48. (a) "Respiration is a vital function of the body". Justify the statements. (b) What is the main difference between aerobic respiration and anaerobic respiration? Give one example of each. What type of respiration takes place (i) in yeast, and (ii) in humans?

• Respiration is a vital function of the body because it provides energy for carrying out all the life processes that are necessary to keep the organisms alive. Most living things need oxygen to obtain energy from This oxygen reacts with the food molecules present in the body cells and burns them slowly to release energy. This energy is stored as ATP molecules in the cells. The process of releasing energy from food is called respiration.

Aerobic Respiration	Anaerobic Respiration
It takes place in the presence of oxygen.	It takes place in the absence of oxygen.
A complete breakdown of food occurs in aerobic respiration.	A partial breakdown of food occurs in anaerobic respiration.
The end products are carbon dioxide and water.	The end products may be ethanol and carbon dioxide (as in yeast cells) or lactic acid (as in muscle cells).
It produces a considerable amount of energy.	Much less energy is produced in anaerobic respiration.

• (i) Anaerobic respiration takes place in

(ii) Aerobic respiration takes place in humans.