CBSE Class 10 Biology Our Environment MCQs Set F

Question. Which of the followings are environment-friendly practices? 
(a) Carrying cloth-bags to put purchases in while shopping.
(b) Switching off unnecessary lights and fans .
(c) Walking to school instead of getting your mother to drop you on her scooter.
(d) All of the above. 

Answer: d

Question. Which one of the following green house gases is a contributor due to incomplete combustion of coal and petroleum? 
(a) Oxides of nitrogen
(b) Methane
(c) Carbon monoxide
(d) Carbon dioxide

Answer: c

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

Answer: b

Question. In a food chain, the third trophic level is always occupied by 
(a) Carnivores.
(b) Herbivores.
(c) Decomposers.
(d) Producers. 

Answer: a

Question. The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about : 
(a) 1%.
(b) 5%.
(c) 8%.
(d) 10%. 

Answer: a

Question. In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level? 
Grass → Grasshopper → Frog → Snake → Hawk
(a) 5 kJ
(b) 50 kJ
(c) 500 kJ
(d) 5,000 kJ 

Answer: d

Question. Select the mismatched pair in the following and correct it. 
(a) Bio-magnification — 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

Assertion and Reason Based MCQs :

Directions : In the following questions, A statement of Assertion (a) is followed by a statement of Reason (R).
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is true.

Question. Assertion (a): Flow of energy in a food chain is unidirectional. 
Reason (R): Energy captured by autotrophs does not revert back to the solar input and it passes to the herbivores. 

Answer: a

Question. Assertion (a): Ozone is both beneficial and damaging. 
Reason (R): Stop the release of chlorofluorocarbons to protect the ozone. 

Answer: b

Question. Assertion (a): First trophic level in a food chain is always a green plant. 
Reason (R): Green plants are called producers. 

Answer: a

Question. Assertion (a): Food chain is responsible for the entry of harmful chemicals in our bodies. 
Reason (R): The length and complexity of food chains vary greatly. 

Answer: b

Question. Assertion (a): Polythene bags and plastic containers are non-biodegradable substances. 
Reason (R): They can be broken down by microorganisms in natural simple harmless substances. 

Answer: c

Question. Assertion (a): Decomposers keep the environment clean. 
Reason (R): They recycle matter by breaking down the organic remains and waste products of plants and animals. 

Answer: a

Question. Assertion (a): The concentration of harmful chemicals is more in human beings. 
Reason (R): Man is at the apex of the food chain. 

Answer: a

Question. Assertion (a): Wastes such as plastics, paper, vegetable or fruit peels, which are generated in our house daily are biodegradable. 
Reason (R): Biodegradable wastes can be broken down into simpler, harmless substance in nature in due course of time by the biological processes such as action of microorganisms. 

Answer: d

Question. Assertion (a): Greater number of individuals are present in lower trophic levels.
Reason (R): The flow of energy is unidirectional.

Answer: b

Question. Assertion (a): Herbivores are called first order consumers. 
Reason (R): Tiger is a top carnivore. 

Answer: b

Question. Assertion (a): CFCs deplete the ozone layer. 
Reason (R): CFCs are used as refrigerants and in fire extinguishers.

Answer: a

Very Short Answer Type Questions :

Question. State the essential function performed by Ozone at the higher levels of the atmosphere.
Answer: It shields the surface of the earth from ultraviolet (UV) radiation from the sun.

Question. We often use the word environment. What does it mean?
Answer: Environment is everything that surrounds us. It is the physical, chemical and biological conditions of the region.

Question. Why is a lake considered to be a natural ecosystem? 
Answer: Because a lake is a self-sustaining system.

Question. In a food chain of frog, grass, insect and snake assign trophic level to frog.
Answer: Grass → Insect → Frog → Snake Frog is 3rd trophic level.

Question. In the following food chain, 100 J of energy is available to the lion. How much energy was available to the producer? 
Plants → Deer → Lion
Answer: Plants are producers. So, energy available to the producer is 10,000 J.

Question. The depletion of ozone layer is a cause of concern. Why?
Answer: Ultraviolet rays from the sun penetrate down the atmosphere and cause health hazards/skin cancer in human beings.

Question. Explain how ozone being a deadly poison can still perform an essential function for our environment. 
Answer: Ozone layer protects us from harmful effects of UV radiation.

Short Answer Type Questions :

Question. You have been selected to talk on 'ozone layer and its protection' in the school assembly on ‘Environment Day‘.
(a) Why should ozone layer be protected to save the environment?
(b) List any two ways that you would stress in your talk to bring in awareness amongst your fellow friends that would also help in protection of ozone layer as well as the environment.
Answer: (a) Because Ozone layer protects/shields the earth from harmful UV radiations of the sun. 
(b) (i) Conducting poster making competition
highlighting effects of ozone layer depletion. 
(ii) Conducting street plays highlighting the ways of environment protection.

