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 biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Which one is growth regulator produced by plants?

  1. NAA

  2. Zeatin

  3. 2, 4-D

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

Naphthaleneacetic acid (NAA) is a type of synthetic auxin, plant hormone. It is a growth regulator. It acts as rooting agent. Zeatin a type of naturally occurring cytokinin, the plant hormone. It was first discovered in Zea maize. A 2, 4-D is a type of synthetic auxin, plant hormone. It acts as weedicide. BAP (Benzylaminopurine) is a type of synthetic cytokinin, a plant hormone. It is involved in various physiological processes of plants like cell division.

Thus, the correct answer is option B.

Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Cytokinins which have specific effect in cytokinesis are modified forms of

  1. Cytosine

  2. Adenine

  3. Guanine

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

Cytokinin is a plant hormone. It has the specific effect in cytokinesis in plants. It is modified form of adenine. Kinetin, zeatin, and 6-benzylaminopurine are adenine type cytokinins. It is adenine molecule that is modified by the addition of 5-carbon sidechains off the 6 position.

Thus, the correct answer is option B.

Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Plant hormones used for inducing morphogenesis in plant tissue culture is

  1. Gibberellins

  2. Ethylene

  3. Cytokinins

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

Morphogenesis is the process of development of shape of an organism. Cytokinins which is present at the site where rapid cell division occurs like root apices, developing shoot buds it helps in plant growth and attaining its shape. So it will help the plant to maintain its shape in tissue culture.

So the correct option is 'Cytokinins'.

Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

State whether the following statements are true or false.
The plant ageing process, senescence, is prevented by cytokinins.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cytokinin is a plant growth hormone that is basic in nature and is responsible for cell division. This results in cell elongation, growth, and development of plants, they work similar to auxins. Cytokinins are helpful in delaying and stopping the senescence of leaves thus resulting in the process of aging to stop by the mobilization of nutrients in the required part of the plant.

So, the correct statement is 'True'.

Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Cytokinins helps to produce all except

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral short growth and adventitious shoot formation

  4. Rooting on cut stem
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Cytokinins are plant hormones that cause increased cell division by stimulating the process of mitosis. They help in the production of new leaves, formation of chloroplasts in leaves, lateral shoot growth and adventitious shoot formation. They do not have any role in root formation. So, the correct option is 'Rooting on the cut stem'.

Multiple choice biology plant growth control of blood glucose hormones in human reproduction testes and ovary

Match the Column-I & Column-II.

(i) Auxin (A) Ripening of fruit
(ii) ABA (B) Bolting
(iii) Gibberellin (C) Sensitivity against adverse conditions
(iv) Ethephon (D) parthenocarpy in tomato

  1. i-C, ii-D, iii-B, iv-A

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

  3. i-D, ii-C, iii-B, iv-A

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

  • (i) Auxin - (D) parthenocarpy in tomato -Auxins are generally produced by the growing apices of the stems and roots, from where they migrate to the regions of their action. Auxins also induce parthenocarpy in
tomatoes. 
  • (ii) ABA - (C) Sensitivity against adverse conditions -ABA(Abscisic acid) acts as a general plant growth inhibitor and an inhibitor of plant metabolism.ABA regulates sensitivity against adverse conditions i.e ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kind of stresses. Therefore, it is also called the stress hormone.
  • (iii) Gibberellin - (B) Bolting -Gibberellins promotes bolting
(internode elongation just prior to flowering) in beet, cabbages and many
plants with rosette habit.
  • (iv) Ethephon - (A) Ripening of fruit - Ethephon in an aqueous solution is readily absorbed and transported within the plant and releases ethylene slowly. Ethephon hastens fruit ripening in tomatoes and apples.
  • So, the correct answer is 'i-D, ii-C, iii-B, iv-A'.

Multiple choice

Root developed by

  1. Auxin

  2. Ga

  3. Cytokinine

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

Auxin is the primary plant hormone responsible for root initiation and development, particularly adventitious root formation. While cytokinins promote shoot growth, a high ratio of auxin to cytokinin stimulates root differentiation.

Multiple choice

Harmone pair for callus development

  1. Auxi and GA

  2. GA and ethylene

  3. Auxin and Cytokinine

  4. Auxin and ABA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Auxins and cytokinins are the two primary classes of plant hormones used in tissue culture. Their relative ratio determines whether cells form a disorganized mass (callus), roots, or shoots.

Multiple choice

Which of the following is not PGR

  1. Auxin

  2. GA

  3. Polyphenols

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

Plant Growth Regulators (PGRs) include auxins, gibberellins (GA), cytokinins, abscisic acid, and ethylene. Polyphenols are secondary metabolites involved in defense and pigmentation, not primary growth regulation.

Multiple choice

Which phytohormone is useful in germination of seeds ?

  1. Auxins

  2. Gibberellins

  3. Ethylene

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

Gibberellins are phytohormones that play a key role in breaking seed dormancy and initiating seed germination. They stimulate the production of hydrolytic enzymes like amylase, which break down stored food reserves to nourish the growing embryo.

Multiple choice

Zn

  1. Activates Carboxylases

  2. Needed in synthesis of Auxin

  3. Macronutrient

  4. All
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

Which plant hormone is responsible for promoting cell division and shoot formation?

  1. Auxin

  2. Cytokinin

  3. Gibberellin

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

Cytokinin is a plant hormone that promotes cell division and shoot formation.