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Cytokinins - class-X

Description: cytokinins
Number of Questions: 105
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Tags: chemical coordination in plants biology plants and animal hormones chemical messages for homeostasis
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Delaying aging of leaves and opening of stomata are due to the action of _______

  1. Auxins 

  2. Gibberellins

  3. Cytokinins

  4. Abscisic acid


Correct Option: C
Explanation:
A. Auxins are the plant hormones which promote cell enlargement and cell differentiation. It also promote fruit growth. It is responsible for phototropic and geotropic responses of plants.
B. Gibberellins are plant hormones which promote cell enlargement and cell differentiation in the presence of auxins. It help in breaking the dormancy in seeds and buds. It also promote fruit growth. It stimulates elongation of shoots of various plants.
C. Cytokinins are plant hormones which promote cell division in plants. It also helps in breaking the dormancy in seeds and buds. The delay the ageing of leaves. It promotes opening of stomata.
D. Abscisic acid (ABA) is a  plant hormone which functions mainly as a growth inhibitor. It promotes the dormancy in seeds and buds [ this is the opposite of breaking the dormancy. It also promotes closing of stomata. It promotes falling of leaves. 
So, the correct answer is 'Cytokinins'.

Cytokinins are known to

  1. Inhibit cytoplasmic movement.

  2. Help in retention of chlorophyll.

  3. Influence water movement.

  4. Promote abscission layer formation.


Correct Option: B
Explanation:

Cytokinins perform several other functions:
- Stimulates cell division.
- Stimulates morphogenesis in tissue culture.
- Stimulates the growth of lateral buds.
- Stimulates leaf expansion.
- Enhance stomatal opening

Cytokinin and ethylene have oppsite effect on:-

  1. Leaf senescence

  2. Elogation of stem

  3. Lateral swelling of stem

  4. Winter dormancy


Correct Option: A
Explanation:

Cytokinins are the plant hormones that are responsible for cell division and elongation, their help in the delay of leaf senescence as they transport nutrients to these parts. Ethylene is a gaseous hormone and is responsible for transverse growth as swelling of the stem, It hastens the senescence of leaves due to the evolution of ethylene gas.

So, the correct option is 'Leaf senescence'.

Find the correct application of cytokinin.

  1. Acts as anti-transparent and induces closure of stomata

  2. To promote root development on various types of cuttings

  3. In tea plantation for giving bushy appearance

  4. Promotes parthenocarpy in fruits like banana and grapes


Correct Option: A

Kinetin was first isolated and identified by

  1. Charles Darwin

  2. Boysen and Jansen

  3. Paal

  4. Miller


Correct Option: D
Explanation:

Kinetin is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Miller and Skoog et al., as compound from autoclaved herring sperm DNA that had cell division-promoting activity.

The chief role of CK is 

  1. To check abscission

  2. To check senescence

  3. To mobilize solutes

  4. To check senescence and to mobilize solutes from one part to other


Correct Option: D
Explanation:

Cytokinin hormone does the major function of checking senescence and mobilising solutes from one part to another. It promotes the cell division or cytokinesis, in plant roots and shoots.

So, the correct answer is option D.

Phytocytomine is a

  1. Kinetin

  2. Giberellin

  3. Auxin

  4. None of the above


Correct Option: A
Explanation:

Phytocytomine is a plant growth regulator. It is a kind of kinetin. It is synthesized from Licheniformis bacillus.

Which of the following contains cytokinin?

  1. Coconut milk

  2. Young kernels of maize

  3. Fruit of cucurbits

  4. Both (A) and (B)


Correct Option: D
Explanation:

Coconut milk and young kernels of maize contains cytokinin. Cytokinis are a class of plant growth substances that promote cell division, or cytokinesis in plant roots and shoots. It is an adenine derivative.

Cytokinin involves

  1. Kinetin, zeatin, BAP

  2. $GA _3$,IBA, Kinetin

  3. Zeatin, $GA _3$, BAP

  4. IAA, Zeatin, kinetin


Correct Option: A

Which one of the following is not true about kinetin?

  1. It promotes bud growth.

  2. It defers senescence.

  3. It helps in retention of chlorophyll.

  4. It inhibits the cell division.


Correct Option: D
Explanation:

Kinetin is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Miller and Skoog et al as a compound from autoclaved herring sperm DNA that had cell division-promoting activity.

Kinetin was isolated by ...............

  1. Skoog and Miller

  2. Darwin and Lamarck

  3. Boysen and Jensen

  4. Went and Smit


Correct Option: A
Explanation:

Kinetin is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Miller and Skoog et al, as a compound from autoclaved herring sperm DNA that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division, provided that auxin was present in the medium. Kinetin is often used in plant tissue culture for inducing formation of callus and ti regenerate shoot tissues from callus.

