Respiration In Plants
Respiration
Living cells respire. Aerobic respiration is the chemical reaction used to release
energy from glucose. It is called aerobic because oxygen from the air is also needed.
Here is the word equation for aerobic respiration:
glucose
oxygen
carbon dioxide
water (+ energy)
(Energy is put in brackets because it not a substance.)
Notice that the word equation for respiration is the reverse of the word equation for
photosynthesis. Check back if you are not sure of this.
Plants
Plant cells respire, just as animal cells do. If they stop respiring, they will die.
Remember that respiration is not the same as breathing, so take care - plants do not
breathe.
Plants respire all the time, whether it is dark or light. They are always taking in
oxygen and releasing carbon dioxide. But they also photosynthesise when they are in
the light - and remember that plants take in carbon dioxide and release oxygen when
they photosynthesise.
So, what happens to a plant overall, over any given period, depends on whether it is
in the dark or the light, and how bright the light is:
Conditions
Photosynthesis v respiration
Overall result
Dark
Respiration
No photosynthesis
Oxygen taken in
Carbon dioxide given out
Dim light
Photosynthesis rate equals
respiration rate
Neither gas is taken in or given
out, as each cancels the other
out
Bright light
Photosynthesis rate greater
than respiration rate
Carbon dioxide taken in
Oxygen given out
Photosynthesis usually results in a net food gain, once respiration has been
accounted for. This means that there is an increase in the biomass of the plant.
Plants that lose their leaves in winter store food produced during the summer by
photosynthesis. They store enough food to last them over winter, and to provide
energy reserves for new growth in the spring.