Question 1: Palette 1/77

NEET 2026 MCQ

Which one of the following is not a characteristic of plant cells in the phase of elongation?

A

New cell wall deposition

B

Cell enlargement

C

Increased vacuolation

D

Large conspicuous nuclei

Question 2: Palette 2/77

NEET 2026 MCQ

$ \text { Match List-I with List-II } $

List-I (Growth Regulator)		List-II (Function/Effect)
A.	$ \text { 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

Question 3: Palette 3/77

NEET 2026 MCQ

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

A

Redifferentiation

B

Elasticity

C

Dedifferentiation

D

Plasticity

Question 4: Palette 4/77

NEET 2026 MCQ

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

A

Ethephon

B

Abscisic acid

C

Gibberellin

D

Indole butyric acid

Question 5: Palette 5/77

NEET 2026 MCQ

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

A

Gibberellin

B

$2,4-\mathrm{D}$

C

Kinetin

D

Abscisic acid

Question 6: Palette 6/77

NEET 2026 MCQ

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 $7^{\text {th }}$ day?

A

460 cm

B

50 cm

C

170 cm

D

230 cm

Question 7: Palette 7/77

NEET 2025 MCQ

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 option with all correct statements.

A

A, D, E only

B

B, D, E only

C

A, B, C only

D

A, C, E only

Question 8: Palette 8/77

NEET 2025 MCQ

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

A

Gibberellin

B

Cytokinin

C

Ethylene

D

Abscisic acid

Question 9: Palette 9/77

NEET 2024 MCQ

Match List-I with List-II :

	List - I		List - II
(A)	Abscisic acid	(I)	Promotes female flowers in cucumber
(B)	Ethylene	(II)	Helps seeds to withstand desiccation
(C)	Gibberellin	(III)	Helps in nutrient mobilisation
(D)	Cytokinin	(IV)	Promotes bolting in beet, cabbage etc.

Choose the correct answer from the options given below:

A

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

B

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

C

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

D

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

Question 10: Palette 10/77

NEET 2024 MCQ

F. Skoog observed that callus proliferated from the internodal segments of tobacco stem when auxin was supplied with one of the following except :

A

Extract of Vascular tissues

B

Coconut milk

C

Abscisic acid

D

Yeast Extract

Question 11: Palette 11/77

NEET 2024 MCQ

Given below are some statements about plant growth regulators.

A. All GAs are acidic in nature.

B. Auxins are antagonists to GAs.

C. Zeatin was isolated from coconut milk.

D. Ethylene induces flowering in Mango.

E. Abscisic acid induces parthenocarpy.

Choose the correct set of statements from the options given below :

A

A, C, D

B

B, E

C

A, B, C

D

B, D, E

Question 12: Palette 12/77

NEET 2024 MCQ

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

A

promotes apical dominance.

B

promotes abscission of mature leaves only.

C

does not affect mature monocotyledonous plants.

D

can help in cell division in grasses, to produce growth.

Question 13: Palette 13/77

NEET 2024 MCQ

Formation of interfascicular cambium from fully developed parenchyma cells is an example for

A

Differentiation

B

Redifferentiation

C

Dedifferentiation

D

Maturation

Question 14: Palette 14/77

NEET 2024 MCQ

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

A

Auxin

B

Gibberellin

C

Cytokinin

D

Abscisic acid

Question 15: Palette 15/77

NEET 2023 MCQ

The phenomenon which is influenced by auxin and also played a major role in its discovery :

A

Phototropism

B

Root initiation

C

Gravitropism

D

Apical Dominance

Question 16: Palette 16/77

NEET 2023 MCQ

Match List - I with List - II.

	List - I		List - II
(A)	Auxin	(I)	Promotes female flower formation in cucumber
(B)	Gibberellin	(II)	Overcoming apical dominance
(C)	Cytokinin	(III)	Increase in the length of grape stalks
(D)	Ethylene	(IV)	Promotes flowering in pineapple

Choose the correct answer from the options given below :

A

(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

B

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

C

(A)-(I), (B)-(III), (C)-(IV), (D)-(II)

D

(A)-(III), (B)-(II), (C)-(I), (D)-(IV)

Question 17: Palette 17/77

NEET 2023 MCQ

Which of the following statements is not correct ?

A

Phase of cell elongation of plant cells is characterized by increased vacuolation.

B

Cells in the meristematic phase of growth exhibit abundant plasmodesmatal connections.

C

Plant growth is generally determinate.

