Biology
Plant Growth and Hormones
727 Questions
Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.
Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones
Plant Growth and Hormones Questions
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Growing stage
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Vegetative stage
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Dormant stage
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Flowering stage
D
Correct answer
Explanation
Jute is a natural plant fiber obtained from jute plant. Harvesting of jute plant is done at the flowering stage. Its stem is then immersed in water for the easy separation of jute fibers.
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action of gravity
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effect of light
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differential hormonal effect
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epinasty and hyponasty
B
Correct answer
Explanation
This option is correct because phototropism is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth which response to a light stimulus.
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auxins
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enzymes
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cytokinin
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gibberellic acid
A
Correct answer
Explanation
This option is correct because auxins are a class of plant growth substances and morphogens (often called phytohormone or hormone). Auxins have an essential role in coordination of many growth and behavioural processes in the plant's life cycle.
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tropism
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habit
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climatic response
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none of these
A
Correct answer
Explanation
This option is correct because movement of plant in response to an external stimulus is known as tropism. One of this stimulus can be a source of light to which the plants show response by bending. This process is known as phototropism.
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heliotropism
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hydrotropism
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phototropism
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geotropism
D
Correct answer
Explanation
This option is correct because geotropism is the movement of plant growth in response to the direction and force of gravity.
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A plant disease
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A plant hormone present in leaves
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A red pigment in flowers
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A plant hormone present in flowers
B
Correct answer
Explanation
Florigen is a hormone produced in response to vernalisation in leaves.
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phytochromes
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cryptochromes
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gibberellins
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cytokinins
B
Correct answer
Explanation
Cryptochromes are blue light photoreceptor cells and regulate many plant responses like germination and photoperiodism.
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Gibberellin
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Auxin
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Cytokinin
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Abscisic acid
C
Correct answer
Explanation
Cytokinin is a group of plant hormones which is mainly responsible for cell division in roots and shoots.
B
Correct answer
Explanation
Gibberellic acids promote linear growth. This is called ‘bolting’.
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Shortening of genetically tall plants
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Rooting in stem cutting
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Elongation of genetically dwarf plants
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Yellowing of young leaves
C
Correct answer
Explanation
Gibberellic acid stimulates internodal growth due to which dwarf plants are able to overcome their dwarfness.
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phototropism
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geotropism
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hydrotropism
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atropism
A
Correct answer
Explanation
Phototropism is the growth of an organism in response to a light stimulus, commonly observed in plant shoots growing toward a light source.
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Auxins
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Cytokinins
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Gibberellins
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Abscisic acid
C
Correct answer
Explanation
Gibberellins are involved in the delaying of leaf senescence.
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Due to phototaxis
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Due to increase in auxin in its shaded area
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Due to presence of cells on the illuminated side
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Due to presence of gibberellin
B
Correct answer
Explanation
Shoot of a plant bends towards light due to increase in auxin in the shaded area.
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roots
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stem
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fruit
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lateral bud
A
Correct answer
Explanation
Indole acetic acid helps in the formation of roots.
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Indole-3-butyric acid, Indole-3-acetic acid, 1-Naphthaleneacetic acid
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N6-furfuryladenine, zeatin, benzyl adenine
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N6-furfuryladenine, Indole-3-butyric acid, Indole-3-acetic acid
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N6-furfuryladenine, zeatin, Indole-3-butyric acid
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Zeatin, Indole-3-butyric acid, 1-Naphthaleneacetic acid
B
Correct answer
Explanation
Kinetin (N6-furfuryladenine) is a type of cytokinin, a class of plant hormone that promotes cell division.
Zeatin is a plant hormone derived from the purine adenine. It is a member of the plant growth hormone family known as cytokinins.
Benzyl adenine or 6-Benzylaminopurine (BAP) is a first-generation synthetic cytokinin that elicits plant growth and development responses, setting blossoms and stimulating fruit richness by stimulating cell division.