Students get through the TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption which is useful for their exam preparation.

TN State Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Answer the following.

Question 1.
What are the steps involved in the digestive process?
Answer:
The process of digestion involves intake of the food (Ingestion), breakdown of the food into micromolecules (Digestion), absorption of these molecules into the bloodstream (Absorption), the absorbed substances becoming components of cells (Assimilation) and elimination of the undigested substances (Egestion). The digestive system includes the alimentary canal and associated digestive glands.

Question 2.
Define the following terms: (i) Thecodont, (ii) Diphyodont, (iii) Heterodont.
Answer:

  1. Each tooth is embedded in a socket in the jaw bone; this type of attachment is called the thecodont.
  2. Human beings and many mammals form two sets of teeth during their lifetime, a set of 20 temporary milk teeth (deciduous teeth) which gets replaced by a set of 32 permanent teeth (adult teeth). This type of dentition is called diphyodont.
  3. The permanent teeth are of four different types (heterodont), namely, Incisors (I) chisel-like cutting teeth, Canines (C) dagger-shaped tearing teeth, Premolars (PM) for grinding, and Molars (M) for grinding and crushing.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 3.
What is plaque? If it persists for a long time what will happen? What are the symptoms of it?
Answer:
Mineral salts like calcium and magnesium are deposited on the teeth and form a hard layer of ‘tartar’ or calculus called plaque. If the plaque formed on teeth is not removed regularly, it would spread down the tooth into the narrow gap between the gums and enamel and causes inflammation, called gingivitis, which leads to redness and bleeding of the gums and to bad smell.

Question 4.
What is the position of the tongue inside the mouth?
Answer:
The tongue is a freely movable muscular organ attached at the posterior end by the frenulum to the floor of the buccal cavity and is free in the front. It acts as a universal toothbrush and helps in intake.

Question 5.
What are the muscles present in the upper and lower regions of the stomach? What are its uses?
Answer:
A cardiac sphincter (gastro oesphageal sphincter) regulates the opening of oesophagus into the stomach. The opening of the stomach into the duodenum is guarded by the pyloric sphincter. It periodically allows partially digested food to enter the duodenum and also prevents regurgitation of food.

Question 6.
What is GERD?
Answer:
If the cardiac sphincter does not contract properly during the churning action of the stomach the gastric juice with acid may flow back into the oesophagus and cause heart bum, resulting in GERD (Gastro Oesophagus Reflex Disorder).

Question 7.
How the stomach can accommodate a large meal?
Answer:
The inner wall of the stomach has many folds called gastric rugae which unfolds to accommodate a large meal.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 8.
How the structure of the small intestine is helping the process of absorption of food after the digestion of food?
Answer:
The ileal mucosa of the small intestine has numerous vascular projections called villi which are involved in the process of absorption and the cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance that increases the surface area enormously.

Question 9.
Give an account of the structure of the large intestine and its associated structures.
Answer:
The large intestine consists of the caecum, colon and rectum. The caecum is a small blind pouch-like structure that opens into the colon and it possesses a narrow finger-like tubular projection called the vermiform appendix. Both caecum and vermiform appendix are large in herbivorous animal and act as an important site for cellulose digestion with the help, of symbiotic bacteria. The colon is divided into four regions – an ascending, a transverse, a descending part and a sigmoid colon. The colon is lined by dilations called haustra (singular – haustrum). The “S” shaped sigmoid colon (pelvic colon) opens into the rectum. The rectum is concerned with the temporary storage of faeces. The rectum opens out through the anus. The anus is guarded by two anal sphincter muscles. The anal mucosa is folded into several vertical folds and contains arteries and veins called anal columns. The anal column may get enlarged and causes piles or haemorrhoids.

Question 10.
Short notes on the following: (i) Serosa, (ii) Muscularis, (iii) Sub-mucose, (iv) Muscosa layers of the alimentary canal.
Answer:
The wall of the alimentary canal from the oesophagus to the rectum consists of four layers namely serosa, muscularis, sub-mucosa and mucosa.

  1. The serosa (visceral peritoneum) is the outermost layer and is made up of thin squamous epithelium with some connective tissues.
  2. Muscularis is made of smooth circular and longitudinal muscle fibres with a network of nerve cells and parasympathetic nerve fibres which controls peristalsis.
  3. The submucosal layer is formed of loose connective tissue containing nerves, blood, lymph vessels and the sympathetic nerve fibres that control the secretions of intestinal juice.
  4. The innermost layer lining the lumen of the alimentary canal is the mucosa which secretes mucous.

