Chapter 15 of NCERT Class 10 Science is Our Management. In this chapter, you will understand the management and analyze the concepts of the food chain, ecosystems, and waste management. In this chapter, there are a total of 9 questions in the exercise. Its complete detailed solution is also given in FREE PDF format by Swiflearn.
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NCERT Solution for Class 10 Science Chapter 15 Our Management PDF
What are trophic levels? Give an example of a food chain and state the
different trophic levels in it.
A trophic level is the species level in an ecosystem on the basis of the nutrition source such as producers, primary consumers, secondary consumers, etc.
The producers belongs to the first trophic level as they produce their own food. As shown in figure, the primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level. Trophic levels Various trophic levels are connected through food chains. For example, in an aquatic food Phytoplankton is the producers, zooplanktons are the primary consumers, and small fish is the secondary consumer and so on.
What is the role of decomposers in the ecosystem?
Decomposers include micro-organisms such as fungi and bacteria and others that obtain nutrients by breaking down the remains of dead animals and plants. They help in breaking down of organic matter or biomass from the body of dead animals and plants into simple inorganic materials, such as CO2, H2O, and also some nutrients.
Why are some substances biodegradable and some non-biodegradable?
Substances such as metal, plastic, silica etc. belongs to the category of non-biodegradable wastes as they cannot be decomposed by the living organisms. These substances are nonbiodegradable because the micro-organisms can’t even break them over a long period of time. Therefore, we call them as non-biodegradable wastes. Other substances such as vegetable wastes, paper, etc. can be easily broken down by enzymes and thus belong to biodegradable wastes.
Give any two ways in which biodegradable substances would affect the
Biodegradable substances affect our environment in the following ways:
(i) The biodegradable substances such as leaves, different parts of plant, and kitchen wastes can be used as manure after composting which enhances the fertility of soil.
(ii) The biodegradable substances mainly contain Carbon. These substances after
decomposition release the stored Carbon back into the atmosphere which is main
component for the process of photosynthesis by which the plant make its food.
Give any two ways in which non-biodegradable substances would
affect the environment.
Non-biodegradable substances affect our environment in the following ways:
(i) They contaminate soil and water resources as they cannot be decomposed over time by Micro-organisms
(ii) These substances, when accidentally eaten by stray animals, can harm them and can even cause their death.
What is ozone and how does it affect any ecosystem?
Ozone (O3) is a colorless gas .This gas acts as a screen for ultraviolet (UV) radiation. It continuously forms at the higher altitude of our atmosphere due to the action of UV rays on molecular oxygen (O2). The UV radiations break down O2 molecules into nascent oxygen as they contain high energy.
UV O O+O 2
Then, this free oxygen atom combines with a molecule of oxygen to form ozone.
O2+ O O3 (ozone is formed)
In recent years, the ozone in the atmosphere is depleting continuously.
Thus the ozone depletion causes a greater amount of UV radiations to comes under or enter the Earth’s atmosphere. This has an indirect and a devastating effect on the ecosystem .Since; ecosystem includes both the biological community and the non-living components of an area. It results in the death of many phytoplankton, thus affecting the photosynthesis process. Plants utilize atmospheric CO2 to make their food. In the absence of plants, the levels of CO2 in the atmosphere will increase, which result to an increase in global warming.
The ozone layer depletion also increases the frequency of infectious or hazardous diseases as it suppresses the immune systems of both animals and human beings. The frequency of skin cancer also increases in human beings because of the direct exposure to ultraviolet radiations.
How can you help in reducing the problem of waste disposal? Give any two
Waste disposal problems can be solved by proper waste management which includes the transport, collection, processing, and disposal of the waste materials.
The problem of waste management can be solved by the following given measures:
• Use separate bins (blue and green) to separate non-biodegradable and biodegradable
wastes for their efficient disposal.
• Reduce the usage of non-biodegradable products such as plastics.
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
(c) Fruit-peels, cake, and lime-juice.
(d) Cake, wood, and grass
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
(b) Grass, goat, and human
Which of the following are environment-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
(d)All of the above
(d) All of the above
What will happen if we kill all the organisms in one trophic level?
If all the organisms of any one trophic level are killed, then it will disrupt the entire food chain as various trophic levels are connected through the food chains.
For example: – Considering the food chain, if all the plants are killed, then all the cows will die due to lack of food. If all the cows are dead, then soon the tigers will also die. Due to these animals death, the population of decomposer will rise in that area. This is just an example of one food chain. However, in nature, these food chains are not isolated and they are interconnected in the form of food web. Therefore, cutting all the plants of an area will not only affect the population of deer, but it will also affect other herbivores animals such as cattle, goat, sheep, etc.
Will the impact of removing all the organisms in a trophic level be different
for different trophic levels? Can the organism so any trophic level be
removed without causing any damage to the ecosystem?
Organisms of all trophic levels are equally important. They are an integral part of the ecosystem and all have their different roles. If in case, all the producers are removed, then it will badly affect all the herbivores as it is their primary source of food. The herbivores death will soon affect the primary carnivores and so on.
Now, suppose all the deer (herbivores) in a region are killed. This can result to an increase in the number of producers. Due to this, there will be an increase in the number of other herbivores such as goat, rabbits, sheep, etc. This will also lead to the increase in population of only consumers of these increased herbivores.
Thus, the ecosystem balance gets disturbed if any of its component organisms are removed.
What is biological magnification? Will the levels of this magnification be
different at different levels of the ecosystem?
Bio magnification is the increase in the concentration of harmful chemicals also known as pollutants within each step of the food chain. The levels of bio magnification will be different at the different trophic levels. For example, in a pond of water, DDT was sprayed and the producers were found to have 0.04 ppm concentration of DDT. Since many types of planktons are eaten by some clams and fish, their body accumulates 0.23 ppm of DDT. Sea gull that feeds on clams accumulates more DDT, as one sea gull eats many clams. The highest concentration of DDT as shown below.
Example of Bio magnifications
What are the problems caused by the non-biodegradable wastes that we
Non-biodegradable substances affect the environment in the following ways:
(i) Since the non-biodegradable substances cannot be broken down, they get stored or absorbed and thus contaminate the soil and the water resources.
(ii) These substances, when unknowingly eaten by some stray animal, can harm them and can even cause their death.
(iii) These substances occupy more space in the landfills and require special disposal techniques.
(iv) These materials can accumulate in the environment and can also enter the food chain.
If all the waste we generate is biodegradable, will this have no impact on
Generation of only biodegradable waste results in a positive impact on the environment. There will be no any pollution caused by the non-biodegradable wastes. The problem associated with disposal and waste management will also not occur. The population of decomposers will increase in order to breakdown the extra generated biodegradable waste.
Why is damage to the ozone layer a cause for concern? What steps are
being taken to limit this damage?
Ozone depletion occurs widely in the stratosphere (which is at high altitude). However, it is more prominent over the Antarctic region and is known as the ozone hole.
Diagram representing ozone hole
Consequences of ozone depletion:
• It causes skin cancer, skin darkening, ageing, and corneal cataracts in human beings.
• It can result in the death of many phytoplankton’s that leads to increase in the global warming.
To limit the damage to the ozone layer, the release of CFCs 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.