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Chapter: 6th Science : Term 3 Unit 4 : Our Environment

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6th Science : Term 3 Unit 4 : Our Environment : Book Back Questions Answers, Solution



I. Choose the appropriate answer


1. Identify the fresh water ecosystem.

a. Pond

b. Lake

c. River

d. All of them

Answer: d) All of them


2. Producers are_______________

a. Animals

b. Birds

c. Plants

d. Snakes

Answer: c) Plants


3. It is a biodegradable waste.

a. Plastic

b. Coconut Shell

c. Glass

d. Aluminium

Answer: b) Coconut Shell


4. It is an undesirable change that occurs in air and water.

a. Recycling

b. Reuse

c. Pollution

d. Reduce

Answer: c) Pollution


5. Usage of chemical pesticides and fertilisers causes ________ pollution.

a. Air pollution

b. Water pollution

c. Noise pollution

d. None of the above

Answer: b) water pollution


II. Fill in the blanks


1. Primary consumers that eat plants are called __________.

2. Temperature, light and wind are ________ factors.

3. __________ is the process of converting waste materials into new materials.

4. Water pollution can spread __________ and chemicals.

5. The 3R’s are Reduce, __________ and Recycle.


III. True or False. If False, give the correct statement


1. The Pacific ocean is an example of an aquatic ecosystem. (True)

2. Bacteria and fungi are called decomposers. (True)

3. Human and animal wastes are examples of non-biodegradable waste. (False)

Human and animal wastes are examples of biodegradable waste.

4. Excessive use of pesticides leads to air pollution. (False)

Excessive use of pesticides leads to land pollution and water pollution.

5. In schools, waste management rules say that we should separate waste in two categories. (True)


IV. Match the following

1. Biotic factor – Terrestrial Ecosystem

2. Sewage - Land pollution

3. Fertilizers - Air pollution

4. Desert - Water Pollution

5. Smoke – Animals


1. Biotic factor - Animals

2. Sewage - Water Pollution

3. Fertilizers - Land pollution

4. Desert - Terrestrial Ecosystem

5. Smoke - Air pollution


V. Arrange the following in a correct sequence and form a food chain


1. Rabbit → Carrot → Eagle → Snake

Carrot → Rabbit → Snake → Eagle

2. Human → Insect → Algae → Fish

Algae → Insect → Fish→ Human


VI. Give very short answer


1. Define ecosystem.

Ecosystem is a community of living and non-living things that work together.

2. What are the two types of ecosystems?

Ecosystems can be either natural or artificial.

3. Write any two things that can be recycled.

(i) We can use old clothes to make paper

(ii) Some plastics can be used to make floor mats, plastic boards and hose pipes.

4. What are the types of pollution.

1. Airpollution

2. Water pollution

3. Land (soil) pollution

4. Noise pollution

5. Give one example of a food chain in an aquatic ecosystem?

Aquatic plant → Aquatic insect → Larva → Fish

6. Name some pollutants.

Any substance that causes pollution is called a pollutant.

 e.g: smoke, fume, chemical residues, plastic waste.

7. What are the pollutions caused by the objects given below?

a. Loud Speaker b. Plastic

a. Loud Speaker

 Noise pollution

b. Plastic

Land pollution


VII. Give short answer


1. What is biodegradable waste?

The term 'Biodegradable' is used for those things that can be easily decomposed by natural agents like water, oxygen, ultraviolet rays of the sun, micro-organisms, etc.

One can notice that when a dead leaf or a banana peel is thrown outside, it is acted upon by several micro-organisms like bacteria, fungi or small insects in a time period. Biodegradable waste includes vegetable and fruit peels, leftover food and garden wastes (grass, leaves, weeds and twigs). 

2. How can we reduce water pollution?

1. Do not pour leftover oil, old medicines or waste down the drain or into the toilet.

2. Reduce the use of chemical pesticides and fertilizers to grow crops.

3. Use waste water for garden in home.

4. Do not litter or dump waste - always use a waste bin.

3. Write the importance of the food chain.

1. Learning food chain helps us to understand the feeding relationship and interaction between organisms in any ecosystem.

2. Understanding the food chain also helps us to appreciate the energy flow and nutrient circulation in an ecosystem. This is important because pollution impacts the ecosystem. The food chain can be used to understand the movement of toxic substances and their impacts.


VIII. Answer in detail


1. Give two examples of how you can avoid or reduce waste?

1. Avoid : Avoid the usage of unwanted materials which create more debris. Before you buy anything, think that "Do I really need it?" (e.g) Avoid buying packaged foods. Refuse to buy use and throw plastic products.

2. Reduce : We can reduce the waste by using durable goods that last longer instead of things that are used once and thrown away, (e.g) Write on both sides of papers. Instead of unnecessary printing, use electronic facilities. Share newspapers, magazines and other things with others.

2. Write a short note on noise pollution.

Noise pollution affects the environment. We all like a quiet and peaceful place since unpleasant or loud sounds disturb us. Loud music, the sounds of motor vehicles, fire works and machines cause noise pollution. Continuous noise disturbs our sleep and does not let us to study. Noise pollution has been directly linked to stress and health impacts such as high blood pressure and hearing loss. Loud noise or even loud music can damage our ears. Noise pollution also disturbs animals. Birds have to communicate (talk) louder so that, they can hear each other in noisy areas. Even underwater noise pollution from ships, can make whales lose their way as they use sounds to navigate.


IX. Question based on Higher Order Thinking Skills


1. What would happen if an organism is removed from the food chain?

When an organism is removed from the food chain there occurs a break in the transmission of energy. Some species do not get food and they become extinct. The other species which depend on them also become extinct. Thus it leads to the death and annihilation of many plants and animals on earth.

2. Explain the link between waste and dangerous diseases like dengue and malaria?

The soil gets polluted by plastic wastes. These plastic wastes are non- biodegradable. They prevent the infiltration and percolation of rain water. As a result the rain water stagnates on the soil. It creates ditches which become a breeding spot for flies and mosquitoes. They breed in these ditches in abundance and spread dangerous diseases like malaria and dengue.


X. See the diagram and answer the following questions

1. Explain what is happening in the picture?

This is the picture of an open dump. Here the waste is dumped and burned. The smoke that comes out causes air pollution by liberating toxic gases into the atmosphere. Moreover the toxic chemicals in the waste leak into the soil and water and pollute them.

2. What types of pollution are caused by open dumps?

Air pollution is caused by the smoke and fumes that go into the air. Land pollution and water pollution are caused by the leakage of toxic chemicals into the soil.

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