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Questions Related to biology

The plant hormone which is essential for cell division is

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

  1. Auxin

  2. Cytokinin

  3. Ethylene

  4. Gibberellin

Show answer
Correct Option: B
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.

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

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

  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

Show answer
Correct Option: D
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.

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

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

  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

Show answer
Correct Option: A
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.

Which of the following causes delaying of senescence?

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

  1. Cytokinins

  2. Auxins

  3. IAA

  4. Ascorbic acid

Show answer
Correct Option: A
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.

Which of the following is a coconut milk factor?

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

  1. Auxin

  2. Cytokinin

  3. Morphactin

  4. None of the above

Show answer
Correct Option: B
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.

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

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

  1. Auxin treatment

  2. Kinetin treatment

  3. Gibberellin treatment

  4. All of the above

Show answer
Correct Option: B
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.

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

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

  1. Phyllocalins

  2. All calins

  3. Kinetins

  4. Florigens

Show answer
Correct Option: C
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.

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

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

  1. Skoog and Miller

  2. Letham

  3. Bensan and Calvin

  4. Thimman and Went

Show answer
Correct Option: B
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.

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 ........................

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

  1. Ethylene

  2. Cytokinins

  3. Gibberellins

  4. Auxins

Show answer
Correct Option: B
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.

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

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

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

  1. Gibberellins

  2. Cytokinins

  3. Auxins

  4. Ethylene

  5. 2,4 - dichlorophenoxy acetic acid

Show answer
Correct Option: B
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'.