Q71
Cut or excised leaves remain green for long if dipped in
Correct Answer
Option B
Solution
(b) Cytokinins retard chlorophyll degradation and delay senescence of excised leaves.
Plant Growth and Development
Q72
Leaf fall can be prevented with the help of
Correct Answer
Option D
Solution
(d) Cytokinins prevent leaf abscission (Richmond-Lang effect).
Q73
Mowing grass lawn facilitates maintenance because of
Correct Answer
Option B
Solution
(b) Mowing removes apical buds, removing apical dominance and stimulating intercalary meristem growth.
Q74
Highest auxin concentration occurs
Correct Answer
Option A
Solution
(a) Highest auxin concentration is at the growing tips (shoot apex).
Q75
Phototropic and geotropic movements are linked to
Correct Answer
Option C
Solution
(c) Auxin mediates both phototropic and geotropic bending.
Q76
Hormone primarily connected with cell division is
Correct Answer
Option C
Solution
(c) Cytokinins (zeatin) are the primary cell-division-promoting hormones.
Q77
Abscisic acid causes
Correct Answer
Option A
Solution
(a) ABA promotes stomatal closure to reduce water loss under stress.
Q78
The hormone responsible for apical dominance is
Correct Answer
Option A
Solution
(a) IAA (indole-3-acetic acid) from the apical bud mediates apical dominance.
Q79
Apical dominance is caused by
Correct Answer
Option D
Solution
(d) Auxin produced in the shoot tip suppresses lateral bud growth (apical dominance).
Q80
Cytokinins help retain
Correct Answer
Option C
Solution
(c) Cytokinins delay senescence by retaining chlorophyll in leaves.
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