Please refer to Our Environment Class 10 Science Important Questions given below. These solved questions for Our Environment have been prepared based on the latest CBSE, NCERT and KVS syllabus and books issued for the current academic year. We have provided important examination questions for Class 10 Science all chapters.
Class 10 Science Our Environment Important Questions
Very Short Answer Type Questions :
Question. What is full form of CFC and UNEP?
Answer:CFC stands for Chloroflurocarbon
UNEP stands for United Nations Environment Programme.
Question. Name any two items which can be easily recycled but are generally thrown in the dust-bin by us.
Answer:(i) Bits of paper (ii) Plastic bottles of water or cold drinks.
Question. Name the gases which have replaced CFCs.
Answer:(i) HFCs (Hydrofluorocarbons), (ii) Perfluorocarbons (PFCs) have replaced CFCs.
Question. Ozone is deadly poisonous, still it performs an essential function. How?
Answer:It protects earth from harmful UV radiations.
Question. Which of the following are not biodegradable: Wool, glass, silver foil, leather?
Answer:Glass, silver foil.
Question. What happens during first step of ozone formation in the the atmosphere?
Answer: UV
O2 → O + O
Question. Why should bio-degradable and non-biodegradable wastes discarded into separate dust bins?
Answer:It saves time and energy by separating them and waste disposal can be done in right way in minimum time.
Question. Name the radiations that are absorbed by ozone layer?
Answer:UV radiations (Ultra-Violet radiations) are absorbed by ozone layer.
Question. Why is excessive use of CFC a cause of concern?
Answer:CFC will deplete ozone layer which prevents UV radiation to reach earth. It causes skin cancer.
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. What will happen if we kill all the organisms in one trophic level?
Answer: If we kill all the organisms in one trophic level, the following effects will take place:
1. The population of organisms in previous trophi’c level will increase.
2. The organisms in next trophic level will not be able to get the food, so they will migrate to some other ecosystem or die.
3. It will cause an ecological imbalance in the food chain.
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. Consider the following food chain which occurs in a forest: Grass -> Deer -> Lion If 10000 J of solar energy is available to the grass, how much energy would be available to the deer to transfer it to the lion?
Answer: 10 J energy would be available to deer to transfer to lion.
Question. Which of the following belong to the first trophic level of a food chain? Grass, Grasshopper, Plants, Rat, Tiger
Answer: Grass and plants belong to the 1st trophic level of a food chain.
Question. Name the phenomenon in which non-biodegradable chemicals get accumulated progressively at each trophic level of a food chain.
Answer: Biological magnification.
Question. Which compounds are responsible for the depletion of ozone layer?
Answer: The compounds responsible for the depletion of ozone layer are chlorofluorocarbons (CFCs).
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. What is meant by a biodegradable waste?
Answer: Biodegradable wastes are those substances which are broken down into simpler, harmlesssubstances in nature in due course of time by the biological processes such as action of micro organisms like certain bacteria.
Examples: Urine and faecal matter, sewage, agricultural residue, paper, wood, cloth and cattle dung.
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. 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,C02 , S02, etc., are released in to the atmosphere which leads to greenhouse effect.
Question. What is the role of decomposers in the ecosystem?
Answer: Role of decomposers in the environment:
1. They return the nutrients to the nutrient pool.
2. They help in completing the different bio-geochemical cycles, thus they maintain the balance in the ecosystem.
Question. What step is being taken to limit the damage to the ozone layer?
Answer:
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. Why are some substances non- biodegradable?
Answer: Some substances are non-biodegradable because they cannot be broken down into simpler harmless substances in nature.
Question. Which class of chemicals is linked to the decrease in the amount of ozone in the upper atmosphere of the earth?
Answer: The chemical compound Chlorofluorocarbon is responsible for decrease of ozone in the upper
atmosphere of the earth.
Question. Name two decomposers operating in our ecosystem.
Answer: Bacteria and fungi.
Question. Select two non-biodegradable substances from the following waste generated in a kitchen:
spoilt food, paper bags, milk bags, vegetable peels, tin cans, used tea leaves.
Answer: Milk bags and tin cans.
Question. What happens when higher energy ultraviolet radiations act on the oxygen at the higher level of the atmosphere?
Answer: When high energy ultraviolet radiations act on oxygen, ozone is produced:
Question. In a food chain, 10,000 joules of energy is available to the producer. How much energy will be available to the secondary consumer to transfer it to the tertiary consumer?
Answer: 10 J will be available to the secondary consumer to transfer to the tertiary consumer.
Question. Write the name and formula of a molecule made up of three atoms of oxygen.
Answer: Ozone and its chemical formula is O3.
Question. List two man-made ecosystems.
Answer: Garden and Pond are man-made ecosystems.
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.
Short Answer Type Questions :
Question. If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer:If all waste we generate is biodegradable, the adverse effect on environment will be minimum. They will produce CO2, methane which is released in atmosphere.Nutrients will be mixed in soil to increase the fertility of soil.
Question. Mention three methods to reduce amount of wastes produced.
Answer:(i) Recycling of non-biodegradable waste.
