Class 10 Science: Our Environment important questions

Our Environment is a chapter of Class 10 Science for the CBSE. These 14 questions are marked Very Important, Important or Practice, and each answer has been checked by our team. Use them to revise, not as a prediction of what will come in the exam.

1. Important · 2 marks

   1. A lot of waste is generated in neighborhood. However, almost all of it is biodegradable. What impact will it have on the environment or human health? Q.no. 27 to 33 are short answer questions.

   Excess generation of biodegradable wastes can be harmful as - Its decomposition is a slow process leading to production of foul smell and gases. It can be the breeding ground for germs that create unhygienic conditions. Q.no. 27 to 33 are short answer questions.

2. Important · 3 marks

   2. Why is damage to the ozone layer a cause for concern? What are its causes and what steps are being taken to limit this damage? Q.no. 34 to 36 are Long answer questions.

   Damage to the ozone layer is a cause for concern because the ozone layer shields the surface of earth from harmful UV radiations from the sun which cause skin cancer in human beings. Synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in the fire - extinguishers are the main reason for the depletion of the ozone layer. Steps taken to limit this damage - Many developing and developed countries have signed and are obeying the directions of UNEP (United Nations Environment Programme) to freeze or limit the production and usage of CFCs at 1986 levels.

3. Practice · 1 marks

   3. In 1987, an agreement was formulated by the United Nations Environment Programme (UNEP) to freeze the production of “X” to prevent depletion of “Y”. “X” and “Y” respectively referred here are: a) Ozone; CFCs b) CFCs; rays UV c) CFCs; Ozone d) UV rays; Diatomic oxygen

   c) CFCs, Ozone

4. Practice · 1 marks

   4. Assertion: Biodegradable substances result in the formation of compost and natural replenishment. Reason: It is due to breakdown of complex inorganic substances into simple organic substances. Question No. 21 to 26 are very short answer questions

   c) A is true but R is false.

5. Practice · 1 marks

   5. Identify the incorrect statement ‘The energy available to the producers is maximum’ because: A. It is the first trophic level which absorbs1% of light energy directly from the source. B. It utilizes the most of the chemical energy for its own respiration, growth, reproduction, movement etc. C. It utilizes 10% of light energy and transfers the rest to the next trophic level. D. It transfers only 10% of light energy to the next trophic level.

   C. It utilizes 10% of light energy and transfers the rest to the next trophic level.

6. Practice · 1 marks

   6. Assertion (A): If the lions are removed from a food chain it will not affect the food chain, however if the plants are removed from a food chain it will disturb the ecosystem. Reason (R): Plants are producers who can make food using sunlight, while lions are consumers. Question No. 21 to 26 are very short answer questions A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.

   D. A is false but R is true.

7. Important · 2 marks

   7. Create a food chain with more than 2 trophic levels that exists in the cabbage farm. If Humans occupy the last trophic level, then how would spraying pesticide affect the humans? Explain. Question No. 27 to 33 are short answer questions

   Cabbage/plant-> rabbit-> snake-> owl (Any other relevant food chain) Pesticides are non-biodegradable and persist for long. So when humans consume plants or any animal that consume this plant, the pesticide enters the food chain and keeps getting accumulated at each trophic level, thus the organism in the last trophic level-human being has the highest concentration of pesticide and this is called biological magnification.

8. Practice · 1 marks

   8. Which are the correct statements related to ozone? (i) Ozone layer helps in increasing the UV radiations reaching earth. (ii) Ozone is a deadly poison. (iii) Ozone layer shields the earth from UV radiations. (iv) Ozone layer prevents UV rays which cause skin cancer. (v) Ozone is formed with the help of Chloroflurocarbons. A. (i), (ii), (iii) B. (ii), (iii), (iv) C. (iii), (iv), (v) D. (i), (iv), (v)

   B. (ii), (iii), (iv)

9. Practice · 1 marks

   9. Which of the following human activities has resulted in an increase of non- biodegradable substances? A. Organic farming B. Increase in tree plantation C. Use of plastic as packaging material D. Composting of kitchen waste

   C. Use of plastic as packaging material.

10. Practice · 1 marks

    10. Assertion (A): Vulture will always have the least amount of pesticides in a food chain. Reason (R): Vulture occupies the last trophic level and it gets only 10% of energy of the previous trophic level. A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.

    D. A is false but R is true

11. Important · 2 marks

    11. About 100 acres of forest land was declared as Natural reserve park. The following organisms were predominant in the Natural reserve park: rabbit, frog, grass, fish, fox, water insects, zebra, peacock, snake, trees, bird, owl, insects, tiger, vulture, duck. Create a food web comprising two separate food chains with different producers by using the above data.

    Tree food chain- tree, zebra, tiger /Any other food chain Grassland food chain- grass, zebra, tiger / Any other food chain Food web- Join the two food chains at a common point (zebra)

12. Practice · 1 marks

    12. A fish living in a pond ecosystem feeds on small aquatic insects (larvae). These insect larvae, in turn, feed on green algae and small photosynthetic bacteria. In this specific food chain, what is the trophic level classification of fish? A. Producer B. Primary Consumer C. Secondary Consumer D. Tertiary Consumer

    C. Secondary Consumer

13. Practice · 1 marks

    13. Assertion (A): In an ecosystem, 1% of energy is available for transfer from one trophic level to the next. Reason (R): An average of 10% of the food eaten by organisms is available for flow in the form of chemical energy. A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.

    D. A is false but R is true

14. Important · 3 marks

    14. Study this food chain in a pond: phytoplankton → zooplankton → small fish → large fish. A. If the energy available at the fourth trophic level is 10 kJ, what will be the energy available at the producer level? B. Is it possible to have three more trophic levels in this food chain? Justify. C. Which trophic level will have the maximum amount of pesticide if it is washed into the water body from agricultural fields? Why?

    A. 10000 KJ B. No, the loss of energy at each step is so much that very little usable energy will be left. C. Large fish, due to biological magnification of pesticide.