Growth is an irreversible, permanent increase in size — of a cell, an organ, or the whole plant — commonly measured as an increase in fresh weight, dry weight, length, area, volume, or cell number. Unlike animals, most plants show indeterminate (open) growth — they retain the ability to form new cells and organs throughout life because of persistent meristems at the root and shoot apic
Plant Growth and Development
Class 1121 previous-year questions from this chapter every option and the correct answer, free · where the marks are
1. Phases of growth and differentiation
Exam focus: Growth plotted against time gives a sigmoid curve, not a straight line — a slow lag phase, a rapid exponential phase, then a stationary phase as the growth rate itself declines — and NEET's graph questions usually just want the segment named correctly.
Plant Growth and Development — Full Chapter
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Chapter one-shot covering growth phases/rates, differentiation, development, plasticity and plant hormones — a complete-chapter lecture that covers growth phases and differentiation directly rather than in isolation.
BotanyNEET 2024show ▾Formation of interfascicular cambium from fully developed parenchyma cells is an example of:
- A.Redifferentiation
- B.Dedifferentiation✓
- C.Maturation
- D.Differentiation
Solution
Mature parenchyma cells regaining the ability to divide and form interfascicular cambium is dedifferentiation; the cambium later redifferentiating into secondary tissues is redifferentiation.
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Save for spaced revision (free account)BotanyNEET 2024show ▾The capacity to generate a whole plant from any cell of the plant is called:
- A.Micropropagation
- B.Differentiation
- C.Somatic hybridisation
- D.Totipotency✓
Solution
The capacity of any plant cell to regenerate a whole plant is totipotency, the basis of tissue culture.
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Save for spaced revision (free account)BotanyNEET 2024show ▾Which of the following are fused in somatic hybridisation involving two varieties of plants?
- A.Somatic embryos
- B.Protoplasts✓
- C.Pollens
- D.Callus
Solution
Somatic hybridisation fuses protoplasts (cells stripped of their walls) from two different varieties or species, e.g. the pomato.
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Save for spaced revision (free account)BotanyNEET 2023show ▾In tissue culture experiments, leaf mesophyll cells are put in a culture medium to form a callus. This phenomenon may be called:
- A.Differentiation
- B.Dedifferentiation✓
- C.Development
- D.Senescence
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BotanyNEET 2022show ▾Which one of the following plants does not show plasticity?
- A.Maize✓
- B.Cotton
- C.Coriander
- D.Buttercup
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BotanyNEET 2021show ▾Plants follow different pathways in response to the environment or phases of life to form different kinds of structures. This ability is called:
- A.Elasticity
- B.Flexibility
- C.Plasticity✓
- D.Maturity
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BotanyNEET 2020show ▾The process of growth is maximum during:
- A.Log phase✓
- B.Lag phase
- C.Senescence
- D.Dormancy
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BotanyNEET 2019show ▾What is the site of perception of the photoperiod necessary for induction of flowering in plants?
- A.Lateral buds
- B.Pulvinus
- C.Shoot apex
- D.Leaves✓
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2. Plant growth regulators: auxin, gibberellin, cytokinin, ethylene, ABA
Exam focus: Auxin's apical dominance is a genuine paradox worth remembering: the same hormone that drives elongation at the shoot apex simultaneously suppresses the lateral buds below it, so it's removing the apex — not adding more auxin — that finally lets the laterals grow.
Plant Hormones: Auxin, Gibberellin, Cytokinin, Ethylene, ABA
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All five hormone classes in one lecture, each paired with the physiological effect NEET expects you to match it to.
BotanyNEET 2025show ▾Which one of the following phytohormones promotes nutrient mobilisation, which helps in the delay of leaf senescence in plants?
- A.Ethylene
- B.Abscisic acid
- C.Gibberellin
- D.Cytokinin✓
Solution
Cytokinins promote nutrient mobilisation and so delay leaf senescence; ethylene and abscisic acid promote senescence.
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Save for spaced revision (free account)ZoologyNEET 2025show ▾Read the following statements on plant growth and development.
