CBSE Solutions for Class 10 English

જવાબ : Manufacturing Kulhads on large scale would result in the depletion of fertile top soil making the land inadequate for the cultivation of crops.

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

જવાબ : CFCs depletes the ozone layer around the earth, hence its production is controlled by United Nations.

જવાબ : Ozone and its chemical formula is O3.

જવાબ : Decline in the thickness of ozone layer in Antartica is termed as ozone hole.

જવાબ : Its concentration increases with increase in trophic level.

જવાબ : Energy available at each trophic level diminishes progressively due to loss of energy at each level.

જવાબ : Each trophic level makes 10% energy available to next trophic level.

જવાબ : Green plants absorb 1% of Sun’s energy that falls on their leaves.

જવાબ : Organisms which depend upon producers for food.

જવાબ : CFC → Chlorofluorocarbon

જવાબ : The average percentage of energy lost when plants are eaten by primary consumers is 90%.

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

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

જવાબ : Grass and plants belong to the 1st trophic level of a food chain.

જવાબ : 1 J energy will be available to deer to transfer it to lion.

જવાબ : 10J of energy will be available to the secondary consumer to transfer to the tertiary consumer.

જવાબ : Explanation: Bacteria and fungi.

જવાબ : One measure of the biodiversity of an area is the number of species found there. Secondly, the range of different life forms is also important.

જવાબ : Hawk will have highest concentration of non-biodegradable chemicals. The phenomenon is called biomagnification.

જવાબ : Herbivores are always at the 2nd trophic level.

જવાબ : Only green plants can make their own food from sunlight. Green plants therefore, always occupy the 1st trophic level in a food chain.

જવાબ : 100 Joules of energy will be available to the organism of the 2nd trophic level.

જવાબ : Green plants can produce their own food by photosynthesis from inorganic compounds and hence are called producers.

જવાબ : Agricultural/crop fields, aquaria, gardens. (any two)

જવાબ : Two biotic components of a biosphere are plants and animals.

જવાબ : Two natural ecosystems are forest and river.

જવાબ : Waste food, paper, cloth, etc.

જવાબ : Plastics that are decomposed by the action of living organisms such as bacteria are called biodegradable plastic.

જવાબ : Plastic cannot be broken-down into smaller particles by the action of bacteria and hence it is called non-biodegradable.

જવાબ : By segregating biodegradable and non-biodegradable material.

જવાબ : The biodegradable and non-biodegradable wastes must be discarded in two different dustbins because biodegradable Wastes gets decomposed by the microorganisms whereas non-biodegradable wastes can be recycled and reused.

જવાબ : Milk bags and tin cans.

જવાબ : It is the sum total of all external conditions and influences that affect the life and development of an organism, i.e. the environment includes all the physical or abiotic and biological or biotic factors.

જવાબ : True

જવાબ : False

જવાબ : True

જવાબ : False

જવાબ : False

જવાબ : False

જવાબ : natural

જવાબ : ultraviolet (UV)

જવાબ : biomagnifications

જવાબ : unidirectional

જવાબ : food web

જવાબ : producers

જવાબ : abiotic

જવાબ : 10%

જવાબ : artificial

જવાબ : Inert

જવાબ : (a) Decomposers: Most of the bacteria and fungi are saprophytes. They obtain their nourishment from organic remains. For this they secrete digestive enzymes over the remains. The remains are converted into soluble absorbable form. This results in decomposition of organic matter. Therefore, bacteria and fungi are called decomposers.
(b) Advantages:
1.    Scavengers: Decomposers function as scavengers by removing organic remains and cleansing the earth.
2.    Mineralization: Decomposers release inorganic nutrients trapped in organic remains. The same are recycled.

જવાબ : Cause of Concern: Ozone layer present in the stratosphere has thinned out by about 8% over the equator and more so over the antarctica where a big ozone hole appears every year. This has increased the level of UV-B radiations reaching the earth by 15-20%. These radiations are causing increased number of skin cancers, cataracts and reduced immunity in human beings. There is increased incidence of blinding of animals, death of young ones, reduced photosynthesis, higher number of mutations and damage to articles.
Steps to Limit Damage,

1. Ban on production and use of halons.
2. Ban on production and use of chlorofluorocarbons.

જવાબ : Polythene is nonbiodegradable. Use of polythene bags often chokes drains and kills animals feeding on garbage besides piling up in garbage disposal sites.
Alternates: Use of cloth bags and paper bags.
Environment: Cloth bags can be used and reused. Both cloth and paper bags are biodegradable.

