CBSE Class 10 Science Chapter 15 Our Environment Very Short Question And Answer
Question 1. What is the physical environment of an ecosystem called? Give one example.
Answer: The physical environment of an ecosystem is called the abiotic or non-living component of an ecosystem. This includes physical factors like temperature, rainfall, wind, etc.
Question 2. What is meant by consumers in an ecosystem1?
Answer:
Those organisms cannot manufacture their food by the process of photosynthesis and depend either on plants or on other organisms.
Question 3. The first trophic level in a food chain is always a green plant. Why?
Answer:
Because only plants can utilize the radiant energy of the sun and transform it into chemical form during photosynthesis.
Question 4. Write the full forms of UNEP and PEC.
Answer:
UNEP = United Nations Environment Programme
PFC = Perfluorocarbon
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Question 5. In an ecosystem, rats feed on grain. Name the tropic level to which the rat belongs.
Answer: Second tropic level.
Question 6. Write the mode of nutrition in fungi.
Answer: Saprophytic.
Question 7. In a certain study conducted d on the occurrence of DDT along food chains in an ecosystem, the concentration of DDT in the grass was found to be 0.5 ppm, in sheep it was and in Inman it was 10 ppm. Why was the concentration of DDT maximum in the case of man?
Answer:
DDT is non-biodegradable and accumulates at each tropic level. Since man is at the highest tropic level, there is a maximum accumulation of DDT in him (biological magnification).
Question 8. Write any consequences if decomposers are removed from the ecosystem.
Answer:
- Dead organisms will pile up.
- There will be no replenishment of soil.
Question 9. Which chemical is used in fire extinguishers? How is it harmful?
Answer: Chlorofluorocarbons-CFCs.It causes depletion of the ozone layer.
Question 10. What is meant by biological magnification?
Answer:
Accumulation of non-biodegradable chemicals progressively at each trophic level in a food chain is called biological magnification.
Question 11. Mention the role of microorganisms like bacteria and fungi in the ecosystem.
Answer:
They break down the dead remains and waste products of organisms.
Question 12. Write the names of aquatic organisms to form a food chain of at least three steps.
Answer:
Algae → insect → mall fish→ big fish
Question 13. Give one property of ultraviolet radiation.
Answer: Ultraviolet radiation causes skin cancer in humans.
Question 14. The “Save the Tiger” campaign is being overemphasized these days by our government. What may be the possible reason?
Answer: To maintain ecological balance in nature and to preserve the gene pool.
Question 15. Why are some substances biodegradable and some non-biodegradable?
Answer: Some inert substances that are not broken down by biological processes are non-biodegradable, and those that are broken by biologicalgical processes are biodegradable.
Question 16. Give any two ways in which biodegradable substances would affect the environment.
Answer: Biodegradable substances produced in large quantities will emit foul odor and will be a place for mosquito and housefly breeding.
Question 17. What is ozone and how does it affect any ecosystem?
Answer: Ozone (O3) is a molecule formed by three atoms of oxygen. Ozone (O3) is a deadly poison. It shields the surface of the earth from ultraviolet (UV) radiation.
Question 18. What are the problems caused by the non-biodegradable wastes that we generate?
Answer: Non-biodegradable substances are inert, and they persist in the environment for a long time. They may harm the various other members of the ecosystem.
Question 19. Why does a food chain generally consist of only three or four steps?
Answer: The loss of energy at each step of the food chain is so great that very little usable energy remains after four trophic levels. Hence, food chains generally consist of only three or four steps.
Question 20. Define a food web. State its significance for the ecosystem.
Answer: A system of interconnected food chains among various organisms is called a food web. A food web maintains ecological balance by maintaining the interdependence of different organisms.
Question 21. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer: Accumulation of harmful chemicals progressively at each trophic level is termed as biological magnification. The level of accumulation will be highest in the last trophic level and least in the first trophic level of the food chain.
Question 22. Why is improper disposal of waste a curse to the environment?
Answer: Wastes pollute our environment, air, soil, and water, and cause harmful effects on all living organisms.
Question 23. Write the common food chain of a pond ecosystem.
Answer: Phytoplankton and aquatic plants fish
Question 24. Why are crop fields known as artificial ecosystems?
Answer: Crop fields are man-made, and some biotic and abiotic components are manipulated by humans.
Question 25. Explain the role of decomposers in the environment.
Answer: Decomposers break down the dead and decaying organic matter and return the nutrients to the soil. Thus, they play a very important role in nutrient recycling in the environment.
Question 26. We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?
Answer: An aquarium is an artificial and incomplete ecosystem in contrast to ponds/lakes which are natural self-sustaining and complete ecosystems.
Question 27. In the following food chain, 5J of energy is available to man. How much energy was available at the producer’s level?
Plant → Sheep→ Man
500 J → 50 J→ 5 J
Answer: 50,000 J of energy was available at the producer level.
Question 28. In comparison to two ecosystems ‘A’ and B’, it is observed that ‘A’ has only first and second-order consumers, while B’ has third–, fourth-, and fifth-order consumers, which of the two would be more stable?
Answer: ‘A’ will be more stable because it has a lesser number of trophic levels.
Question 29. How is ozone formed in the upper part of the atmosphere of the Earth?
Answer: Ozone at higher levels of the atmosphere is a product of UV radiations acting on oxygen(O2) molecule