(ii) Reuse of waste such as newspapers can be used for making carry bags and envelopes.
(iii) Biodegradable domestic waste should be disposed in pits to form manure.
(iv) Biogas plants should be used for disposal of waste in rural areas.
Question. What is ozone and how does it affect any ecosystem?
Answer:Ozone is a triatomic (O3) gas formed in upper atmosphere by action of UV light on oxygen. It protects earth from harmful UV radiations.
Question. List two causes of depletion of ozone layer. Mention any two harmful effects of depletion of this layer.
Answer:Two causes of depletion of ozone layer are: (i) CFCs (ii) Aerosols
Two harmful effects of depletion of this layer are:
(i) UV radiations can reach the earth and causes skin cancer, harmful to eyes and immune system will be disturbed.
(ii) It may lead to variations in rainfall, ecological disturbance.
Question. Construct an aquatic food chain showing four trophic levels.
Answer: Food chain in aquatic ecosystem:
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. 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 micro organisms that obtain energy from the chemical breakdown of dead organisms of animals or plants. These micro organisms 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. Explain the phenomenon of “biological magnification” How does it affect organisms belonging to different trophic levels particularly the tertiary consumers?
Answer: The process in which harmful chemicals enter a food chain and get accumulated progressively at each trophic level is called biological magnification.
Harmful and toxic chemicals enter our bodies when they are added to soil and water. Use of pesticides to protect the food crops from diseases and pests and chemical wastes of factories are dumped in open or disposed off into rivers. These chemicals are washed down into the soil and ultimately to water table or get absorbed or taken up from the soil by the plants along with water and minerals and in this way harmful chemicals enter the food chain. The quantity of these harmful chemicals increase with increase in trophic level of the food chain because these substances are not degradable. Man is at the top of the food chain, so concentration is maximum in human beings.
Thus, accumulation of DDT has been maximum in man as DDT is used to destroy pests. DDT is accumulated in the following way in this food chain:
This is the reason why our food grains such as wheat and rice, vegetables and fruits and even meat contain varying amounts of pesticides residues. So, the highest trophic level at the extreme right of food chain has the maximum concentration of harmful chemicals in a food chain.
Question. “Damage to the ozone layer is a cause for concern.” Justify this statement. Suggest any two steps to limit this damage.
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.
Two steps to limit this damage are as follows:
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. 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 (02) 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. (a) What is ‘environmental pollution’?
(b) Distinguish between biodegradable and non-biodegradable pollutants.
(c) Choose the biodegradable pollutants from the list given below:
Sewage, DDT, radioactive waste, agricultural waste.
Answer: (a) Environmental pollution is an undesirable change in the physical, chemical or biological characteristics of the natural environment, brought about by man’s activities. This pollution may affect the soil, rivers, seas or the atmosphere.
(c) Biodegradable pollutants are sewage and agricultural waste.
Question. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the environment.
Answer: Bacteria and fungi breakdown the dead remains and waste products of organisms. These micro organisms 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.
Two advantages of decomposers to the environment are as follows:
1. Decomposers feed, on the dead bodies of plants and animals. They return the simple components to soil and help in making the steady state of ecosystem by recycling of nutrients. They, therefore, create a balance in the environment.
2. They also act as scavengers or cleansing agents of the atmosphere.
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 micro organisms 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. 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) Ozone layer is a rich zone of ozone found in upper atmosphere. It helps in shielding the Earth from the harmful UV radiations coming from the Sun. If ozone layer gets depleted, UV radiations can directly reach the Earth’s surface and drastically affect the life on Earth. For instance, UV radiations coming from the Sun causes skin cancer. So, it is very important to protect the ozone layer so as to save our environment and the planet Earth.
(b) Some of the ways to help protect and stop the depletion of the ozone layer include: Not buying products in aerosol cans, maintaining air-conditioning filters and units.
In order to halt the depletion of the ozone layer, countries around the world have banned the use of chlorofluorocarbons and other ozone-depleting substances. These compounds produce chlorine and bromine atoms high in the atmosphere, and these atoms react with ozone, destroying it.
By reducing the use of fluorescent lights.
By minimising the use of vehicles to limit the emission of harmful gases that cause damage to the ozone layer, we can contribute to its protection.
Question. (a) Why is it necessary to conserve our environment?
(b) State the importance of green and blue dustbins in the safe disposal of the household waste.
Answer:(a) It is necessary to conserve our environment because
(i) It helps in protecting the ozone layer.
(ii) It helps in maintaining animal and human food chains.
(iii) It provides us with many useful products such as medicines and wood.
(b) Disposal of household waste is carried out in 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 3 R’s— Reduce, Reuse and Recycle.
Question.(i) What is the height of ozone from the equator?
(ii) Name the rays against which ozone layer provides protection.
(iii) Name one effect of depletion of ozone layer.
Answer:(i) 10 to 16 km (ii) UV rays (iii) Global warming.
Question. When the government banned the use of polybags in Delhi, the vegetable grocers found it difficult as it affected their sales. The market committee held a meeting and decided to spread awareness about harmful effect of polybags.
