NCERT Science Class 10 Chapter 14 Our Environment CBSE Board Sample Problems Short Answer

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We often observe domestic waste decomposing in the by lanes of residential colonies. Suggest ways to make people realize that the improper disposal of waste is harmful to the environment.


Some of ways to make people realize that the improper disposal of waste is harmful to the environment are:

  • 1m proper disposal of waste will serve as a breeding ground for mosquitoes and will create favourable conditions for the spread of various diseases.

  • Improper disposal of waste will release harmful gases in the environment which makes the environment unclean and unhygienic for normal living of organisms.

  • The waste will flow to water bodies along with the rain water and become a threat to aquatic organisms


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 between the living and non-living components of the biosphere. The unfavourable conditions created by man himself threatened the survival not only of himself 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.

(a) Why ¡s it necessary to conserve our environment?

(b) State the importance of green and blue dust-bins in the safe disposal of the household waste.

(C) List two values exhibited by your classmate who is an active member of Eco-club of your school.


  • It ¡s necessary to conserve our environment because

    • It helps in protecting the ozone layer.

    • It helps in maintaining animal and human food chains.

    • It provides us with many useful products such as medicines and wood.

  • Disposal of household waste is carried out ¡n green and blue bins, respectively. It will be very useful in the separate disposal of biodegradable and non-biodegradable wastes. This will also ensure the application of 3Rs—reduce, reuse and recycle.

  • Two values exhibited are

    • Creating environmental awareness among students and society.

    • Working hard on prevention of environmental degradation of surroundings.


We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?


  • Ponds and lakes are natural ecosystem and they have self-cleaning mechanism due to food chain and other environmental factors.

  • But, an aquarium being an artificial eco system do not have such mechanism.

  • Therefore, we need to clean aquarium.


Accumulation of harmful chemicals in our bodies can be avoided. Explain how this can be achieved?


  • We should drink plenty of water, eat healthy food, perform exercise and do not take stress to avoid accumulation of harmful chemicals in our body.

  • We should eat more vegetables especially cruciferous vegetables (such as broccoli, cauliflower, etc.) than meat so that biological magnification will be least.


What are the problems caused by the non-biodegradable wastes that we generate?


The problems caused by non-biodegradable wastes are:

  • They cause bio magnification.

  • They increase pollution.

  • They make environment unclean.

  • They kill useful microorganisms.


Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?


  • The damage to the ozone layer is a cause for concern because:

    • It causes skin cancer, ageing and corneal cataracts in human beings.

    • It can result in the death of many phytoplankton’s that leads to increased global warming.

  • To limit the damage to the ozone layer, the release of CFC5 into the atmosphere must be reduced. CFCs used as refrigerants and in fire extinguishers should be replaced with environmentally-safe alternatives.

  • Also, the release of CFCs through industrial activities should be controlled.


Give difference between food chain and food web.


Give difference between food chain and food web

Food Chain

Food web

It refers to a natural system by which energy is transmitted from one organism to another.

It consists of a number of interconnected food chains.

Members of higher trophic level feed upon a single type of organism.

Members of higher trophic level feed upon many organisms.

It does not have any effect on improving the adaptability and competitiveness of the organism.

Food webs improve the adaptability and competitiveness of the organism.

Example- Carrots ---> rabbit --> snake --> eagle.

Example- A hawk might also eat a mouse, a squirrel, a frog or some other animal. The snake may eat a beetle, a caterpillar, or some other animal.


If all the waste we generate is biodegradable, will this have no impact on the environment?


  • If all the waste generated would be biodegradable, this will also create problem.

  • As the number of decomposers will be quite low so wastes cannot be broken down into harmless, simpler substance at right time.

  • It will become breeding ground for flies causing spread of diseases. It will also emit foul smell which makes the life of people miserable.


What is ozone and how does it affect any ecosystem?


  • Ozone ()) is a molecule, made up of three atoms of oxygen.

  • Ozone () forms a layer in the upper atmosphere. It is very essential for the life on this planet.

  • It shields the surface of the earth from ultra-violet radiation (UV) coming from sun as these radiations are very harmful causing skin cancer and cataract in humans.

  • It also does harm to the crops.


What is the role of decomposers in the ecosystem?


Various roles played by decomposers in the ecosystem are:

  • They clean the environment.

  • They decompose biodegradable substances into useful substances.

  • They release nutrients into soil by decomposing dead and decaying matter, thus making the soil fertile.

  • They maintain the nutrient pool by returning the nutrients in the pool.


What are trophic levels? Give an example of a food chain and state the different trophic levels in it.


  • The various links or steps in a food chain at which the transfer of food and energy takes place are called trophic levels.

  • The producers form the first trophic level as they manufacture food.

  • The primary consumers form the second trophic level, the secondary consumers form the third and the tertiary consumers form the fourth trophic level.

The producers form the first trophic level as they manufactu …

The Producers Form the First Trophic Level

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  • In the above figure, Grass is the producer which ¡s eaten by the grasshopper known as primary consumer.

  • Then the grasshopper is eaten by shrew, secondary consumer and lastly shrew eaten up by owl, tertiary consumer.


Why are some substances biodegradable and some non-biodegradable?


  • Substances are classified as biodegradable and non-biodegradable because some substances can be decomposed by microorganisms and some cannot.

  • Substances that are broken down into simple soluble forms are called biodegradable substances and the substances that are not decomposed by microorganisms into harmless substances are called non-biodegradable substances.