NEET Plant Growth and Development PYQs & Practice Questions

10 free NEET Biology questions on Plant Growth and Development, starting with previous year questions (2016–2026). Tap “Show answer” to check each one. No login needed.

Topics: Role of Ethylene in Fruit Ripening · Natural Source of Cytokinin · Overcoming Apical Dominance · Storage of Fruits · Parameters of Growth · Synergistic Action of Hormones · Plasticity in Plant Growth · Hormonal Use in Sugarcane Cultivation · Hormonal Antagonism - ABA and GA · Monocarpic Plants · Perception of Photoperiod · Auxin Herbicide - Selective Action on Dicot Weeds

1. Q1NEET 2026Arithmetic Growth Rate

   Length of the stem at time 0 is 20 cm. The arithmetic growth rate is 30 cm per day. What is the length of the stem at the end of the 7th day?

   • A. 170 cm
   • B. 230 cm
   • C. 460 cm
   • D. 50 cm
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   Answer: A — 170 cm

   For arithmetic growth, Length at time t = L0 + (growth rate × t) = 20 + (30 × 7) = 20 + 210 = 230 cm.

2. Q2NEET 2026Gibberellins - Physiological Effects

   Which of the following plant growth regulators promotes internode elongation prior to flowering in cabbage?

   • A. Gibberellin
   • B. Indole butyric acid
   • C. Ethephon
   • D. Abscisic acid
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   Answer: —

   Gibberellins are well known for causing a marked increase in internode elongation (bolting) prior to flowering in rosette plants such as cabbage.

3. Q3NEET 2026Synthetic Auxins as Herbicides

   Which of the following plant growth regulators is used as herbicide?

   • A. Kinetin
   • B. Abscisic acid
   • C. Gibberellin
   • D. 2,4-D
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   Answer: C — Gibberellin

   2,4-Dichlorophenoxyacetic acid (2,4-D) is a synthetic auxin widely used as a selective herbicide to kill broad-leaved weeds (dicots) without affecting monocot crops like cereals.

4. Q4NEET 2025Phytohormones - Cytokinin Function

   Which one of the following phytohormones promotes nutrient mobilization which helps in the delay of leaf senescence in plants?

   • A. Ethylene
   • B. Abscisic acid
   • C. Gibberellin
   • D. Cytokinin
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   Answer: C — Gibberellin

   Cytokinins help overcome apical dominance and promote nutrient mobilization, which helps delay leaf senescence.

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5. Q5NEET 2025Plant Growth Regulators - True Statements

   Read the following statements on plant growth and development. A. Parthenocarpy can be induced by auxins. B. Plant growth regulators can be involved in promotion as well as inhibition of growth. C. Dedifferentiation is a pre-requisite for re-differentiation. D. Abscisic acid is a plant growth promoter. E. Apical dominance promotes the growth of lateral buds. Choose the options with all correct statements.

   • A. A,B,C Only
   • B. A,C,E Only
   • C. A,D,E Only
   • D. B,D,E Only
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   Answer: —

   Parthenocarpy can be induced by auxins (A, correct). Growth regulators like auxins, gibberellins, cytokinins are promoters, while ABA is an inhibitor - so PGRs are involved in both promotion and inhibition (B, correct). Dedifferentiation (cell division forming new cells) is a pre-requisite for redifferentiation into permanent tissues (C, correct). Abscisic acid is a growth inhibitor, not promoter (D, incorrect). Apical dominance suppresses (not promotes) the growth of lateral buds (E, incorrect). So A, B, C Only.

6. Q6NEET 2024Auxin Herbicide - Selective Action on Dicot Weeds

   Auxin is used by gardeners to prepare weed-free lawns. But no damage is caused to grass as auxin

   • A. Does not affect mature monocotyledonous plants.
   • B. Can help in cell division in grasses, to produce growth
   • C. Promotes apical dominance
   • D. Promotes abscission of mature leaves only
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   Answer: —

   Synthetic auxins like 2,4-D are used as selective herbicides because they do not affect mature monocotyledonous plants (grasses) but kill broad-leaved dicot weeds. 11th NCERT Page No. 176.

7. Q7NEET 2024Plant Growth Regulators - Gibberellin

   Spraying sugarcane crop with which of the following plant growth regulators, increases the length of stem, thus, increasing the yield?

   • A. Cytokinin
   • B. Abscisic acid
   • C. Auxin
   • D. Gibberellin
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   Answer: C — Auxin

   Gibberellins promote stem elongation. Spraying sugarcane crop with gibberellins increases the length of the stem, which directly increases the commercial yield of sugarcane as the stem is the harvested product.

8. Q8NEET 2023Role of Ethylene

   Which hormone promotes internode/petiole elongation in deep water rice?

   • A. Kinetin
   • B. Ethylene
   • C. 2,4-D
   • D. GA3
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   Answer: A — Kinetin

   Ethylene promotes rapid internode/petiole elongation in deep water rice plants, helping them keep pace with rising flood water levels.

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9. Q9NEET 2023Dedifferentiation

   In tissue culture experiments, leaf mesophyll cells are put in a culture medium to form callus. This phenomenon may be called as:

   • A. Dedifferentiation
   • B. Development
   • C. Senescence
   • D. Differentiation
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   Answer: —

   Dedifferentiation is the phenomenon where living differentiated cells (like leaf mesophyll cells) regain the capacity to divide under appropriate conditions, forming a mass of undifferentiated cells (callus).

10. Q10NEET 2023Gibberellins - Effect on Conifers

    Spraying of which of the following phytohormone on juvenile conifers helps in hastening the maturity period, that leads to early seed production?

    • A. Gibberellic Acid
    • B. Zeatin
    • C. Abscisic Acid
    • D. Indole-3-butyric Acid
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    Answer: —

    Spraying gibberellic acid (GA3) on juvenile conifers hastens maturity and leads to early seed production, a well-documented commercial application of gibberellins.