Organisms need energy for many processes. For example:
The energy required for these processes is supplied by cellular respiration, but we usually just call it respiration for short.
Cellular respiration is an exothermic reaction which occurs continuously in living cells. Energy is transferred from glucose molecules, which were originally made by plants during photosynthesis. The energy released from breaking down glucose fuels a majority of our living processes.
Cellular respiration involves breaking down glucose molecules while releasing energy in the process. This is why the reaction is exothermic.
The diagram below illustrates the relationship between photosynthesis and cellular respiration:
Respiration produces carbon dioxide, which is used in photosynthesis. Then the cycle repeats.
There are two different types of respiration:
|Product(s)||Carbon dioxide and water||Animal cells: lactic acid|
Plant cells and yeast: carbon dioxide and ethanol
|Energy released||Relatively large amount||Relatively small amount|