NCERT Solutions for Class 10 Science Chapter 15 Our Environment
Chapter 15 Our Environment NCERT Solutions for Class 10 Science will be useful in understanding the concepts and scoring good marks in the exams. These NCERT Solutions are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. Students can cross check their answers and also whether they learned it properly or not. You will learn about topics like components of an ecosystem, food chain and food web, ozone layer depletion and management of garbage.
Chapter 15 Our Environment NCERT questions and answers are prepared as per the accordance of latest CBSE guidelines so you can score maximum marks. You can study in an organized manner and outperform your classmates. NCERT Solutions prepared by our experts try to provide all round clarity of questions.
| Study Reference for Class 10 Chapter 15 Our Environment |
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Page No: 257
1. Why are some substances biodegradable and some non-biodegradable?
Answer
Substances are classified as biodegradable and non-biodegradable because some substances can be decomposed by microorganisms and some cannot.
Substances that are broken down into simple soluble forms are called biodegradable substances and the substances that are not decomposed by microorganisms into harmless substances are called non biodegradable substances.
2. Give any two ways in which biodegradable substances would affect the environment.
Answer
Biodegradable substances affect the environment by:
→ The biodegradable substances such as tree leaves, plant parts, and kitchen wastes can be used as humus after composting. This will enhance the soil fertility.
→ The biodegradable substances mainly contain carbon. These substances after decomposition release that carbon back into the atmosphere.
3. Give any two ways in which non-biodegradable substances would affect the environment.
Answer
Non-biodegradable substances affect the environment by:
→ They contaminate soil and water resources as they cannot be decomposed by micro-organisms.
→ These substances, when accidentally eaten by stray animals, can harm them and can even cause their death.
Page No: 261
1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer
The various links or steps in a food chain at which the transfer of food and energy takes place are called trophic levels.
The producers form the first trophic level as they manufacture food. The primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level.
2. What is the role of decomposers in the ecosystem?
Answer
Various role played by decomposers in the ecosystem are:
→ They clean the environment.
→ They decompose biodegradable substances into useful substances.
→ They release nutrients into soil by decomposing dead and decaying matter, thus making the soil fertile.
→ They maintain the nutrient pool by returning back the nutrients in the pool.
Page No: 264
1. What is ozone and how does it affect any ecosystem?
Answer
Ozone (O3) is a molecule, made up of three atoms of oxygen.
Ozone (O3) forms a layer in the upper atmosphere. It is very essential for the life on this planet. It shields the surface of the earth from ultra-violet radiation (UV) coming from sun as these radiations are very harmful causing skin cancer and cataract in humans. It also does harm to the crops.
2. How can you help in reducing the problem of waste disposal? Give any two methods.
Answer
We can help in reducing the problem of waste disposal by these methods:
→ By separating biodegradable substances from non-biodegradable substances.
→ By reducing, reusing and recycling non-biodegradable substances.
Exercise
1. 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
2. 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
3. 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 scooter
(d) All of the above
Page No: 265
4. What will happen if we kill all the organisms in one trophic level?
Answer
If we kill all the organisms of one trophic level it will create an imbalance in the ecosystem. As an Example, In a food chain Grass → Dear → Lion, If we remove all lions then population of deer will increase which will cause over-grazing. This will lead to deforestation. It may even lead to soil erosion causing further conversion of fertile land into barren desert.
5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Answer
Impact of removing all organisms of a trophic level is different for different trophic levels.
For example, if we remove producers from a food chain, no organism will get food, if we remove herbivores from a food chain then carnivores will die and producers will also die due to competition for space and nutrients. No, we can't remove any trophic level without causing damage to the ecosystem as one is dependent on other for their survival. If we remove any one this will create imbalnce in the ecosystem.
6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer
Biological magnification is defined as the phenomena of accumulation or increase in the concentration of some toxic substances at each trophic level.
7. What are the problems caused by the non-biodegradable wastes that we generate?
Answer
The problems caused by non-biodegradable wastes are:
→ The cause biomagnification.
→ They increase pollution.
→ They make environment unclean.
→ They kill useful microorganisms.
8. If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer
If all the waste generated would be biodegradable this will also create problem. As the numbers of decomposers will be quite low so wastes cannot be broken down into harmless simpler substance at right time. It will became breeding ground for flies causing spread of diseases. It will also emits foul smell which makes the life of people miserable.
Answer
Biodegradable substances affect the environment by:
→ The biodegradable substances such as tree leaves, plant parts, and kitchen wastes can be used as humus after composting. This will enhance the soil fertility.
→ The biodegradable substances mainly contain carbon. These substances after decomposition release that carbon back into the atmosphere.
3. Give any two ways in which non-biodegradable substances would affect the environment.
Answer
Non-biodegradable substances affect the environment by:
→ They contaminate soil and water resources as they cannot be decomposed by micro-organisms.
→ These substances, when accidentally eaten by stray animals, can harm them and can even cause their death.