Which of the following is not properly matched?

  1. Explant - excised plant part used for callus formation

  2. Cytokinins - root initiation in callus

  3. Somatic embryo - embryo produced from a vegetative cell

  4. Anther culture - haploid plants

  5. Callus - undifferentiated mass of cells


Correct Option: B
Explanation:

Plant cells are totipotent means, each cell retains total potential to generate a new plant. Callus is an undifferentiated mass of cell generated in plant tissue culture from meristematic cells from which entire plant can be regenerated. The small piece of meristematic tissue which is used in tissue culture to generate callus is called an explant. The ratio between auxin and cytokinin is an important factor deciding initiation of roots and shoots. Phytohormone cytokinin promotes growth of shoot whereas auxin promotes growth of roots. Anther culture is done for production of haploids because anthers contain haploid microspores which can be used to generate new plants. Somatic embryos are produced by direct fusion of somatic cells one with nucleus and another without nucleus.

A plant hormone which delays senescence and helps in cell division is .............

  1. Auxin

  2. Gybberellin

  3. Cytokinin

  4. Abscissic acid


Correct Option: C
Explanation:

Cytokinins are the plant hormones which has manifold effects on plants. It includes delaying of senescence, active cell division and so on. Cytokinins increase cell division by stimulating proteins needed for mitosis. Mitosis is non-sexual cell division that occurs in all living things producing additional cells for body growth. The active principle responsible for inducing cell division was isolated first from the extracts of yeasts. Such a substance was called kientin, later the name was changed and called as cytokinin.

Richmond Lang effect is due to .........................

  1. Cytokinin

  2. Auxin

  3. ABA

  4. All of the above


Correct Option: A
Explanation:

Cytokinins are the phytohormones which can delay plant senescence by the stimulation of cell division. Cytokinins also prevent the destruction of chlorophyll and consequently the plant parts do not turn yellow. This is known as Richmond Lang effect after the workers who discovered it.

Cytokinin 

  1. Is a hormone whose main function is to induce the cell division.

  2. Is the process of cell division.

  3. Refers to cell division.

  4. Causes dormancy.


Correct Option: A
Explanation:

Cytokinins are phytohormones which have specific effects on cytokinesis and were discovered as kinetin (a modified form of adenine, a purine) from the autoclaved herring sperm DNA. Kinetin does not occur naturally in plants. Search for natural substances with cytokinin-like activities led to the isolation of zeatin from corn-kernels and coconut milk. Since, the discovery of zeatin, several naturally occurring cytokinins and some synthetic compounds with cell division promoting activity, have been identified. Natural cytokinins are synthesised in regions where rapid cell division occurs, for example, root apices, developing shoot buds, young fruits etc.

Thus, the correct answer is option A.

The excised leaf does not turn yellow if it is induced to root. This is 

attributed to ....................

  1. Ethylene

  2. Cytokinins

  3. Gibberelins

  4. Auxins


Correct Option: B
Explanation:

One effect of cytokinins on plant cells is to delay the aging process. Plant cells, like all living cells, go through a natural aging process known as senescence. Senescence is accelerated in cells of plant parts that are cut, such as flower stems. Botanists think that plants must have a continual supply of cytokinins from the roots. Cut stems, of course, lose their source of cytokinins and therefore age rapidly. When cytokinins are sprayed on leaves of a cut stem of many species, they remain green, whereas unsprayed leaves turn yellow and die.

Which of the following is a coconut milk factor?

  1. Auxin

  2. ABA

  3. Morphactin

  4. Cytokinin


Correct Option: D
Explanation:

During the 1940s and 1950s, researchers were trying to find substances that might induce plant cells to divide in tissue culture, a technique in which cells are isolated from plants and grown in a nutrient medium. They discovered that cells would not divide without a substance found in coconut milk. Because coconut milk has a complex chemical composition, investigators did not chemically identify the division-inducing substance for some time. Finally, researchers isolated an active substance from a different source, aged DNA from herring sperm. They called it cytokinin because it induces cytokinesis, or cytoplasmic division. In 1963, researchers identified the first plant cytokinin, zeatin, in corn. Since then, similar molecules have been identified in other plants. Biologists have also synthesized several cytokinins. Cytokinins are structurally similar to adenine, a purine base that is part of DNA and RNA molecules.

