
Answer:
c) All positively charged species are electrophiles

Question 15.
Electrophiles are
a) Lewis bases
b) Lewis acids
c) Amphoteric
d) All of these
Answer:
b) Lewis acids

Question 16.
Electrophiles are
a) Electron loving species
b) Electron hating species
c) Nucleus loving reagents
d) Nucleus hating reagents
Answer:
a) Electron loving species

Question 17.
Nucleophiles are
a) Electron loving
b) Electron hating
c) Nucleus loving
d) Nucleus hating
Answer:
c) Nucleus loving

Question 18.
Which of the following statement is false about an electrophile?
a) Electron – deficient species
b) An acidic reagent
c) A reagent which attacks an electron – deficient site in a molecule
d) A species which seeks a pair of electrons
Answer:
c) A reagent which attacks an electron – deficient site in a molecule

Question 19.
Methyl carbanium ion is
a) Electrophile
b) Lewis acid
c) Nucleophile
d) Both (a) and (b)
Answer:
c) Nucleophile

Question 20.
Ammonia molecule is
a) A nucleophile
b) An electron deficient
c) A electrophile
d) An acid
Answer:
a) A nucleophile

Question 21.
Methyl carbanion is
a) Electrophile
b) Lewis acid
c) Both (a) and (b)
d) Nucelophile
Answer:
d) Nucelophile

Question 22.
Which of the following statements is correct about inductive effect?
a) Implies the transfer of lone pair of electrons from more electronegative atom to lesser electronegative atom in a molecule.
b) Implies the transfer to lone pair of electrons from lesser electronegative atom to the more electronegative atom in a molecule
c) Increases with increase in distance
d) Implies the atoms ability to cause bond polarization
Answer:
d) Implies the atoms ability to cause bond polarization

Question 23.
The displacement of electrons in a multiple bond in the presence of attacking reagent is called
a) inductive effect
b) electromeric effect
c) resonance
d) Hyper-conjugation
Answer:
b) electromeric effect

Question 24.
The electromeric effect in organic compounds is a
a) Temporary effect
b) Permanent effect
c) Temporary or permanent effect
d) All of the above
Answer:
a) Temporary effect

Question 25.
Which of the following is not the correct condition for resonance?
a) The positions of all the atomic nuclei in the resonating structures may be differ
b) The resonating structures must have the same number of unpaired or paired electrons
c) The molecules exhibiting resonance must be planar in nature
d) The resonating structures must have nearly the same energies
Answer:
a) The positions of all the atomic nuclei in the resonating structures may be differ

Question 26.
Resonance is due to ______.
a) delocalization of sigma electrons
b) migration of H atoms
c) migration of proton
d) delocalization of pi electrons
Answer:
d) delocalization of pi electrons

Question 27.
Resonance in benzene is accompanied by delocalization of n – electrons. Each n electron is attached with
a) 4 carbons
b) 2 carbons
c) 3 carbons
d) 6 carbons
Answer:
d) 6 carbons

Question 28.
Reaction mechanism describes
a) Sequential account of each step describing the details of electron movement
b) energy changes during bond breaking and bond formation
c) kinetics of the reaction
d) all of these
Answer:
d) all of these

Question 29.
Substitution reaction may be
a) Free radical substitution
b) Nucleophilic substitution
c) Electrophilic substitution
d) All are correct
Answer:
d) All are correct

Question 30.
CH₃ – CH₂ – X + KOH_(alc) → CH₂ = CH₂ + KX + H₂O is
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
c) elimination reaction

Question 31.
CH₄ + Cl₂ CH₃Cl + HCl is an example
for
a) free radical substitution reaction
b) electrophilic substitution reaction
c) nucleophile substitution reaction
d) nueclophilic addition reaction
Answer:
a) free radical substitution reaction

Question 32.
C₆H₆ + 3 Cl₂ C₆H₆Cl
a) free radical substitution reaction
b) electrophilic addition reaction
c) free radical addition reaction
d) nueclophilic addition reaction
Answer:
c) free radical addition reaction

Question 33.
Which one of the following orders is correct regarding the – I effect of the substituents?
a) – NR₂ < – OR > – F
b) -NR₂ > – OR > – F
c) -NR₂ < – OR< – F
d) -NR₂ > – OR < – F
Answer:
c) -NR₂ < – OR< – F