Page No: 261
1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer
The various links or steps in a food chain at which the transfer of food and energy takes place are called trophic levels.
The producers form the first trophic level as they manufacture food. The primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level.
In the above fig. Grass is the producer which is eaten by the grasshooper known as primary consumer. Then the grasshooper is eaten by shrew, secondary consumer and lastly shrew eaten up by owl, tertiary conusmer.
Answer
Various role played by decomposers in the ecosystem are:
→ They clean the environment.
→ They decompose biodegradable substances into useful substances.
→ They release nutrients into soil by decomposing dead and decaying matter, thus making the soil fertile.
→ They maintain the nutrient pool by returning back the nutrients in the pool.
Page No: 264
1. What is ozone and how does it affect any ecosystem?
Answer
Ozone (O3) is a molecule, made up of three atoms of oxygen.
Ozone (O3) forms a layer in the upper atmosphere. It is very essential for the life on this planet. It shields the surface of the earth from ultra-violet radiation (UV) coming from sun as these radiations are very harmful causing skin cancer and cataract in humans. It also does harm to the crops.
2. How can you help in reducing the problem of waste disposal? Give any two methods.
Answer
We can help in reducing the problem of waste disposal by these methods:
→ By separating biodegradable substances from non-biodegradable substances.
→ By reducing, reusing and recycling non-biodegradable substances.
Exercise
1. 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
2. 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
3. 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 scooter
(d) All of the above
► (d) All of the above
Page No: 265
4. What will happen if we kill all the organisms in one trophic level?
Answer
If we kill all the organisms of one trophic level it will create an imbalance in the ecosystem. As an Example, In a food chain Grass → Dear → Lion, If we remove all lions then population of deer will increase which will cause over-grazing. This will lead to deforestation. It may even lead to soil erosion causing further conversion of fertile land into barren desert.
5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Answer
For example, if we remove producers from a food chain, no organism will get food, if we remove herbivores from a food chain then carnivores will die and producers will also die due to competition for space and nutrients. No, we can't remove any trophic level without causing damage to the ecosystem as one is dependent on other for their survival. If we remove any one this will create imbalnce in the ecosystem.
6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer
Biological magnification is defined as the phenomena of accumulation or increase in the concentration of some toxic substances at each trophic level.
The levels of biomagnification will be different at 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 fishes and clams, their body accumulates 0.23 ppm of DDT. Sea gull that feeds on clams accumulates more DDT as one sea gull eats many clams. Hawk, the top carnivore, has the highest concentration of DDT.
7. What are the problems caused by the non-biodegradable wastes that we generate?
Answer
The problems caused by non-biodegradable wastes are:
→ The cause biomagnification.
→ They increase pollution.
→ They make environment unclean.
→ They kill useful microorganisms.
8. If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer
If all the waste generated would be biodegradable this will also create problem. As the numbers of decomposers will be quite low so wastes cannot be broken down into harmless simpler substance at right time. It will became breeding ground for flies causing spread of diseases. It will also emits foul smell which makes the life of people miserable.
9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Answer
The damage to the ozone layer a cause for concern because:
→ It causes skin darkening, skin cancer, ageing, and corneal cataracts in human beings.
→ It can result in the death of many phytoplanktons that leads to increased global warming.
→ It causes skin darkening, skin cancer, ageing, and corneal cataracts in human beings.
→ It can result in the death of many phytoplanktons that leads to increased 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.
Go Back To NCERT Solutions for Class 10 Science
Chapter 15 Our Environment Class 10 NCERT Solutions
Class 10 Science NCERT Solutions are helpful resources that can help you in covering the entire syllabus and getting command over the subject. It will serve as beneficial tool that can be used to recall various questions any time. Chapter 15 of NCERT Solutions Class 10 Science consists of 9 exercise questions and 9 in-text questions.
Topics in the Chapter
• Eco-system - What Are Its Components?
→ Food Chains and Webs
• How Do Our Activities Affect The Environment?
→ Ozone Layer and How it is Getting Depleted
→ Managing the Garbage we Produce
NCERT Solutions for Class 10 Science Chapters:
FAQ on Chapter 15 Our Environment
What is acid rain?
Oxides of sulphur and nitrogen when dissolves in rain water form sulphuric acid and nitrous acid or nitric acid. The polluted rain with these acid is called acid rain.
What is trophic level?
Various levels or steps in a food chain in which transfer of food takes place from one organism to another are called trophic levels.
What percentage of solar energy is trapped and utilized by plants?
Plants utilized only 1% of total sun’s energy, which is utilized by plants in the process of photosynthesis.
How Ozone layer is advantage for us?
Ozone layer protects the ecosystem from the harmful effects of ultraviolet rays coming from the Sun. UV rays may cause skin cancer, cataract to us.
What limits the number of trophic levels in a food chain?
There is a loss of energy as we go from one trophic level to the next, this limits the number of trophic levels in a food chain.