1. What is the effect of gibberellins on senescence in many plant parts?
A.
They delay senescence
B.
They immediately cause senescence
C.
They stop seed germination
D.
They prevent cell division
Correct Answer:
They delay senescence
Explanation:
Gibberellins can delay senescence, helping plant tissues remain active for a longer period.
2. Which visible change may be delayed by gibberellin treatment in aging leaves?
A.
Yellowing
B.
Root formation
C.
Seed coat formation
D.
Flower pollination
Correct Answer:
Yellowing
Explanation:
Gibberellins may delay leaf yellowing, which is a common visible sign of senescence.
3. Delaying senescence by gibberellins helps plant leaves remain functional for a longer period. What does this mean?
A.
Leaves can continue photosynthesis longer
B.
Leaves lose all chlorophyll immediately
C.
Leaves stop absorbing water
D.
Leaves become seeds
Correct Answer:
Leaves can continue photosynthesis longer
Explanation:
When senescence is delayed, leaves remain green and photosynthetically active for a longer time.
4. Which pigment is commonly retained when gibberellins delay leaf senescence?
A.
Chlorophyll
B.
Melanin
C.
Haemoglobin
D.
Keratin
Correct Answer:
Chlorophyll
Explanation:
Delayed senescence helps maintain chlorophyll, keeping leaves green for a longer period.
5. What is the main result of delayed senescence in a leaf?
A.
The leaf remains green longer
B.
The leaf becomes dry instantly
C.
The leaf loses its cells immediately
D.
The leaf changes into a root
Correct Answer:
The leaf remains green longer
Explanation:
Gibberellin-induced delay of senescence can preserve the green appearance of leaves.
6. Gibberellins may be used after harvesting mainly to help some plant tissues remain fresh by delaying what process?
A.
Senescence
B.
Pollination
C.
Seed dispersal
D.
Root branching
Correct Answer:
Senescence
Explanation:
Post-harvest gibberellin treatment can help delay senescence and maintain freshness in suitable plant tissues.
7. Which condition is most likely in a leaf whose senescence has been delayed by gibberellins?
A.
It retains chlorophyll
B.
It loses chlorophyll rapidly
C.
It becomes a flower
D.
It stops all metabolic activity
Correct Answer:
It retains chlorophyll
Explanation:
Gibberellins can delay the breakdown of chlorophyll associated with leaf senescence.
8. Why can delaying senescence be useful in crop plants?
A.
It may keep leaves active for longer
B.
It prevents every type of plant growth
C.
It causes leaves to fall immediately
D.
It stops chlorophyll formation permanently
Correct Answer:
It may keep leaves active for longer
Explanation:
Delaying senescence can extend the period during which leaves remain functional and photosynthesize.
9. Which statement correctly describes the relationship between gibberellins and senescence?
A.
Gibberellins can postpone the aging of some plant tissues
B.
Gibberellins always speed up aging in all plant tissues
C.
Gibberellins remove all chlorophyll from young leaves
D.
Gibberellins change leaves directly into fruits
Correct Answer:
Gibberellins can postpone the aging of some plant tissues
Explanation:
A recognized effect of gibberellins is delaying senescence, or aging, in certain plant tissues.
10. A leaf treated with gibberellin stays green longer than an untreated leaf. Which process has been delayed?
A.
Leaf senescence
B.
Seed germination
C.
Pollen formation
D.
Root absorption
Correct Answer:
Leaf senescence
Explanation:
Maintaining green color for a longer time indicates that gibberellin has delayed leaf senescence.
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