Question 34.
Decreasing – I power of given groups is
(1) -CN
(2) -NO₂
(3) – NH₃⁺
(4) -F
a) 2 > 1 > 4 > 3
b) 2 > 3 > 4 > 1
c) 3 > 2 > 4 > 1
d) 3 > 2 > 1 > 4
Answer:
d) 3 > 2 > 1 > 4

Question 35.
Which of the following belongs to – I group?
a) – C₆H₅
b) – CH₃
c) – CH₂CH₃
d) – C (CH₃)₃
Answer:
a) – C₆H₅

Question 36.
Which of the following functional group shows + R effect?
a) – CHO
b) – NO₂
c) -CN
d) – NR₂
Answer:
d) – NR₂

Question 37.
Hyper conjugation is
a) σ – π conjugation
b) Due to delocalization of σ and π bonds
c) No bond resonance
d) All of these
Answer:
d) All of these

Question 38.
+ R power of the given groups
(1) -O^–
(2) – NH₂
(3) – OH
(4) – NHCOCH₃ in decreasing order is
a) 1 > 2 > 3 > 4
b) 4 > 3 > 2 > 1
c) 1 > 3 > 2 > 4
d) 1 > 4 > 3 > 2
Answer:
a) 1 > 2 > 3 > 4

Question 39.
In pyridine:

Number of conjugated electrons are:
a) 6
b) 8
c) Zero
d) 5
Answer:
a) 6

Question 40.
In hyper conjugation, the atom involved is
a) β – H atom
b) α – H atom
c) γ – H atom
d) All
Answer:
b) α – H atom

Question 41.
Hyper conjugation involves overlap of the following orbtials
a) σ – σ
b) σ – p
c) p – p
d) π – π
Answer:
b) σ – p

Question 42.
+ I effect is shown by
a) – NO₂
b) – Cl
c) – Br
d) – CH₃
Answer:
d) – CH₃

Question 43.
Zero inductive effect is exerted by
a) C₆H₅ –
b) – H
c) CH₃ –
d) – Cl
Answer:
b) – H

Question 44.
Hyper conjugation is most useful for stabilizing which of the following carbocations?
a) neo – Pentyl
b) tert – Butyl
c) iso – Propyl
d) Ethyl
Answer:
b) tert – Butyl

Question 45.
Hyper conjugation phenomenon is possible in
a) H₂C = CH₂
b) CH₃CH₂ – CH = CH₂
c) C₆H₅CH = CH₂
d) (CH₃)₃C – CH = CH₂
Answer:
b) CH₃CH₂ – CH = CH₂

Question 46.
Among the following carbocations which is more stable
a) (C₆H₅)₃C⁺
b)
c)
d)
Answer:
a) (C₆H₅)₃C⁺

Question 47.
The compound which gives the most stable carbonium ion on dehydration
a)
b)
c) CH₃ – CH₂ – CH₂ – CH₂OH
d)
Answer:
b)

Question 48.
Which carbocation is more stable?

Answer:
a)

Question 49.
Arrange the following groups in order of decreasing – R (Or – M) power
(1) NO₂
(2) SO₃H
(3) CF₃
(4) CHO
a) 1 > 3 > 2 > 4
b) 1 > 2 > 3 > 4
c) 1 > 4 > 3 > 2
d)4 > 3 > 2 > 1
Answer:
a) 1 > 3 > 2 > 4

Question 50.
The reaction intermediate produced by homolytic cleavage of bond is called
a) carbocations
b) carbanions
c) free radicals
d) carbenes
Answer:
c) free radicals

Question 51.
Most stable carbocation is
a) CH₃ – ⁺CH₂
b) ⁺CH₂CHCl₂
c) ⁺CH₂CH₂Cl
d) ⁺CH₂ – CH₂NO₂
Answer:
a) CH₃ – ⁺CH₂

Question 52.
Carbocation is a reaction intermediate in which of the following reactions
a) E₁ reactions
b) Electrophilic addition reactions of alkenes and alkynes
c) S_N¹ reactions
d) All of the above
Answer:
d) All of the above

Question 53.
Halogenation of an alkane takes place through the intermediate
a) Carbocation
b) carbanion
c) carbon free radical
d) carbene
Answer:
c) carbon free radical

Question 54.
Which free radical is the most stable?

