alleryStart learning →How do guard cells open and close a stoma?
ABy dividing and then fusing again
BBy swelling or shrinking with osmotic change
CBy growing new cell walls each day
DBy absorbing light of a set wavelength
Answer & Solution
Correct answer: B. By swelling or shrinking with osmotic change
1. Each stoma is flanked by a pair of guard cells.
2. Those guard cells regulate the opening and closing of the stoma.
3. They do so by swelling or shrinking in response to osmotic changes.
4. Water movement therefore drives the gate, which is why a dry day forces the pore shut.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 8 "Photosynthesis", section 8.1 Overview of Photosynthesis_
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