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.


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