Practice important
Guard Cell Response
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. What is the main effect of abscisic acid on stomata during water stress?
A.
It causes stomatal closure
B.
It causes stomatal opening
C.
It increases leaf growth
D.
It promotes pollen formation
Correct Answer:
It causes stomatal closure
Explanation:
Abscisic acid signals guard cells to close the stomata during water stress, helping reduce water loss from the leaf.
2. In which cells does abscisic acid mainly act to regulate stomatal opening and closing?
A.
Root hair cells
B.
Guard cells
C.
Xylem cells
D.
Palisade cells
Correct Answer:
Guard cells
Explanation:
Abscisic acid acts on guard cells, which control the opening and closing of stomatal pores.
3. Why does abscisic acid cause stomatal closure during drought?
A.
To reduce water loss
B.
To increase water loss
C.
To increase leaf temperature permanently
D.
To promote seed germination
Correct Answer:
To reduce water loss
Explanation:
Closing the stomata reduces the escape of water vapour from the leaf, helping the plant conserve water during drought.
4. What happens to the turgor of guard cells when abscisic acid causes stomatal closure?
A.
It decreases
B.
It increases greatly
C.
It remains permanently unchanged
D.
It changes into cell wall pressure
Correct Answer:
It decreases
Explanation:
Abscisic acid promotes the loss of ions and water from guard cells, decreasing their turgor and causing the stomatal pore to close.
5. Which movement from guard cells is associated with abscisic acid-induced stomatal closure?
A.
Movement of potassium ions out of the cells
B.
Movement of potassium ions into the cells
C.
Movement of starch into the nucleus
D.
Movement of chlorophyll out of the leaf
Correct Answer:
Movement of potassium ions out of the cells
Explanation:
Abscisic acid promotes ion efflux, including the loss of potassium ions from guard cells. Water then leaves the cells, reducing their turgor and closing the stomata.
6. What is the immediate result of water leaving guard cells after abscisic acid action?
A.
Guard cells become flaccid
B.
Guard cells become highly turgid
C.
Guard cells divide rapidly
D.
Guard cells form root hairs
Correct Answer:
Guard cells become flaccid
Explanation:
Water loss makes guard cells less turgid or flaccid, which brings the stomatal pore toward closure.
7. When is abscisic acid likely to promote stomatal closure?
A.
During drought conditions
B.
During abundant water availability only
C.
During fruit ripening only
D.
During active root branching only
Correct Answer:
During drought conditions
Explanation:
Drought increases the importance of abscisic acid signalling in guard cells, leading to stomatal closure and reduced water loss.
8. How does stomatal closure help a plant respond to water stress?
A.
It limits transpiration
B.
It increases transpiration
C.
It stops ion movement in every plant cell
D.
It increases water loss from roots
Correct Answer:
It limits transpiration
Explanation:
Closed stomata restrict the loss of water vapour through transpiration, helping the plant cope with water stress.
9. Which change in guard cells is promoted by abscisic acid before stomatal closure?
A.
Loss of ions and water
B.
Gain of water only
C.
Formation of new chloroplasts
D.
Rapid enlargement of the stomatal pore
Correct Answer:
Loss of ions and water
Explanation:
Abscisic acid promotes the loss of ions from guard cells, followed by water loss. This reduces guard-cell turgor and closes the stomata.
10. What would be the likely effect of increased abscisic acid in guard cells during dry weather?
A.
The stomatal pore would close
B.
The stomatal pore would open wider
C.
The guard cells would become more turgid
D.
The stomata would produce seeds
Correct Answer:
The stomatal pore would close
Explanation:
During dry weather, increased abscisic acid causes guard cells to lose ions and water, lowering their turgor and closing the stomatal pore.
Short Questions and Answers
Practice short questions and answers related to
Guard Cell Response
.
Short questions are currently unavailable for this page.