Tag: cytokinins

Quizzes (2) Questions (105)

Questions Related to cytokinins

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

The growth regulator that retards ageing of plant organs is

  1. Auxin

  2. Gibberellin

  3. Cytokinin

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

Cytokinin is the plant growth regulator which promotes cell division. The hormone retards the process of ageing which is known as senescence. There is stimulation for the production of chlorophyll and the fruits and leaves are prevented from falling. There is breaking of the bud dormancy which allows reproductive growth in the plants.

Thus, the correct answer is option C. 

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

Which one of the following is primarily concerned with cell division ? 

  1. GA$ _3$

  2. IAA

  3. Cytokinin

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

Cytokinins are the plant growth hormones that regulate the cell division in root and shoot of the plant both in vivo and in vitro. They do so by regulating the controls that govern the transition of the cell from one stage of the cell cycle to the next one. Thus, option C is correct  

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

Chemically, cytokinins are related to

  1. Carotenoid

  2. Terpenes

  3. Aminopurines

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

Cytokinins are the growth substances which act primarily on cell division and have little or no effect on extension growth. Cytokinins are derivatives of purine base, adenine, bearing furfuryl substituent. Thus option C is the correct answer. 

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

The growth regulator that retards ageing of plant organs is called as

  1. Auxin

  2. Gibberellin

  3. Cytokinin

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

Cytokinins have a striking quality to retard senescence (i.e., process of ageing) in plants. External application of cytokinins delay the rate of chlorophyll disappearance and protein degradation which usually accompanies the process of senescence in leaves.

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

Induction of cell division and delay in senescence is done by

  1. Cytokinins

  2. Auxins

  3. Gibberellic acid

  4. CoA
Reveal answer Fill a bubble to check yourself
A 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. Cytokinins delay senescence of leaves via their effect on translocation of metabolites and by reducing breakdown of proteins and chlorophyll (the Richmond-Lang effect). Option A is correct. Cytokinins treated leaves withdraw their nutrients from adjacent leaves and maintain their viability. Option C is incorrect as gibberellins (GA) cause cell elongation. Treatment with gibberellins causes bolting (stem elongation) and reverses dwarfism by increasing the intermodal length. Exogenous application of gibberellins prevents senescence in leaves and fruits. Auxin serves as inhibitor of leaf senescence by inhibiting synthesis of abscission layer at the base of petiole or pedicel which in turn causes leaf shedding. Option B is incorrect as auxin is the hormone of cell division and cell expansion both. CoA is a coenzyme which is involved in many metabolic activities like synthesis and oxidation of fatty acid. This makes option D incorrect as CoA is not a plant growth hormone

So, the correct answer is 'Cytokinins'

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

Which of the following hormone induces cell division?

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Trypsin
Reveal answer Fill a bubble to check yourself
C 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. This makes option C correct. Option A is incorrect as auxins are the growth hormones that cause cell division as well as cell expansion, thereby causing growth while cytokinins are not involved in cell expansion but only in cell division. Option B is incorrect as gibberellins cause cell elongation. Treatment with gibberellins causes bolting (stem elongation) and reverses dwarfism by increasing the intermodal length. Trypsin is a globular protein with 24kD and one polypeptide chain of 220 residues and serves as proteolytic enzyme (protein digesting enzyme). Option D is incorrect. 

Thus, the correct answer is option C.

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. Indole acetic acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option D is incorrect as IAA is an auxin that causes apical dominance. It involves withdrawal of root manufactured cytokinins towards apical bud which in turn makes the lateral bud cytokinins deficient. Cytokinins deficiency suppresses growth of lateral buds as cytokinins are the hormones of cell division. Pruning is cutting off the apical portion of branches to induce growth which in turn lowers the amount of auxin synthesized as shoot apex. The lowered auxin synthesis allows translocation of cytokinins to lateral bud stimulating cell division and growth of lateral branches. This makes option C correct. Option A is incorrect as ethylene inhibits lateral buds and causes apical dominance. Option B is incorrect as gibberellins are the hormones of stem elongation of genetic dwarfs and seed germination. 

Thus, the correct answer is option C.

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

The plant hormone which is essential for cell division is

  1. Auxin

  2. Cytokinin

  3. Ethylene

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

The cytokinins are plant growth substances which act primarily on cell division and little or no effect on extension growth. The most important function of cytokinins is the promotion of cell division. It is now well established that these are true cell division factors. The varying amount of cytokinins, along with sufficient auxin is required for the growth of callus in the tissue culture experiments. Thus option B is the correct answer.

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

I. Assertion: Seeds and growing fruit are rich in cytokinin.
II. Reason: Cytokinin promotes cell division.

  1. I and II both are true, II is not correct explanation for I

  2. I and II both are false

  3. I is false II is true

  4. I and II both are true, II is correct explanation for I
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cytokinin promotes cell division and cell elongation. Thus they are found in the region where there is rapid cell division like fruits and seeds.