CBSE – 10th Standard Science

Class 10 Question Bank Chapter 15 – Our environment

Qus 1. What is an eco-system?

Ans. An ecosystem consists of biotic components comprising living organisms and abiotic components comprising.


Qus2. Garden is an ecosystem. Explain?

Ans. When we visit a garden we will find different plants, trees; flower bearing plants like rose, jasmine, and animals like frogs, insects and birds. All these living organisms interact with each other. So garden is an ecosystem.


Qus 3. Name some natural and artificial ecosystems.

Ans. Forests, ponds and lakes, these are natural ecosystems while gardens and crop-fields are human made (artificial) ecosystems.

Qus 4. Who are producers?

Ans. All green plants and certain blue green algae which can produce food by photosynthesis are called the producers.

Qus 5. Who are consumers?

Ans. The organisms which consume the food produced, either directly from producers or indirectly by feeding on other consumers are the consumers.

Qus 6. How can be consumers classed?

Ans. Consumers can be classed variously as herbivores, carnivores, omnivores and parasites.

Qus,7. Who are decomposers?

Ans. When an organism dies, the microorganisms, comprising bacteria break-down the dead remains and waste products. These microorganisms are the decomposers.

Qus 8. What is food chain?

Ans. A series of organisms feeding on one another or organisms taking part at various biotic levels form a food chain.


Qus 9. What is trophic level?

Ans. Each step or level of the food chain forms a trophic level.

Qus 10. Who are at the first trophic level?

Ans. The autotrophs or the producers are at the first trophic level.

Qus 11. What do autotrophs do?

Ans. They fix up the solar energy and make it available for heterotrophs or the consumers.

Qus 12. Who are at the second trophic level?

Ans.The herbivores or the primary consumers come at the second trophic level.

Qus 13. Who are at the third trophic level?

Ans. Small carnivores or the secondary consumers are at the third trophic level.

Qus 14. Who are at the fourth trophic level?

Ans. Larger carnivores or the tertiary consumers form the fourth trophic level.

Qus 15. How do we get energy?

Ans. The food we eat acts as a fuel to provide us energy to do work and the interactions among various components of the environment involves flow of energy.

Qus 16. What do the autotrophs do with the energy present in sunlight?

Ans.The autotrophs capture the energy present in sunlight and convert it into chemical energy. This energy supports all the activities of the living world.

Qus 17.  From autotrophs where does the energy go?

Ans. From autotrophs, the energy goes to the heterotrophs and decomposers.

Qus 18. How do green plants convert into food energy?

Ans. The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert it into food energy.

Qus 19. What happens when green plants are eaten by primary consumers?

Ans. When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment, some amount goes into digestion and the rest goes towards growth and reproduction.

Qus 20. What amount of organic matter reaches the next level of consumers?

Ans. 10% can be taken as the average value for the amount of organic matter that is present at each step and reaches the next level of consumers.

Qus 21. How many steps a food chain consists of?

Ans. Since so little energy is available for the next level of consumers, food chains generally consist of only three or four steps.

Qus 22. How do food chains vary?

Ans. The length and complexity of food chains vary greatly. Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms.

Qus 23. What is food web?

Ans. Instead of a straight line food chain, the relationship can be shown as a series of branching lines called a food web.


Qus 24. What is ozone?

Ans. Ozone is a deadly poison. However, at the higher levels of the atmosphere, it shields the surface of the earth from ultraviolet (UV) radiation from the Sun.


Qus 25. How ozone is formed?

Ans. Ozone (O3) is a molecule formed by three atoms of oxygen. Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen (O2) molecule.


Qus 26. What is ultraviolet (UV) radiation?

Ans. Ultraviolet (UV) radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

Qus 27. From when the amount of ozone in the atmosphere began to drop sharply?

Ans. The amount of ozone in the atmosphere began to drop sharply in the 1980s.


Qus 28. Why the amount of ozone in the atmosphere began to drop sharply?

Ans. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers.


Qus 29. What does UNEP stands for?

Ans. UNEP stands for United Nations Environment Programme.

Qus 30. What agreement did UNEP succeed to forge?

Ans. In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels.


Try these:-

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.

What is the role of decomposers in 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?