Answer:
a)

Question 55.
The most stable carbonium ion is
a) Methyl carbonium ion
b) Primary carbonium ion
c) Secondary carbonium ion
d) Tertiary carbonium ion
Answer:
d) Tertiary carbonium ion

Question 56.
Stability of which intermediate is not govern by hyperconjugation?
a) Carbon cation
b) carbon anion
c) carbon free radical
d) carboniumion
Answer:
b) carbon anion

Question 57.
Which of the following is an electrophilic reagent?
a) H₂O
b) OH^–
c) NO₂⁺
d) All of these
Answer:
c) NO₂⁺

Question 58.
CH₂ = CH₂ + Br₂ → CH₂Br – CH₂Br is an example for
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
a) addition reaction

Question 59.
R – X + OH^–_(aq) → R – OH + X⁺_(aq) is an example for
a) addition reaction
b) substitution reaction
c) elimination reaction
d) molecular rearrangement
Answer:
b) substitution reaction

Question 60.
C₆H₆ + Cl₂ C₆H₅Cl + HC1 is an example for
a) Free radical substitution reaction
b) Electrophilic substitution reaction
c) Nucleophilic addition reaction
d) Nucelophilic substitution reaction
Answer:
b) Electrophilic substitution reaction

Question 61.
Alkenes readily undergo
a) Substitution reactions
b) Addition reactions
c) Elimination reactions
d) Rearrangement reactions
Answer:
b) Addition reactions

Question 62.
Nitration of benzene is
a) nucleophilic substitution
b) nucleophilic addition
c) electrophilic substitution
d) free radical substitution
Answer:
c) electrophilic substitution

Question 63.
The reaction (CH₃)₃C – Br (CH₃)₃ C – OH is
a) elimination reaction
b) substitution reaction
c) free radical reaction
d) displacement reaction
Answer:
b) substitution reaction

Question 64.
Inductive effect involves
a) displacement of σ – electrons
b) delocalization of π – electrons
c) delocalization of σ – electrons
d) displacement of π – electrons
Answer:
b) delocalization of π – electrons

Question 65.
Compound which shows positive mesomeric effect
a) H₂C = CH – Cl
b) C₆H₅ – NO₂
c) H₂C = CH – CH₂Cl
d) both b & c
Answer:
a) H₂C = CH – Cl

Question 66.
The stability order, in the following carbocations,
CH₃CH₂⁺ (I), (CH₃)₂ ⁺CH (II), (CH₃)₃ C⁺ (III), ⁺CH₃ (IV)
a) I > IV > III > II
b) I > II > III > IV
c) III > IV > I > II
d) III > II > I > IV
Answer:
d) III > II > I > IV

Question 67.
Which is most stable carbocation?
a) n – propyl cation
b) iso – propyl cation
c) Ethyl cation
d) Triphenylmethyl cation
Answer:
d) Triphenylmethyl cation

Question 68.
Which one of the following carbanions is least stable?
a) CH₃CH₂^–
b) HC ≡ C^–
c) (C₆H₅)₃C^–
d) (CH₃)₃C^–
Answer:
d) (CH₃)₃C^–

Question 69.
Among the following, the strongest nucleophile is
a) C₂H₅SH
b) CH₃COO^–
c) CH₃NH₂
d) NCCH₂^–
Answer:
a) C₂H₅SH

Question 70.
Which of the following is least reactive in a nucleophile substitution reaction?
a) (CH₃)₃C – Cl
b) CH₂ = CHCl
c) CH₃CH₂Cl
d) CH₂ = CHCH₂Cl
Answer:
b) CH₂ = CHCl

II. Very short question and answers (2 Marks):

Question 1.
What is mechanism of reaction?
Answer:
Many chemical reactions are depicted in one or more simple steps. Each step passes through an energy barrier, leading to the formation of short lived intermediates or transition states. The series of simple steps which collectively represent the chemical change, from substrate to product is called as the mechanism of the reaction. The slowest step in the mechanism determines the overall rate of the reaction.

