Plant Growth and Development – Plant Growth: NEET MCQs with Answers

12 free questions on Plant Growth and Development – Plant Growth for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Plant Growth: Phases of Plant growth and plant growth rate; Conditions of growth

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Question 1

Previous-year question
Consider the following statements on plant growth and development and choose the option in which all the statements are correct. [NEET 2025]
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.
  1. A, B, C only
  2. A, C, E only
  3. A, D, E only
  4. B, D, E only
Show answer
Answer: (A) A, B, C only
Explanation: Auxins induce parthenocarpy, e.g. in tomatoes (A correct); PGRs can be promoters or inhibitors of growth (B correct); and dedifferentiated cells divide and then redifferentiate, so dedifferentiation precedes redifferentiation (C correct). D is wrong as ABA is a growth inhibitor, and E is wrong because apical dominance inhibits the growth of lateral buds.

Question 2

Previous-year question
Which of the following statements is incorrect? [NEET (Manipur) 2023]
  1. The phase of cell elongation in plant cells is characterised by increased vacuolation.
  2. Cells in the meristematic phase of growth show abundant plasmodesmatal connections.
  3. Plant growth is generally determinate.
  4. Plant growth is measurable.
Show answer
Answer: (C) Plant growth is generally determinate.
Explanation: Plant growth is generally indeterminate (open), because meristems retain the capacity to divide throughout life. The other statements are correct: elongating cells show increased vacuolation, meristematic cells have abundant plasmodesmatal connections, and growth can be measured by parameters such as fresh/dry weight, length and area.

Question 3

Previous-year question
During which phase is the rate of growth the highest? [NEET 2020]
  1. Dormancy
  2. Log phase
  3. Lag phase
  4. Senescence
Show answer
Answer: (B) Log phase
Explanation: In the sigmoid growth curve, growth is slow in the initial lag phase, then rapid and exponential in the log (exponential) phase, before slowing in the stationary phase. Dormancy and senescence show little or no growth.

Question 4

Previous-year question
The typical growth curve in plants is [AIPMT 2015]
  1. linear
  2. stair-steps shaped
  3. parabolic
  4. sigmoid
Show answer
Answer: (D) sigmoid
Explanation: When growth is plotted against time, cells, tissues, organs and whole plants growing in a natural environment all give an S-shaped or sigmoid curve, consisting of a lag phase, an exponential phase and a stationary phase.

Question 5

Previous-year question
A few normal seedlings of tomato were kept in a dark room. After a few days they were found to have become white-coloured, like albinos. Which of the following terms will you use to describe them? [AIPMT 2014]
  1. Mutated
  2. Embolised
  3. Etiolated
  4. Defoliated
Show answer
Answer: (C) Etiolated
Explanation: Plants grown in complete darkness fail to synthesise chlorophyll and develop pale, spindly shoots with long internodes and small unexpanded leaves. This condition is called etiolation and it is reversed as soon as the plants are returned to light.

Question 6

Previous-year question
The opening of floral buds into flowers is a type of [AIPMT 2007]
  1. autonomic movement of locomotion
  2. autonomic movement of variation
  3. paratonic movement of growth
  4. autonomic movement of growth
Show answer
Answer: (D) autonomic movement of growth
Explanation: Opening of floral buds results from unequal growth of the upper and lower surfaces of the petals (epinasty), which is an internally controlled (autonomic) growth movement rather than a locomotory or variation movement.

Question 7

Previous-year question
The typical growth curve in plants is [AIPMT 2015]
  1. stair-steps shaped
  2. parabolic
  3. sigmoid
  4. linear
Show answer
Answer: (C) sigmoid
Explanation: The typical growth curve obtained in plants is sigmoid, or S-shaped. It is obtained under conditions of limited nutrient availability and has three major phases — the lag phase, the log (exponential) phase and the stationary phase.
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Question 8

Previous-year question
The process of growth is at its maximum during the [NEET (Sep.) 2020]
  1. lag phase
  2. senescence
  3. dormancy
  4. log phase
Show answer
Answer: (D) log phase
Explanation: Growth is maximum during the log (exponential) phase, because in this phase the growth rate of the cells gradually rises to a maximum. In exponential growth the initial increase is slow (lag phase) and only afterwards does it accelerate rapidly, before finally levelling off in the stationary phase.

Question 9

Previous-year question
The leaves of many grasses are able to fold and unfold because they [1988]
  1. possess specialised bulliform cells
  2. are very thin
  3. have parallel vascular bundles
  4. are isobilateral
Show answer
Answer: (A) possess specialised bulliform cells
Explanation: Bulliform or motor cells are large, empty, colourless cells in the upper epidermis of grass leaves. When they lose turgor under water stress the leaf rolls inward to reduce water loss, and it unfolds again when they regain turgor.

Question 10

Previous-year question
A klinostat is employed in the study of [1994]
  1. photosynthesis
  2. osmosis
  3. respiration
  4. growth movements
Show answer
Answer: (D) growth movements
Explanation: A klinostat slowly rotates a potted plant about a horizontal axis so that no side of the shoot or root is exposed to gravity for longer than another. This nullifies the unilateral gravitational stimulus and is used to demonstrate that geotropic curvature depends on a one-sided stimulus.

Question 11

Previous-year question
Which one increases in the absence of light? [1990]
  1. Elongation of internodes
  2. Uptake of minerals
  3. Ascent of sap
  4. Uptake of water
Show answer
Answer: (A) Elongation of internodes
Explanation: A plant kept in darkness becomes etiolated — its internodes elongate excessively, the stem remains pale and slender, and the leaves stay small and unexpanded. Light normally restrains stem elongation through phytochrome, so in its absence the inhibition is lifted and the shoot grows abnormally long in search of light.

Question 12

Previous-year question
Typical growth curve in plants is [AIPMT 2015]
  1. Linear
  2. Stair-steps shaped
  3. Parabolic
  4. Sigmoid
Show answer
Answer: (D) Sigmoid
Explanation: The typical growth curve in plants is sigmoid (S-shaped), with lag, log (exponential), and stationary phases --- characteristic of organisms growing in a natural environment.

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