"AKC SCIENCE CLASSES"
CLASS 10 TH (CBSE AND MP BOARD)
CHAPTER 15
OUR ENVIRONMENT
EXERCISES QUESTIONS ANSWERS
Q.01:- Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruits-peels, cake and lime-juice
(d) Cake, wood anf grass.
Ans:- (c) Fruits-peels, cake and lime-juice.
Q.02:- 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.
Ans:- (b) Grass, goat and human.
Q.03:- 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.
Ans:- (d) All of the above.
Q.04:- What will happen if we kill all organisms in one trophic level?
Ans:- If we kill all the organisms of a trophic level, the number of organism in next trophic level will decrease drastically due to non-availability food. On the contrary, the number of individuals in lower trophic level will increase because no one will be there to feed upon them, resulting in imbalance eco-system.
Q.05:- 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 eco-system?
Ans:- Removing producers :- Herbivores would not be able to survive; eco-system would collapse.
Removing herbivores :- Producers would grow unchecked; carnivores would not get food.
Removing carnivores :- Herbivores would increase to unsustainable levels.
Removing decomposers :- Waste material and animal dead remains would pile u and nutrients would not be available to the producers.
Some or the other damage would be caused to the eco-system if the organisms of any trophic level are removed. However, impact of removing producers or decomposers would be severe as the whole ecosystem would collapse. Without plants sun's energy cannot be converted to chemical energy which is the basis of life on earth. Without decomposers the nutrients cannot be recycled and made available to producers.
Q.06:- What is biological magnification? Will the levels of this magnification be different at different levels of the eco-system?
Ans:- Biological Magnification is a phenomenon which explains the increasing concentration of harmful chemical (like DDT) with each increase in trophic level. From the soil the chemicals (mainly pesticides, heavy metals, etc.), are absorbed by the plants. The primary consumers eat these plants and the harmful chemicals come to reside in their bodies. As these chemicals are not degradable, they accumulate in the bodies of the organisms and the top level of the food chain gets the highest concentration of these harmful chemicals. Most of the plants products which we eat are grown in fields in which pesticides and fertilisers have been used. These are absorbed by the plants and cannot be removed by washing or other means. As humans are at the top level of the food chain these chemicals get accumulated in our bodies and cause various disorders.
Levels of bio-magnification would increase as the trophic level increases and would be higher for higher trophic levels.
Q.07:- What are the problems caused by the non-biodegradable wastes that we generate?
Ans:- The problems caused by the non-biodegradable wastes that we generate are :-
- Clogging of drains.
- Death of cattle by ingestion of plastic
- Soil destruction
- Non-aesthetic look
- Bio-magnification of poisonous chemicals in our body or other animals which disturb body metabolism resulting in various diseases
- Pollution of air, water and land
- Destruction of balance of eco-system.