Question

30. (A). Read the following passage carefully and answer the Trees help to support man's life by supplying the atmosphere with oxygen which is essential to lifel The oxygen in the air is constantly being used up and turned into carbon di-oxide which is the food Wthat plants eat. The leaves of trees (in fact, of all green plants) absorb this carbon dioxide and with the help of sunlight breaks it down into carbon and oxygen. The carbon is used to make starch and the oxygen is released into the air, replacing the oxygen used up by animals. But for this, animals would soon die for lack of oxygen. Starch and other carbon compounds made in the green leaves of trees(and of other green plants too) serve as food for animals. The tiny green cells of plants are wonderful laboratories which produce all the starch in the world. But for this service done by plants, all animals would sooner or later die for lack of food. (i) What is the food that the plants eat? 1 (11) How do trees help to support man's life? 1 (ii) Why is oxygen turned into carbon di-oxide ? (iv) How do the leaves of trees break down carbon di-oxide into carbon and oxygen?​

Answer 1

Answer:

Trees support man's life by supplying the atmosphere with oxygen, which is essential to life.

The oxygen in the air is constantly being used up and turned into carbon dioxide when animals

breathe and things burn. Carbon dioxide is the food that plants consume. The green leaves of

trees and plants absorb this carbon dioxide and with the help of sunlight break it down into carbon

and oxygen The carbon dioxide is used to make starch, and the oxygen is released into the air,

so replacing the oxygen used up by animals. But for this, animals would soon die for lack of

oxygen

Starch and other carbon compounds made in green leaves of trees and plants serve as

food for animals. The tiny green cells of plants are wonderful laboratories, which produce all the

starch in the world. But for this service done by plants, all animals would sooner or later die for

lack of food; they must get all their food either directly from plants or indirectly by eating animals

that have fed on plants. You must have noticed how on a hot day it is often cooler under a tree that

inside a building. This is because the leaves of trees breathe out a lot of water vapour and this

helps to cool the air, more or less as a mud pot cools the water in it. In this way forests help to cool

the atmosphere and the rain clouds passing through it, so causing rain where new forests have

been planted, rainfall is known tohave increased. question = how is cooling of the atmosphere helpful for human being?