D

Plant growth is measurable.

Question 18: Palette 18/77

NEET 2023 MCQ

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

A

Gibberellic Acid

B

Zeatin

C

Abscisic Acid

D

Indole-3-butyric Acid

Question 19: Palette 19/77

NEET 2023 MCQ

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

A

Kinetin

B

Ethylene

C

2, 4-D

D

GA₃

Question 20: Palette 20/77

NEET 2022 MCQ

The ability of plants to follow different pathways in response to environment leading to formation of different kinds of structures is called

A

Differentiation

B

Redifferentiation

C

Development

D

Plasticity

Question 21: Palette 21/77

NEET 2022 MCQ

Which of the following growth regulators is an adenine derivative?

A

Abscisic acid

B

Auxin

C

Cytokinin

D

Ethylene

Question 22: Palette 22/77

NEET 2022 MCQ

Which one of the following plants does not show plasticity?

A

Cotton

B

Coriander

C

Buttercup

D

Maize

Question 23: Palette 23/77

NEET 2022 MCQ

The gaseous plant growth regulator is used in plants to:

A

speed up the malting process

B

promote root growth and roothair formation to increase the absorption surface

C

help overcome apical dominance

D

kill dicotyledonous weeds in the fields

Question 24: Palette 24/77

NEET 2022 MCQ

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

ABA

B

Gibberellin

C

Ethylene

D

Cytokinin

Question 25: Palette 25/77

NEET 2021 MCQ

Plants follow different pathways in response to environment of phases of life to form different kinds of structures. This ability is called

A

Maturity

B

Elasticity

C

Flexibility

D

Plasticity

Question 26: Palette 26/77

NEET 2021 MCQ

The site of perception of light in plants during photoperiodism is

A

Leaf

B

Shoot apex

C

Stem

D

Axillary bud

Question 27: Palette 27/77

NEET 2021 MCQ

The plant hormone used to destroy weeds in a field

A

IBA

B

IAA

C

NAA

D

2, 4-D

Question 28: Palette 28/77

NEET 2020 MCQ

Which of the following is not an inhibitory substance governing seed dormancy?

A

Para-ascorbic acid

B

Abscisic acid

C

Gibberellic acid

D

Phenolic acid

Question 29: Palette 29/77

NEET 2020 MCQ

Name the plant growth regulator which upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop

A

Abscisic acid

B

Cytokinin

C

Gibberellin

D

Ethylene

Question 30: Palette 30/77

NEET 2019 MCQ

What is the site of perception of photoperiod necessary for induction of flowering in plants?

A

Shoot apex

B

Leaves

C

Lateral buds

D

Pulvinus

Question 31: Palette 31/77

NEET 2017 MCQ

Fruit and leaf drop at early stages can be prevented by the application of

A

ethylene

B

auxins

C

gibberellic acid

D

cytokinins.

Question 32: Palette 32/77

NEET 2016 MCQ

You are given a tissue with its potential for differentiation in an artificial culture. Which of the following pairs of hormones would you add to the medium to secure shoots as well as roots?

A

IAA and gibberellin

B

Auxin and cytokinin

C

Auxin and abscisic acid

D

Gibberellin and abscisic acid

Question 33: Palette 33/77

NEET 2016 MCQ

Phytochrome is a

A

flavoprotein

B

glycoprotein

C

lipoprotein

D

chromoprotein

Question 34: Palette 34/77

NEET 2016 MCQ

The Avena curvature is used for bioassay of

A

IAA

B

ethylene

C

ABA

D

GA₃.

Question 35: Palette 35/77

NEET 2015 MCQ

Auxin can be bioassayed by

A

potometer

B

lettuce hypocotyl elongation

C

Avena coleoptile curvature

D

hydroponics.

Question 36: Palette 36/77

NEET 2015 MCQ

What causes a green plant exposed to the light, on only one side, to bend towards the source of light as it grows?

A

Light stimulates plant cells on the lighted side to grow faster.

B

Auxin accumulates on the shaded side, stimulating greater cell elongation there.

C

Green plants need light to perform photosynthesis.

D

Green plants seek light because they are photoreopic.

Question 37: Palette 37/77

NEET 2015 MCQ

Typical growth curve in plants is

A

stair-steps shaped

B

parabolic

C

sigmoid

D

linear.

Question 38: Palette 38/77

NEET 2014 MCQ

Which one of the following growth regulators is known as 'stress hormone'?

