Plant Growth and Development — NEET UG practice

77 questions

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Sample questions with solutions

Q1 · 2026

Match List-I with List-II

List-I (Growth Regulator)	List-II (Function/Effect)
A. 2,4-D	I. Brewing industry
B. $\mathrm{GA}_3$	II. Stimulation of stomatal closure
C. Kinetin	III. Herbicide
D. ABA	IV. Nutrient mobilisation

Choose the correct answer from the options given below :

A.
A-III, B-I, C-IV, D-II
B.
A-IV, B-III, C-II, D-I
C.
A-I, B-IV, C-III, D-II
D.
A-I, B-II, C-IV, D-III

Answer: A

Match 2,4-D with its use: 2,4-D is a synthetic auxin widely sprayed on fields to kill broad-leaved weeds. So,

\text{2,4-D} \rightarrow \text{Herbicide (III)}

Match $\mathrm{GA}_3$ with its industrial use: gibberellic acid is used to speed up the malting process in the brewing industry by promoting amylase production in barley seeds. Therefore,

\mathrm{GA}_3 \rightarrow \text{Brewing industry (I)}

Match Kinetin with its physiological role: kinetin is a cytokinin that helps in mobilizing nutrients from other parts of the plant toward the site where it is applied, thereby delaying senescence. Hence,

\text{Kinetin} \rightarrow \text{Nutrient mobilisation (IV)}

Match ABA with its stress response role: abscisic acid increases in concentration during water stress and causes the closure of stomata to reduce water loss through transpiration. So,

\text{ABA} \rightarrow \text{Stimulation of stomatal closure (II)}

Hence, the correct matching is A-III, B-I, C-IV, D-II, so the answer is A.

Q2 · 2026

Heterophyllous development in response to environment is an example of which of the following phenomena?

A.
Redifferentiation
B.
Elasticity
C.
Dedifferentiation
D.
Plasticity

Answer: D

Understand heterophylly: heterophylly refers to a plant producing leaves of different shapes at different stages of development or under different environmental conditions — for example, in cotton, coriander, and larkspur, juvenile and adult leaves look completely different, and aquatic plants may show different leaf shapes above and below water.
Recognize the underlying concept: the ability of a plant to follow different developmental pathways depending on the environment or the stage of life it is in, forming different structures, is called plasticity. Given this,

\text{Heterophylly} \rightarrow \text{Plasticity}

Eliminate the other options: redifferentiation is when a dedifferentiated cell regains the ability to divide into a specialized structure; dedifferentiation is when mature, differentiated cells regain the capacity to divide; elasticity is not a term used to describe developmental flexibility in this context.

Hence, the correct answer is D. Plasticity.

Q3 · 2026

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

A.
Gibberellin
B.
$2,4-\mathrm{D}$
C.
Kinetin
D.
Abscisic acid

Answer: B

Understand what a herbicide does: a herbicide is a chemical used to selectively kill unwanted plants (weeds) without harming the desired crop.
Identify the synthetic auxin used for this purpose: among the auxin family, 2,4-D (2,4-dichlorophenoxyacetic acid) is an artificial auxin that is widely sprayed in fields to kill broad-leaved weeds (dicots) while leaving narrow-leaved monocot crops largely unaffected. So,

\text{2,4-D (synthetic auxin)} \rightarrow \text{Herbicide}

Eliminate the other options: Gibberellin promotes elongation and bolting; Kinetin is a cytokinin that promotes cell division and delays senescence; Abscisic acid is a stress hormone that promotes dormancy — none of these act as herbicides.

Hence, the correct answer is B. $2,4-\mathrm{D}$ .

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