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Samacheer Kalvi 3rd Standard Science Book Solutions Term 3 Chapter 1 Our Environment

I. Choose the correct answer:

Question 1.
Which of these is an example for biotic factor?
(a) Water
(b) Goat
(c) Air
Answer:
(b) Goat

Question 2.
Our environment is surrounded by ________.
(a) biotic factors
(b) abiotic factors
(c) both biotic and abiotic factors
Answer:
(c) both biotic and abiotic factors

Question 3.
Human beings depend on ________ for their food.
(a) plants
(b) soil
(c) wood
Answer:
(a) plants

Question 4.
_________ are the primary producers.
(a) Non-green plants
(b) Green plants
(c) dry leaves
Answer:
(b) Green plants

Question 5.
Which is an example for decomposer?
(a) Mango tree
(b) Bacteria
(c) Deer
Answer:
(b) Bacteria

Question 6.
Which of these living things would die if there were no green plants on Earth?

(a) a and c only
(b) b and d only
(c) d and a only
(d) a, b, c and d
Answer:
(d) a, b, c and d

II. Fill in the blanks:

Question 1.
_________ is a consumer. (Cow / Soil)
Answer:
Cow

Question 2.
A young plant is known as _______. (tree / sapling)
Answer:
sapling

Question 3.
Planting of sapling provides ________. (oxygen / land)
Answer:
oxygen

Question 4.
World Environment bay is ________. (June 15th / June 5th)
Answer:
June 5th

Question 5.
________ get food from dead plants and animals. (becomposers / Producers)
Answer:
decomposers

III. Match the following:

Answer:

IV. Say true or false.

Question 1.
Abiotic factors are important for biotic factors.
Answer:
True

Question 2.
River is an example for biotic factor.
Answer:
False

Question 3.
‘Van Mahotsav’ is organised during the first week of July every year.
Answer:
True

Question 4.
Plants are the consumers.
Answer:
False

Question 5.
Plants provide food and shelter to living things.
Answer:
True

V. Answer the following.

Question 1.
Vijay placed two things ‘p’ and ‘R’ (one living and one non-living) in seperate cages with food and water.

a. Which thing is likely to be a living thing? Give reason for your answer.
Answer:
Only living thing ‘P’ can gain weight after taking food and water. Other thing ‘R’ will not show any weight gain.

b. What will be the weight of living thing in week 6?
Answer:
12 kg

Question 2.
Write two examples for biotic and abiotic factors.
Answer:

Question 3.
Write any three differences between living and non-living things.
Answer:

Question 4.
List the abiotic factors needed for insects.
Answer:
Soil, Small Creatures, Air, Plants.

Question 5.
What are the biotic factors of a balanced ecosystem?
Answer:
The biotic factors in an ecosystem includes producers, consumers, and decomposers.

Question 6.
Why plants are called primary producers?
Answer:
Green plants make their own food by the process of photosynthesis. Hence, they are called primary producers.

Question 7.
Write any four benefits of plants.
Answer:
(i) Provide oxygen for breathing.
(ii) Provide food and shelter to living things.
(iii) Help in bringing rainfall.
(iv) Offer a good environment to live.

In-Text Activity:

Let us try (Text Book Page No. 58):

Question 1.
Write the names of the animals that you see in the previous page picture.

Answer:

Question 2.
Classify the following into natural things and man-made things.
(Dam, river, coconut tree, building, jasmine flower, hill, cloud, silver vessel, cell phone, temple, cake, air, sun, ship, water, pencil, book, doll, football, sunflower, crocodile, aeroplane)

Answer:

Let us connect (Text Book Page No. 59):

Match the following sources with their products and uses.

Answer:

Let us try (Text Book Page No. 61):

Question 1.
Classify the following as Biotic / Abiotic factors.

Answer:

Question 2.
Think and Answer (Text Book Page No. 61):

a. A swing goes to and fro. Is it living or non-living? ________
Answer:
non-living.

b. We get wood from trees which are the living things. A chair is made from wood. Is the chair a living thing or a non-living thing?
Answer:
non-living thing.

Try to Answer (Text Book Page No. 62):

Look at the picture and answer the question.

