Energy is obtained from both aerobic and anaerobic respiration during exercise. Give three differences between aerobic and anaerobic respiration.

aerobic respiration uses oxygen for eaxaplme a relaxed human will be inhaling oxygen and their bodies using it to break down glucose in their cells.  glucose + oxygen = carbon dioxide + water

However anaerobic respiration occurs in muscles during hard excercise, does not use oxygen. in anaerobic respiration, glucose is not completely broken down and therefore not as much energy is released. Glucose --> lactic acid. There is often a bulid up of lctic acid in the muscle when there is no oxygen present, this lactic acid needs to be oxidised to carbon dioxide and water. 

In plants  and yeast, anaerobic respiration results in the production of ethanol and carbon dioxide