Why does a plant lose water during active photosynthesis?
AGuard cells must dry out to stay rigid
BStomata must open to let carbon dioxide in
CStomata must open to let oxygen gas in
DChloroplasts must split water for carbon
Answer & Solution
Correct answer: B. Stomata must open to let carbon dioxide in
1. Carbon dioxide can only reach the mesophyll if the stomata are open.
2. Because stomata must open to allow for that uptake, water escapes from the leaf.
3. The loss therefore happens during active photosynthesis, when the pores are needed most.
4. In dry heat this trade-off forces desert plants to evolve ways of conserving water.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 8 "Photosynthesis", section 8.3 Using Light Energy to Make Organic Molecules_
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