photorespiration

Question

Photorespiration predominantly occurs in which plant type under high oxygen?

RankGuru · Accepted Answer

1. **RuBisCO Dilemma**: The enzyme RuBisCO can bind both $CO_2$ (carboxylation) and $O_2$ (oxygenation).
2. **Photorespiration**: When RuBisCO binds $O_2$ instead of $CO_2$, it starts a wasteful process called photorespiration ($C_2 \ cycle$) that consumes energy and releases $CO_2$.
3. **Occurrence**: This happens primarily in **$C_3$ plants** when $O_2$ levels are high or temperatures increase.
4. **Mechanism in $C_4$**: $C_4$ plants have evolved to concentrate $CO_2$ inside bundle sheath cells, effectively 'hiding' RuBisCO from $O_2$ and thus almost entirely avoiding photorespiration.

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photorespiration

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