CBSE Class 10 Science Chapter-15 Our Environment – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Science Chapter 15 – Our Environment prepared by expert Science teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 10 Science Chapter-15 Our Environment Important Questions
CBSE Class 10 science Important Questions Chapter 15 – Our Environment
2 Mark Questions
1. Give scientific terms for the following-
(a) the process of eating and being eaten
(b) the relationship between abiotic and biotic component
Ans. (a) Food chain
(b) Ecosystem
2. What is meant by environment? Name its components.
Ans. The aggregate of all external conditions and their influences affecting the life and the development of an organism in its natural habitat is environment. It has two components-
(1) Abiotic components (non-living): For example- air, water, soil, temperature, etc.
(2) Biotic components (living): For example- Plant, animals and micro-organisms.
3. What is 10% law? Give an example
Ans. According to 10% law only 10% of energy is available at the next trophic level. For example- If energy available at producer level is 1000J then at next level only 10% of 1000J i.e. 100J is available.
4. What is artificial ecosystem? Give two examples.
Ans. Man-made ecosystem are called artificial ecosystem. For example- Garden, Aquarium.
5. Energy transfer is said to be unidirectional whereas biochemical transfer is said to be cyclic. Why?
Ans. The flow of energy is unidirectional because the energy lost as heat to the environment can’t be reutilized by plants for photosynthesis. Energy decrease at each trophic level (10% of previous level). Hence it can’t be reused again. Whereas, biochemical transfer is cyclic because nutrients utilized by plants and animals are returned to environment after the death of organisms.
6. Why is there a need to ban the use of polythene bags?
Ans. Polythene bags need to be banned because they are non-biodegradable; micro-organisms are not able to decompose it. So it goes on accumulating on the land and causes land pollution.
7. What is the significance of food chain?
Ans. Significance of food chain-
(a)It is a means of transfer of food from one trophic level to another.
(b)It provides information about the living components of our ecosystem.
(c)It helps us in understanding the interactions and interdependence among different organisms in an ecosystem.
(d)It is a pathway for the flow of energy in any ecosystem.
8. How would you dispose the following wastes:
(a) domestic wastes like vegetables peels
(b) industrial wastes
Ans. (a) Domestic wastes like vegetables peels should be disposed off in a pit.
(b) Industrial wastes should be treated first to remove poisonous salts or chemicals and disposed off in water resources like river.
9. Why vegetarian food habit help us in getting more energy?
Ans. A person having vegetarian food habits is closed to the producer level get maximum amount of energy as compare to the organism at higher trophic level because only 10% of energy is available at the successive level than previous level.
10. Write a food chain having two trophic levels.
Ans. Plants
man
11. Diagrammatically represent the transfer of energy in a food chain.
Ans.
Transfer of energy in a food chain.
12. Consider the following food chains-
(a) Plants mice snakes hawks
(b) Plants micehawks
If energy available at the producer level in both the food chains is 100J. In which case will hawks get more energy and how much?
Ans. Hawk get more energy in food chain having three trophic levels.
Energy available to hawk is 1J.
13. Why is there a need to ban the use of polythene bags?
Ans. Polythene bags are non- biodegradable, they are not decomposed by micro-organisms hence, cause land pollution.
14. What are the two functions of ecosystem?
Ans. Interactions of any ecosystem refers to its functions these interactions are-
(a)Biogeochemical cycles- The cyclic transfers between the living and non- living components.
(b)Flow of energy- in a food chain, through various steps of eating and being eaten food energy flow from one tropic level to another.
15. What percentage of solar energy is trapped and utilized by plants?
Ans. Plants utilized only 1% of total sun’s energy, which is utilized by plants in the process of photosynthesis.
16. What are the harmful effects of acid rain?
Ans. (1) Acid rain makes the soil acidic which affects the growth of trees and cereal crops badly.
(2) It makes the water of lakes, ponds, etc acidic which affects the growth of aquatic plants and animals.
(3) Bacteria useful for maintaining soil fertility are killed.
(4) It affects the historical monuments and building badly specially those made up of marble.
17. Differentiate between abiotic and biotic components of ecosystem.
Ans.
18. Give any two methods reducing the problem of waste disposal.
Ans. (a) Use of recycled material.
(b) Separation of biodegradable and non-biodegradable waste during disposal.
19. Give reason: “Life on earth depends on the sun.”
Ans. Sun is the ultimate source of energy on earth. Only plants can convert solar energy into chemical energy (food), which is transferred to different organisms at various trophic levels. Energy stored in fossil fuel is also transferred solar energy because they made up of decomposed plants and animals. Hence, solar energy is utilized and transformed in different form which is utilized by us.