A

Abscisic acid

B

Ethylene

C

GA₃

D

Indole acetic acid

Question 39: Palette 39/77

NEET 2014 MCQ

Dr. F. went noted that if coleoptile tips were removed and placed on agar for one hour, the agar would produce a bending when placed on one side of freshly-cut coleoptile stumps. Of what significance is this experiment?

A

It made possible the isolation and exact identification of auxin.

B

It is the basis for quantitative determination of small amounts of growth-promoting substances.

C

It supports the hypothesis that 1AA is auxin.

D

It demonstrated polar movement of auxins.

Question 40: Palette 40/77

NEET 2014 MCQ

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?

A

Mutated

B

Embolised

C

Etiolated

D

Defoliated

Question 41: Palette 41/77

NEET 2013 MCQ

The pineapple which under natural condition is difficult to blossom has been made to produce fruits throughout the year by application of

A

NAA, 2, 4-D

B

Phenyl acetic acid

C

Cytokinin

D

IAA, IBA.

Question 42: Palette 42/77

NEET 2013 MCQ

During seed germination its stored food is mobilized by

A

ABA

B

gibberellin

C

ethylene

D

cytokinin.

Question 43: Palette 43/77

NEET 2012 MCQ

Vernalization simulates flowering in

A

zamikand

B

turmeric

C

carrot

D

ginger.

Question 44: Palette 44/77

NEET 2012 MCQ

Through their effects on plant growth regulators, what do the temperature and light control in the plants?

A

Apical dominance

B

flowering

C

Closure of stomata

D

Fruit elongation

Question 45: Palette 45/77

NEET 2012 MCQ

Which one of the following generally acts as an antagonist to gibberellins?

A

Zeatin

B

Ethylene

C

ABA

D

IAA

Question 46: Palette 46/77

NEET 2010 MCQ

One of the commonly used plant growth hormone in tea plantations is

A

ethylene

B

abscisic acid

C

Zeatin

D

indole-3-acetic acid.

Question 47: Palette 47/77

NEET 2010 MCQ

Root development is promoted by

A

abscisic acid

B

auxin

C

gibberellin

D

ethylene.

Question 48: Palette 48/77

NEET 2010 MCQ

Phototropic curvature is the result of uneven distribution of

A

gibberellin

B

phytochrome

C

cytokinins

D

auxin.

Question 49: Palette 49/77

NEET 2010 MCQ

Coiling of garden pea tendrils around any support is an example of

A

thigmotaxis

B

thigmonasty

C

thigmotropism

D

thermotaxis.

Question 50: Palette 50/77

NEET 2010 MCQ

Photoperiodism was first characterised in

A

tobacco

B

potato

C

tomato

D

cotton.

Question 51: Palette 51/77

NEET 2009 MCQ

Which one of the following acids is a derivative of carotenoids?

A

Indole-3-acetic acid

B

Gibberellic acid

C

Abscisic acid

D

Indole butyric acid

Question 52: Palette 52/77

NEET 2009 MCQ

One of the synthetic auxin is

A

IAA

B

GA

C

IBA

D

NAA

Question 53: Palette 53/77

NEET 2008 MCQ

Senescence as an active developmental cellular process in growth and functioning of a flowering plant, is indicated in

A

annul plants

B

floral parts

C

vessels and tracheid differentiation leaf abscission.

D

leaf abscission.

Question 54: Palette 54/77

NEET 2008 MCQ

Importance of day length in flowering of plants was first shown in

A

cotton

B

Petunia

C

Lemna

D

tobacco.

Question 55: Palette 55/77

NEET 2007 MCQ

Which one of the following pairs, is not correctly matched?

A

Gibberellic acid - Leaf fall

B

Cytokinin - Cell division

C

IAA - Cell wall elongation

D

Abscissic acid - Stomatal closure

Question 56: Palette 56/77

NEET 2007 MCQ

The wavelength of light absorbed by P_r form of phytochrome is

A

680 nm

B

720 nm

C

620 nm

D

640 nm.

Question 57: Palette 57/77

NEET 2007 MCQ

Opening of floral buds into flowers, is a type of

A

autonomic movement of variation

B

paratonic movement of growth

C

autonomic movement of growth

D

autonomic movement of locomotion.

Question 58: Palette 58/77

NEET 2006 MCQ

Treatment of seeds at low temperature under moist conditions to break its dormancy is called

A

stratification

B

scarification

C

vernalization

D

chelation.

