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Chapters1 - Chemical Reactions and Equations
2 - Acids, Bases and Salts
3 - Metals and Non-metals
4 - Carbon and its Compounds
5 - Periodic Classification of Elements
6 - Life Processes
7 - Control and Coordination
8 - How do Organisms Reproduce
9 - Heredity and Evolution
10 - Light - Reflection and Refraction
11 - Human Eye and Colourful World
12 - Electricity
13 - Magnetic Effects of Electric Current
14 - Sources of Energy
15 - Our Environment
16 - Management of Natural Resources
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Chapter 15 - Our Environment
Why are some substances biodegradable and some non-biodegradable?
Give any two ways in which biodegradable substances would affect the environment.
Give any two ways in which non-biodegradable substances would affect the environment.
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
List two important roles play in the environment by decomposers.
What is ozone and how does it affect any ecosystem?
How can you help in reducing the problem of waste disposal? Give any two methods.
Pages 264 - 265
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
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
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
What will happen if we kill all the organisms in one trophic level?
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?
What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
What are the problems caused by the non-biodegradable wastes that we generate?
If all the waste we generate is biodegradable, will this have no impact on the environment?
Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
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