NCERT solutions of class 10 science chapter 15-Our Environment
NCERT solutions of Class 10 science chapter 15-our environment are created here for helping the class 10 students to boost their preparation of the cbse board exam. All NCERT solutions are explained scientifically in a proper way. NCERT solutions of class 10 science chapter -15 will give complete idea of the environment in which we are living.
The chapter -our environment is consist of useful peaces of information regarding the safeguard of bour environment because our environment is in danger by the excess use of fossil fuels, here in this chapter there are given complete idea about the settlement of waste materials whether it is biodegradable or non-biodegradable wastes.
Q1.Why are some substances biodegradable and some non-biodegradable?
Ans. The food eaten by us is digested by us, digestion is the process in which enzymed secreted by our body breaks up the complex molecules to simple molecules, on the same way molecules of ome of the waste or dead animal or plants are changed to simple molecules through the bacteria available in the environment and then absorbed by the soil as a nutrients. and minerals.,these processes are known as biological process and such substances which are acted by enzymes in settling them to their different components known as biodegradable.
Some of the substance burried by us or eaten by us are not changed to their components by the biological processes or bacteria known as non-biodegrable,such as plastic , coal and other hydrocarbon. These substances may be inert and simply persist in the environment for a long time or may harm our ecosystem.
Q2.Give any two ways in which biodegradable substances would affect the environment.
Ans. The bacteria acts on waste material like food peels of vegetables and fruits, dead animals and their remieders dumped in dustbin and the open area converts them into their comments ,in this process foul smelling gases are released that makes impure air of adjoining area.
The dumping of biodegradable waste also breeds mosquito and flies which carries bacteria to our food items and their bite to our body causing different kind of diseases .
Q3.Give any two ways in which non -biodegradable substances would affect the environment.
Ans.The food items packaged by polythene when eaten by cow or other animal ,it is choked up inside their intestine that may cause their death.
If the use of polythene is continued, it’s layer on the earth will obstruct the rainwater to go inside the soil of earth that would result the agricultural field become barren and underground water lower up seaking the dryness inside the earth and the land will be fragmented into many pieces.
Q1.What are trauphic levels? Give all example of a food chain and state the different trauphic levels in it.
Ans.The trauphic levels are groups of animals in which every organisms get food from the environment in such a way that they depend on each other.
Example. Snake, frog, insects grass in which grass is first trauphic level ,insects second trauphic level ,frog third trauphic level and snake is fourth trauphic level.
Q2.What is the role of decomposers in the ecosystem?
Ans. The role of decomposers or so called saprophites decomposes the dead plants and animals and their remieders into their components that are absorbed by the soil. Decomposers (bacteria) converts atmospheric nitrogen gas into nitrgeneous compounds making the soil enriched with nutrients for plants.
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Q1.What is ozone and how does it affect any ecosystem?
Ans. When UV rays of sunlight incident on our atmosphere, it splitted up oxygen molecule into atoms .Since oxygen atom is highly reacted, it combines with oxygen molecule and thus forms ozone gas, the layer of ozone protect us from dangerous UV rays that causes skin cancer ,so if UV rays are allowed to enter the atmosphere ,the survival of all the organisms will be endangered. Ozone gas itself is a harmful gas to human health.
Q2.How can you help in reducing the problem of waste disposal?Give any two methods.
Ans. The waste disposal can be treated with three R’s reuse reduction and recycle. We have to mimise the use of non biodegradable substance like plastics and polythene and prefer them to be recycled and reuse
The waste material which are biodegradable can be used to generate energy ,since biodegradable substances ultimately transformer into soil, so that can be used to build small beautiful region adaptable for different kinds of plants which may become as a tourist spot.
Q1. Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
Ans. The groups (a) Grass, flowers and leather (c) Fruit,-peels, cake and lime-juice (d) Cake, wood and Grass are consist of all biodegradable items and the group (b) Grass, wood and plastic doesn’t contain all biodegradable items because plastics is non -biodegradable item.
Q2. Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Ans.(b) Grass, goat and human
Q3. Which of the following are environmental-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 these above
Ans. (d) All of these above
Q4. What will happen if we kill all the organisms in one tropic level?
Ans. If we kill all the organisms of one tropic level, it will lead to an increase in the number of organisms at the lower tropic level and decrease in the number of organisms at the higher trophic level. This will result in disruption in the food web and hence the ecosystem.
Q5. Will the impact of removing all the organisms in a tropic level be different for differ tropic levels? Can the organisms of any tropic level be removed without causing any damage to the ecosystem?
Ans. Yes, the impact of removing all the organisms in a tropic level will be different for differ tropic levels. It will not be possible to remove any organism in any trophic level without causing damage to the ecosystem.
Q6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Ans. Biological magnification can be defined as the progressive increase in the concentration of non-biodegradable wastes in the food chain. As there is an increase in the magnification at the primary level of the ecosystems, all the other levels do get affected and the concentration may vary when compared to first level.
Q7. What are the problems caused by the non-biodegradable wastes that we generate?
Ans. Following are the problems caused by the non-biodegradable wastes:
1. These substances cannot be decomposed by the microorganisms.
2. As the quantity increases, dumping becomes a problem.
3. Non-biodegradable wastes like heavy metals may enter the food chain in the upper trophic levels.
4. They may escape to the ground water which causes soil infertility and disturbance in ph of the soil.
Q8. If all the waste we generate is biodegradable, will this have no imapact on the environment?
Ans. The production of a large amount of biodegradable waste will create a threat to the environment. The degradation of such huge amount of biodegradable material requires a large number of decomposers which are not available. Incomplete degradation will result in the breeding ground for flies causing the spread of diseases. Emission of foul smell can also make life miserable.
Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Ans. The ozone layer is a protective cover for the earth. It prevents harmful UV rays from entering the earth as these rays harmful and can result in skin cancer. But the air pollutants like chlorofluorocarbons (CFCs) are the main reason for the depletion of ozone layers. Too much UV rays are harmful to plants as they affect photosynthesis, destroy planktons and decomposers. These are the reasons why damage of ozone layer is a cause of concern.
Steps taken to limit this is that many developing and developed countries have signed and are obeying the directions of UNEP(United Nations Environment Programme) to freeze or limit the production and usage of CFCs.