Biology

Plant Growth and Hormones

727 Questions

Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.

Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones

Plant Growth and Hormones Questions

Multiple choice evs whose forests? improved methods of agriculture cropping patterns food for all conservation of forest and wildlife wildlife deforestation and conservation

Farmer is interested in increasing yield of sugarcane by increasing its height which growth hormone would you suggest to achieve his goal?

  1. Auxin

  2. Cytokinin

  3. Gibberellin

  4. ABA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Auxins have a cardinal role in the coordination of many growths and behavioral processes in the plant's life cycle and are essential for plant body development. So the correct option is ' Auxin'.

Multiple choice biology control and coordination in living organisms enzymes and hormones hormones coordination in human beings- chemical control

For artificial ripening of fruit, which of the following is used?

  1. Testosterone

  2. Insulin

  3. Ethylene

  4. Estrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene gas is used for artificial ripening of fruits. Ethylene is also an important natural plant hormone, used to induce ripening process under controlled conditions of temperature. Ethylene treatment breaks down the green chlorophyll pigment in the exterior part of the peel and allows the yellow or orange carotenoid pigments to be expressed.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

The hormone that promotes anabolism and inhibits catabolism is the

  1. tri iodo Thyroxine

  2. auxins

  3. insulin

  4. morphactin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The hormone that promotes anabolism and inhibits catabolism is insulin.
Insulin is an anabolic hormone that promotes energy storage in the form of glycogen, triglycerides and proteins. Thus, insulin promotes anabolism (building up of tissues) and inhibits catabolism (breaking down of tissues) in muscle, liver, and fat cells. It increases the rate of synthesis of glycogen, fatty acids, and proteins.

Multiple choice chemistry biomolecules enzymes and hormones hormones coordination in human beings- chemical control

Match the following.
        SET-A                                 SET-B
Type of hormone               Name of hormone
1) Steroid hormone            a) Cytokinins
2) Non Steroid                   b) Estrogens
3) Plant hormone               c) Auxins
4) Peptide hormone           d) Insulin

  1. 1-b, 2-b, 3-c, 4-d

  2. 1-b, 2-a, 3-d, 4-c

  3. 1-b, 2-a,d 3-a,c, 4-d

  4. 1-c, 2-a, 3-d, 4-b
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Estrogens are steroidal hormones. They contain steroid (cholesterol) nucleus in their structure.

Cytokinins and Insulin are non steroidal hormones. They do not contain steroid (cholesterol) nucleus in their structure.

Cytokinins and Auxins are plant hormones. Auxins play vital role in several growth and behavioral processes in the plant's life cycle and are essential for plant body development.

Insulin is a peptide hormone. It affect the properties of plasma membrane. It is secreted in pancreatic islets. It controls carbohydrate metabolism and maintains glucose level in the blood.

1-b 
2-a,d
3-a,c 
4-d
Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Which one is paired incorrectly?

  1. Auxin - Isolated from human urine

  2. Zeatin - Isolated from corn kernels and coconut milk

  3. Gibberellins - Isolated from fungus G. fujikori

  4. Abscisic acid - Isolated from ripened oranges
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Kogl et al. (1931) isolated auxin from human urine called heteroauxin which was identified as indole-3-acetic acid (IAA).
Zeatin is a cytokinin-like substance isolated and crystallised by Letham (1963-65) from milky endosperm of corn (Zea mays). It also occurs in coconut milk.
Yabuta and Sumiki (1938) isolated a chemical substance from the cultural filtrate of fungus Gibberella fujikuroi in crystalline form and named it gibberellic acid.
Cousins (1910) found that ripe oranges produced a volatile substance that hastened ripening of unriped bananas nearby. With the help of gas chromatography, it was found that the ripening causing volatile substance was ethylene.
So, the correct answer is 'Abscisic acid - Isolated from ripened oranges'.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

To speed up the malting process in brewing industry the growth hormone used is ____________.

  1. auxin

  2. gibberellin

  3. kinetin

  4. ethylene.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gibberellins are used to speed up the malting process in brewing industry. They increase the yield of malt from barley grains.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Read the given statements and identify the plant hormones X, Y and Z.
(i) Hormone Y suppresses flowering in mango and also promotes rapid internode/petiole elongation in deep water rice plants and hence helping leaves or upper part of shoot to remain above water.
(ii) Hormone X promotes root growth and root hair formation.
(ii) Hormone Z inhibits the seed germination, increases the tolerance of plant to various stresses, play important role in seed development maturation and dormancy.