Question. What is Ozone? Name the chemicals that damage the Ozone layer. 
Answer: Ozone is a gas made up of three oxygen atoms, occurs naturally in small amounts in the upper atmosphere and protects life on Earth from the Sun's ultraviolet (UV) radiations. The chemical that damage Ozone layer is Chlorofluorocarbon (CFCs).

Question. 'Energy flow in food chains is always unidirectional'. Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body.
Answer: (i) In a food chain the energy moves progressively through the various trophic levels and is no longer available to the organisms of the previous trophic level/ energy captured by the autotrophs does not revert back to the solar input. 
(ii) Pesticides used for crop protection when washed away/down into the soil/water bodies absorbed by plants/ producers. 
(iii) On consumption they enter our food chain and being non-biodegradable, these chemicals get accumulated progressively and enter our body.

Question. Write the harmful effects of using plastic bags, on the environment. Suggest alternatives to plastic bags.
Answer: Plastic bags are non-biodegradable wastes, they are not degraded, they begin to stink, emitting foul gases, spoil the beauty of places and contaminate soil, water and air with toxins.
Cloth bags are used instead of plastic bags because they are stronger, more durable and washable.

Question. (a) Define ecosystem.
(b) Autotrophs are at the first level of food chain. Give reason.
(c) In a food chain of frogs, grass, insects and snakes, assign trophic level to frogs. To which category of consumers do they belongs to?
Answer: (a) Ecosystem: It is the functional unit of the environment comprising living and non-living components.
(b) The first trophic level in a food chain is always producers (plants) because they have the ability to trap solar energy with the help of chlorophyll. As a result, they produce food by photosynthesis.
(c) Frogs are secondary consumers.

Question. Differentiate between the food habits of organisms belonging to first and second trophic levels.
Answer: Difference between food habits of organisms belonging to first trophic level and second trophic level:
(a) The organisms at the first trophic levels are primary producers which make organic compounds using inorganic inputs like light, water, carbon dioxide etc. e.g., Plants.
(b) The organisms at the second trophic level are primary consumer. They are herbivores who eat plants (producers) for nutrition. e.g., Deer.

Question. How is ozone both beneficial and damaging? How can we prevent the damaging effect of ozone?
Answer: Damaging as it is a deadly poison. Beneficial as it shields the surface of the earth from UV radiations of the Sun.
By not using synthetic chemicals like CFCs, that deplete layer.

Question. Why must we conserve our forests? List two factors responsible for causing deforestation.
Answer: Forests help in preventing soil erosion / protect biodiversity / maintain ground water level / help in rainfall / provide raw materials / prevent floods / (any other two points).
Exploitation by industries / increase in population / urbanization / cattle grazing / (any other two points)

Long Answer Type Questions :

Question. Suggest any four activities in daily life which are eco-friendly. 
Answer: Activities in daily life which are eco-friendly are given below :
(i) Use of compost and vermicompost in place of fertilisers.
(ii) Separation of biodegradable and non-biodegradable substances. 
(iii) Gardening 
(iv) Use of gunny bags or paper bags in place of polythene. 
(v) Rain water harvesting.

Question. Name the wastes which are generated in your house daily. What measures would you take for their disposal? 
Answer: The wastes which are generated in our house daily are :
(i) Paper wastes like newspapers, bags, kitchen wastes, etc.
(ii) Plastic bags.
(iii) Vegetable or fruit peels. 
Measures taken for proper disposal are:
(i) Prepare a compost pit for kitchen wastes.
(ii) Safe disposal of plastic bags.
(iii) Segregation of biodegradable and non-biodegradable wastes.
(vi) Fruit peels can be placed near trees or plants, which on decomposition will enrich the soil with nutrients.
(v) Recycling of paper wastes.

Study the passage and answer the questions given below :
The activities of man had adverse effects on all forms of living organisms in the biosphere.
Unlimited exploitation of nature by man disturbed the delicate ecological balance betweenthe living and non-living components of the biosphere. The unfavourable conditions created
by man himself threatened the survival not only of him but also of the entire living organisms on the mother earth. One of your classmates is an active member of ‘Eco club’ of your school which is creating environmental awareness amongst the school students, spreading the same in the society and also working hard for preventing environmental degradation of the surroundings.

Question. Degradation of non-biodegradable waste is difficult because : 
(a) Non-biodegradable wastes cannot be recycled.
(b) Microorganisms cannot decompose it.
(c) They can be made into organic wastes.
(d) All of the above

Answer: b

Question. Which of these group(s) contains only nonbiodegradable items? 
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelite, DDT
(a) (iii)
(b) (iv)
(c) (i) and (iii)
(d) (ii) and (iv)

Answer: d

Question. Which of the following does NOT exist in a balanced ecosystem? 
(a) Interconnected food chains.
(b) Interdependence among living organisms and the environment.
(c) Animals dependent on plants but plants are not dependent on animals.
(d) Communities made up of different populations of organisms.

Answer: c

Question. The green dustbin signifies: 
(a) Non- biodegradable waste
(b) Biodegradable waste
(c) Plastic waste
(d) Garbage

Answer: b