Which of the non-living things can float?
a. Iron rod
b. Stone
c. Air filled ball
d. Coin
Answer:
c. Air filled ball

Let us try (Text Book Page No. 62):

The following statements describe some of the characteristics of living things. Identify and write the characteristic features using the given hints.
(Characteristics Hints: Move, Breathe, feel, Needs food, Grow, Reproduce)

Answer:

Let us play (Text Book Page No. 62):

Divide the class into two groups and ask the first group to write any five biotic factors and the second group to write any five abiotic factors seen around the school.

Answer:

Write the needs of the following (Text Book Page No. 63):

Question 1.
Birds : _____, _____, _____, ______
Answer:
air, water, sunlight, winds, trees.

Question 2.
Insects : _____, _____, _____, ______
Answer:
Soil, small creatures, plants, air.

Question 3.
Human beings : _____, _____, _____, ______
Answer:
Plants, water, air , animals, sunlight.

Let us discuss (Text Book Page No. 64):

Question 1.
There is a large banyan tree in a park. Monkeys and all birds have made the tree their home. Humans too spend time under the tree. Discuss with your friends, how the tree, monkeys, birds, and humans are interdependent.

Question 2.
Why is the plant most important living thing?
Answer:
Monkeys and birds have made the tree their home. Humans too spend time under the tree.

Question 3.
Discuss in a group and create an interlink of living and non-living factors.

Answer:

Let us try (Text Book Page No. 64):

Question 1.
write the abiotic factors needed for the following biotic factors to survive.
(Air, Water, Sunlight, Soil, Land, Wheat, Fruits, Grass, Hen)
a. Animals: __________
b. Plants: _________
c. Human beings: _________
Answer:
a. Animals: Air, water, sunlight, grass
b. Plants: Sunlight, water, air, soil
c. Human beings: Sunlight, water, air, land, wheat, fruits, hen

Question 2.
An animal that,

a. Flies in the air is : ________
Answer:
Butterfly

b. Lives in water is : ________
Answer:
Fish

c. Moves on the ground is : ________
Answer:
Snake

d. Eats only plants is : ________
Answer:
Herbivore

Intext Question:

Imagine an environment where there are only plants, deer, and lions.

Question 1.
What will happen to the deer, if we remove all the lions?
Answer:
If all the Lions are removed from the forest, then the number of secondary consumers will be increased and scarcity of plant (food) occur due to the overpopulation of deers and cause an imbalance in the ecosystem.

Question 2.
What will happen to the plants, if there are no lions to eat the deer?
Answer:
If all the deer are removed from the forest, other host unable to get food. Such as, lions unable to get sufficient food for being alive and as a result, the lion population gradually die due to starvation. This will affect the food chain and leads to an imbalance in ecosystem.

Question 3.
If all the plants are eaten, what will happen to the deer?
Answer:
Deers unable to get sufficient food for being alive, as a result deer population gradually die due to starvation.

Let us try (Text Book Page No. 66):

Classify the following biotic factors.
(Tulsi, Fungi, Mango tree, Rabbit, Eagle, Cat, Dog, Cucumber plant, Human, Grass, Crocodile, Crow, Bacteria)

Question 1.
Producers: _________, _________, _________, ________, _________
Answer:
Mango tree, Tulsi, Cucumber, Plant, Grass.

Question 2.
Consumers: _________, _________, _________, ________, _________
Answer:
Eagle, Human, Crocodile, Crow, Rabbit, Cat, Dog.

Question 3.
Decomposers: _________, _________, _________, ________, _________
Answer:
Fungi, Bacteria.

Let us discuss (Text Book Page No. 66):

Question 1.
Let us discuss and write.
Plants and human beings are living things. Why do human beings depend on plants?
Answer:
Human beings depend on plants for their food, clothing, breathing, medicines, etc.

Let us try (Text Book Page No. 66):

The names of several natural resources are hidden in the box be! find as many possible. Some words are repeated.