Question 11.
Write about the brief account on salivary and gastric glands of the digestive system.
Answer:
The stomach wall has gastric glands that secrete gastric juice and the intestinal mucosa secretes intestinal juice.
Salivary glands: There are three pairs of salivary glands in the mouth. They are the largest parotids gland in the cheeks, the sub-maxillary/ sub-mandibular in the lower jaw and the sublingual beneath the tongue. These glands have ducts such as Stenson’s duct, Wharton’s duct and Bartholin’s duct or duct of Rivinis respectively. The salivary juice secreted by the salivary glands reaches the mouth through these ducts. The daily secretion of saliva from salivary glands ranges from 1000 to 1500 ml.
Gastric glands: The wall of the stomach is lined by gastric glands. Chief cells or peptic cells or zymogen cells in the gastric glands secrete gastric enzymes and Goblet cells secrete mucus. The Parietal or oxyntic cells secrete HCl and an intrinsic factor responsible for the absorption of Vitamin B12 called Castle’s intrinsic factor.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 12.
Describe the structure of the liver, which is considered the largest gland in our body with a neat sketch.
Answer:
Liver: The liver, the largest gland in our body is situated in the upper right side of the abdominal cavity, just below the diaphragm. The liver consists of two major left and right lobes; and two minor lobes. These lobes are connected with the diaphragm. Each lobe has many hepatic lobules (functional unit of the liver) and is covered by a thin connective tissue sheath called the Glisson’s capsule. Liver cells (hepatic cells) secrete bile which is stored and concentrated in a thin muscular sac called the gall bladder. The duct of the gall bladder (cystic duct) along with the hepatic duct from the liver forms the common bile duct. The bile duct passes downwards and joins with the main pancreatic duct to form a common duct called the hepato-pancreatic duct. The opening of the hepato-pancreatic duct into the duodenum is guarded by a sphincter called the power of regeneration and liver cells are replaced by new ones every 3-4 weeks.
TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption 1

Question 13.
Apart from bile secretion, what are the other functions carried out by liver?
Answer:

  1. Destroys ageing and defective blood cells.
  2. Stores glucose in the form of glycogen or disperses glucose into the bloodstream with the help of pancreatic hormones.
  3. Stores fat-soluble vitamins and iron.
  4. Detoxifies toxic substances.
  5. Involves in the synthesis of non-essential amino acids and urea.

Question 14.
What is the dual role performed by the Pancreas?
Answer:
The second-largest gland in the digestive system is the Pancreas, which is a yellow7 coloured, compound elongated organ consisting of exocrine and endocrine cells. It is situated between the limbs of the ‘U’ shaped duodenum. The exocrine portion secretes pancreatic juice containing enzymes such as pancreatic amylase, trypsin and pancreatic lipase and the endocrine part called Islets of Langerhans secretes hormones such as insulin and glucagon. The pancreatic duct directly opens into the duodenum.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 15.
Define the term digestion.
Answer:
The process of digestion converts solid food into absorbable and assimilable forms. This is accomplished by mechanical and chemical processes.

Question 16.
Name the types of Salivary glands.
Answer:
There are three pairs of salivary glands in the mouth. They are the largest parotids gland in the cheeks, the sub-maxillary/sub-mandibular in the lower jaw and the sublingual beneath the tongue.

Question 17.
State the functions of Salivary amylase on food.
Answer:
The mucus in saliva prepares the food for swallowing by moistening, softening, lubricating and adhering the masticated food into a bolus. About 30 per cent of polysaccharide, starch is hydrolyzed by the salivary amylase enzyme into disaccharides (maltose).

Question 18.
Define the term ‘Chyme’.
Answer:
Food remains in the stomach for 4 to 5 hours, the rhythmic peristaltic movement chums and mixes the food with gastric juice and make it into a creamy liquid called chyme.

Question 19.
Mention the names of the enzymes in the stomach.
Answer:
Inactive pepsinogen, Rennin

Question 20.
What is the role of HCl in the stomach?
Answer:
The HCl provides an acidic medium (pH 1.8) which is optimum for pepsin, kills bacteria and other harmful organisms and avoids putrefaction.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 21.
What is the function of mucus present in gastric juice?
Answer:
The mucus and bicarbonates present in the gastric juice play an important role in lubrication and protection of the mucosal epithelium from the eroding nature of the highly acidic HCl.

Question 22.
Mention the names of Pancreatic enzymes.
Answer:
Bicarbonate neutralizes stomach acid. Trypsin and chymotrypsin digest proteins. Carboxypeptidase digests peptides. Amylase digests starch and glycogen. Lipase digests lipids. Nuclease digests nucleic acids.

