Biology

Plant Growth and Hormones

695 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

Induction of cell division and delay in senescence are due to

  1. Gibberellin

  2. Auxin

  3. Cytokinin

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

Cytokinin is a plant hormone. It plays major role in cell proliferation and cell division. It also delays the destruction of chlorophyll and protein. During senescence, cytokinin levels are low. It delays in senescence of leaves when sprayed externally by delaying the destruction of chlorophyll and proteins in leaves

So, the correct answer is 'Cytokinin'

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

Which is not a function of cytokinin?

  1. Delay is senescence

  2. Breaking seed dormancy

  3. Promoting bud dormancy

  4. Promoting stomatal opening
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cytokinin (CK) is a plant hormone. It promotes cell division and delays senescence in plants. It improves nutrient mobilization and thus delays leaf senescence. When applied externally, it mobilizes nutrients towards sites of application. It also promotes stomatal opening along with auxin hormone. It also breaks the dormancy of seeds and induce seed germination. 

Thus, the correct answer is option C.

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

Natural cytokinins are synthesised in tissues that are

  1. Storing food

  2. Differentiating

  3. Dividing

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

Cytokinin is a plant hormone that is involved in various physiological processes. It is growth promoting hormone. It stimulates cell division or cytokinesis and hence the name was given. It is synthesized in high concentration in tissues that are dividing such as cambium.

Thus, the correct answer is option C.

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

Natural cytokinins are synthesized in tissues for

  1. Differentiating

  2. Senescent

  3. Dividing

  4. Storing food
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Cytokinin is a naturally occurring plant growth hormone (PGR) extracted from coconut milk.
Cytokinins are synthesized in root apex, endosperm of seeds, and young fruits where cell division takes place continuously. 
They stimulate cell division, cell enlargement and cell differentiation and also prevent ageing of plant parts.
Hence, natural cytokinins are synthesized in tissues for dividing.
So, the answer is C.
Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Hormone that is associated with retaining the chloroplast chlorophyll is ?

  1. Auxin

  2. ABA

  3. Cytokinin

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

Cytokinin is a plant hormone which acts as plant growth regulator. It is associated with retaining the chloroplast chlorophyll in the leaves. The cytokinin has anti-senescence effect on the plant. It delays the senescence of the leaves and prevents the destruction of chloroplast.

Thus, the correct answer is option C.

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

Which plant hormone promotes cell division?

  1. Gibberellins

  2. Cytokinin

  3. Ethylene

  4. Auxins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Cytokinins(CK) are a class of plant growth hormones that promote cell division, or cytokinesis in plants roots and shoots. For example, Kinetin and benzyl-aminopurine.
  • They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.
  • Hence the plant hormone promotes cell division is Cytokinin.
  • So, the correct answer is 'Cytokinin'.
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 foration

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

Phytohormone concerned in the cell division is called cytokinins. It is involved in the formation of chloroplast in leaves, new leaves formation, lateral shoot growth and adventitious shoot formation.

So, the correct option is ‘rooting on cut stem’.

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

Choose the correct answer from the alternatives given.
Application of which of the following hormones prevents plant tissues from senescing or ageing?

  1. Abscisic acid

  2. Auxin

  3. Cytokinin

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

Cytokinins help overcome apical dominance. They promote nutrient mobilization which helps in the delay of leaf senescence.

So, the correct option is 'Cytokinin'.

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

Choose the correct answer from the alternatives given.
A hormone that causes cell division and is found in coconut milk or in dividing root tissue is:

  1. abscisic acid

  2. auxin

  3. cytokinin

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

In the presence of auxin (but not in its absence) kinetin stimulated tobacco pith parenchyma tissue to proliferate in culture. Later, zeatin was identified as the first naturally occurring cytokinin in immature maize endosperm (Letham, 1973), and turns out to be the abundant cytokinin in coconut milk.

So, the correct option is 'cytokinin'.

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

Choose the correct answer from the alternatives given.
Cytokinins

  1. are plant hormones that promote cell division

  2. are used in combination with auxin to produce plants from undifferentiated callose tissue.

  3. also work with oligosaccharins to effect tissue differentiation

  4. all of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It helps to produce new leaves, chloroplasts in leaves, lateral shoot growth and adventitious shoot formation. Cytokinins help overcome apical dominance. They promote nutrient mobilisation which helps in the delay of leaf senescence.

Natural cytokinins are synthesised in regions where rapid cell division occurs, for example, root apices, developing shoot buds, young fruits etc.
So, the correct option is 'all of the above'.

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

Cytokinins are mostly ____________.

  1. glucosides

  2. phenolics

  3. amino purines

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

Cytokinins are plant growth hormones which are basic in nature, either amino purine or phenyl urea derivatives, that promote cytokinesis (= cell division) either alone or in conjunction with auxin. Kinetin, a synthetic cytokinin, is 6-furfuryl amino purine. Zeatin, a natural cytokinin, is 6-hydroxy 3-methyl trans 2-butenyl amino purine.

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

Select the pair that consists of plant growth promoters only.

  1. Auxins and cytokinins

  2. Gibberellins and ABA

  3. Ethylene and ABA

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Auxins and cytokinins are plant growth promoters, the roles played by auxin and cytokinin are as follows.

Auxins: Cell enlargement and longitudinal growth of root and shoot.
             Reactivation of cambium in the growth season, that is, responsible for secondary growth, promotes apical dominance and parthenocarpy, inhibits abcission.
Cytokinins: induces morphogenesis that is differentiation of cells into tissues and organs.delays senescence, breaks dormancy and promotes seed germination, enhances expression of a sexual characteristic- femaleness in some plants.
Auxin/cytokinin ratio influences root and shoot formation and growth
So, the correct answer is 'Auxins and cytokinins'

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

Which among the following is not a function of cytokinins?

  1. Essential for Cytokinesis during cell division

  2. Delays the senescence of leaves

  3. Helps in fruit ripening

  4. Helps to overcome apical dominance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fruit ripening or climacteric fruit ripening is induced by ethylene in most of the fruits, and therefore is not a function of cytokinins.

So, the correct answer is 'Helps in fruit ripening'

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

Natural cytokinins are synthesized in regions where rapid cell division occurs. Such regions are

  1. Root apices

  2. Developing shoot buds

  3. Young fruits

  4. All of these.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
About 18 types of cytokinins have been discovered till now. Some of them are constituents of t RNAs. Roots are considered as the major source of cytokinin synthesis; from roots, the cytokinins pass upwardly through the xylem. Cytokinin synthesis also occurs in the areas where cell division takes place e.g., growing embryos and developing seeds, endosperm of seeds, young fruits, developing shoot buds, etc.
So the correct option is 'All of these'.