We have provided you with Extra and Important Questions from Class 10 Science Chapter 15 Our Environment. This Extra and Important Questions will help you to score 100% in your Board Exams. These extra questions will be helpful to revise the important topics and concepts.

Our Environment Class 10 Important Questions with Answers Science Chapter 15

Extra Questions for Class 10 Science Chapter 15 Very Short Answer Type

Question: How is the increase in demand for energy affecting our environment adversely?

Answer: The increase in demand for energy affects our environment adversely. Due to this increase, pollutants like CO, CO_², SO_², etc., are released in to the atmosphere which leads to greenhouse effect.

Question: Why is ozone layer getting depleted at the higher levels of the atmosphere?

Answer: Ozone layer is getting depleted at the higher levels of the atmosphere due to effect of chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers.

Question: Name any two abiotic components of an environment.

Answer: Two abiotic components of an environment are temperature and rainfall.

Question: What are the two main components of our environment?

Answer: The two main components of our environment are the biotic or living components and abiotic or non-living components.

Question: Why are green plants called ‘producers’?

Answer: Green plants are called ‘producers’ because they can produce food by photosynthesis in the presence of sunlight.

Question: Which disease is caused in human beings due to depletion of ozone layer in the atmosphere?

Answer: Skin cancer is caused in human beings due to the depletion of ozone layer in the atmosphere.

Question: Why did United Nations act to control the production of chlorofluorocarbons (CFCs) used in refrigerators?

Answer: CFCs deplete the ozone layer around the earth, hence their production is controlled by United Nations.

Question: Which compounds are responsible for the depletion of ozone layer? [Delhi]

Answer: The compounds responsible for the depletion of ozone layer are chlorofluorocarbons (CFCs).

Question: Define ‘trophic level’.

Answer: Trophic level is the position that an organism occupies in a food chain, where transfer of food or energy takes place.

Question: What are the various steps in a food chain called?

Answer: The various steps in a food chain are called trophic levels.

Question: What is the important function of presence of ozone in earth’s atmosphere?

Answer: The important function of presence of ozone in earth’s atmosphere is that it shields the surface of the earth from ultraviolet (UV) radiations of the sun.

Question: Give an example to illustrate that indiscriminate use of pesticides may result-in the degradation of the environment.

Answer: The pesticides used in crop field are washed down into the water bodies. From water bodies, these are absorbed by aquatic plants and animals of a food chain and thereby degrades the environment.

Question: Why is it necessary to conserve our environment?

Answer: It is necessary to conserve our environment to prevent depletion of natural resources and environmental damage, thereby sustaining life.

Question: Why are some substances non- biodegradable?

Answer: Some substances are non-biodegradable because they cannot be broken down into simpler harmless substances in nature.

Extra Questions for Class 10 Science Chapter 15 Short Answer Type

Question: What step is being taken to limit the damage to the ozone layer?

Answer: Steps is being taken to limit the damage to the ozone layer are:

1. Judicious use of aerosol spray propellants such as fluorocarbon and chlorofluorocarbons which cause depletion or hole in ozone layer.
2. Control over large scale nuclear explosions and limited use of supersonic planes.

Question: What is the role of decomposers in the ecosystem?

Answer: Role of decomposers in the environment:

• They return the nutrients to the nutrient pool.
• They help in completing the different bio-geochemical cycles, thus they maintain the balance in the ecosystem.

Question: How is ozone formed in the upper atmosphere? Why is the damage of ozone layer a cause of concern to us? State a cause of this damage.

Answer: Ozone is formed in upper atmosphere by the reaction of ultraviolet (UV) radiations on oxygen (O2) molecule.

The damage to ozone layer is a cause of concern to us as due to its damage, more ultraviolet rays reach the earth’s surface causing various health hazards.

A cause of this damage is the presence of large amount of chlorofluorocarbons in the atmosphere.

Question: State two problems caused by the non- biodegradable waste that we generate in our daily life.

Answer: Two problems caused by non-biodegradable waste that we generate in our daily life are:

1. It clogs drains.
2. It causes water and soil pollution.

Question: What are biodegradable and non- biodegradable substances? Select two biodegradable pollutants from the following: Agricultural waste, glass, plastic, sewage, DDT.

Answer: Biodegradable substances are those substances which are broken down into simpler, harmless substances in nature in due course of time by the biological processes such as microorganisms like certain bacteria.

Non-biodegradable substances are those substances which cannot be broken down into simpler, harmless substances in nature.

Two biodegradable pollutants are agricultural waste and sewage.

Question: Explain ‘biological magnification’ with the help of an example.

Answer: Pesticides used in crops are washed down into the soil. From soil these are absorbed by plants along with water and minerals and thus, they enter the food chain. While consuming the crops, human beings also consume these pesticides which get accumulated in our bodies. This phenomenon is known as biological magnification.

Question: Describe how decomposers facilitate recycling of matter in order to maintain balance in the ecosystem.