Richmond-Lang effect due to cytokinins pertains to 

  1. Root formation

  2. Apical dominance

  3. Delay of senescence

  4. Leaf formation


Correct Option: C
Explanation:

The ageing process in plants is known as senescence. Cytokinins delay the process of scenescence. The ability of cytokinins to delay the process of senescence is known as Richmond-Lang effect.

Thus, the correct answer is option C.

The growth regulator that retards ageing of plant organ is ..................

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Abscisic acid


Correct Option: C
Explanation:

One important effect of cytokinins on plant cells is to delay the aging process. Plant cells, like all living cells, go through a natural aging process known as senescence. Senescence is accelerated in cells of plant parts that are cut, such as flower stems. Botanists think that plants must have a continual supply of cytokinins from the roots. Cut stems, of course, lose their source of cytokinins and therefore age rapidly. When cytokinins are sprayed on leaves of a cut stem of many species, they remain green, whereas unsprayed leaves turn yellow and die.

Apical dominance can be overcome by application of 

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Florigen


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. Cytokinins and auxin also interact in the control of apical dominance. Here, their relationship is antagonistic: auxin inhibits the growth of axillary buds, and cytokinin promotes their growth.

Thus, the correct answer is option C.

First natural cytokinin was discovered by 

  1. Miller

  2. Letham

  3. Calvin

  4. Haberlandt


Correct Option: A
Explanation:
Cytokinins are the growth hormones which was discovered by Miller. It mainly helps in the cell division. Kinetin was first discovered cytokinin which had the immense potential to promote cytokinesis. Zeatin is the natural cytokinin  traced in corn.
So, the correct answer is option A.

Richmond lang effect is .........................

  1. The effect of kinetins in delaying senescence

  2. The effect of auxin on root and shoot formation

  3. The effect of traumatic acid in wound formation

  4. None of the above


Correct Option: A
Explanation:

Cytokinin causes delay of senescence called Richmond Lang effect. It checks disappearance of chlorophyll and degradation of protein synthesis in leaves. 
Senescense of leaves leads to yellowing and finally leads to the fall from the plant.  If a young excised leaf is kept in water, it slowly changes its color to yellow and dies.  If such leaves are provided with cytokinin, the yellowing is significantly delayed and such an effect is called Richmond and Langs effect; named after the discoverers. 

The first cytokinin was discovered by 

  1. Skoog

  2. Went

  3. Addicott

  4. Miller


Correct Option: D
Explanation:
The first cytokinin was isolated from herring sperm in 1955 by Miller. This compound was named as kinetin because of its ability to promote cytokinesis. Natural cytokinins are synthesized in regions where rapid cell division is occurring. e.g., root apices, developing shoot buds, young fruits etc.
Cytokinins overcome apical dominance. They promote nutrient mobilization that help in delay of leaf senescence.
Thus, the correct answer is option D.

Which of the following induces morphogenesis in tissue culture?

  1. Gibberellin

  2. Cytokinin

  3. IAA

  4. Ethylene


Correct Option: B
Explanation:

During the 1940s and 1950s, researchers were trying to find substances that might induce plant cells to divide in tissue culture, a technique in which cells are isolated from plants and grown in a nutrient medium. They discovered that cells would not divide without a substance found in coconut milk. Because coconut milk has a complex chemical composition, investigators did not chemically identify the division-inducing substance for some time. Finally, researchers isolated an active substance from a different source, aged DNA from herring sperm. They called it cytokinin because it induces cytokinesis, or cytoplasmic division. In 1963, researchers identified the first plant cytokinin, zeatin, in corn. Since then, similar molecules have been identified in other plants. Biologists have also synthesized several cytokinins. Cytokinins are structurally similar to adenine, a purine base that is part of DNA and RNA molecules.
Morphogenesis means generation of proper morphological form of a plant body. Cytokinins promote cell division and differentiation of young, relatively unspecialized cells into mature, more specialized cells in intact plants (morphogenesis). 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. Cytokinins and auxin also interact in the control of apical dominance. Here their relationship is antagonistic: auxin inhibits the growth of axillary buds, and cytokinin promotes their growth.

Richmond-Lang effect is shown by

  1. Auxins

  2. Sugars

  3. Kinetin

  4. Gibberellins


Correct Option: C
Explanation:

Kinetins are a type of phytohormone (cytokinin). One of the important physiological effect of cytokinins is that they delay senescence. This delay in senescence of mature plant parts is known as Richmond Lang effect.

Thus, the correct answer is option C.

Cytokinin

  1. Is a hormone whose main function is to induce cell division.

  2. Is the process of cell division.

  3. Retards cell division.

  4. Causes dormancy.


Correct Option: A

Hormone concerned primarily with cell division is 

  1. GA$ _{3}$

  2. IAA

  3. NAA

  4. Cytokinin


Correct Option: D
Explanation:

Cytokinin is a type of phytohormone. It encourages the process of cell division and cell differentiation. They promote cytokinesis, and so the term 'Cytokinin'. They affect apical dominance and axillary bud growth.