(i) How will you convince people that plastics are harmful to the environment?
(ii) What alternatives of polythene bags do we have, which are environment friendly?
(iii) Not many people in Delhi have stopped using polythene bags even though they are officially banned. How can schools enaculate environmental values in students?
Answer:(a) They need to be told that cows and other animals eat polythene which is fatal for them. Coloured polythene is also very harmful for vegetables and fruits.
(ii) Paper bags, jute bags, bags of biodegradable materials are ecofriendly and carrying your own shopping bag is also more convenient.
(iii) Schools must teach students to protect environment. They should make paper bags and distribute to small shopkeepers regularly so that gradually their habits will change.
Question. (a) Improvement in our lifestyle has resulted in greater amount of waste generation. Suggest one change we can incorporate in our lifestyle in order to reduce non-biodegradable waste.
(b) The following organisms form a food chain:
Insect, Hawk, Grass, Snake, Frog
Which of these will have highest concentration of non-biodegradable chemicals? Name the phenomenon.
Answer:(a) (i) More use of disposable items like paper plates, plastic and polythene which are recyclable.
(ii) Change in packaging Suggestion. Reuse of plastic containers
(b) Hawk will have highest concentration of non-biodegradable chemicals. This process is called biomagnification.
Question. (a) Water is an elixir of life, a very important natural resource. Your Science teacher wants you to prepare a plan for a formative assessment activity, “How to save water, the vital natural resource”.Write any two ways that you will suggest to bring awareness in your neighbourhood, on ‘how to save water’.
(b) Name and explain any one way by which underground water table does not go down further.
Answer:
(a) Water is one of the most precious natural resources that has vital importance in our lives. It is an essential component of the human body and is used almost everywhere in our day-to-day activities, such as cooking, washing, in agriculture and industries. It is an indispensable part of our life, without which the life on earth is not possible. However, the amount of fresh water available for sustaining life is very less. So, it is very important to conserve water. For creating awareness among people, we can adopt the following two ways.
(i) Door to door campaigning. (ii) Nukkad Nataks
(b) Underground water table can be recharged through rainwater harvesting. Rainwater harvesting is a process by which rain water is collected and stored for the purpose of recharging the ground water or for future use like for irrigation and agriculture, for livestock, etc. In India, rainwater harvesting is an old tradition, which is followed till now in many parts of India. For example, bawris are traditional architectural rainwater harvesters that were built for collecting water, in the state of Rajasthan.
There are two ways of rainwater harvesting:
(i) Surface runoff harvesting: In urban areas, rain water that flows away from the surface can be collected and used for various purposes.
(ii) Rooftop rainwater harvesting: The rainwater on the roofs of the buildings is collected through canals that drains the water into ground water reservoirs. This stored water can later be utilised.
Question. How is ozone both beneficial and damaging? How can we prevent the damaging effect of ozone? List one way.
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 depletes O3 layer.
Question. (a) Complete the following table:
(b) How is ozone formed at the higher levels of atmosphere?
Answer:
Question. What is ozone? How and where is it formed in the atmosphere? Explain how it affects an ecosystem.
OR
What is ozone and how does it affect any ecosystem?
Answer:Ozone is a molecule containing three atoms of oxygen (O3). It is a highly poisonous gas present in the upper layers of the atmosphere.
Formation of ozone: The UV radiations from Sun split some molecules of oxygen (O2) apart into free oxygen atoms (O + O). These atoms then combine with oxygen molecules to form ozone.
Ozone layer shields the surface of the earth against damaging UV radiations of the Sun.
Question. Differentiate between biodegradable and non-biodegradable substances with the help of one example each. List two changes in habit that people must adopt to dispose of non-biodegradable waste for saving the environment.
Answer:
Two habits to dispose of non-biodegradable wastes are:
(i) Use of separate dustbins for biodegradable and non-biodegradable wastes,
(ii) Reuse of things such as polybags, etc.,
(iii) Recycling of wastes
(iv) Use of cotton /jute bags for carrying vegetables etc. (Any two)
Question. Mention the negative effect of our lifestyle on the environment.
Answer:(i) Global warming occurs due to increase in number of vehicles and over use of fossil fuels.
(ii) Due to excessive use of deodrants, perfumes, CFCs, etc. ozone layer is getting depleted.
(iii) Air pollution occurs due to industralisation.
(iv) Wastes causes pollution due to release of sewage in water bodies.
(v) Pollution of soil occurs due to overuse of chemicals is agriculture.
Question. (a) What do you understand by ‘watershed management’? List any two advantages of watershed management.
(b) Human beings occupy the top level in any food chain. What are the consequences of this on our body?
Answer:
(a) Soil and water conservation in a scientific way is called ‘watershed management’.
Advantages: (i) Increase in production and income of watershed communities,
(ii) Mitigate draughts and floods, (iii) Increase the life of downstream dam reservoir.
(b) Maximum level of biomagnification occurs in human beings because of progressive accumulation.
We get very small amount of energy as only 10% of previous energy gets transferred to each trophic level.