જવાબ : Domestic waste is often thrown outside the living quarters or some common place near the homes for municipal staff to pick up and dispose the same. The waste is, however, spread by stray cattle, pigs and dogs and is left to decompose. It is an improper method of waste disposal being harmful to environment as well as to all of us. It produces stink and becomes a source of several diseases. The scattered decomposing waste attracts flies, mosquitoes and rats.
Therefore, a proper waste disposal method involving biodegradable in covered green bins and nonbiodegradable in covered blue bins be adopted. The municipal staff can take the wastes from the bins.

જવાબ :

1. Cloth bags are stronger and more durable as compared to plastic bags.
2. They are washable.
3. They are reused time and again.
4. Cloth bags do not pollute environment.
5. They are made of biodegradable material which can also be recycled.

જવાબ : Green plants are also called producers because only they can synthesise organic food from inorganic raw materials with the help of solar energy in the process of photosynthesis. This food is not only used by green plants but also all other organisms called consumers.

જવાબ : Eco-system is the whole biotic community in a given area plus its abiotic environment (physical factor like temperature, rainfall, wind, soil and mineral) both interacting with each other and maintain a balance in nature. Eco-system can be as large as a forest, or small as a pond and lake. This function system may be natural as forest or may be artificial example a crop field or an aquarium. Thus the eco-system has biotic and abiotic components.

જવાબ : The flow of energy in a food chain follows 10% law. The energy used or lost in environment as heat, cannot enter at any trophic level in the food chain. Only solar energy can enters in the food chain at producer level and ultimately get lost as heat.

જવાબ : When any harmful chemical like DDT, BHC enters in a food chain the concentration of chemical increases as the tropic level is increased (i.e., next higher level). The phenomenon is called biological magnification.
These chemical, get accumulated progressively at each tropic level. It is maximum at the top (highest) tropic level. The tertiary consumers occupy the top tropic level (in most of the food chains) so there is maximum concentration of the harmful chemicals ant they are affected badly.

જવાબ : The ozone shields the surface of the earth from ultraviolet (UV) radiation from the sun. These radiations are highly damaging as they can cause cancer in both plants and animals, damage to eyes and immune system. They can also lead to variations in global rainfall, ecological disturbances and dwindling of global food supplies. Due to these reasons, damage to the ozone layer is a major cause for concern.
Steps which are taken to limit this damage:

1. To decrease the use of synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers?
2. In 1987, the United Nations Environment Programmed (UNEP) succeeded in reaching an agreement to freeze CFC production at 1986

જવાબ : The accumulation of harmful chemicals in the body of living organisms at different tropic levels in a food chain is called biological magnification. Yes, the concentration of these harmful chemicals will be different at different tropic levels. It will be maximum at the last tropic levels which are mostly of the top carnivores (quaternary consumers).

જવાબ : Ozone (O₃) is a molecule formed by three atoms of oxygen. At the higher of the atmosphere, it shields the surface of the earth from ultraviolet (UV) radiation from the Sun. It may affect any ecosystem in the following ways:

1. At the surface of the earth, it is a deadly poison for all lower forms of life.

જવાબ : Role of decomposers in the ecosystem:

1. They help in breaking down the complex organic into simple inorganic that go into the soil and are used up by the plants.
2. They the nutrient pool of the putting in this way, ad as cleansing agents of nature.
3. They help in maintaining the fertility of by adding humus content to it.

જવાબ :

1. These inert substances simply persist in the environment. This means that these substances require land area for dumping.
2. Excess of fertilizers, pesticides and other chemicals changes soil chemistry and also affect aquatic life.
3. Most of these chemicals and heavy metal are easily absorbed by the organisms. This causes biological magnification.

જવાબ : Following is the role of a decomposer in the ecosystem:

• They act as a cleansing agent of the environment by decomposing the dead plants and animals
• They help in recycling the nutrients
• They provide space for new beings in the biosphere by decomposing the dead

જવાબ : In the food chain, the transfer of food or energy takes place at various levels and these levels are known as tropic levels.

• Grass represents the first tropic level
• The goat represents the second tropic level

જવાબ : The reason why some substances are biodegradable and some non-biodegradable is because the microorganisms like bacteria and decomposers like saprophytes have a specific role to play. They can breakdown only natural products like paper, wood, etc. but they cannot breakdown man-made products like plastics. Based on this, some substances are biodegradable and some non-biodegradable.

જવાબ : Following are the ways in which biodegradable substances would affect the environment:

• They keep the environment clean as they are easily decomposed.

