Chapter 4 – Environmental Balance
EXERCISES
1. What’s the solution?
We have to remove insects from the grain without using insecticides.
Ans:
(a) Let the grain dry in the sunlight. The harsh sunlight does not allow eggs and caterpillars to grow in the grain.
(b) Keep dried Neem leaves in the container in which the grains are stored. Neem acts as a repellent for insects.
(c) Grains like beans are smeared with mud. The mud particles keep the weevils away from infesting the grains.
(d) The place where grain is stored should be cool and dry. It should be airy. The chances of insect infestations are lower in such storage places.
2. Use your brain power !
Make up a food chain :
Frog, kite, worm, snake, grass.
Ans: The food chain is,
Grass → Worm → Frog → Snake → Kite
3. Answer the following questions.
(a) What is a food chain? Give an example of it.
Ans:
(1) One living thing is dependent on another living thing for the purpose of feeding. Therefore, they are interconnected with each other like a chain. This relationship is called a food chain.
For example:
Plants prepare food with the help of sunlight. The leaves of this plant are nibbled by a caterpillar. Grasshoppers eat these caterpillars. Grasshoppers are eaten by sparrows. This is a food chain.
Sunlight → Plants → Caterpillar → Grasshopper → Sparrow
(b) How is the balance in the environment maintained?
Ans:
(1) In any environment, food chains and food webs are present.
(2) Due to this, there are interactions among different types of living things.
(3) Similarly, non-living things too move in a cyclic manner in this environment.
(4) Living and non-living things give and take different materials in the water cycle, carbon dioxide-oxygen cycle, etc.
(5) Microorganisms bring about decomposition in the soil and add required substances.
(6) When all these cycles and interactions take place in an environment without any check, then there is balance in that environment.
4. What substances in the soil are useful for the growth of plants ?
Ans:
(1) Plants require water, minerals, and other substances in the soil for their growth.
(2) The substances formed due to the decomposition of dead and decaying plant and animal material are very useful for plants.
(3) These substances help in the rapid growth of plants.
5. True or false?
(a) Micro – organisms form a part of the environment.
Ans: True
(b) It is necessary to maintain biodiversity.
Ans: True
(c) A grasshopper eats birds.
Ans: False