alleryStart learning →What proportion of the oxygen produced by a leaf is used by its own mitochondria?
AAbout 10 percent of it
BAbout 30 percent of it
CAbout 50 percent of it
DAbout 90 percent of it
Answer & Solution
Correct answer: A. About 10 percent of it
1. Splitting water at photosystem II releases oxygen as a waste product.
2. About 10 percent of that oxygen is used by mitochondria in the leaf.
3. It supports oxidative phosphorylation there, since plants respire as well as photosynthesise.
4. The remainder escapes to the atmosphere where aerobic organisms use it to support respiration.
5. The word about again marks an approximate share rather than a fixed proportion.
6. A figure of 90 percent inverts the split between what is kept and what is released.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 8 "Photosynthesis", section 8.2 The Light-Dependent Reactions of Photosynthesis_
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