20. What are trophic levels? Give an example of a food chain and state the different trophic
level in it.
Ans. Each step in a food chain constitutes a trophic level. For example
21. What is the role of decomposers in the ecosystem?
Ans. They decompose dead remains of plants and animals and their wastes organic products into simple inorganic substances which are released into the atmosphere for reuse by the plants. Thus, they help in recycling of materials.
22. What is ozone and how does it affects any ecosystem?
Ans. Ozone is a form of oxygen. It has the molecular formula
. It is present at a higher level in the atmosphere. It protects the ecosystem from the harmful effects of ultraviolet rays coming from the Sun. UV rays may cause skin cancer, cataract to us.
23. How can you help in reducing the problems of waste disposal? Give any two methods.
Ans. The following measures can be adopted for reducing the problem of waste disposal:
(i) Reduce the volume of wastes by burning in incinerator.
(ii) Produce compost and biogas from biodegradable waste.
24. What will happen if we kill all the organisms in one trophic level?
Ans. If we kill all the organisms in one trophic level, the number of individuals in the next trophic level will decrease due to non-availability of food. Also, the number of individuals in the previous trophic levels will increase because there is no one to feed on them. This will cause imbalance in the environment.
25. 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?
Ans. Yes, the impact of removing all the organisms of a trophic level will be different for different
trophic levels. The effect will be time related. If we remove all the producers, primary consumers will be affected instantly. Secondary consumers will affect after a gap and tertiary consumers after a longer gap.
26. If all the wastes we generate is biodegradable, will this have no impact on the environment?
Ans. It will have only short term impact on environment, the action of decomposers will slow down and some air/water pollution will be caused. However, in longer term, there will be no impact of biodegradable wastes on the environment.
27. What are the problems caused by non-biodegradable wastes that we generate?
Ans. (a) Non-biodegradable pesticides and fertilizers run off to water bodies to cause water pollution.
(b)Some of the non-biodegradable pesticides like DDT enter the food chain and cause biomagnifications in humans and other animals.
28. What limits the number of trophic levels in a food chain.
Ans. There is a loss of energy as we go from one trophic level to the next, this limits the number of trophic levels in a food chain.
29. What is the harm of clay cups?
Ans. Clay cups cause depletion of top fertile soil as they are formed from the same.
30. State one reason to justify the position of man at the apex of most food chains?
Ans. The position of man is at the apex of most food chains as he is an intelligent organism and can take any advantageous position by manipulation.
31. Which food chains are advantageous in terms of energy?
Ans. The two step chains in which man is close to producer are advantageous. For example, Producer—* Man
32. If all the wastes we generate is bio-degradable what impact may this have on the environment?
Ans. Cleaner environment without any pollution, more nutrients will be released into the nutrient pool, will help to maintain ecological balance.
33. Write the harmful effect of ozone depletion.
Ans. i. Cause the skin cancer
ii. Damage to eyes
iii. Immune system
34. Which of the following will have the maximum concentration of harmful chemicals in its body? Peacock, frog, Grass. Snake. Grasshopper
Ans. Out of Grass Grasshopper, Frog, Peacock; Peacock will have maximum concentration of harmful chemicals in its body.
35. Why energy of herbivores never come back to the autographs?
Ans. Energy of herbivorous never comes back to autographs as flow of energy is always unidirectional. So once it passes the trophic level it is no longer available to the previous level.
36. Give the correct sequence of various & trophic levels in a food chain.
Ans.
37. What is biological magnification and give its causes?
Ans. The increased concentration of chemicals at any trophic level is called biological magnification. It occurs due to the excessive use of pesticides which enter our food chain.
38. DDT has entered food chain. Which food habit is safer- vegetarian or non- vegetarian?
Ans. Vegetarian habit is safer. Being closer to producers, less DDT will accumulate in our body Bio magnification leads to higher level of DDT in higher trophic levels.
39. Aquarium requires regular cleaning whereas lakes normally do not. Why?
Ans. Normally a lake has more diverse forms of life and hence a larger number of food chains. This leads to natural cleaning. Thus, the ecosystem is more stable. The aquarium has a very limited number of food chains and unable to sustain itself. Bu, sometimes there is excessive growth of algae in lake. Then it also needs to be cleaned.
40. How will accumulation of bio degradable waste effect our environment?
Ans. Accumulation of bio degradable waste will:
(a) not let minerals return to mineral pool
(b) become site of pest breeding