CBSE Class 10 Biology Our Environment Management Of Natural Resources Worksheet Set 06

This printable worksheet for CBSE Class 10 Science (Biology) Chapter 13, Our Environment, has 18 questions with answers: fill in the blanks, true or false, matching, one-word answers and simple energy-transfer numericals based on the 10% law. It is a quick revision of ecosystem components, trophic levels, the food web, ozone and the CFC agreement, with no multiple-choice questions and no diagrams, so it prints well.

Fill in the Blanks

Question 1. Fill in the blanks:
(1) The hierarchies within a food web are called ___________ levels.
(2) Without the ___________ in a food web many chemicals would not be recycled.
(3) Decrease in ozone in stratosphere is linked to release of synthetic chemicals like ___________.
(4) The ___________ make the energy from sunlight available to the rest of the ecosystem.
(5) The use of chemicals like CFCs has endangered the ___________ layer.
(6) The waste we generate may be ___________ or ___________.
(7) All the interacting organisms in an area together with the non-living constituents of the environment form an ___________.
Answer:
(1) trophic
(2) decomposers
(3) chlorofluorocarbons (CFCs)
(4) producers
(5) ozone
(6) biodegradable, non-biodegradable
(7) ecosystem
In simple words: Each blank is a key term of the chapter.

Teacher's Note:
1. Write the full term, not a short form.
2. Decomposers and producers are both needed in every ecosystem.

Question 2. Fill in the blanks:
(1) Gardens and crop fields are examples of ___________ ecosystem.
(2) The decomposers comprising micro-organisms like ___________ and ___________.
(3) The energy flows from ___________ to the heterotrophs and decomposers.
(4) The flow of energy is always ___________ in food chains.
(5) The interlocking pattern of various food chains is referred as ___________.
(6) The disposal of the waste we generate is causing serious ___________ problems.
(7) The plants trap ___________ energy and convert it into ___________ energy.
(8) The energy available at each successive trophic level is ___________ of the previous level.
Answer:
(1) artificial
(2) bacteria, fungi
(3) autotrophs (producers)
(4) unidirectional
(5) food web
(6) environmental
(7) light, chemical
(8) 10%
In simple words: Energy moves one way, and each level gets one tenth of the previous one.

Teacher's Note:
1. Chemical energy is stored in food.
2. The 10% law applies at each step.

Question 3. Fill in the blanks:
(1) The biodegradable substances were broken down by the activity of ___________ secreted by ___________.
(2) The series of organism feeding on one another is called ___________.
(3) UNEP stands for ___________.
(4) The process by which producers prepare their own food in presence of sunlight is called ___________.
(5) Ozone is getting depleted due to ___________ used in refrigerants and in fire extinguishers.
(6) The process by which the harmful chemicals entered in food chain are not degradable and get accumulated progressively at each level is called ___________.
(7) Herbivores, carnivores, omnivores and parasites are examples of ___________.
(8) ___________ can be taken as average value for the amount of organic matter that is present at each step and reaches the next level of consumers.
Answer:
(1) enzymes, micro-organisms
(2) food chain
(3) United Nations Environment Programme
(4) photosynthesis
(5) chlorofluorocarbons (CFCs)
(6) biological magnification
(7) consumers
(8) 10%
In simple words: These blanks cover enzymes, food chains, UNEP, photosynthesis and biomagnification.

Teacher's Note:
1. Biomagnification is also called biological magnification.
2. Check the final answer against the chapter.

