CBSE Class 10 Science Our Environment VBQs Set 03

Question. Which one of the following is an artificial ecosystem?
(a) Pond (b) Crop field (c) Lake (d) Forest
Answer: (b) Crop field

Question. An ecosystem includes
(a) all living organisms
(b) non-living objects
(c) both living organisms and non-living objects
(d) sometimes living organisms and sometimes nonliving objects
Answer: (c) both living organisms and non-living objects

Question. Excessive exposure of humans to UV-rays results in (i) damage to immune system (ii) damage to lungs (iii) skin cancer (iv) peptic ulcer
(a) (i) and (ii)
(b) (ii) and (iv)
(c) (i) and (iii)
(d) (iii) and (iv)
Answer: (c) (i) and (iii)

Question. Which group of organisms are not constituents of a food chain?
(a) Grass, lion, rabbit
(b) Plankton, man, fish, grasshopper
(c) Wolf, grass, snake, tiger
(d) Frog, snake, eagle, grass, grasshopper
Answer: (c) Wolf, grass, snake, tiger

Question. If a grasshopper is eaten by a frog, then the energy transfer will be from
(a) producer to decomposer
(b) producer to primary consumer
(c) primary consumer to secondary consumer
(d) secondary consumer to primary consumer
Answer: (c) primary consumer to secondary consumer

Question. Why is improper disposal of waste a curse to environment?
Answer: It pollutes air, water, and soil, causes diseases, leads to eutrophication in water bodies, and acts as a source for pathogens.

Question. Write the common food chain of a pond ecosystem.
Answer: Phytoplanktons and aquatic plants \( \rightarrow \) Zooplanktons, small aquatic animals, larvae \( \rightarrow \) Fish \( \rightarrow \) Bird.

Question. What are the advantages of cloth bags over plastic bags during shopping?
Answer: (i) Stronger and more durable. (ii) Capable of carrying more. (iii) Washable. (iv) Biodegradable and non-polluting. (v) Recyclable. (vi) Reusable.

Question. Why are crop fields known as artificial ecosystems?
Answer: Because they are man-made and the biotic and abiotic components are maintained and nourished by humans.

Question. Suggest one word for each of the following statements/definitions: (a) The physical and biological world where we live in. (b) Each level of food chain where transfer of energy takes place. (c) The physical factors like temperature, rainfall, wind and soil of an ecosystem. (d) Organisms which depend on the producers either directly or indirectly for food.
Answer: (a) Environment or biosphere. (b) Trophic level. (c) Abiotic factors. (d) Consumers or heterotrophs.

Question. Select the mis-matched pair in the following and correct it. (a) Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain (b) Ecosystem — Biotic components of environment (c) Aquarium — A man-made ecosystem (d) Parasites — Organisms which obtain food from other living organisms.
Answer: (b) Ecosystem — Both biotic and abiotic components of the environment.

Question. We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why? 
Answer: Natural ecosystems are self-sustaining and have a perfect recycling of materials. An aquarium is an artificial, incomplete ecosystem that lacks natural recycling mechanisms.

Question. Suggest any four activities in daily life which are eco-friendly.
Answer: (i) Using cloth bags. (ii) Gardening. (iii) Harvesting rainwater. (iv) Using compost.

Question. Give two differences between food chain and food web. 
Answer: (i) Food chain is a single pathway; food web is an interconnection of multiple chains. (ii) Food chain has limited species; food web has numerous populations of different species.

Question. Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Answer: Kitchen waste, paper, plastic, etc. Measures: (i) Segregation of biodegradable and non-biodegradable. (ii) Reusing plastic. (iii) Composting kitchen waste.

Question. Suggest suitable mechanism (s) for waste management in fertiliser industries.
Answer: (i) Using wet scrubbers for gaseous wastes. (ii) Treating effluents before discharge. (iii) Recovering sulphur. (iv) Recycling water.

Question. What are the by-products of fertiliser industries? How do they affect the environment?
Answer: Oxides of nitrogen and sulphur. They cause air pollution and acid rain, which harms soil, crops, and buildings.

Question. Explain some harmful effects of agricultural practices on the environment.
Answer: (i) Fertilizers change soil chemistry. (ii) Pesticides lead to biomagnification. (iii) Cropping causes loss of soil fertility. (iv) Excessive groundwater use lowers water table.

Question. Select the incorrect food chain.
(a) Grass → Frog → Vulture
(b) Grass → Grasshopper → Frog → Snake → Eagle
(c) Grass → Deer → Lion
(d) Phytoplankton → Zooplankton → Small Fish → Large Fish → Man
Answer: (a) Grass → Frog → Vulture

Question. Ecosystem includes:
(a) All biotic and abiotic factors
(b) All plants and animal species
(c) Plants found in land only
(d) Both (a) and (b)
Answer: (d) Both (a) and (b)

Question. Flow of energy in a ecosystem is always ________ whereas flow of minerals is ________.
(a) Unidirectional, cyclic
(b) Bidirectional, unidirectional
(c) Multidirectional, bidirectional
(d) No specific direction for both.
Answer: (a) Unidirectional, cyclic

Question. Accumulation of non biodegradable substances in the food chain in increasing amount at each higher trophic level is known as
(a) Eutrophication
(b) Pollution
(c) Biological magnification
(d) Accumulation
Answer: (c) Biological magnification

Question. Assertion: Biodegradable waste and non biodegradable waste should be discarded separately.
Reason: Biodegradable wastes are not harmful.
(a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
(b) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
(c) Assertion is true but the Reason is false.
(d) The statement of the Assertion is false but the Reason is true.
Answer: (c) Assertion is true but the Reason is false.

Question. Assertion: Pond is a natural ecosystem.
Reason: Ponds are formed naturally.
(a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
(b) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
(c) Assertion is true but the Reason is false.
(d) The statement of the Assertion is false but the Reason is true.
Answer: (a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.

Question. What are the advantages of using cloth or jute bags over polythene bags?
Answer: Cloth or jute bags are reusable, stronger, and biodegradable, whereas polythene bags cause environmental pollution and are non-biodegradable.

Question. In a food chain consisting of grass, deer and lion, 100 J of energy is available to lion. How much energy was available to grass from Sun?
Answer: If Lion has 100 J, Deer had 1,000 J, and Grass had 10,000 J. Since grass only captures 1% of solar energy, the solar energy was 1,000,000 J.

Question. ‘All flesh of carnivore are grass’. Justify the statement.
Answer: Carnivores eat herbivores who eat plants. Without plants (grass), there would be no herbivores and thus no food for carnivores.

Question. Make an aquatic food chain and state the trophic level at which concentration of pesticide is maximum and why?
Answer: Phytoplankton \( \rightarrow \) Small Fish \( \rightarrow \) Large Fish \( \rightarrow \) Crane. Concentration is maximum in the Crane due to biological magnification.

Question. How is ozone formed in the upper atmosphere? How is the ozone hole formed? What are the consequences of ozone hole and how could we control the damage?
Answer: Formed by UV splitting \( O_2 \). Hole is formed by CFCs releasing chlorine. Consequences include skin cancer and cataracts. Control: Limit use of CFCs and ozone-depleting substances.

Question. (a) What is 10% law? (b) Why do not food chains normally go beyond 4 or 5 trophic levels? (c) What is a food web?
Answer: (a) Only 10% of energy is transferred to the next trophic level. (b) Because too little energy remains to support higher levels. (c) An interlocking pattern of various food chains.