Oxygen in water and soil:
When water is heated for some time (before it starts boiling), we can see that small bubbles forms at the inner surface of the vessel. The bubbles are seen as the air dissolved in water escapes. The water turns to vapour and begins to boil when heating continues.
Aquatic animals inhale dissolved oxygen in water. When water is poured on a lump of soil, small air bubbles come out of the soil, indicating the presence of the air.
Air bubbles from soil
Several plants and organisms that are living in the soil use oxygen to breathe. Various organisms like earthworms, rabbits, meerkats, and kangaroo mice form burrows and holes deep inside the soil.
Rabbit and earthworm
These holes makes the air to move in and out of the soil. During the raining season, when water fills up these spaces in the soil, animals and worms come out for respiration.
Plants prepare their food with the help of oxygen in the process of photosynthesis. They produce oxygen more than they consume during this process. Through the process of photosynthesis, they helps to balance oxygen and carbon dioxide in the atmosphere. Here, we can see how both the plants and animals are interdependent on each other.
Uses of air:
1. The movement of air helps to rotate windmill. Windmills are used to generate electricity. It is also used to run mills and draw water from tube wells.
2. It is used to sail yachts, gliders, aeroplanes, parachutes, etc.
A man flying a glider
3. It helps birds, bats and insects to fly.
A flying bird
4. It is also used in the dispersal of seeds and acts as a pollinating agent.
Dispersal of seeds
5. Air plays a vital role in the water cycle process, which gives us rain.