True or False

Question 4. Write true or false. If a statement is false, correct it.
(1) Non-biodegradable articles are the ones which cannot be digested.
(2) Ozone is formed in stratosphere by action of ultraviolet radiations on oxygen.
(3) Biodegradable wastes should be separated and kept in blue colour bins for garbage collectors.
(4) Blue green algae are producers.
(5) The reproduction and other activities of living organisms are affected by the abiotic components of ecosystem.
(6) Specific enzymes are needed for the break-down of a particular substance.
(7) The materials like plastics are not acted upon by physical process.
(8) Secondary consumers in a food chain are always carnivores.
(9) Carbon dioxide causes depletion of ozone layer thereby allowing more UV-radiations to reach the earth.
(10) The abiotic components of the environment are the living factors.
(11) The amount of usable energy remains constant as it is passed from one trophic level to another.
(12) The energy within an ecosystem is fixed and never changes.
Answer:
(1) True
(2) True
(3) False: biodegradable wastes go in the green bin; the blue bin is for non-biodegradable (dry) waste.
(4) True
(5) True
(6) True
(7) False: physical processes such as heat and pressure do act on plastics, but only very slowly; microbes cannot degrade them.
(8) True
(9) False: CFCs, not carbon dioxide, deplete the ozone layer.
(10) False: abiotic components are the non-living factors.
(11) False: usable energy decreases at each trophic level.
(12) False: energy is transformed and lost as heat at each step, and it flows in one direction.
In simple words: Check each statement against the facts of the chapter.

Teacher's Note:
1. Statements on the greenhouse effect, ecology and the human impact on the biosphere are left out because they are outside this chapter.
2. Rewrite false statements correctly to earn full marks.

Match the Following

Question 5. Match Column I with Column II.
Column I: (A) Grass (B) Grasshopper (C) Frog (D) Hawk
Column II: (p) Primary carnivore (q) Secondary carnivore (r) Producer (s) Primary consumer
Answer:
(A) → (r) producer
(B) → (s) primary consumer
(C) → (p) primary carnivore
(D) → (q) secondary carnivore
In simple words: Follow the chain: grass, grasshopper, frog, hawk.

Teacher's Note:
1. Arrange the organisms in food chain order first.
2. A primary carnivore eats herbivores.

Question 6. Match Column A with Column B.
Column A: (A) Third trophic level (B) Accumulation of pesticides at higher trophic level (C) Green plants (D) Flow of energy in an ecosystem (E) Consists of 3 atoms of oxygen (F) Main cause of depletion of ozone layer (G) Second trophic level (H) Break-down of dead organic compounds
Column B: (p) Ozone (q) CFCs (r) Herbivore (s) Biomagnification (t) Decomposers (u) Producers (v) Unidirectional (w) Carnivores
Answer:
(A) → (w) carnivores
(B) → (s) biomagnification
(C) → (u) producers
(D) → (v) unidirectional
(E) → (p) ozone
(F) → (q) CFCs
(G) → (r) herbivore
(H) → (t) decomposers
In simple words: Each term has exactly one partner.

Teacher's Note:
1. Match the sure ones first and eliminate.
2. Ozone is O₃.

One-Word Answers and Short Questions

Question 7. Suggest one word for each of the following statements or definitions.
(i) The physical and biological world where we live in.
(ii) Each level of food chain where transfer of energy takes place.
(iii) The physical factors like temperature, rainfall, wind and soil of an ecosystem.
(iv) Organisms which depend on the producers either directly or indirectly for food.
Answer:
(i) Environment
(ii) Trophic level
(iii) Abiotic factors
(iv) Heterotrophs (consumers)
In simple words: One precise term answers each definition.

Teacher's Note:
1. Do not write a sentence where one word is asked.
2. Consumers are heterotrophs.

Question 8. What is the functional unit of the environment comprising of the living and non-living components called?
Answer:
It is called an ecosystem.
In simple words: The ecosystem is the unit of the environment.

Teacher's Note:
1. It includes biotic and abiotic components.
2. Check the final answer against the chapter.

Question 9. Name two natural ecosystems and two artificial ecosystems?
Answer:
Natural ecosystems: forest and pond (also lake, river, ocean).
Artificial ecosystems: garden and crop field (also aquarium, park).
In simple words: Natural ones form on their own, artificial ones are made by people.

Teacher's Note:
1. Give two of each.
2. Check the final answer against the chapter.

Question 10. Which one term in the following includes the others? Air, flora, fauna, environment, water, sunlight, soil.
Answer:
Environment includes all the others: air, water, sunlight and soil (abiotic) and flora and fauna (biotic).
In simple words: Environment is the whole; the rest are its parts.

