Welcome to the Quiz!
This quiz contains 10 questions from a mix of 1 subtopics.
Which of the following factors can trigger stomata to open?
(Select all that apply)
decreased O2 levels within the leaf air spaces
increased humidity
decreased CO2 levels within the leaf air spaces
increased light intensity
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What is the first step in the mechanism of stomatal opening?
activation of ATP-dependent proton pumps
starch in guard cells breaking down to form malate ions
K+ channels opening and K+ entering the guard cells
water entering the guard cells via osmosis
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What happens to malate ions during stomatal closure?
they remain unchanged
they are transported into chloroplasts and converted into starch
they are broken down to release energy
they are actively transported out of the guard cells
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What is the role of abscisic acid (ABA) in stomatal closure?
(Select all that apply)
it binds to specific receptors on guard cell membranes
it triggers Ca2+ to leave the guard cell cytoplasm
it causes guard cells to become flaccid
it permanently increases the turgor pressure in guard cells
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Which of the following is NOT an adaptation of guard cells?
outer walls for structural support
no chloroplasts for photosynthesis
elastic inner walls for flexibility
many vacuoles for efficient water storage
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What prevents the expansion of guard cells in all directions, directing them to increase in length rather than diameter?
membrane folds
elastic inner walls
cellulose microfibrils
waxy cell walls
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What triggers K+ channels to open and allow K+ to enter the guard cells during stomatal opening?
lower H+ concentration inside guard cells
increased ATP production
increased water potential inside guard cells
higher H+ concentration inside guard cells
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Which of the following is a direct consequence of ABA binding to specific receptors on guard cell membranes?
opening of ion channels, leading to the influx of malate ions and K+
inhibition of proton pumps
immediate decrease in water potential inside the guard cells
activation of proton pumps
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What happens to the starch in guard cells during stomatal opening?
it is converted into glucose for energy
it is broken down to form malate ions
it remains unchanged
it is synthesised from malate ions
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Which of the following best describes the role of abscisic acid (ABA) in stomatal closure?
ABA increases the water potential inside the guard cells, causing them to become turgid and close the stomatal pore
ABA triggers a series of events that lead to the loss of turgor pressure in guard cells, causing stomatal closure
ABA directly closes the stomatal pore
ABA has no role in stomatal closure
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