Question 59: Palette 59/77

NEET 2006 MCQ

An enzyme that can stimulate germination of barley seeds is

A

invertase

B

$\alpha $-amylase

C

lipase

D

protease

Question 60: Palette 60/77

NEET 2006 MCQ

How does pruning help in making the hedge dense?

A

It releases wound hormones.

B

It induces the differentiation of new shoots from the rootstock.

C

It frees axillary buds from apical dominance.

D

The apical shoot grows faster after pruning.

Question 61: Palette 61/77

NEET 2006 MCQ

Farmers in a particular region were concerned that pre-mature yellowing of leaves of a pulse crop might cause decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield?

A

Application of iron and magnesium to promote synthesis of chlorophyll

B

Frequent irrigation of the crop

C

Treatment of the plants with cytokinins along with a small does of nitrogenous fertilizer

D

Removal of all yellow leaves and spraying the remaining green leaves with 2, 4, 5-trichlorophhenoxy acetic acid

Question 62: Palette 62/77

NEET 2005 MCQ

The ability of the Venus Flytrap to capture insects is due to

A

specialized ''muscle-like'' cells

B

chemical stimulation by the prey

C

a passive process requiring no special ability on the part of the plant

D

rapid turgor pressure changes.

Question 63: Palette 63/77

NEET 2004 MCQ

Cell elongation in internodal regions of the green plants takes place due to

A

indole acetic acid

B

cytokinins

C

gibberellins

D

ethylene.

Question 64: Palette 64/77

NEET 2004 MCQ

One set of the plant was grown at 12 hours day and 12 hours night period cycles and it flowered while in the other set night phase was interrupted by flash of light and it did not produce flower. Under which one of the following categories will you place this plant?

A

Long day

B

Darkness neutral

C

Day neutral

D

Short day

Question 65: Palette 65/77

NEET 2003 MCQ

Nicotiana sylvestris flowers only during long days and N.tabacum flowers only during short days. If raised in the laboratory under different photoperiods, they can be induced to flower at the same time and can be cross-fertilized to produce self-fertile offspring. What is the best reason for considering N.sylvestris and N.tabacum to be separate species?

A

They cannot interbreed in nature

B

They are reproductively distinct

C

They are physiologically distinct

D

They are morphologically distinct

Question 66: Palette 66/77

NEET 2003 MCQ

Plants deficient of element zinc, show its effect on the biosynthesis of plant growth hormone

A

auxin

B

cytokinin

C

ethylene

D

abscisic acid.

Question 67: Palette 67/77

NEET 2003 MCQ

Differentiation of shoot is controlled by

A

high auxin : cytokinin ratio

B

high cytokinin : auxin ratio

C

high gibberellin : auxin ration

D

high gibberellin : cytokinin ratio.

Question 68: Palette 68/77

NEET 2003 MCQ

Coconut milk factor is

A

abscisic acid

B

an auxin

C

a gibberellin

D

cytokinin

Question 69: Palette 69/77

NEET 2002 MCQ

Dwarfness can be controlled by treating the plant with

A

cytokinin

B

gibberellic acid

C

auxin

D

antigibberellin.

Question 70: Palette 70/77

NEET 2002 MCQ

Seed dormancy is due to the

A

ethylene

B

abscisic acid

C

IAA

D

starch.

Question 71: Palette 71/77

NEET 2001 MCQ

Hormone responsible for senescence is

A

ABA

B

auxin

C

GA

D

cytokinin

Question 72: Palette 72/77

NEET 2001 MCQ

Which of the following prevents the fall of fruits?

A

GA₃

B

NAA

C

Ethylene

D

Zeatin

Question 73: Palette 73/77

NEET 2001 MCQ

Which hormone breaks dormancy of potato tuber?

A

Gibberellin

B

IAA

C

ABA

D

Zeatin

Question 74: Palette 74/77

NEET 2001 MCQ

Which plant is LDP?

A

Tobacco

B

Glycine max

C

Mirabilis jalapa

D

Spinach

Question 75: Palette 75/77

NEET 2000 MCQ

If the apical bud has been removed then we observe

A

more lateral branches

B

more axillary buds

C

plant growing stops

D

flowering stops.

Question 76: Palette 76/77

NEET 2000 MCQ

By which action a seed coat becomes permeable to water

A

scarification

B

stratification

C

vernalization

D

all of the above.

Question 77: Palette 77/77

NEET 2000 MCQ

Which hormone is responsible for fruit ripening?

A

Ethylene

B

Auxin

C

Ethyl chloride

D

Cyctokinin