(A) Parthenocarpy can be induced by auxins.
(B) Plant growth regulators can be involved in the promotion as well as the inhibition of growth.
(C) Dedifferentiation is a pre-requisite for redifferentiation.
(D) Abscisic acid is a plant growth promoter.
(E) Apical dominance promotes the growth of lateral buds.
Choose the option with all correct statements:
- A.A, B, C only✓
- B.A, C, E only
- C.A, D, E only
- D.B, D, E only
Solution
Auxins induce parthenocarpy (A); growth regulators can promote or inhibit growth (B); cells must dedifferentiate before they can redifferentiate (C). Abscisic acid is a growth inhibitor, and apical dominance suppresses lateral buds. Hence A, B and C.
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Save for spaced revision (free account)BotanyNEET 2024show ▾Auxin is used by gardeners to prepare weed-free lawns. But no damage is caused to grass, as auxin:
- A.promotes abscission of mature leaves only.
- B.does not affect mature monocotyledonous plants.✓
- C.can help in cell division in grasses, to produce growth.
- D.promotes apical dominance.
Solution
2,4-D and other synthetic auxins kill dicot weeds but leave mature monocots such as grasses unaffected, which is why they are used to keep lawns weed-free.
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Save for spaced revision (free account)BotanyNEET 2024show ▾Spraying a sugarcane crop with which of the following plant growth regulators increases the length of the stem, thus increasing the yield?
- A.Gibberellin✓
- B.Cytokinin
- C.Abscisic acid
- D.Auxin
Solution
Gibberellin sprayed on sugarcane increases internode length, so the stem — where sugar is stored — grows longer and yield rises.
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Save for spaced revision (free account)BotanyNEET 2023show ▾Spraying which of the following phytohormones on juvenile conifers helps hasten the maturity period, leading to early seed production?
- A.Indole-3-butyric acid
- B.Gibberellic acid✓
- C.Zeatin
- D.Abscisic acid
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BotanyNEET 2023show ▾Which hormone promotes internode/petiole elongation in deep-water rice?
- A.
- B.Kinetin
- C.Ethylene✓
- D.2,4-D
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BotanyNEET 2022show ▾The gaseous plant growth regulator is used in plants to:
- A.Kill dicotyledonous weeds in the fields
- B.Speed up the malting process
- C.Promote root growth and root hair formation to increase the absorption surface✓
- D.Help overcome apical dominance
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BotanyNEET 2022show ▾Production of cucumber has increased manifold in recent years. Application of which of the following phytohormones has resulted in this increased yield, as the hormone is known to produce female flowers in the plants?
- A.Cytokinin
- B.ABA
- C.Gibberellin
- D.Ethylene✓
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BotanyNEET 2021show ▾The plant hormone used to destroy weeds in a field is:
- A.IAA
- B.NAA
- C.2,4-D✓
- D.IBA
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BotanyNEET 2021show ▾The site of perception of light in plants during photoperiodism is the:
- A.Shoot apex
- B.Stem
- C.Axillary bud
- D.Leaf✓
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BotanyNEET 2020show ▾Which of the following is not an inhibitory substance governing seed dormancy?
- A.Gibberellic acid✓
- B.Abscisic acid
- C.Phenolic acid
- D.Para-ascorbic acid
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BotanyNEET 2020show ▾Name the plant growth regulator which, upon spraying on a sugarcane crop, increases the length of the stem, thus increasing the yield of the sugarcane crop.
- A.Cytokinin
- B.Gibberellin✓
- C.Ethylene
- D.Abscisic acid
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BotanyNEET 2019show ▾It takes a very long time for pineapple plants to produce flowers. Which combination of hormones can be applied to artificially induce flowering in pineapple plants throughout the year, to increase yield?
- A.Auxin and ethylene✓
- B.Gibberellin and cytokinin
- C.Gibberellin and abscisic acid
- D.Cytokinin and abscisic acid
The worked solution is part of a paid pack.