Practice important
Salinity Tolerance
MCQ questions and answers.
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10
MCQ Questions
1. How does abscisic acid help a plant tolerate saline conditions?
A.
It promotes excessive opening of stomata
B.
It helps reduce water loss by closing stomata
C.
It prevents all root growth
D.
It increases salt entry into leaves
Correct Answer:
It helps reduce water loss by closing stomata
Explanation:
Under salinity stress, abscisic acid promotes stomatal closure, which reduces transpiration and helps the plant conserve water.
2. Salinity stress commonly causes an increase in which plant hormone?
A.
Abscisic acid
B.
Ethylene only
C.
Auxin only
D.
Gibberellin only
Correct Answer:
Abscisic acid
Explanation:
Salinity stress stimulates the production and accumulation of abscisic acid, which helps coordinate the plant's response to water shortage and excess salts.
3. What is the immediate effect of ABA on stomata during salt stress?
A.
Stomatal closure
B.
Stomatal enlargement
C.
Stomatal multiplication
D.
Permanent stomatal opening
Correct Answer:
Stomatal closure
Explanation:
ABA signals guard cells to close the stomata during salinity stress, limiting water loss from the plant.
4. Why is reducing transpiration useful for a plant growing in salty soil?
A.
It helps conserve water
B.
It increases salt absorption
C.
It stops photosynthesis permanently
D.
It removes all salts from the soil
Correct Answer:
It helps conserve water
Explanation:
Salty soil makes it difficult for roots to absorb water. Reducing transpiration through ABA-induced stomatal closure helps conserve the water already present in the plant.
5. During salinity stress, ABA signaling in guard cells mainly helps the plant to:
A.
Maintain water balance
B.
Increase leaf salt accumulation
C.
Destroy root tissues
D.
Stop mineral transport completely
Correct Answer:
Maintain water balance
Explanation:
ABA signaling causes stomatal closure, helping maintain water balance when saline conditions reduce water availability.
6. Which plant organ is especially important for sensing saline conditions and initiating ABA-related responses?
A.
Roots
B.
Flowers only
C.
Fruits only
D.
Seeds only
Correct Answer:
Roots
Explanation:
Roots directly contact the saline soil and can help detect salt and water stress, leading to ABA-mediated responses in the plant.
7. ABA helps plants under salinity stress by activating responses that improve:
A.
Water conservation
B.
Salt production
C.
Leaf shedding in every case
D.
Stomatal opening throughout the day
Correct Answer:
Water conservation
Explanation:
A major role of ABA during salinity stress is to conserve water, mainly by promoting stomatal closure and coordinating stress responses.
8. What may happen to transpiration when ABA levels rise during salinity stress?
A.
Transpiration decreases
B.
Transpiration always doubles
C.
Transpiration becomes unrelated to stomata
D.
Transpiration stops salt from entering soil
Correct Answer:
Transpiration decreases
Explanation:
Higher ABA levels cause stomatal closure, which generally decreases transpiration and reduces water loss under saline conditions.
9. Which response is most closely associated with ABA-mediated salinity tolerance?
A.
Closing stomata to limit water loss
B.
Opening stomata widely to increase water loss
C.
Increasing salt movement into leaves
D.
Preventing roots from contacting soil
Correct Answer:
Closing stomata to limit water loss
Explanation:
ABA-mediated stomatal closure is a key response that helps plants tolerate the water deficit associated with saline soil.
10. A plant exposed to high salt concentration produces more ABA. What is the likely result?
A.
Guard cells lose water and stomata close
B.
Guard cells gain water and stomata open widely
C.
Roots stop detecting salt
D.
Leaves absorb more water through stomata
Correct Answer:
Guard cells lose water and stomata close
Explanation:
ABA promotes ion and water loss from guard cells, causing stomatal closure and helping the plant conserve water during salinity stress.
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Salinity Tolerance
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