NCERT Books Solutions For Class 10 Science Chapter 15 Our Environment
NCERT Solutions For Class 10 Science Chapter 15 Our Environment is the first stepping stone for a student in the competitive world. With the introduction of the CBSE Board Exam for class 10 a few years back, this has become an important gateway for a student as based on the results of class 10th a student selects his future stream of Science, Commerce, or Arts.
Takshila Learning provides you with detailed and well explained NCERT Solutions for Class 10 of each chapter of each subject for NCERT Class 10. These NCERT Solutions help you to easily understand every concept so that you can score high in your CBSE Class 10 Board Exams.
Below you can find the NCERT solution for Class 10th Science. You can get a Solution for the all-important question of “Our Environment”
Ques 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 micro-organisms and some cannot. Substances that are broken down into simple soluble forms are called biodegradable substances and substances that are not decomposed by micro-organisms into harmless substances are called non-biodegradable substances.
Ques 2: Give any two ways in which biodegradable substance would affect the environment.
Answer: Biodegradable substances affect the environment by:
- The biodegradable substances such as three leaves, plant parts, and kitchen waste can be used as Humus after composting. This will enhance the soil fertility.
- The biodegradable substances Mainly contains carbon. The substances after decomposition release that carbon back into the atmosphere.
Ques 3: Give any two ways in which non-biodegradable substance 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 death.
Intext questions (set 2)
Page no. 261
Ques 1: What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer: In food chain, the transfer food or energy takes place at the various levels and these levels are known as trophic levels.
Example:
Grass → Goat → Man
In food chain,
- Grass represents the first trophic level
- Goat represents the second trophic level
- Man represents the third trophic level.
Ques 2: What is the role of decomposers in the ecosystem?
Answer: Various role played by decomposers in the ecosystems are:
- They clean the environment.
- The decompose a biodegradable substance into useful substances.
- The 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.
Intext questions (set 3)
Page no. 265
Ques 1: What is ozone and how does it affect the 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 ultraviolet radiation (UV) coming from sun as these radiations are very harmful causing skin cancer and cataracts in humans. It also does harm to the crops.
Ques 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:
Page no. 265
Q1. Which of the following groups contain only biodegradable items?
- Grass, flowers and leather
- Grass, wood and plastic
- Fruit peels, cake and lime juice
- Cake, wood and grass
Answer: (c) Fruit peels, cake and lime juice
(d) cake, wood and grass.
Q2. Which of the following constitute a food-chain?
- Grass, wheat and mango
- Grass, goat and human
- Goat, cow and elephant
- Grass, fish and goat
Answer: (b) Grass, goat and human.
Q3. Which of the following are environment-friendly particles?
- Carrying cloth bags to put purchases in while shopping
- Switching off unnecessary lights and fans
- Walking to school instead of getting your mother to drop you on her scooter
- All of the above
Answer: (d) all of the above
Q4. What will happen if we kill all the organisms in one trophic level?
Answer: If we kill all the organism of one trophic level it will create an imbalance in the ecosystem as an example, in the food chain grass-dear-lion, if we remove all the lion, 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 a fertile land into a barren desert.
Q5. Will the impact of removing all the organisms in 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 traffic level is different from different trophic levels.
For example: If we remove producers from a food chain, no organism will get food, if you remove herbivorous 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 anyone this will create imbalance in the ecosystem.
Q6. 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 of increase in the concentration of some toxic substances at each traffic level.
The level 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 accumulate more DDT as one sea gull eats more clams. Hawks, the top Carnivore has the highest concentration of DDT.
Q7. What are the problems caused by the non-biodegradable wastes that we generate?
Answer: The problem caused by non-biodegradable wastes are:
- The cause biomagnification.
- They increased pollution.
- They make environment unclean.
- They kill useful microorganisms.
Q8. 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 number of decomposers will be quite low so waste cannot be broken down into harmless simpler substances at the right time. It will become breeding ground for flies causing spread of diseases. It will also emit foul smell which makes the life of people miserable.
Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Answer: 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 death of many phytoplankton that leads to increased global warming.
To limit the damage to the ozone layer, the release of CFCs into the atmosphere must be reduced. CFC is used as refrigerant and in fire extinguishers should be replaced with environmentally safe alternatives. Also, the release of CFCs through industrial activities should be controlled.
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NCERT Solutions For Class 10 Science
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