જવાબ : Following are the ways in which non-biodegradable substances would affect the environment:

• They cause air, soil and water pollution.

જવાબ : Following are the ways to reduce the problem of waste disposal:

• 3 R’s: By following the 3 R’s one can reduce the problem of waste disposal. The 3 R’s are reduce, recycle and reuse. Reducing the usage of their own vehicles and opting for public transport can reduce air pollution. Recycling and reusing of plastics is also a way to reduce waste disposal.

જવાબ : Yes, the impact of removing all the organisms in a tropic level will be different for different tropic levels. For example, if all the producers are removed, there is a chance of death or migration of the primary consumers which will upset the tropic levels. This is same for all the levels. Therefore, the removal of organisms at any level would upset the whole ecosystem as the food chain is disturbed. The survival of the higher level animals is completely dependent on the animals at the lower levels.

જવાબ : 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.

જવાબ : Following are the problems caused by the non-biodegradable wastes:

• These substances cannot be decomposed by the microorganisms.
• As the quantity increases, dumping becomes a problem.
• Non-biodegradable wastes like heavy metals may enter the food chain in the upper tropic levels.

જવાબ : Biodegradable wastes are decomposed by the microorganisms into simpler substances which can be used by the producers as a raw material. But following are the effects of too much of biodegradable wastes:

• As the decomposition of the biodegradable wastes is slow, they produce an awful smell and when inhaled by humans it can be harmful.
• The dumping areas can be a place where harmful organisms may start to breed which can be harmful to humans as well as plants and animals.
• Increase in the number of aquatic organisms may result in depletion of oxygen.

જવાબ : 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 the ozone layer. Too much of 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.

જવાબ : (i) Recycling: The solid wastes like paper, plastics and metals, etc. are recycled.
(ii) Preparation of Compost: Biodegradable domestic wastes such as leftover food, fruit and vegetable peels and leaves of potted plants, etc. can be converted into compost by burying in a pit dug into ground

જવાબ : The food chain would end and ecological balance would be affected.

1. If the herbivores are killed, then the carnivores would not be able to get food and would die.
2. If carnivores are killed, then the population of herbivores would increase to unsustainable level.

જવાબ : Yes, the impact of removing all the organisms in a tropic level will be different for different tropic levels. For example, on removing producers; herbivores would not be able to survive or they would migrate and ecosystem would collapse. If herbivores are removed, producers would grow unchecked and carnivores would not get food. If carnivores are removed, herbivores would increase to unsustainable levels and could destroy the producers. If decomposers are removed, the dead animals would pile up due to which the environment would become polluted. In addition to this, if dead animals will not decompose, the recycling of nutrients in the soil will be stopped and its fertility will be reduced. As a result the green cover of the earth will be lost. Thus to maintain the balance of the ecosystem the presence of organisms is necessary at each tropic level.

જવાબ : Biological magnification: The increase in concentration of harmful chemical substances like pesticides in the body of living organisms at each tropic level of a food chain is called biological magnification.
Yes, levels of bio-magnification would increase as the tropic level increases and would be the highest for topmost tropic level. It would affect their biological process such as growth, reproduction, etc.

જવાબ : The problems caused by the non-biodegradable wastes are:

1. If the quantity of non-biodegradable matter increases in the nature then bio-magnification of poisonous chemicals in our body increases.
2. If the non-biodegradable waste keeps on increasing there will not be left any substance for new organisms.
3. The increasing quantity of non-biodegradable waste will cause imbalance of ecosystem.

જવાબ : The damage to the ozone layer is a cause for concern because if the ozone layer in the atmosphere disappears completely, then all the extremely harmful ultraviolet radiations coming from the sun would reach the earth. These ultraviolet radiations would cause skin cancer and other ailments in men and animals and also damage the plants.
In an attempt to protect the ozone layer, the United Nations Environment Programme (UNEP) unanimously forged an agreement among its member countries to freeze CFC production at 1986 levels.

જવાબ : If all the waste we generate is biodegradable, it will also have impact on the environment. If it is disposed of properly, the problem of air, water and soil pollution can be lessened to an extent. There would be less health problems and humans would be disease-free.
But if it is not disposed off properly, it will affect the environment adversely.

જવાબ :

1 (iii)
2 (i)
3 (iv)
4 (ii).

જવાબ :

a. Scavenger
b. Abiotic
c. Biotic
d. Pesticides

જવાબ :

a. Patricide
b. Lion
c. Goat
d. Decompose
e. Ozone

જવાબ :