Question 2.
What is Positive Mesomeric effect? Give example.
Answer:
Positive resonance effect occurs, when the electrons move away from substituent attached to the conjugated system. It occurs, if the electron releasing substituents are attached to the conjugated system. In such cases, the attached group has a tendency to release electrons through resonance. These electron releasing groups . are usually denoted as +R or +M groups.
Example:
– OH , – SH , – OR , – SR, – NH₂, – O – etc…

Question 3.
What is Negative Mesomeric effect? Give example.
Answer:
Negative resonance effect occurs, when the electrons move towards the substituent attached to the conjugated system. It occurs if the electron withdrawing substituents are attached to the conjugated system. In such cases, the attached group has a tendency to withdraw electrons through resonance. These electron withdrawing groups are usually denoted as -R or -M groups.
Example:
NO₂, > C = O, – COOH, – C ≡ N etc..

Question 4.
Explain hyper conjugate effect of vinyl chloride molecule.
Answer:
Hyper conjugation effect is also observed when atoms/groups having lone pair of electrons are attached by a single bond, and in conjugation with a π bond. The lone pair of electrons enters into resonance and displaces π electrons resulting in more than one structure.

Question 5.
What are the types of substitution reaction?
Answer:
In this reaction an atom or a group of atoms attached to a carbon atom is replaced by a new atom or a group of atoms. Based on the nature of the attacking reagent, these reactions can be classified as

• Nucleophilic substitution
• Electrophilic substitution
• Free radical substitution

Question 6.
Explain free radical substitution reaction with the suitable example.
Answer:

Aliphatic electrophilic substitution
A general aliphatic electrophilic substitution is represented as

Question 7.
Explain Nucleophilic Addition reaction with suitable example.
Answer:

Example:
Addition of HCN to acetaldehyde

Question 8.
Explain free radical addition reaction with suitable example.
Answer:
A general free radical addition reaction can be represented as below.


In the above reaction, Benzoyl perioxide acts as an radial initiator. The mechanism involves free radicals.

Question 9.
Write a note on Functional Group inter conversion.
Answer:
Organic synthesis involves functional group inter conversions. A particular functional group can be converted into other functional group by reacting it with suitable reagents. For example: The carboxylic acid group (-COOH) presents in organic acids can be transformed to a variety of other functional group such as – CH₂-OH, – CONH₂, – COCl by treating the acid with LiAlH₄, NH_3, and SOCl₂ respectively.

Question 10.
After cutting an apple it turn brown. Why?
Answer:
Apples contain an enzyme called polyphenol oxidase (PPO), also known as tyrosinase. Cutting an apple exposes its cells to the atmospheric oxygen and oxidizes the phenolic compounds present in apples. This is called the enzymatic browning that turns a cut apple brown. In addition to apples, enzymatic browning is also evident in bananas, pears, avocados and even potatoes.

III. Short answer questions (3 Marks):

Question 1.
Explain hybridization of carbon in carbocation.
Answer:
In a carbocation, the carbon bearing positive charge is sp² hybridised and hence it has a planar structure. In the reaction involving such a carbocation, the attack of a negatively charged species (nucleophiles) take place on either side of the carbocation as shown below.

Shape of carbocation

The carbanions are generally pyramidal in shape and the lone pair occupies one of the sp3 hybridized orbitais. An alkyl free radical may be either pyramidal or planar.

Shape of carbanion

Shape of Carbon radical

Question 2.
Write three types of electron movement in organic reaction.
Answer:

• lone pair becomes a bonding pair.
• bonding pair becomes a lone pair.
• a bond breaks and becomes another bond.

Type: 1
A lone pair to a bonding pair
Example:

Type: 2
A bonding pair to a lone pair
Example:

Type: 3
A bonding pair to an another bonding pair
Example:

Question 3.
Explain hyper conjugate effect of acrylonitrile.
Answer:
When electronegative atoms or group of atoms are in conjugation with a π – bond,they pull π – electrons from the multiple bond. In case of carbocations, greater the number of alky groups attached to the carbon bearing positive charge, greater is number of the hyper conjucate structure. thus the stability of various carbocations decreases in the order :
3° Carbocation > 2° Carbocation > 1° Carbocation.

