Class 10 Science Chapter 15 Board Questions

Class 10 Science Chapter 15 Board Questions of Our Environment. Questions from ten years CBSE Board Exams papers and CBSE Sample papers are given with answers. Questions of 1 mark, 2 marks, 3 marks and 5 marks are given separately with suitable length of answers. The collection of previous years questions contains all the questions from last 5 years papers questions and important questions from last 10 years papers. Answers of each question is given using NCERT Textbooks for 2020-2021. All the answers are prepared under the guidance of subject experts. Answers are upto mark as per CBSE Guidelines.

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Class 10 Science Chapter 15 Board Questions for Exams

Class: 10Science
Chapter: 15Board Questions with Answers

Class 10 Science Chapter 15 Board Questions with proper solutions and answers are given below. All the questions are done by the experts and answers of questions are as per marks. For example, 1 mark questions are answered in one word or one sentence. All the answers are taken from latest NCERT Textbook 2020-2021.

10th Science Chapter 15 Board Questions Set – 1 (1 Mark)

Mention one negative effect of our affluent life style on the environment. [CBSE 2013]

Our activities in our affluent life style pollute the environment.

Why has there been huge hue and cry again CFCs? [CBSE 2011]

CFCs on reaching the upper layer of atmosphere cause ozone layer depletion and depletion and allow UV rays to earth atmosphere.

Name the radiation from the sun that are absorbed by ozone layer. Mention one harmful effect caused by them.

Ultraviolet radiation are absorbed by ozone layer. Ultraviolet radiation cause skin cancer.

What is a meant by non-biodegradable waste? Identify biodegradable waste from the following: Empty packet of chips, empty bottle of mineral water, empty paper box of sweets, empty tin a cold drink. [CBSE 2012]

Substance that do not breakdown by biodegradable process are called non-biodegradable waste. Empty paper box of sweets is biodegradable.

Select from the following substance which have posed a threat to the environment: Aerosols, consumer, bacteria, CFCs. [CBSE 2012]

Aerosols, CFCs.

10th Science Chapter 15 Board Questions Set – 2 (1 Mark)

State two methods to get rid of non-biodegradable wastes. [CBSE 2013]

We should carry cloth bags when we go for shopping. Non-biodegradable water should be collected separately and sent for recycling.

Construct an aquatic food chain ending with shark? [CBSE 2013]

Plankton → Crab → Fish → Shark

How do autotrophs obtain CO2 and N2 to make their food? [CBSE 2008]

Autotroph obtain CO2 from the atmosphere and N2 from the soil.

Why is ozone layer getting depleted at the higher levels of the of the atmosphere? [CBSE 2008]

Depletion of ozone layer is due to the use of chlorofluorocarbons which are used as refrigerant and in fire extinguisher.

Name any two abiotic component of an environment. [CBSE 2008]

Soil and water.

Question: What advantage over an aquatic organism does a terrestrial organisms have with regard to obtaining oxygen for respiration? [CBSE 2008]
Answer: The aquatic organisms use oxygen dissolved in water while terrestrial organisms obtained it from the atmosphere, where the amount of oxygen is much higher.

10th Science Chapter 15 Board Questions Set – 3 (1 Mark)

State the function of digestive enzymes. [CBSE 2008]

Digestive enzymes breakdown the food into smaller, water soluble molecules.

Where do plants get each of the raw materials required for photosynthesis? [CBSE 2008]

Plant get carbon dioxide from the atmosphere and water from the soil for photosynthesis.

What is meant by the term Environment? [CBSE 2006]

Environment is the sum total of all external and influence that affect the life and development of an organism. Environment includes all the physical or biotic and biological or biotic factor.

Name any two non-biodegradable wastes. [CBSE 2003]

DDT any polythene bags.

Name any two biodegradable wastes. [CBSE 2003]

Cloth and paper

10th Science Chapter 15 Board Questions Set – 4 (1 Mark)

Which of the following are biodegradable? (a) Wool, glass, silver foil, leather. (b) Leather shoe, earth pot, silver spoon, jute bags. (c) Tomato leaves, Aluminium wire, synthetic fibre, wood. [CBSE 2002]

(a) Wool and leather.
(b)Leather shoe, earth pot, and jute bags.
(c) Tomato leaves and wool.

