Summary

Summary

Conclusion:

• All living organisms need air to survive. Air cannot be seen but can be felt when it moves.
• Air is a mixture of several gases.
• Oxygen is needed for respiration. Carbon dioxide is given out as a by-product after respiration.
• Insects take in air with the help of tiny holes in their bodies called spiracles; earthworms breathe through their skin, which is kept moist with the help of a substance called mucus.
• Some aquatic animals like whales and dolphins as well as mammals breathe with the help of lungs.
• Amphibians like frogs breathe with the help of lungs, when on land. In water, these animals breathe with the help of their moist skin.
• Birds breathe through lungs and air sacs that are open all the time.
• There are several causes of air pollution: excessive burning of fuels like wood, coal, and petroleum, machines releasing gases, vehicles releasing smoke, and several types of harmful gases released by industries.