can some one please give me 'our environment' class 10cbse questions from intext to exercise (written).
Answers
Answer:
You are 10 I am 6
Explanation:
Answer:
Page Number: 260
Question 1
What are trophic levels ? Give an example of food chain and state the different trophic levels in it.
Answer:
Trophic Levels : The various steps in a food chain at which the transfer of food (or energy) takes place are called trophic levels.
Example : A food chain operating in a grassland is given below :
Grass → Insects → Frog → Birds
NCERT Solutions for Class 10 Science Chapter 15 Our Environment Intext Questions Page 260 Q1
In this food chain
Grass represents first trophic level.
Grasshopper represents second trophic level.
Frog represents third trophic level.
Eagle represents fourth tropic level.
Question 2
What is the role of decomposers in the ecosystem ?
Answer:
(i) Decomposers help in decomposing the dead bodies of plants and animals and hence act as cleansing agents of the environment.
(ii) Decomposers also help in putting back the various elements of which dead plants and animals are made, back into the soil, air and water for reuse by the producers like crop plants.
(iii) They help in recycling of the nutrients.
(iv) They decompose dead remains thereby providing space for new life to settle in the biosphere.
Page Number: 262
Question 1
Why are some substances biodegradable and some non-biodegradable ?
Answer:
The microorganism like bacteria and other decomposer organisms (called saprophytes) present in our environment are specific in their action. They break down the materials or products made from natural materials (say, paper) but do not break down man-made materials such as plastics. So, it is due to the property of decomposer organisms of being specific in their action that some waste materials are biodegradable, whereas others are non-biodegradable.
Question 2
Give any two ways in which biodegradable substances would affect the environment.
Answer:
(i) Biodegradable substances are decomposed by the action of microorganisms and decomposed materials are recycled through geo-chemical cycle.
(ii) These substances keep the environment clean.
Question 3
Give any two ways in which non-biodegradable substances would effect the environment.
Answer:
(i) They cause air, water and soil pollution.
(ii) They may cause bio-magnification in the food chain and end up in humans.
Page Number: 264
Question 1
What is ozone and how does it affect any ecosystem ?
Answer:
Ozone (O3) is an isotope of oxygen, i.e., it is a molecule formed by three atoms of oxygen.
At the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiations from the sun. These radiations are highly damaging to organisms. Ultraviolet rays can cause skin cancer.
Question 2
How can you help in reducing the problem of waste disposal ? Give any two methods.
Answer:
(i) Recycling : The solid wastes like paper, plastics and metals, etc. are recycled.
(ii) Preparation of Compost: Biodegradable domestic wastes such as left over food, fruit and vegetable peels and leaves of potted plants, etc. can be converted into compost by burying in a pit dug into ground.
NCERT Solutions for Class 10 Science Chapter 15 Textbook Chapter End Questions
Question 1
Which of the following groups contain only biodegradable item ?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit peels, cake and lime juice
(d) Cake, wood and grass
Answer:
(a) Grass, flowers and leather.
Question 2
Which of the following constitutes a food-chain ?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Answer:
(b) Grass, goat and human.
Question 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 on her scooter
(d) All of the above
Answer:
(d) All of the above.
Question 4
What will happen if we kill all the organisms in one trophic level ?
Answer:
The food chain would end and ecological balance would be affected.
If the herbivores are killed, then the carnivores would not be able to get food and would die.
If carnivores are killed, then the population of herbivores would increase to unsustainable level.
If producers are killed, then the nutrient cycle in that area would not be completed.