Definition - What does photorespiration mean?

In plants, photorespiration is a process that only happens under higher light intensities. Also known as C2 photosynthesis, this process refers to a wasteful pathway that happens when the plant’s Calvin cycle processes oxygen instead of carbon dioxide. This process of respiration occurs only in light and is normally initiated in the plant’s chloroplasts.

MaximumYield explains photorespiration

Under conditions of water limitation, hot weather and high light intensity, the plant’s Calvin-Benson cycle becomes limited due to photorespiration. Indeed, this particular process has been shown to convert sugar back into carbon dioxide. This reaction produces a molecule of phosphoglycolate and a molecule of PGA which is converted into CO2.

Contrary to the process of respiration, photorespiration does not produce any ATP. In C3 plants, this process has been shown to lower the overall rate of photosynthesis. In C4 plants, on the other hand, photorespiration has quite a negligible effect. Additionally, the process of photorespiration also creates an interaction between the following organelles:

  • Peroxisome
  • Chloroplast
  • Mitochondria
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