Tag: cytokinins

Questions Related to cytokinins

Which among the following is not a function of cytokinins?

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

  1. Essential for Cytokinesis during cell division

  2. Delays the senescence of leaves

  3. Helps in fruit ripening

  4. Helps to overcome apical dominance

Show answer
Correct Option: C
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'

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

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

  1. Root apices

  2. Developing shoot buds

  3. Young fruits

  4. All of these.

Show answer
Correct Option: D
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'.

A plant hormone used for Inducing morphogenesis in plant tissue culture is ______________.

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

  1. abscisic acid

  2. gibberellin

  3. cytokinin

  4. ethylene.

Show answer
Correct Option: C
Explanation:

Cytokinins play a vital role in morphogenesis in plants. It opposes initiation of roots in stem cuttings treated with auxin and results in the formation of callus at the cut end. It is now well known that kinetin-auxin interaction controls the momhogenetic differentiation of shoot and root meristems.

In addition to auxins, ................ must be supplied to the culture medium to obtain a good callus in plant tissue culture.

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

  1. ABA

  2. Cytokinins

  3. Gibberellins

  4. Ethylene

Show answer
Correct Option: B
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 answer is 'cytokinins'.

Cytokinins help to produce all except

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

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral shoot growth and adventitious shoot formation

  4. Rooting on cut stem

Show answer
Correct Option: D
Explanation:

Rooting of cut stem is induced by spraying synthetic auxins like NaphthaleneAceticAcid and not cytokinins, in plants that are vegetatively propagated by stem cuttings.

So, the correct answer is 'Rooting on cut stem'

Cytokinins are present in greater concentration in young fruits and seeds.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Cytokinins are the plant hormones that stimulates cell division. They are naturally synthesized by young plant parts such as root tips, fruits and seeds.

The hormone that used to keep flowers fresh is 

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

  1. Auxin

  2. Gibberellic acid

  3. Cytokinin

  4. Ethylene

Show answer
Correct Option: C
Explanation:

Cytokinin helps in delaying senescence in plant parts that are cut like flowers and are used to keep cut flowers fresh i.e. increases shelf life of the cut flowers.


So, the correct answer is 'Cytokinin'.

First natural cytokinin was discovered by

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

  1. Skoog and Miller

  2. Letham

  3. Benson and Calvin

  4. Thimann and Went

Show answer
Correct Option: A
Explanation:

The first cytokinin was isolated from herring sperm in 1955 by Miller and his associates . This compound was named kinetin because of its ability to promote cytokinesis. Hall and deRopp reported that kinetin could be formed from DNA degradation products in 1955. The first naturally occurring cytokinin was isolated from corn in 1961 by Miller. It was later called zeatin. 

Therefore, the correct answer is option A.

Pruning of plants promotes branching, because the axillary buds get sensitized to

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

  1. Ethylene

  2. Gibberellin

  3. Cytokinin

  4. IAA

Show answer
Correct Option: C
Explanation:

Cytokinin are a class of plant growth substance that promote cell division or cytokinesis in plant roots and shoots. They are involved primarily in cell growth and differentiation but also affects apical dominance, axillary bud growth and leaf sensecence. Pruning of plants promote branching because the axillary buds get sensitized to cytokinin.

Therefore, the correct answer is option C.

In tissue culture, differentiation of shoot is controlled by ...........................

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

  1. Light Intensity

  2. Temperature shock

  3. Low Auxin and high CK $\left (High\, \frac{Cyto}{Auxin}\, Ratio \right )$

  4. None of the above

Show answer
Correct Option: C
Explanation:

Cytokinins promote cell division and differentiation of young, relatively unspecialized cells into mature, more specialized cells in intact plants. They are a required ingredient in any plant tissue culture medium and must be present for cells to divide. In tissue culture, cytokinins interact with auxin during the formation of plant organs such as roots and stems. For example, in tobacco tissue culture a high ratio of auxin to cytokinin induces root formation, whereas a low ratio of auxin to cytokinin induces shoot formation.