So, option D " Cytokinin" is the correct answer.

The hormone present in higher concentration in fruits and seeds is

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Ethylene


Correct Option: C
Explanation:

Auxin promotes stem elongation. It is present in high concentration in apical meristem. Gibberellin controls shoot elongation, seed germination and delay the senescence in leaves and fruit. Cytokinin promotes cell growth and division. It is present in higher concentration in developing areas such as young fruits and seeds. Ethylene helps in fruit ripening, senescence and abscission.

Thus, the correct answer is option C.

Choose the right from the following.

i. In light, hormone auxin, helps the cells to grow longer in plants .
ii. Plant hormone gibberellins helps in growth of a stem.
iii. Cytokinins inhibits cell division.
iv. Abscisic acid promote growth in plants.

  1. Option i and iii are correct.

  2. Option ii and iv are correct.

  3. Option i and ii are correct.

  4. Option i and iv are correct.


Correct Option: C
Explanation:

Plants have certain chemical substances in them that transmit messages for maintaining different functions of the body. 

One of the important function of auxins is that they help in the growth of the plants in the din growth like the growth of the stem.
Gibberellins help in the growth of different plant parts like stems.
Cytokinins help in cell division and differentiation, and so option iii is incorrect.
Abscisic acid retards plant growth, so option iv is also incorrect. 
So, option C " Option I and ii are correct" is the correct option.

The plant hormone that promote cell division

  1. Abscisic acid

  2. Auxins

  3. Gibberellins

  4. Cytokinins


Correct Option: D
Explanation:

Abscisic acid is a plant growth hormone involved in seed dormancy and responses of plants to stress. This makes option A incorrect. Auxins promote the formation of lateral and adventitious roots, regulate the flower bud development and induce vascular differentiation. This makes option B incorrect. Gibberellins are responsible for stem elongation, breaking seed dormancy, mobilization of endosperm reserves as well as regulate sex determination, flower initiation and fruit set. This makes option C incorrect. 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. This makes option D correct. 

The growth regulator that retards ageing of plant organs is

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Abscisic acid


Correct Option: C
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. 

The growth regulator that retards ageing of plant organs is 

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Abscisic acid


Correct Option: C
Explanation:

Cytokinins delay destruction of chlorophyll and proteins and thereby delaying the leaf senescence/ageing. Thus, option C is correct .


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

  1. GA$ _3$

  2. IAA

  3. Cytokinin

  4. NAA


Correct Option: C
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  

Chemically, cytokinins are related to

  1. Carotenoid

  2. Terpenes

  3. Aminopurines

  4. Indole


Correct Option: C
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. 

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

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Abscisic acid


Correct Option: C
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.

Induction of cell division and delay in senescence is done by

  1. Cytokinins

  2. Auxins

  3. Gibberellic acid

  4. CoA


Correct Option: A
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'

Which of the following hormone induces cell division?

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Trypsin


Correct Option: C
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.

Pruning of plants promotes branching because the axillary buds get 
sensitized to
  1. Ethylene

  2. Gibberellin

  3. Cytokinin

  4. Indole acetic acid


Correct Option: C
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.

The plant hormone which is essential for cell division is

  1. Auxin

  2. Cytokinin

  3. Ethylene

  4. Gibberellin


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.

  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


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

  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


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?

  1. Cytokinins

  2. Auxins

  3. IAA

  4. Ascorbic acid


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?

  1. Auxin

  2. Cytokinin

  3. Morphactin

  4. None of the above


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

  1. Auxin treatment

  2. Kinetin treatment

  3. Gibberellin treatment

  4. All of the above


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

  1. Phyllocalins

  2. All calins

  3. Kinetins

  4. Florigens


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

  1. Skoog and Miller

  2. Letham

  3. Bensan and Calvin

  4. Thimman and Went


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

  1. Ethylene

  2. Cytokinins

  3. Gibberellins

  4. Auxins


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

  1. Gibberellins

  2. Cytokinins

  3. Auxins

  4. Ethylene

  5. 2,4 - dichlorophenoxy acetic acid


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'.

A plant hormone used for inducing morphogenesis in plant tissue culture

is ........................

  1. Abscisic acid

  2. Gibberellins

  3. Cytokinins

  4. Ethylene


Correct Option: C
Explanation:

Morphogenesis is the process of organ formation. Cytokinin is a plant hormone which plays a major role in organ formation or morphogenesis with the presence of auxin. It helps in rapid multiplication of cells by repeated cytokinesis and karyokinesis.

