Plant Growth and Development – Development: NEET MCQs with Answers

12 free questions on Plant Growth and Development – Development 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: Development: Sequence of developmental process in a plant cell

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Question 1

Previous-year question
What is the site of perception of the photoperiod necessary for the induction of flowering in plants? [NEET 2019]
  1. Lateral buds
  2. Pulvinus
  3. Shoot apex
  4. Leaves
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Answer: (D) Leaves
Explanation: The leaves contain the phytochrome that senses the duration of the light and dark periods. Once induced, they produce a floral stimulus that migrates to the shoot apex and brings about the change from vegetative to floral development.

Question 2

Previous-year question
Plants follow different pathways in response to the environment or phases of life to form different kinds of structures. This ability is called [NEET 2021]
  1. elasticity
  2. flexibility
  3. plasticity
  4. maturity
Show answer
Answer: (C) plasticity
Explanation: Plasticity is the ability of plants to follow different developmental pathways in response to environment or to their phase of life, thereby forming different kinds of structures. Examples include the heterophylly of cotton, buttercup, coriander and larkspur, where juvenile leaves differ in shape from mature ones. Plasticity may be intrinsic or extrinsic.

Question 3

Previous-year question
Which one of the following plants does not show plasticity? [NEET 2022]
  1. Coriander
  2. Buttercup
  3. Maize
  4. Cotton
Show answer
Answer: (C) Maize
Explanation: Heterophylly — the production of differently shaped leaves at the juvenile and mature phases — is an expression of plasticity, and it is seen in coriander, buttercup and cotton but not in maize. Plasticity is the ability of a plant to modify itself by forming different kinds of structures in response to its environment or its phase of life.

Question 4

Previous-year question
Geocarpic fruits are produced by [2001]
  1. groundnut
  2. onion
  3. carrot
  4. watermelon
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Answer: (A) groundnut
Explanation: After fertilisation the stalk of the groundnut flower elongates and bends downward, pushing the young ovary into the soil, where the pod matures underground. Fruits developing below the ground in this way are described as geocarpic.

Question 5

Previous-year question
The movement of the leaves of the sensitive plant, Mimosa pudica, is due to [2009]
  1. hydrotropism
  2. thermonasty
  3. chemonasty
  4. seismonasty
Show answer
Answer: (D) seismonasty
Explanation: A touch or shock causes a sudden loss of water from the cells on the lower side of the pulvinus at the base of each leaflet, so turgor falls and the leaflets fold within seconds. The response is independent of the direction of the stimulus, which makes it a nastic movement induced by shock, or seismonasty.

Question 6

Previous-year question
The coiling of garden pea tendrils around a support is an example of [2008]
  1. thigmotropism
  2. thigmotaxis
  3. thermotaxis
  4. thigmonasty
Show answer
Answer: (A) thigmotropism
Explanation: Contact with the support inhibits growth on the side that touches it while growth continues on the opposite side, so the tendril curves round the object. Because the response is a growth curvature directed by the position of the stimulus, it is a tropic movement — thigmotropism.

Question 7

Previous-year question
The opening of floral buds into flowers is a type of [2007]
  1. autonomic movement of growth
  2. autonomic movement of variation
  3. autonomic movement of locomotion
  4. paratonic movement of growth
Show answer
Answer: (A) autonomic movement of growth
Explanation: The unfolding of a flower bud results from unequal growth of the inner and outer faces of the perianth, and it proceeds from the plant's own internal rhythm rather than in response to any directional external stimulus. It is therefore an autonomic movement of growth, of the kind called nastic.
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Question 8

Previous-year question
Anthesis is a phenomenon that refers to [2004]
  1. development of the anther
  2. reception of pollen by the stigma
  3. opening of the flower bud
  4. formation of pollen
Show answer
Answer: (C) opening of the flower bud
Explanation: Anthesis is the opening of the flower bud, at which point the anthers dehisce and the flower becomes functional for pollination. The transfer of pollen to the stigma is pollination, and the formation of pollen within the anther is microsporogenesis.

Question 9

Previous-year question
What will be the effect on phytochrome in a plant subjected to continuous red light? [1995]
  1. Phytochrome synthesis increases
  2. The level of phytochrome decreases
  3. Destruction and synthesis of phytochrome remain in equilibrium
  4. Phytochrome is wholly converted to the Pr form
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Answer: (B) The level of phytochrome decreases
Explanation: Continuous red light drives the whole pool into the Pfr form, and Pfr is the labile form that is steadily degraded by the cell. With conversion running one way and destruction continuing, the total amount of phytochrome in the tissue falls.

Question 10

Previous-year question
The wavelength of light absorbed by the Pr form of phytochrome is [2008]
  1. 620 nm
  2. 680 nm
  3. 640 nm
  4. 720 nm
Show answer
Answer: (B) 680 nm
Explanation: Pr absorbs in the red region, with its maximum near 660 nanometres, and on doing so is converted into Pfr; Pfr in turn absorbs far-red light at about 730 nanometres and reverts to Pr. Of the values offered, 680 nanometres lies in the red band and is the intended answer.

Question 11

Previous-year question
A proteinaceous pigment that controls activities concerned with light is [2001]
  1. anthocyanin
  2. phytochrome
  3. carotenoids
  4. chlorophyll
Show answer
Answer: (B) phytochrome
Explanation: Phytochrome is a bluish-green chromoprotein consisting of a light-absorbing tetrapyrrole attached to a protein, and it regulates seed germination, stem elongation, leaf expansion and flowering. Chlorophyll and the carotenoids are photosynthetic pigments and anthocyanin is a vacuolar colouring matter.

Question 12

Previous-year question
The pigment that absorbs red and far-red light in plants is [1997]
  1. phytochrome
  2. xanthophyll
  3. carotene
  4. cytochrome
Show answer
Answer: (A) phytochrome
Explanation: Phytochrome exists in two interconvertible forms: Pr absorbs red light and is thereby converted to Pfr, while Pfr absorbs far-red light and reverts to Pr. Pfr is the physiologically active form, and the ratio of the two at the end of the dark period conveys the length of the night to the plant.

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