Question 23.
Describe the role of intestinal juice in the digestive process.
Answer:
The enzymes in the intestinal juice such as maltase, lactase, sucrase (invertase), dipeptidases, lipases, nucleosidases act on the breakdown products of bile and pancreatic digestion.
TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption 2

Question 24.
Write a short note on Absorption and Assimilation.
Answer:
Absorption is a process by which the end product of digestion passes through the intestinal mucosa into the blood and lymph. The villi in the lumen of the ileum are the absorbing units, consisting of a lacteal duct in the middle surrounded by fine network of blood capillaries. The process of absorption involves active, passive and facilitated transport. Small amounts of glucose, amino acids and electrolytes like chloride ions are generally absorbed by simple diffusion. The passage of these substances into the blood depends upon concentration gradients. However, some of the substances like fructose are absorbed with the help of the carrier ions like Na+. This mechanism is called facilitated transport.
Nutrients like amino acids, glucose and electrolytes like Na+ are absorbed into the blood against the concentration gradient by active transport. The insoluble substances like fatty acids, glycerol and fat-soluble vitamins are first incorporated into small, spherical water soluble droplets called micelles and are absorbed into the intestinal mucosa where they are re-synthesized into protein-coated fat globules called chylomicrons which are then transported into the lacteals within the intestinal villi and eventually empty into the lymphatic duct. The lymphatic ducts ultimately release the absorbed substances into the bloodstream. While the fatty acids are absorbed by the lymph duct, other materials are absorbed either actively or passively by the capillaries of the villi. Water-soluble vitamins are absorbed by simple diffusion or active transport. The transport of water depends upon the osmotic gradient.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 25.
Write a note on Egestion.
Answer:
The digestive waste and unabsorbed substances in the ileum enter into the large intestine and it mostly contains a fibre called roughage. The roughage is utilized by symbiotic bacteria in the large intestine for the production of substances like vitamin K and other metabolites. All these substances are absorbed in the colon along with water. The waste is then solidified into faecal matter in the rectum. The faecal matter initiates a neural reflex causing an urge or desire for its removal. The egestion of faeces through the anal opening is called defaecation. It is a voluntary process and is carried out by a peristaltic movement.

Question 26.
What is the energy value of carbohydrate and their sources?
Answer:
Carbohydrates are sugar and starch. These are the major source of cellular fuel which provides energy. The caloric value of carbohydrate is 4.1 calories per gram and its physiological fuel value is 4 Kcal per gram.

Question 27.
Name the deficiency diseases of protein.
Answer:
Marasmus and Kwashiorkor.

Question 28.
Write a short note on the following:

  1. Indigestion,
  2. Constipation,
  3. Vomiting,
  4. Jaundice,
  5. Liver cirrhosis,
  6. Gall stones,
  7. Appendicitis,
  8. Hiatus hernia.

Answer:

  1. Indigestion: It is a digestive disorder in which the food is not properly digested leading to a feeling of fullness of the stomach. It may be due to inadequate enzyme secretion, anxiety, food poisoning, overeating and spicy food.
  2. Constipation: In this condition, the faeces are retained within the rectum because of irregular bowel movement due to poor intake of fibre in the diet and lack of physical activities.
  3. Vomiting: It is reverse peristalsis. Harmful substances and contaminated food from the stomach are ejected through the mouth. This action is controlled by the vomiting centre located in the medulla oblongata. A feeling of nausea precedes vomiting.
  4. Jaundice: It is the condition in which the liver is affected and the defective liver fails to break down haemoglobin and to remove bile pigments from the blood. Deposition of these pigments changes the colour of the eye and skin yellow. Sometimes, jaundice is caused due to hepatitis viral infections.
  5. Liver cirrhosis: Chronic disease of the liver results in degeneration and destruction of liver cells resulting in an abnormal blood vessel and bile duct leading to the formation of fibrosis.
    It is also called deserted liver or scarred liver. It is caused due to infection, consumption of poison, malnutrition and alcoholism.
  6. Gall Stones: Any alteration in the composition of the bile can cause the formation of stones in the gall bladder. The stones are mostly formed of crystallized cholesterol in the bile. The gall stone causes obstruction in the cystic duct, hepatic duct and also hepato-pancreatic duct causing pain, jaundice and pancreatitis.
  7. Appendicitis: It is the inflammation of the vermiform appendix, leading to severe abdominal pain. The treatment involves the removal of the appendix by surgery. If treatment is delayed the appendix may rupture and results in infection of the abdomen, called peritonitis.
  8. Hiatus hernia (Diaphragmatic hernia): It is a structural abnormality in which the superior part of the stomach protrudes slightly above the diaphragm. In some people, injury or other damage may weaken muscle tissue, by applying too much pressure (repeatedly) on the muscles around the stomach while coughing, vomiting, and straining during bowel movement and lifting a heavy object. Heart bum is also common in those with a hiatus hernia. In this condition, stomach contents travel back into the oesophagus or even into oral cavity and cause pain in the centre of the chest due to the eroding nature of acidity.