Cytokinesis refers to ................

  1. Division of chromosomes

  2. Division of cytoplasm

  3. Division of nucleus

  4. None of the above


Correct Option: B
Explanation:

Cytokinin is a plant hormone which is vital for the mitotic divisions taking place in plants. It thus enables cytokinesis and karyokinesis in the cells. This makes cytokinin an important constituent in callus culture.

Cytokinins are mostly produced in

  1. Shoot apex

  2. Root apex

  3. Young leaves

  4. Lateral buds


Correct Option: B
Explanation:

Cytokinin is a plant hormone. It promotes cell division. It also delays the destruction of chlorophyll and protein. It shows delay of senescence in leaves.  It is mostly produced in the root apex. When an excised leaf is induced to root, it does not turn yellow because root apex synthesizes cytokinin hormone.

Thus, the correct answer is option B.

Delay in senescence is caused by the spray of 

  1. IBA

  2. GA

  3. Cytokinin

  4. ABA


Correct Option: C
Explanation:

Senescence means aging. Cytokinin is a plant hormone. It plays major role in cell proliferation and cell division. During senescence, cytokinin levels are low. It delays in senescence of leaves when sprayed externally by delaying the destruction of chlorophyll and proteins in leaves. 

Thus, the correct answer is option C.

Cytokinins are generally

  1. Acids

  2. Aminopurines

  3. Phenols

  4. Glucosides


Correct Option: B
Explanation:

The first cytokinin discovered was an aminopurine derivative named kinetin. Except zeatin which is adenine derivative, all other present cytokinins are aminopurines. All the naturally occurring cytokinins are substituted purines, in which sixth carbon is substituted by amino group.

Thus, the correct answer is option B.

Cell mitosis is induced by

  1. Colchicine

  2. Gibberellic acid

  3. Nitrosoguanidine

  4. Kinetin


Correct Option: D
Explanation:

Kinetin is a type of cytokinin which is a plant hormone. It promotes cell division. It induces the cell mitosis by maintaining the protein like cyclins and CDKS that are important for mitosis. 

Thus, the correct answer is option D.

Kinetin like properties are present in

  1. Pineapple

  2. Soyabean

  3. Groundnut

  4. Coconut milk


Correct Option: D
Explanation:

Kinetin is a type of cytokinin which is a plant hormone. It promotes cell division. The first known cytokinin hormone was found in coconut milk. Coconut milk is liquid endosperm. It promotes cell division same as kinetin. It stimulates the embryo to grow when it is supplied with food.

Thus, the correct answer is option D.

Flowering in some short day plants is promoted by

  1. Auxins

  2. Gibberellins

  3. Cytokinins/ABA

  4. Ethylene


Correct Option: B
Explanation:

Gibberellin is a plant hormone which helps in growth of stem. The rapid growth and flowering with cell division and cell elongation is called as bolting. Bolting requires either long days or cold treatment. Bolting can be induced by higher level of gibberellin under normal conditions. Hence, it induces flowering in some short day plants.

Thus, the correct answer is option B.

Cytokinins have the ability to

  1. Induce morphogenesis

  2. Substitute cold treatment

  3. Convert dwarf plants to tall plants

  4. None of the above


Correct Option: A
Explanation:

Cytokinins are plant hormones that are involved in various physiological processes. They promotes cell division by stimulating mitosis. Due to increased rate of mitosis, they induce shoot and root morphogenesis. They also plays important role in formation of fruits and seeds.

Thus, the correct answer is option A.

Cut pr excised leaves remain green for long if induced to root or dipped in

  1. Gibberellins

  2. Cytokinins

  3. Auxins

  4. Ethylene


Correct Option: B
Explanation:

Cytokinin is a plant hormone. It promotes cell division. It also delays the destruction of chlorophyll and protein. It shows delay of senescence in leaves and keeps leaves green for long time. So when cut or excised leaves are induced to root, it will remain green because root synthesizes cytokinin hormone.

Thus, the correct answer is option B.

The regulator which retards ageing senescence of plant parts is

  1. Cytokinin

  2. Auxin

  3. Gibberellin

  4. Abscisic acid


Correct Option: A
Explanation:

Cytokinins is a plant hormone. It retards ageing senescence of plant parts and thus keep them productive for longer duration. This is called as Richmond Lang effect. It delays destruction of chlorophyll. It has an effect on protein synthesis and mobilizing nutrients. 

Thus, the correct answer is option A.

