Free Plant Growth Regulators MCQs with Answers
47 Plant Growth Regulators MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Plant growth regulators are chemical messengers that control growth, development and responses to the environment. The topic covers auxins, gibberellins, cytokinins, abscisic acid and ethylene, including cell elongation, apical dominance, tropisms, seed germination, dormancy, fruit ripening and leaf fall, with growth promoters distinguished from inhibitors.
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47 questions · page 2 of 3
- A. All leaves
- B. A few leaves
- C. All branches except one
- D. All floral bud except one
Explanation: Removing all floral buds except one is the correct method to promote the growth of larger chrysanthemum flowers.
Correct answer: All floral bud except one- A. 15.5 hours
- B. 9 hours
- C. 11 hours
- D. 13 hours
Explanation: Hyoscyamus, like many plants, has a specific photoperiod requirement known as the critical day length, which is the minimum daylight hours…
Correct answer: 15.5 hours- A. Hydrotropism
- B. Chemotropism
- C. Chemotactic
- D. Seismetactic
Explanation: Chemotropism: Chemotropism is the growth movement of a plant part towards or away from a chemical stimulus.
Correct answer: Chemotropism- A. Epinasty
- B. Thermonasty
- C. Photonasty
- D. Seismonasty
Explanation: Epinasty refers to the downward or outward bending or opening of flower buds or leaf buds.
Correct answer: Epinasty- A. Auxins
- B. Ethylene
- C. Abscisic acid
- D. Gibberellins
Explanation: Abscisic acid is a plant hormone that plays a crucial role in inducing and maintaining seed and bud dormancy.
Correct answer: Abscisic acid- A. geoannual rhythm
- B. lunar rhythm
- C. circadian rhythm
- D. tidal rhythm
Explanation: Circadian rhythms are intrinsic 24-hour cycles that affect physiological, mental, and behavioral functions in living organisms.
Correct answer: circadian rhythm- A. phytohormones
- B. Gibberllin
- C. auxins
- D. cytokinesis
Explanation: All plant hormones are collectively known as growth hormones. They include growth promoters, e.g., auxins, cytokinins, gibberellins, etc.
Correct answer: phytohormones- A. Triple response
- B. Sex expression
- C. Flower initiation
- D. Leaf, flower, and fruit fall
Explanation: Abscisic acid (ABA) is a plant hormone that plays a key role in inhibiting growth and promoting dormancy in plants.
Correct answer: Leaf, flower, and fruit fall- A. F.A.D
- B. Chlorophyll a
- C. I.A.A
- D. ABA
Explanation: The correct answer is I.A.A (Indole-3-acetic acid), which is an auxin, a class of plant hormones that are essential for cell elongation…
Correct answer: I.A.A30. Tobacco is a:
- A. Long day plant
- B. Short day plant
- C. Day-neutral plant
- D. Intermediate plant
Explanation: Tobacco is classified as a short-day plant. These plants require long periods of darkness and shorter daylight hours to initiate…
Correct answer: Short day plant- A. Gibberellic acid
- B. Indole acetic acid
- C. Flsrcen
- D. Ethylene gas
Explanation: Ethylene gas is known as the 'ripening hormone' because it initiates the ripening process in fruits.
Correct answer: Ethylene gas- A. An algae
- B. A fungus
- C. A bacterium
- D. A virus
Explanation: The correct answer is that gibberellins were first isolated from a fungus, specifically Gibberella fujikuroi.
Correct answer: A fungus- A. Apical buds
- B. Lateral buds
- C. Parthenocarpy
- D. Root growth
Explanation: Auxins are plant hormones that play a crucial role in regulating plant growth processes.
Correct answer: Lateral buds- A. Auxin
- B. Gibberellins
- C. Cytokinin
- D. Abscisic acid
Explanation: Leaf senescence is a degenerative process among which cellular organelles and biomolecules are broken down and resultant catabolites are…
Correct answer: Cytokinin- A. Flowers
- B. Flower-buds
- C. Leaves (CORRECT)
- D. Fruits
Explanation: Florigen is a plant hormone produced in the leaves. It acts as a long-distance signaling molecule that travels to the shoot apical…
Correct answer: Leaves (CORRECT)- A. Photoperiodism
- B. Vernalization
- C. Dormancy
- D. Phytochrome
Explanation: Seeds of some plants do not germinate even under favourable conditions. This is called dormancy. It is under endogenous control.
Correct answer: Dormancy- A. Leaf-tip
- B. Leaf-margin
- C. Leaf-base
- D. Middle-vein
Explanation: Pulvini may be present at the base or apex of the petiole, they consist of a core of vascular tissue within a flexible, bulky cylinder of…
Correct answer: Leaf-base- A. Photo-receptor
- B. Photo-taxis
- C. Photo-tropism
- D. Photo-Periodism
Explanation: Photoperiodism is the ability of plants and animals to measure environmental day length (photoperiod), typically by monitoring night…
Correct answer: Photo-Periodism- A. 2˚C
- B. 3˚C
- C. 4˚C
- D. 10˚C
Explanation: Vernalization requires an exposure to temperatures between 0-6 °C for several months.
Correct answer: 4˚C- A. Auxins
- B. Cytokinins
- C. Ethylene
- D. Gibberellins
Explanation: Gibberellin is a plant hormone regulating key processes in plants; many of them are of significant agricultural importance, such as seed…
Correct answer: Gibberellins