Teacher's Note:
1. Think of the largest set.
2. Check the final answer against the chapter.

Question 11. What are planktons?
Answer:
Planktons are tiny organisms that float in water. Phytoplankton are microscopic plants (producers) and zooplankton are tiny animals that feed on them.
They form the first two steps of aquatic food chains.
In simple words: Planktons are tiny floating organisms at the base of aquatic food chains.

Teacher's Note:
1. Phyto means plant and zoo means animal.
2. Check the final answer against the chapter.

Question 12. A student went to study a local pond. In one part of the pond she noticed tadpoles scraping at some pond weed. In another part she saw a water beetle holding a tadpole in its jaws.
(i) Construct a food chain for the pond ecosystem.
(ii) How many trophic levels are there in this chain?
Answer:
(i) Pond weed → Tadpole → Water beetle.
(ii) There are three trophic levels: producer, primary consumer and secondary consumer.
In simple words: Read who eats whom and write it in order.

Teacher's Note:
1. Follow the arrows from the eaten to the eater.
2. Count each organism as one trophic level.

Energy Transfer Numericals (10% Law)

Question 13. In the following food chain, grass provides 4000 J of energy to the grasshopper. Grass, grasshopper, frogs, snakes. How much energy will be available to snakes and frogs?
Answer:
The grasshopper receives 4000 J.
Frogs receive 10% of 4000 J = 400 J.
Snakes receive 10% of 400 J = 40 J.
In simple words: 4000 J → 400 J → 40 J.

Teacher's Note:
1. Since 4000 J is the energy given to the grasshopper, the frog gets 400 J and the snake 40 J; some answer keys shift every value down one step (40 J and 4 J), which does not match the wording.
2. The same wording in a board question (500 J provided to rats) gives rats 500 J, snakes 50 J, hawks 5 J.

Question 14. In a food chain of frog, grass, insect and snake assign trophic level to frog.
Answer:
The food chain is Grass → Insect → Frog → Snake.
Frog occupies the third trophic level (secondary consumer).
In simple words: Grass is first, insect second, frog third.

Teacher's Note:
1. Arrange the organisms in order first.
2. Producers occupy the first trophic level.

Question 15. In the following food chain, 100 J of energy is available to the lion. How much energy was available to the producer? Plant → Deer → Lion
Answer:
Let the energy of the deer be x. 10% of x = 100 J, so x = 1000 J.
Let the energy of the plant be y. 10% of y = 1000 J, so y = 10,000 J.
In simple words: Going back up the chain, multiply by 10 at each step.

Teacher's Note:
1. Work backwards from the lion.
2. Two steps give a factor of 100.

Question 16. Consider the following food chain which occurs in forest: Grass → Deer → Lion. If 10000 J of solar energy is available to grass, how much energy would be available to deer to transfer it to lion.
Answer:
Taking 10,000 J as the energy of the producer (grass): deer receive 10% = 1000 J.
The deer can then pass 10% of this, 100 J, to the lion.
In simple words: 10,000 J → 1000 J (deer) → 100 J (lion).

Teacher's Note:
1. Some answer keys reduce the 10,000 J to 1% first and get 1 J, which is not the usual board answer; 1000 J is used here.
2. State clearly which level has which energy.

Question 17. An organism having 35 J of energy will transfer how much energy to next trophic level?
Answer:
Only 10% is transferred: 10% of 35 J = 3.5 J.
In simple words: One tenth of 35 J is 3.5 J.

Teacher's Note:
1. Use 10/100 × 35.
2. Check the final answer against the chapter.

Question 18. What will be the amount of energy available to the organisms of 2nd trophic level of food chain if energy available at the first trophic level is 1000 J.
Answer:
Energy at the second trophic level = 10% of 1000 J = 100 J.
In simple words: One tenth of 1000 J is 100 J.

Teacher's Note:
1. The 10% law applies to every step.
2. The third level would get 10 J.