Cytokinins are mostly

  1. Glucosides

  2. Aminopurines

  3. Acidic

  4. Phenolic


Correct Option: A
Explanation:

The first cytokinin discovered was an aminopurine derivative named kinetin. Except zeatin which is adenine derivative, all other present cytokinins are aminopurines. All the naturally occurring cytokinins are substituted purines, in which sixth carbon is substituted by amino group.

Thus, the correct answer is 'Glucosides'.

Hormone discovered through tissue culture technique is

  1. Auxin

  2. Cytokinin

  3. Gibberellin

  4. Abscisic acid


Correct Option: B
Explanation:

Hormone discovered through tissue culture technique is cytokinin. Cytokinin was discovered by Skoog and Miller. The first cytokinin discovered was kinetin. This was isolated as a DNA degradation product. 

Thus, the correct answer is option B.

Hormone that promotes growth of lateral buds/has negative effect on apical dominance is

  1. Cytokinin

  2. Gibberellin

  3. Auxin

  4. Both B and C


Correct Option: A
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones auxin produced in the tip of the shoot. It promotes apical dominance and does not allow lateral / axillar buds to grow. Another plant hormone, cytokinin is responsible for having negative effect on the apical dominance. It promotes the growth of lateral buds.  

So, the correct answer is 'Cytokinin'

Interfascicular cambium formation is induced by

  1. Auxin

  2. Cytokinin

  3. Gibberellin

  4. Ethylene


Correct Option: B
Explanation:

Cytokinin is a plant hormone which is involved in growth and development of plants. It is required for the cambial growth. Kinetin, a type of cytokinin promotes cell division. It induces formation of interfascicular cambium in plants.

Thus, the correct answer is option B.

Cytokinin synthesis is maximum in

  1. Roots

  2. Leaves

  3. Shoot tip

  4. Fruit


Correct Option: A
Explanation:

Cytokinin is a plant hormone. It promotes cell division. It also delays the destruction of chlorophyll and protein. It shows delay of senescence in leaves. It is mostly produced in the root apex. Roots synthesize maximum amount of cytokinin hormone.

Thus, the correct answer is 'Roots'.

Which of the following is a cytokinin?

  1. Phytochrome

  2. Leucine

  3. Ethylene

  4. Zeatin


Correct Option: D
Explanation:

Cytokinin is a plant hormone which is involved in various physiological processes of plants. Zeatin is the most common type of naturally occurring cytokinin. It is found in maize. It is also found in the coconut milk. It promotes cell division.

Thus, the correct answer is option D.

Induction of cell division and delay in senescence are due to

  1. Gibberellin

  2. Auxin

  3. Cytokinin

  4. Ethylene


Correct Option: C
Explanation:

Cytokinin is a plant hormone. It plays major role in cell proliferation and cell division. It also delays the destruction of chlorophyll and protein. During senescence, cytokinin levels are low. It delays in senescence of leaves when sprayed externally by delaying the destruction of chlorophyll and proteins in leaves

So, the correct answer is 'Cytokinin'

Which is not a function of cytokinin?

  1. Delay is senescence

  2. Breaking seed dormancy

  3. Promoting bud dormancy

  4. Promoting stomatal opening


Correct Option: C
Explanation:

Cytokinin (CK) is a plant hormone. It promotes cell division and delays senescence in plants. It improves nutrient mobilization and thus delays leaf senescence. When applied externally, it mobilizes nutrients towards sites of application. It also promotes stomatal opening along with auxin hormone. It also breaks the dormancy of seeds and induce seed germination. 

Thus, the correct answer is option C.

Which plant hormone was discovered as kinetin?

  1. ABA

  2. Ethylene

  3. Auxin

  4. Cytokinin


Correct Option: D
Explanation:

Kinetin was first isolated from herring sperm DNA by Miller and Skoog. It is a type of naturally occurring cytokinin, a plant hormone. It promotes growth. It induces cell division or cytokinesis.

Thus, the correct answer is option D.

Transport of cytokinin in the plant body is

  1. Basipetal

  2. Lateral

  3. Acropetal

  4. On all sides


Correct Option: C
Explanation:

Cytokinin is a plant hormone that is synthesized in the root. It shows acropetal transport. It is exactly opposite to the basipetal transport of auxin hormone. Acropetal transport is the translocation of hormone towards the shoot apex.

Thus, the correct answer is option C.

Natural cytokinins are synthesised in tissues that are

  1. Storing food

  2. Differentiating

  3. Dividing

  4. Senescent


Correct Option: C
Explanation:

Cytokinin is a plant hormone that is involved in various physiological processes. It is growth promoting hormone. It stimulates cell division or cytokinesis and hence the name was given. It is synthesized in high concentration in tissues that are dividing such as cambium.