Answer:

Let us connect (Text Book Page No. 67):

Answer:

Let us do (Text Book Page No. 67):

A. Write any two uses of trees.
Answer:

1. Trees provide shade and shelter
2. Trees clean the air.

E. Write some slogans on 5ave Plants and paste them on the tree in your school campus/roadsides. (E.g., Take care of the Earth and it will take care of you. It’s not yours, nor mine, it’s ours).
Answer:

1. It is time for greeny and not greedy.
2. Love your life & plant more trees.

3rd Standard Science Guide Our Environment Additional Questions and Answers

I. Choose the correct answer.

Question 1.
Our ________ consists of both living and non-living things.
(a) body
(b) environment
(c) none of these
Answer:
(b) environment

Question 2.
_______ is the science that deals with the relationship between living things and their environment.
(a) Zoology
(b) Botonay
(c) Ecology
Answer:
(c) Ecology

Question 3.
_______ in an ecosystem includes producers, consumers and decomposers.
(a) Biotic factors
(b) Abiotic factors
(c) Non-biotic factors
Answer:
(a) iotíc factors

Question 4.
Flesh eating animals are called ________.
(a) herbivores
(b) carnivores
(c) omnivores
Answer:
(b) carnivores

Question 5.
Van mahotsav means _________.
(a) festival of India
(b) festival of lights
(c) festival of forests
Answer:
(c) festival of forests

II. Fill in the blanks.

Question 1.
A person who protects the environment is _________. (educationalist / environmentalist)
Answer:
environmentalist

Question 2.
Amoeba is an _________ organism. (multicellular / unicellular)
Answer:
unicellular

Question 3.
Plants _________ move around like animals. (can / cannot)
Answer:
cannot

Question 4.
Plants that do not produce their food and depend on other plants are called _____ plants. (saprophytic/parasitic)
Answer:
parasitic.

Question 5.
_________ is an Example of decomposers. (Fungi / Cat)
Answer:
Fungi

III. Say true or false.

Question 1.
Plants grow and their shoots show movements towards the Sun.
Answer:
True

Question 2.
Non-living things in our environment are called biotic factors.
Answer:
False

Question 3.
The living things in our environment are called biotic factors.
Answer:
True

Question 4.
Both plant and flesh-eating animals are called carnivores.
Answer:
False

Question 5.
Plants provide food and shelter to living things.
Answer:
True

IV. Match the following.

Answer:

V. Answer the following.

Question 1.
What is meant by the biotic factor?
Answer:
Living organisms in our environment are called biotic factors. E.g., Lion, Plantain, Dove, Human beings etc.

Question 2.
What is meant by abiotic factor?
Answer:
Non-living things in our environment are called abiotic factors. E.g., Air, Soil, Water, Sunlight, Temperature etc.

Question 3.
Write a short note on Amoeba.
Answer:
Amoeba is a unicellular organism. It has the ability to alter its shape. It was discovered in 1975.

Question 4.
What is a decomposer?
Answer:
Organisms that feed on the wastes, dead plants, and animals are called decomposers. They return the nutrients to the soil. E.g., Bacteria, Fungi.

Question 5.
List out the important initiatives to protect our environment?
Answer:
Some important initiatives to protect our environment.

• The Chipko Movement – 1970
• The Environment Protection Act – 1986
• National GreenTribunal – 2010
• Appiko Movement – 1983

Question 6.
Name some Man-made things.
Answer:
Temple, house, car, pen, pencil, book, dolls, aeroplane etc, are Man-made things.

Question 7.
What is ecology?
Answer:
Ecology is the science that deals with the relationship between living things and their environment.

VI. Answer in detail.

Question 1.
Explain the biotic factors in an ecosystem.
Answer:
Answer:
Producers:

• The living things that can prepare their own food are called producers.
• Green plants are the producers. They make their own food by the process of photosynthesis. Hence, they are called ‘primary producers’.

Consumers:

• The living things that eat the food prepared by. the producers are called consumers.
• Most of the living things depend directly or indirectly on producers for their food.
• Consumers can be divided into three types based on their food as herbivores (plant-eating animal), ‘carnivores (flesh-eating animal), omnivores (both plant and flesh-eating animal).

Decomposers:

• Organisms that feed on the wastes, dead plants, and animals are called decomposers.
• They return the nutrients to the soil.
  E.g., Bacteria, Fungi.

Samacheer Kalvi 3rd Standard Science Guide