Biology
Plant Growth and Hormones
695 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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auxins
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gibberellins
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kinetin
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sugars
C
Correct answer
Explanation
The Richmond-Lang effect refers to the delay of senescence in detached leaves by the application of cytokinins. Kinetin is a well-known synthetic cytokinin.
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avena curvature test
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green leaf test
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dwarf maize test
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cell division test
A
Correct answer
Explanation
The Avena curvature test is the classic biological assay used to detect and quantify the presence of auxins based on the growth response of oat coleoptiles.
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vitamin
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kinetin
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gibberellins
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X-rays
C
Correct answer
Explanation
Gibberellins are plant hormones known for promoting stem elongation, which can overcome genetic dwarfism in certain plant varieties.
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for slowing down the ripening of apples
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for speeding up the ripening of fruits
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as a saturated hydrocarbon
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for retarding the ripening of tomatoes
B
Correct answer
Explanation
Ethylene is a gaseous plant hormone that promotes fruit ripening. It is commercially used to accelerate this process in harvested fruits.
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Benzylaminopurine
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Kinetin
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Zeatin
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Dihydrozeatin
A
Correct answer
Explanation
Common cytokinin of tissue culture is Benzylaminopurine.
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IAA
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2,4–D
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Gibberellic acid
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Zeatin
B
Correct answer
Explanation
2,4–D is a synthetic plant hormone. It is a synthetic auxin (plant hormone) and one of the most widely used herbicides in the world.
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Indole butyric acid
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Gibberellic acid
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Cytokinin
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Abscisic acid
C
Correct answer
Explanation
Cytokinins are known to delay senescence in leaf tissues and promote mitosis. Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary, having generally opposite effects.
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Auxin
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Gibberellic acid
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Cytokinin
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Abscisic acid
B
Correct answer
Explanation
Gibberellic acid is the hormone which promotes internodal elongation. It can stimulate rapid stem and root growth, induce mitotic division in the leaves of some plants and increase seed germination rate.
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spindle elongation
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polyploidy
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spindle formation
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mitosis
B
Correct answer
Explanation
Alkaloid obtained from 'Autumn crocus' is used to induce polyploidy.
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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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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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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.
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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.