Class 10 › Science Our Environment Class 10 Science · Chapter 13
Practice all → Summary Questions & answers Practise this chapter → View all Page 1 free about 8 min read , Full kit about 55 min read Page 1 free about 8 min read , Full kit about 55 min read View all 12 amazing Marks Booster kits → The environment is a system in which living organisms interact with one another and with their non-living surroundings, forming ecosystems. Energy from the sun flows through ecosystems along food chains and food webs, passing from producers to consumers across trophic levels; only about 10% of the energy is transferred at each level, which limits the length of food chains. Materials, by contrast, are cycled and reused. Human activity affects the environment in major ways: the build-up of biodegradable and non-biodegradable wastes creates disposal problems, and the depletion of the ozone layer by chemicals like CFCs increases harmful ultraviolet radiation reaching the Earth. Understanding these links helps explain why pollution and waste management matter, and why protecting natural balances is essential for the health of all organisms, including humans.
Ecosystem
A community of organisms interacting with their physical environment.
Food chain
A sequence showing the flow of energy from one organism to the next.
Trophic level
A step or feeding level in a food chain.
Biodegradable waste
Waste that can be broken down by natural processes.
Q1 Why are food chains usually limited to three or four trophic levels? Answer Q2 Why is the depletion of the ozone layer a cause for concern? Answer Q3 What is an ecosystem? Name its two components. Answer Q4 What are producers, consumers and decomposers? Answer Q5 What is a food chain and a trophic level? Answer Q6 State the ten per cent law of energy flow. Answer Q7 Differentiate between biodegradable and non-biodegradable substances with examples. Answer Q8 Why is the ozone layer important, and what damages it? Answer Q9 Why are food chains usually not very long? Answer Q10 How can the problems caused by non-biodegradable waste be reduced? Answer Q1 You might have seen an aquarium. Let us try to design one. Answer Q2 What are the things that we need to keep in mind when we create an aquarium? The fish would need a free space for swimming (it could be a large jar), water, oxygen and food. Answer Q3 We can provide oxygen through an oxygen pump (aerator) and fish food which is available in the market. Answer Q4 If we add a few aquatic plants and animals it can become a self-sustaining system. Can you think how this happens? An aquarium is an example of a human-made ecosystem. Answer Q5 Can we leave the aquarium as such after we set it up? Why does it have to be cleaned once in a while? Do we have to clean ponds or lakes in the same manner? Why or why not? Answer Q1 While creating an aquarium did you take care not to put an aquatic animal which would eat others? What would have happened otherwise? Answer Q2 Make groups and discuss how each of the above groups of organisms are dependent on each other. Answer Q3 Write the aquatic organisms in order of who eats whom and form a chain of at least three steps. → → Answer Q4 Would you consider any one group of organisms to be of primary importance? Why or why not? Answer Q1 Newspaper reports about pesticide levels in ready-made food items are often seen these days and some states have banned these products. Debate in groups the need for such bans. Answer Q2 What do you think would be the source of pesticides in these food items? Could pesticides get into our bodies from this source through other food products too? Answer Q3 Discuss what methods could be applied to reduce our intake of pesticides. Answer Q1 1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it. Answer Q2 2. What is the role of decomposers in the ecosystem? Answer Q1 Find out from the library, internet or newspaper reports, which chemicals are responsible for the depletion of the ozone layer. Answer Q2 Find out if the regulations put in place to control the emission of these chemicals have succeeded in reducing the damage to the ozone layer. Has the size of the hole in the ozone layer changed in recent years? Answer Q1 Collect waste material from your homes. This could include all the waste generated during a day, like kitchen waste (spoilt food, vegetable peels, used tea leaves, milk packets and empty cartons), waste paper, empty medicine bottles/strips/bubble packs, old and torn clothes and broken footwear. Answer Q2 Bury this material in a pit in the school garden or if there is no space available, you can collect the material in an old bucket/flower pot and cover with at least 15 cm of soil. Answer Q3 Keep this material moist and observe at 15-day intervals. Answer Q4 What are the materials that remain unchanged over long periods of time? Answer Q5 What are the materials which change their form and structure over time? Answer Q6 Of these materials that are changed, which ones change the fastest? Answer Q1 Use the library or internet to find out more about biodegradable and non-biodegradable substances. Answer Q2 How long are various non-biodegradable substances expected to last in our environment? Answer Q3 These days, new types of plastics which are said to be biodegradable are available. Find out more about such materials and whether they do or do not harm the environment. Answer Q1 1. Why are some substances biodegradable and some non-biodegradable? Answer Q2 2. Give any two ways in which biodegradable substances would affect the environment. Answer Q3 3. Give any two ways in which non-biodegradable substances would affect the environment. Answer Q1 Find out what happens to the waste generated at home. Is there a system in place to collect this waste? Answer Q2 Find out how the local body (panchayat, municipal corporation, resident welfare association) deals with the waste. Are there mechanisms in place to treat the biodegradable and non-biodegradable wastes separately? Answer Q3 Calculate how much waste is generated at home in a day. Answer Q4 How much of this waste is biodegradable? Answer Q5 Calculate how much waste is generated in the classroom in a day. Answer Q6 How much of this waste is biodegradable? Answer Q7 Suggest ways of dealing with this waste. Answer Q1 Find out how the sewage in your locality is treated. Are there mechanisms in place to ensure that local water bodies are not polluted by untreated sewage. Answer Q2 Find out how the local industries in your locality treat their wastes. Are there mechanisms in place to ensure that the soil and water are not polluted by this waste? Answer Q1 Disposable cups in trains
If you ask your parents, they will probably remember a time when tea in trains was served in plastic glasses which had to be returned to the vendor. The introduction of disposable cups was hailed as a step forward for reasons of hygiene. No one at that time perhaps thought about the impact caused by the disposal of millions of these cups on a daily basis. Some time back, kulhads, that is, disposable cups made of clay, were suggested as an alternative. But a little thought showed that making these kulhads on a large scale would result in the loss of the fertile top-soil. Now disposable paper-cups are being used. What do you think are the advantages of disposable paper-cups over disposable plastic cups? Answer Q1 Search the internet or library to find out what hazardous materials have to be dealt with while disposing of electronic items. How would these materials affect the environment? Answer Q2 Find out how plastics are recycled. Does the recycling process have any impact on the environment? Answer Q1 1. What is ozone and how does it affect any ecosystem? Answer Q2 2. How can you help in reducing the problem of waste disposal? Give any two methods. Answer Q1 1. Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass Answer Q2 2. Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat Answer Q3 3. Which of the following are environment-friendly practices?
(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above Answer Q4 4. What will happen if we kill all the organisms in one trophic level? Answer Q5 5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem? Answer Q6 6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem? Answer Q7 7. What are the problems caused by the non-biodegradable wastes that we generate? Answer Q8 8. If all the waste we generate is biodegradable, will this have no impact on the environment? Answer Q9 9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage? Answer
A series showing the flow of energy from one organism to the next is a:
A water cycle B nitrogen cycle C food storage D food chain
Flashcards & interactive practice 
