Q21
Tendrils twining is due to
Correct Answer
Option A
Solution
(a) Tendrils coil around supports due to thigmotropism.
Plant Growth and Development
Q22
Flowering dependent on cold treatment is
Correct Answer
Option D
Solution
(d) Vernalisation = induction of flowering by cold treatment.
Q23
Movement of auxin is
Correct Answer
Option D
Solution
(d) Auxin moves basipetally in shoots and acropetally in roots.
Q24
Ethylene gas is used for
Correct Answer
Option C
Solution
(c) Ethylene promotes fruit ripening.
Q25
A chemical believed to be involved in flowering is
Correct Answer
Option C
Solution
(c) Florigen (proposed by Chailakhyan) is the hypothetical flowering hormone.
Q26
The method that renders the seed coat permeable to water so that embryo expansion is not physically retarded is
Correct Answer
Option D
Solution
(d) Scarification breaks seed coat barriers (mechanical or chemical) to allow water entry.
Q27
Proteinaceous pigment which controls activities concerned with light is
Correct Answer
Option A
Solution
(a) Phytochrome is the photoreceptor protein pigment that controls photoperiodic and other light-mediated responses.
Q28
Which one is a long-day plant?
Correct Answer
Option D
Solution
(d) Spinach is a long-day plant; it flowers when days exceed a critical length.
Q29
The pigment that absorbs red and far red light in plants is
Correct Answer
Option C
Solution
(c) Phytochrome absorbs red (660 nm) and far-red (730 nm) light.
Q30
One set of a plant was grown at 12h day/12h night and flowered; when night phase was interrupted by light it did not flower. This plant is a
Correct Answer
Option D
Solution
(d) Short day plants require an uninterrupted dark period; light interruption prevents flowering.
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