### ZIMSEC O Level Combined Science Notes: Respiration

• During the gaseous exchange process oxygen is taken into the body and carbon dioxide is expended.
• Oxygen is needed to burn fuels to release energy.
• Food is a fuel and oxygen is used by th cells to “burn” the fuel.
• The burning process is very slow and there are not flames involved.
• The energy in the food molecules is released slowly inside cells.
• Respiration is the release of energy when glucose is broken down in the presence of oxygen.
• $\text{Glucose+Oxygen}\rightarrow \text{Carbon Dioxide+Water+Energy}$
• Glucose and oxygen are delivered to body cells by the blood.
• Here it is broken down to release energy.
• Water and carbon dioxide are released as waste.
• Respiration is the opposite of photosynthesis.
• In respiration food is broken down to release energy and in photosynthesis solar energy is used to make food.
• All living things respire.
• Plants respire during the night and photosynthesis during the day.

To access more topics go to the Combined Science Notes page.