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

Question 29.
What is diarrhoea? Why diarrhoea is caused? What are its symptoms? How it can be treated.
Answer:
Diarrhoea is the most common gastrointestinal disorder worldwide. It is sometimes caused by bacteria or viral infections through food or water. When the colon is infected, the lining of the intestine is damaged by the pathogens, thereby the colon is unable to absorb fluid. The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. Unless the condition is treated, dehydration can occur. Treatment is known as oral hydration therapy. This involves drinking plenty of fluids – sipping small amounts of water at a time to rehydrate the body.

Question 30.
What is called Obesity? How can it be assessed?
Answer:
Obesity is caused due to the storage of excess body fat in adipose tissue. It may induce hypertension, atherosclerotic heart disease and diabetes. Obesity may be genetic or due to excess intake of food, endocrine and metabolic disorders.

Choose the correct answer.

1. Each tooth is embedded in a socket in the jaw bone called:
(a) thecodont
(b) diphyolont
(c) heterodont
(d) both (b) & (c)
Answer:
(a) thecodont

2. Tartar is the deposited minerals of on the teeth.
(a) Sodium and Calcium
(b) Calcium and Magnesium
(c) Sodium and Potassium
(d) Magnesium and Sodium
Answer:
(b) Calcium and Magnesium

3. A cartilaginous flap that prevents the entry of food in to the glottis is called:
(a) Buccal cavity
(b) Gullet
(c) Epiglottis
(d) Calculus
Answer:
(b) Gullet

4. The inner wall of the stomach has many folds called ………. Which unfold to accommodate a large meal.
(a) Villi
(b) Sigmoid colono
(c) Haustra
(d) Gastric rugae
Answer:
(d) Gastric rugae

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

5. The mucal layer of ileum has lymphoid tissue known as
(a) Peyer’s patches
(b) Crypts of Leiberkuhn
(c) Zymogen cells
(d) Haemmorhoids
Answer:
(a) Peyer’s patches

6. The duct of the parotid gland is called:
(a) Wharton’s duct
(b) duct of Rivinis
(c) Stenson’s duct
(d) Bartholin’s duct
Answer:
(c) Stenson’s duct

7. The opening of the bile duct into the duodenum is guarded by a sphincter called:
(a) cardiac sphincter
(b) pyloric sphincter
(c) anal sphincter
(d) sphincter of oddi
Answer:
(d) sphincter of oddi

8. Masticated food particles passed into pharynx and then into the oesophagus by the process called:
(a) deglutition
(b) dentition
(c) mastication
(d) putrifaction
Answer:
(a) deglutition

9. Who is known as the “Father of gastric physiology.
(a) Aristotle
(b) William Beaumont
(c) Alexis
(d) A.C Guyton and Hall
Answer:
(b) William Beaumont

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

10. The functional unit of liver is:
(a) Goblet cells
(b) Hepatic lobules
(c) micelles
(d) gastric glands
Answer:
(b) Hepatic lobules

11. The caloric value of carbohydrate is:
(a) 9 k cal
(b) 5.65 k cal
(c) 4.1k cal
(d) 3.2 k cal
Answer:
(c) 4.1k cal

12. Peptic ulcer is caused by the bacterium called:
(a) Streptococcus
(b) Vibrio cholerae
(c) Lactobacillus
(d) Helicobacter pylori
Answer:
(d) Helicobacter pylori

13. A normal BMI range for adult is:
(a) 19-25
(b) 18-26
(c) 19-28
(d) 17-25
Answer:
(a) 19-25

TN Board 11th Bio Zoology Important Questions Chapter 5 Digestion and Absorption

14. Match the following:

(i) ICMR (a) Gastro Oesophagus Reflex Disorder
(ii) BMI (b) World Health Organization
(iii) GERD (c) Indian Council of Medical Research
(iv) WHO (d) Body Mass Index

(a) (i)-(c); (ii)-(d); (iii)-(a); (iv)-(b)
(b) (i)-(a); (ii)-(b); (iii)-(d); (iv)-(c)
(c) (i)-(b); (ii)-(a); (iii)-(c); (iv)-(d)
(d) (i)-(d); (ii)-(c); (iii)-(a); (iv)-(b)
Answer:
(a) (i)-(c); (ii)-(d); (iii)-(a); (iv)-(b)