  1. Y-ABA, X-Auxin, Z-GA
  2. Y-$C _2H _4$, X-Auxin, Z-GA
  3. Y-Auxin, X-$C _2H _4$, Z-GA

  4. Y-GA, X-auxin, Z-ABA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

i) Gibberilic Acid (GA) suppresses flowering in mango, GA$ _3$, it is applied periodically to mango plants in their 1-4 yrs of growth to inhibit flowering and promote vegetative growth. GA plays a role in internode elongation in submerged parts of the rice plant.

Auxin along with cytokinin promotes root growth and root hair formation.
ABA is a stress hormones, it protects the plant from unfavorable environmental conditions, by preventing seed germination (due to oxygen deficit, water stress etc).
So, the correct answer is 'Y-GA, X-auxin, Z-ABA'

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Read the given statements and select the option that is/are incorrect ones.


(i) Cytokinin is primarily concerned with cell division.
(ii) $C _2H _4$ breaks seed and bud dormancy.
(iii) ABA stimulates the opening of stomata.
(iv) $C _2H _4$ initiates germination in peanut seeds, sprouting of potato tubers.
(v) ABA is synergistic to GA.

  1. (i), (ii) and (iv)

  2. (iii) and (ii)

  3. (iii) and (v)

  4. (iv) and (v)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

ABA is regarded as the stress hormone or a growth inhibitor. In conditions of water stress ABA initiates closure of stomata to prevent water loss through transpiration. It is antagonistic to GA as the latter promotes seed germination,  while ABA prevents seed germination.

So, the correct answer is ' (iii) and (v)'

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Match the plant hormones listed in column I with their major role listed in column II and select the corret option from the codes given below.

Column I Column II
(A) Auxin (i) Fruit ripening
(B) Cytokinin (ii) Phototropism
(C) Abscisic acid (iii) Suppression of cell division
(D) Ethylene (iv) Stomatal opening and closing
(v) Growth of lateral buds


  1. A - (v), B - (iii), C - (iv), D - (ii)

  2. A - (iii), B - (ii), C - (iv), D - (i)

  3. A - (ii), B - (v), C - (iv), D - (i)

  4. A - (ii), B - (iv), C - (v), D - (iii)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(A) Auxin - (ii) Phototropism

(B) Cytokinin - (v) Growth of lateral buds

(C) Abscisic acid - (iv) Stomatal opening and closing

(D) Ethylene - (i) Fruit ripening

So, the correct answer is 'A - (ii), B - (v), C - (iv), D - (i)'.
Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

In plant tissue culture experiments, high auxin to cytokinin ratio favours .............. development and high cytokinin to auxin ratio favours .............. development.

  1. Root, shoot

  2. Shoot, root

  3. Root, root

  4. Shoot, shoot
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Callus is an unorganized, undifferentiated mass of diving cells formed during tissue culture which requires both auxins and cytokinins for its growth and differentiation. In callus, shoot regeneration is promoted by a cytokinin, such as BAP (Benzylaminopurine) and root regeneration is promoted by an auxin, such as NAA (Naphthalene acetic acid). Thus, shoot and root regenerations in callus are controlled by auxin-cytokinin balance. Usually, an excess of auxins promote root regeneration and that of cytokinins promote shoot regeneration.
So the correct option is 'root, shoot'.
Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Small cut pieces of soft stems are placed in growth medium with following plant hormone. Which combination of plant hormones will show the slowest growth? 

  1. Auxin+Cytokinin

  2. Gibberellins+Auxin

  3. Gibberellins+Cytokinin

  4. Abscisic Acid+Auxin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Abscisic acid is growth inhibiting hormone whereas auxin, gibberellin and cytokinin are growth promoting hormones. Options A,B, and C include all growth promoting hormones whereas option D includes both growth promoting and growth inhibiting hormones. Therefore, this combination of hormones will show slowest growth.

So option D is the correct answer.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Cytokinin and auxin are antagonistic in which of the following function?

  1. Cell division

  2. Phototropism

  3. Apical dominance

  4. Geotropism
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • The main function of Auxin is to promote stem elongation and inhibition of growth of lateral buds to maintain apical dominance.
  • It is produced in the stem tips, buds and root tips to promote growth and it also helps to repair wounds in plants.
  • The function of cytokinins is to increase the cell division by stimulating the process of mitosis which helps in plant growth and formation of shoots and buds.
  • Cytokinins promote sprouting of lateral buds and overcome apical dominance.
  • Cytokinin and auxin are antagonistic for apical dominance.
  • So the correct answer is 'Apical dominance'.
Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Which of the following plant hormones is not acidic in nature?

  1. Gibberellin

  2. Auxin

  3. Cytokinin

  4. ABA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gibberellins are diterpenoid acids, Auxins are indole derivatives (often acidic), and ABA (Abscisic acid) is acidic. Cytokinins are adenine derivatives and are generally basic or neutral in nature.