Question 4.
What are the different types of organic reactions?
Answer:
Organic compounds undergo many number of reactions, however in actual sense we can fit all those reactions into the below mentiohed six categories.

1. Substitution reactions
2. Addition reactions
3. Elimination reactions
4. Oxidation and reduction reactions
5. Rearrangement reactions
6. Combination of the above

Question 5.
Explain nucleophilc substituion reaction with suitable example.
Answer:
This reaction can be represented as

Here Y^– is the incoming nuclophile or and attacking species and x^– is the leaving group.

Example:
Hydrolysis of alkyl halides by aqueous KOH.
CH₃Br  CH₃OH + Br^–
Aliphatic nucleophilic substitution reactions take place either by S_N¹ or S_N² mechanism.

Question 6.
Explain Electrophilic Addition Reaction with suitable example.
Answer:
A general electrophilic addition reaction can be represented as below.

Example:
Bromination of alkene to give bromo alkane

Question 7.
What are oxidation and reduction reactions? Give suitable example.
Answer:
Many oxidation and reduction reactions of organic compounds fall into one of the four types of reaction that we already discussed but others do not. Most of the oxidation reaction of organic compounds involves gain of oxygen or loss of hydrogen Reduction involves gain of hydrogen and loss of oxygen.
Example:

IV. Long answer questions (5 Marks):

Question 1.
Explain different types of Fission of a covalent bond.
Answer:
All organic molecules contain covalent bonds which are formed by the mutual sharing of electrons between atoms. These covalent bonds break in two different ways, namely homolytic cleavage (symmetrical splitting) and heterolytic cleavage (unsymmetrical splitting). The cleavage of a bond in the substrate is influenced by the nature of the reagent (attacking agent).

Homolytic Cleavage:
Homolytic cleavage is the process in which a covalent bond breaks symmetrically in such way that each of the bonded atoms retains one electron. It is denoted by a half headed arrow (fish hook arrow). This type of cleavage occurs under high temperature or in the presence of UV light in a compound containing non polar covalent bond formed between atoms of similar electronegativity.

In such molecules, the cleavage of bonds results into free radicals. They are short lived and are highly reactive. The type of reagents that promote holmolytic cleavage in substrate are called as free radical initiators. For example Azobisisobutyronitile (AIBN) and peroxides such as benzoyl peroxide are used as free radical initiators in polymerisation reactions.

As a free radical with an unpaired electron is neutral and unstable, it has a tendency to gain an electron to attain stability. Organic reactions involve homolytic fission of C – C bonds to form alkyl free radicals. The stability of alkyl free radicals is in the following order:
C(CH₃)₃ > CH(CH₃)₂ > CH₂CH₃ > CH₃

Heterolytic Cleavage:
Heterolytic cleavage is the process in which a covalent bond breaks unsymmetrically such that one of the bonded atoms retains the bond pair of electrons. It results in the formation of a cation and an anion. Of the two bonded atoms, the most electronegative atom becomes the anion and the other atom becomes the cation. The cleavage is denoted by a curved arrow pointing towards the more electronegative atom.

For example, in tert-butyl bromide, the C – Br bond is polar as bromine is more electronegative than carbon. The bonding electrons of the C – Br bond are attracted more by bromine than carbon. Hence, the C – Br undergoes heterolytic cleavage to form a tert-butyl cation during hydrolysis.

Let us consider the cleavage in a carbon-hydrogen (C-H) bond of aldehydes or ketones We know that the carbon is more electronegative than hydrogen and hence the heterolytic cleavage of C-H bonds results in the formation of carbanion (carbon bears a negative charge). For example in aldol condensation the OH- ion abstracts a a-hydrogen from the aldehyde, which leads to the formation of the below mentioned carbanion.

Question 2.
Explain the acidic nature of carboxylic acid.
Answer:
When a halogen atom is attached to the carbon which is nearer to the carboxylic acid group, its -I effect withdraws the bonded electrons towards itself and makes the ionisation of H easy. The acidity of various chioro acetic acid is in the following order. The strength of the acid increases with increase in the -J effect of the group attached to the carboxyl group.

Trichioro acetic acid > Dichloro acetic acid > Chloro acetic acid > acetic acid.

Similarly, the following order of acidity in the carboxylic acids is due to the +I effect of alkyl group.