In a certain study constructed on occurrence of DDT along food chain in an ecosystem the concentration of DDT in grass was found to be 0.5 ppm in sheep it was 2 ppm and in man it was 10ppm. Why was the concentration of DDT maximum in case of man? [CBSE 2011]

DDT is non-biodegradable. It accumulates at each topic level. As man is positioned at the highest tropic level, there is maximum accumulation of DDT in man. This phenomenon is called biological magnification.

Explain how does making of kulhads affect our environment? [CBSE 2013]

A lot of soil is needed for making kulhads. It results in large scale depletion of top fertile soil. Moreover, disposal of used kulhaads is not so easy.

Define a food web. State it significance for ecosystem. [CBSE 2013]

A system of food chain which are interconnected between various organisms is called a food web. The significance of food web is in the maintenance of ecological balance based upon interdependence of different organism.

Name two natural ecosystem? [CBSE 2016, 2017]

Two natural ecosystem are:
(a) Temperate forest
(b) Grassland
(c) Lake
(d) Tropic forest
(e) Ocean

Question: What are decomposers? Write the role of decomposers in the environment. [CBSE 2016, 2017]
Answer: Decomposers are microorganism that derive their nutrition from dead remains and waste product organisms. They play a vital role in our environment by breaking down the complex organic substance into simpler inorganic substance which is made available for plant and other organisms. Hence they act as scavengers and not only keep the environment clean but also replenish the minerals.

10th Science Chapter 15 Board Questions Set – 5 (2 Marks)

State one important function of ozone layer in the atmosphere. How is it formed there? Which component are responsible for the depletion of ozone layer? How do these compounds enter into the atmosphere? [CBSE 2008]

Ozone layer prevents harmful ultraviolet radiation to reach earth atmosphere. Ozone is formed at higher level of atmosphere by the action of UV radiation on O2 molecules. High energy UV radiation split apart some oxygen molecules into the atomic oxygen which react with molecular oxygen to form ozone molecules. Chlorofluorocarbon are responsible for the depletion of ozone layer. These compounds which are used into refrigerators and fire extinguisher get leaked during manufacture or repair and go up high into the atmosphere.

Differentiate between autotropic, heterotrophs and decomposers and give one example of each. [CBSE 2013]

Autotrophs: (i) These are the organisms that make their own food from carbon dioxide and water by the action of sunlight in the presence of chlorophyll.
Example: Green plant.
Heterotrophs: (i) These are the organisms that cannot make their own food and are dependent on others for their food requirement.
(ii) Example: Animals.
Decomposers: (i) These are the organisms that decompose complex molecules present in the dead remains of plant and animals.
Examples: Bacteria

(a) What is an ecosystem? List its two main components. (b) We do not clean pounds or lakes, but an aquarium needs to be clean regularly. Explain [CBSE 2013, 2017]

(a) A self-sustaining functional unit consisting of living and non-livings component is called ecosystem.
Components: Biotic components like plants and animals. Non-biotic components like soil, wind, light etc.
(b) A pond is a complete, natural and self-sustaining ecosystem whereas an aquarium is an artificial and incomplete ecosystem, without decomposers therefore it needs regular cleaning for proper running.

Why are bacteria and fungi called decomposers? List any two advantage of decomposers. [CBSE 2008]

Bacteria and fungi are called decomposers because they degrade and decomposers dead remains of plants and animals into simpler inorganic substances which go into the soil as nutrients.
Advantages: (i) Decomposers degrade garbage and organic wastes which would otherwise cause environment problem. It prevents foul smell and checks spread of diseases.
(ii) Decomposers recycle the nutrients through biogeochemical cycle.

How would you dispose the following waste? (i) Domestic wastes like vegetable peels. (ii) Industrial wastes like metallic cans. (iii) Plastic materials. [CBSE 2004]

(i) Domestic wastes like vegetable peels can be disposed by compositing. To carry out composting, we dig a pit and bury the domestic waste into in it. It should be covered by about one-foot layer of soil.
(ii) Industrial waste like metallic cans be disposed by melting and recycling into solid metal again.
(iii) Plastic materials like plastic bags and buckets etc., can be recycled and reused.

10th Science Chapter 15 Board Questions Set – 6 (3 Marks)

(i) What is meant by the garbage management? (ii) Suggest four methods to manage the garbage? [CBSE 2013]

(i) Proper disposal of the waste in such a manner that it does not cause any damage to the environment is called garbage management.
(ii) Method to manage the garbage:
(a) As biodegradable and non-biodegradable wastes are to be treated differently, should be collected differently.
(b) Non-biodegradable waste should be sent for recycling.
(c) Hazardous waste like surgical waste and electronic parts should not be thrown in the open ground.
(d) Disposal should be carry out at specific centres only.