Thus, the correct answer is option C.

Natural cytokinins are synthesized in tissues for

  1. Differentiating

  2. Senescent

  3. Dividing

  4. Storing food


Correct Option: C
Explanation:
Cytokinin is a naturally occurring plant growth hormone (PGR) extracted from coconut milk.
Cytokinins are synthesized in root apex, endosperm of seeds, and young fruits where cell division takes place continuously. 
They stimulate cell division, cell enlargement and cell differentiation and also prevent ageing of plant parts.
Hence, natural cytokinins are synthesized in tissues for dividing.
So, the answer is C.

The precursor of Serine and Cytokine is?

  1. Oxalocetate

  2. $3$-phosphoglycerate

  3. Phosphoenolpyruvate

  4. Erythrose-$4$-phosphate


Correct Option: A

Hormone that is associated with retaining the chloroplast chlorophyll is ?

  1. Auxin

  2. ABA

  3. Cytokinin

  4. Gibberelins


Correct Option: C
Explanation:

Cytokinin is a plant hormone which acts as plant growth regulator. It is associated with retaining the chloroplast chlorophyll in the leaves. The cytokinin has anti-senescence effect on the plant. It delays the senescence of the leaves and prevents the destruction of chloroplast.

Thus, the correct answer is option C.

Which plant hormone promotes cell division?

  1. Gibberellins

  2. Cytokinin

  3. Ethylene

  4. Auxins


Correct Option: B
Explanation:
  • Cytokinins(CK) are a class of plant growth hormones that promote cell division, or cytokinesis in plants roots and shoots. For example, Kinetin and benzyl-aminopurine.
  • They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.
  • Hence the plant hormone promotes cell division is Cytokinin.
  • So, the correct answer is 'Cytokinin'.

Cytokinins helps to produce all except.

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral short growth and adventitious shoot foration

  4. Rooting on cut stem


Correct Option: D
Explanation:

Phytohormone concerned in the cell division is called cytokinins. It is involved in the formation of chloroplast in leaves, new leaves formation, lateral shoot growth and adventitious shoot formation.

So, the correct option is ‘rooting on cut stem’.

Choose the correct answer from the alternatives given.
Application of which of the following hormones prevents plant tissues from senescing or ageing?

  1. Abscisic acid

  2. Auxin

  3. Cytokinin

  4. Ethylene


Correct Option: C
Explanation:

Cytokinins help overcome apical dominance. They promote nutrient mobilization which helps in the delay of leaf senescence.

So, the correct option is 'Cytokinin'.

Choose the correct answer from the alternatives given.
A hormone that causes cell division and is found in coconut milk or in dividing root tissue is:

  1. abscisic acid

  2. auxin

  3. cytokinin

  4. gibberelthi


Correct Option: C
Explanation:

In the presence of auxin (but not in its absence) kinetin stimulated tobacco pith parenchyma tissue to proliferate in culture. Later, zeatin was identified as the first naturally occurring cytokinin in immature maize endosperm (Letham, 1973), and turns out to be the abundant cytokinin in coconut milk.

So, the correct option is 'cytokinin'.

Choose the correct answer from the alternatives given.
Cytokinins

  1. are plant hormones that promote cell division

  2. are used in combination with auxin to produce plants from undifferentiated callose tissue.

  3. also work with oligosaccharins to effect tissue differentiation

  4. all of the above.


Correct Option: D
Explanation:

It helps to produce new leaves, chloroplasts in leaves, lateral shoot growth and adventitious shoot formation. Cytokinins help overcome apical dominance. They promote nutrient mobilisation which helps in the delay of leaf senescence.

Natural cytokinins are synthesised in regions where rapid cell division occurs, for example, root apices, developing shoot buds, young fruits etc.
So, the correct option is 'all of the above'.

Cytokinins are mostly ____________.

  1. glucosides

  2. phenolics

  3. amino purines

  4. organic acids.


Correct Option: C
Explanation:

Cytokinins are plant growth hormones which are basic in nature, either amino purine or phenyl urea derivatives, that promote cytokinesis (= cell division) either alone or in conjunction with auxin. Kinetin, a synthetic cytokinin, is 6-furfuryl amino purine. Zeatin, a natural cytokinin, is 6-hydroxy 3-methyl trans 2-butenyl amino purine.

Select the pair that consists of plant growth promoters only.

  1. Auxins and cytokinins

  2. Gibberellins and ABA

  3. Ethylene and ABA

  4. All of these


Correct Option: A
Explanation:

Auxins and cytokinins are plant growth promoters, the roles played by auxin and cytokinin are as follows.

