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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.

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

Cytokinin is a hormone whose main function is ..................

  1. Induction of cell division and delay in senescence

  2. To take part in cell division

  3. Refers to cell movements

  4. To cause dormancy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are derivatives of pure adenine. It is a true cell division factor, promotes meristematic tissue regions. It prevents destruction of chlorophyll in leaves.

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

Which of the following causes delaying of senescence?

  1. Cytokinins

  2. Auxins

  3. IAA

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

Cytokinins retard the aging in plants. The effect is called as Richmond-Lang effect. Richmond-Lang effect is retardation of aging due to cytokinins which acts by retarding the rate of destruction of chlorophyll and yellowing of leaves.

Thus, the correct answer is option A.

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

Which of the following is a coconut milk factor?

  1. Auxin

  2. Cytokinin

  3. Morphactin

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

Kinetin is present in the coconut water, which is actually a liquid endosperm. Hence, the name coconut milk factor. It actually serves as the nourishment for the growth of embryo in coconut. Coconut water is also used as artificial blood plasma.

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

Guttman (1957) found a quick increase in the amount of RNA in the nuclei on onion root after .............

  1. Auxin treatment

  2. Kinetin treatment

  3. Gibberellin treatment

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kinetin promotes the synthesis of RNA, proteins, etc., which help in initiation of root, breaking of seed dormancy, etc. In the case of onion root, which underwent kinetin treatment more RNA could be spotted out because of this reason.

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

RNA formation is induced by .............

  1. Phyllocalins

  2. All calins

  3. Kinetins

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

Kinetins induce the synthesis of RNA. Kinetin is a type of cytokinin, a class of plant hormone that promotes cell division. It was originally isolated by Miller and Skoog et al. It was given the name kinetin because of its ability to induce cell division. Kinetin is often used in plant tissue culture for inducing formation of callus and to regenerate shoot tissues from callus. Florigen induces flowering.

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

Cytokinin was first synthesized by ...................

  1. Skoog and Miller

  2. Letham

  3. Bensan and Calvin

  4. Thimman and Went
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cytokinins are a class of plant growth substances that promote cell division or cytokinesis in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth and leaf senescence. Letham first synthesized it from corn milk.

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

An excised leaf does not turn yellow if it is induced to root. This is attributed to synthesis in root of ...................
or
Leaf ageing is retarded by ........................

  1. Ethylene

  2. Cytokinins

  3. Gibberellins

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

According to Richmond lang effect, cytokinin hormone in plants will cause retardation of chlorophyll and several other proteins. Thus, it helps in reducing the senescence.

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

The cut flowers and vegetables can be kept fresh a long period by this

plant hormone ...............

  1. Gibberellins

  2. Cytokinins

  3. Auxins

  4. Ethylene

  5. 2,4 - dichlorophenoxy acetic acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cytokinin is the plant hormone which is found to have profound effects in delaying the ageing of plant and thus increases the shelf life of vegtables and fruits. It acts by retarding the destruction and degeneration of chlorophyll and proteins. This is called as 'Richmond Lang effect'.