Distinguish between biodegradable and non-biodegradable substances. List two effects of each of them on the environment. [CBSE 2008]

Biodegradable substances: Substances which ca be broken down by microorganisms like bacteria and fungi are called biodegradable substances. For example, paper, vegetable and fruit peels, human excreta.
Non-biodegradable substances: Substances that cannot be broken down by microorganisms into simpler and harmless substances are called non-biodegradable substances. For example, polythene bags, Aluminium cans, DDT, etc.
Effects of biodegradable substances: (i) They produce foul smell causing air pollution. If thrown in water, it will cause water pollution.
(ii) They serve as breeding ground for files and mosquitoes which are carriers of diseases like cholera, typhoid and malaria.
Effects of non-biodegradable substances: (i) Non- biodegradable pesticides and fertilisers run off with rain water to water bodies cause water pollution and affect the soil making it acidic or alkaline.
(ii) Some of the non-biodegradable pesticides enter the food chain and affect badly humans and other organisms.

(a) Distinguish between producers and decomposers. (b) Classify the following as producers and decomposers: Green plants, Bacteria, Fungi, Blue-green algae. [CBSE 2008]

(a) Producers: (i) Organisms which produce food with the help of carbon dioxide from the atmosphere and nitrogen from the soil using energy of the Sun, are called producers.
(ii) They produce food by the process of photosynthesis.
(iii) Example: Green plants.
Decomposers: (i) Decomposition are microorganisms like bacteria or fungi which break down the dead remains of animals and plants into simpler inorganic substances.
(ii) They breakdown organic matter by the catabolic process of decomposition.
(iii) Example: Bacteria.
(b) Producers: Green plants, Blue-green algae
Decomposers: Bacteria, Fungi.

(a) Name the process by which autotrophs prepare their own food. (b) List the three events which occur during the process. (c) State two sources from which plants obtain nitrogen for the synthesis of proteins and other components. [CBSE 2016]

(a) The autotrophs prepare their own food by a process known as photosynthesis.
(b) Autotrophs can make organic compounds like sugar and starch as follows:
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy as well as splitting of water molecules into hydrogen and oxygen.
(iii) Reduction of carbon dioxide to carbohydrates.
(c) Two sources of nitrogen:
(i) From soil- From roots of certain plants.
(ii) By industrial fixation or during lightning.

(a) State two differences between autotrophic nutrition and heterotrophic nutrition. (b) Give one example of each of these nutrition. [CBSE 2008]

(a) Autotrophic nutrition:(i) Nutrition in green plants is autotrophic nutrition.
(ii) These organisms prepare their own food.
Heterotrophic nutrition:
(i) Nutrition in animals is heterotrophic nutrition.
(ii) These organisms depend on others for their food.
(b) Example of Autotrophic nutrition- Green plants preparing their food in presence of sunlight, CO2 and H2O. This process is called photosynthesis.
Example of Heterotrophic nutrition- Tiger eating a deer or bacteria deriving its nutrition from dead organisms.

Question: What is ten per cent law? Explain with an example how energy flows through different trophic levels. [CBSE 2015]
Answer: Energy available at each successive trophic level of food chain is ten per cent of that at the previous level.
This is called ten per cent law. Thus, 90 per cent energy is lost to the surrounding at each trophic level. However, plants absorb only one per cent of radiant energy of the Sun during photosynthesis.


(a) What is environment pollution?
(b) Distinguish between biodegradable and non-biodegradable pollutants.
(c) Choose the biodegradable pollutants from the list given below: Sewage, DDT, radioactive waste, agriculture waste. [CBSE 2007]


(a) An undesirable change in the physical, chemical or biological characteristics of the natural environment brought about by man’s activities is called environmental pollution.
(b) Biodegradable pollutants: These pollutants can be broken down into simpler substances by the action of microorganism. They are obtained from living organism and cause minimum pollution.
Non-biodegradable pollutants: These pollutants cannot be broken down into simpler substances by the action of microorganisms. They are obtained from non-living things and cause a lot of pollution.
(c) Sewage and agricultural wastes are biodegradable wastes.