Tag: plants and animal hormones

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Questions Related to plants and animal hormones

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

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

  1. abscisic acid

  2. gibberellin

  3. cytokinin

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

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

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

  1. ABA

  2. Cytokinins

  3. Gibberellins

  4. Ethylene
Reveal answer Fill a bubble to check yourself
B 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 answer is 'cytokinins'.
Multiple choice biology chemical coordination in plants cytokinins plant hormones plants and animal hormones

Cytokinins help to produce all except

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral shoot growth and adventitious shoot formation

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

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

First natural cytokinin was discovered by

  1. Skoog and Miller

  2. Letham

  3. Benson and Calvin

  4. Thimann and Went
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. Ethylene

  2. Gibberellin

  3. Cytokinin

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

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

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

  1. Light Intensity

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

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

Coconut water is rich in 

  1. Auxins

  2. Gibberellin

  3. Abscisic acid

  4. Cytokinin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cytokinins stimulate cell division, even in non-meristematic cells, in presence of auxin. They are most abundant in the growing tissues which are active site of cell division, for example: root, embryos, fruits etc. Coconut water is the liquid endosperm, the actively dividing tissue which serves as nutrition source for developing coconut embryo. Coconut water is used as growth promoter of developing embryos in tissue culture studies. It stimulates the growth of cultures of embryo due to presence of cytokinins. This makes option D correct. Abscisic acid (ABA) is a growth retardation hormone which inhibits seed germination and seedling growth. This makes option C incorrect as endosperm does not have growth retardation hormone. Option A is incorrect as auxin is the hormone of cell division and cell expansion, i.e., overall growth, while endosperm carries the hormone for cell division to increase the cell number only. Option B is incorrect as gibberellins are the hormone of stem elongation in genetic dwarf plants only.

Thus, the correct answer is option D.