Answer: Decomposers are microorganisms that obtain energy from the chemical breakdown of dead organisms of animals or plants. These microorganisms breakdown the complex organic substances of dead organisms into simple inorganic substances that go into the soil and are used up once more by the plants. Decomposers thus, help in recycling of matter.

Question: “Damage to the ozone layer is a cause for concern.” Justify this statement.

Answer: Ozone layer prevents the harmful ultraviolet radiation to enter the atmosphere and reach the earth’s surface. Depletion of ozone layer has become a cause for concern because it can cause serious effects on human body and other organisms of the environment like fatal diseases such as skin cancer, changes in genetic material DNA, eye damage, etc.

Question: Why are bacteria and fungi called decomposers?

Answer: Bacteria and fungi breakdown the dead remains and waste products of organisms. These microorganisms are called the decomposers as they breakdown the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.

Question: List two environment friendly practices or habits which need to be followed by every member of a family community. Explain how these practices will support the “save the environment” mission. [CBSE 2014]

Answer:

1. Use of paper bags or jute bags instead of plastic bags.Segregate biodegradable and non-biodegradable wastes in separate dustbins.
2. Use fuels like CNG, unleaded petrol or other ecofriendly fuels in vehicles..

Due to uses of environment friendly practices or habits we can save our environment

Question: We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why? [NCERT Exemplar]

Answer: A pond or a lake is a natural, self-sustaining, and complete ecosystem. But, an aquarium is an artificial and incomplete ecosystem that needs human intervention for its cleaning and upkeep.

Question: Our food grains such as wheat and rice, vegetables and fruits, and even meat are found to contain varying amounts of pesticide residues. State the reason to explain how and why it happens? [CBSE 2014]

Answer: The harmful pesticides like DDT enter the plant body on being absorbed from the soil. When these are eaten by animals they get accumulated in the animal’s body as they are neither metabolized nor excreted out of their body. The concentration of these harmful chemicals gets increased at successive levels and are thus found in food grains as well as meat.

Question: Explain phenomenon of “biological magnification”. How does it affect organisms belonging to different trophic levels particularly the tertiary consumers? [CBSE 2010]

Answer:The levels of harmful toxicants/pesticides like DDT gets increased at successive trophic levels as they are neither metabolised nor excreted by the organism. They get accumulated in organism’s body with their higher concentrations at higher trophic levels. This is called as biological magnification.Since, the tertiary consumers are at the top of the food chain, so a higher amount of these toxicants is present in them compared to the lower trophic levels.

Extra Questions for Class 10 Science Chapter 15 Long Answer Type

Question: Suggest any four activities in daily life which are eco-friendly. [NCERT Exemplar]

Answer: The eco-friendly activities in life are

• Planting of trees.
• Segregating biodegradable and non-biodegradable wastes.
• Using cloth bags, jute bags or paper bags instead of plastic bags.
• Creating awareness on environment protection through initiatives and campaigns.
• Using of manures and organic agricultural methods.
• Using less of chemical fertilizers and pesticides.
• Controlling pollution by using fuels like CNG.

Question: Make food chains in (i) forest (ii) grassland (iii) pond.

How does food chain differ from a food web?

Answer: Food chains in:(i) Forest: Plants → Deer → Lion

(ii) Grassland: Plants → Grasshopper → Frog → Snake → Eagle

(iii) Pond: Aquatic plants → Scorpion Fish → Flamingo

Food Chain: It is a series of organisms feeding on one another.Food Web: It is a network of food chains consisting of a number of interlinked food chains.

Question: Name the wastes which are generated in your house daily. What measures would you take for their disposal? [NCERT Exemplar]

Answer: The wastes generated in our house daily are:

• Kitchen wastes
• Paper wastes like newspapers, bags, envelopes
• Plastic bags
• Vegetable/fruit peels/rinds

The measures which can be taken for their disposal are:

• Segregate the wastes as biodegradable, non-biodegradable and hazardous ones.
• Dispose of the plastic bags and bottles in a proper way.
• Vegetable/fruit peels can be used to make compost.
• Paper wastes can be used for recycling.
• Prepare a vermicompost pit for the organic wastes from the kitchen.

Question: Explain some harmful effects of agricultural practices on the environment. [NCERT Exemplar]

Answer:

• Change in the chemistry of soil and killing of useful microbes due to excessive use of fertilisers.
• Biological magnification occurs due to excessive use of chemical pesticides.
• Water table gets lowered due to the excess use of ground water.
• Soil fertility is lost due to extensive cropping.
• The natural ecosystems is harmed due to ploughing during agriculture.

Question: “Energy flow in a food chain is unidirectional”. Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body. [CBSE 2014]

Answer:The flow of energy in an ecosystem occurs from a lower trophic level to the next trophic level i.e., from producers to consumers. It follows the ten percent law and thus cannot return back to producers from consumers. Hence, the flow of energy in a food chain is unidirectional.

The pesticides like DDT enter the food chain after getting absorbed by plants from the soil. Once they enter the food chain, they are neither metabolized nor excreted from the body of the organism. Its concentration increases in the successive trophic level of the food chain.