Auxins: Cell enlargement and longitudinal growth of root and shoot.
             Reactivation of cambium in the growth season, that is, responsible for secondary growth, promotes apical dominance and parthenocarpy, inhibits abcission.
Cytokinins: induces morphogenesis that is differentiation of cells into tissues and organs.delays senescence, breaks dormancy and promotes seed germination, enhances expression of a sexual characteristic- femaleness in some plants.
Auxin/cytokinin ratio influences root and shoot formation and growth
So, the correct answer is 'Auxins and cytokinins'

Which among the following is not a function of cytokinins?

  1. Essential for Cytokinesis during cell division

  2. Delays the senescence of leaves

  3. Helps in fruit ripening

  4. Helps to overcome apical dominance


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

  1. Root apices

  2. Developing shoot buds

  3. Young fruits

  4. All of these.


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 ______________.

  1. abscisic acid

  2. gibberellin

  3. cytokinin

  4. ethylene.


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.

  1. ABA

  2. Cytokinins

  3. Gibberellins

  4. Ethylene


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

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral shoot growth and adventitious shoot formation

  4. Rooting on cut stem


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.

  1. True

  2. False


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 

  1. Auxin

  2. Gibberellic acid

  3. Cytokinin

  4. Ethylene


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

  1. Skoog and Miller

  2. Letham

  3. Benson and Calvin

  4. Thimann and Went


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

  1. Ethylene

  2. Gibberellin

  3. Cytokinin

  4. IAA


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

  1. Light Intensity

  2. Temperature shock

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

  4. None of the above


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.

Coconut water is rich in 

  1. Auxins

  2. Gibberellin

  3. Abscisic acid

  4. Cytokinin


Correct Option: D
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.

The word cytokinin which induces cell division was given by ...............

  1. Yabuta

  2. Brown

  3. Letham

  4. Fitting


Correct Option: C
Explanation:

In botany, kinins were the first name given for these phytohormones. It resulted in lot of confusion. Thus, it was later changed to cytokinins to avoid confusion. It was coined by Letham in 1963.

Cell division is initiated by

  1. Cytokinin

  2. Auxin

  3. Gibberellin

  4. ABA


Correct Option: A
Explanation:

The cytokinin hormones promote cell division and tissue growth, and depend upon the presence of auxins to determine the extent of their activity. When the ratio of cytokinins to auxins is relatively high, stem and leaf growth is stimulated. 

So the correct option is 'Cytokinin'.

The name zeatin was coined by

  1. Skoog

  2. Miller

  3. Letham

  4. Melvin


Correct Option: C
Explanation:

Zeatin is a natural cytokinin first isolated from maize. It is an adenine derivative. The name zeatin was coined by Letham. It stimulates cell division or cytokinesis in plants.

Thus, the correct answer is option A.

Kinetin is

  1. Indolebutyric acid

  2. Indole acetic acid

  3. Butyric acid

  4. 6-furfuryl amino-purine


Correct Option: D
Explanation:

Kinetin is a type of cytokinin, a plant hormone. It is involved in cell division. Chemically it is 6-furfuryl amino-purine. It stimulates growth and development in plant.

Thus, the correct answer is option D.

6-(4-Hydroxy-3 Methyl-trans-2-butenylamine) purine is also called

  1. Methyl jasmonate

  2. Zeatin

  3. Brasinolide

  4. Triacontanol


Correct Option: B
Explanation:

A 6-(4-Hydroxy-3 Methyl-trans-2-butenylamine) purine is a chemical name of trans zeatin. It is a type of cytokinin, plant hormone. It was first found in Zea maize. It stimulates the cell division process in plants. It acts as plant growth regulator.

Thus, the correct answer is option B.

Natural hormone isolated from coconut milk and corn kernels is

  1. Florigen

  2. ${GA} _{3}$

  3. Auxins

  4. Zeatin


Correct Option: D
Explanation:

Zeatin is a type of cytokinin, a plant hormone. It stimulates cell division. It is present in coconut milk. It was first isolated from Zea maize (corn kernels). It stimulates growth in plants. 

Thus, the correct answer is option D.

Cytokinin is not found in

  1. Root apex

  2. Shoot apex

  3. Young fruits

  4. Mature fruits


Correct Option: D
Explanation:

Cytokinin is a plant hormone that promotes cell division in root apex, shoot apex and young fruits. It is also involved in apical dominance and leaf senescence. They are not found in mature fruits.

Thus, the correct answer is option D.

Which one is growth regulator produced by plants?

  1. NAA

  2. Zeatin

  3. 2, 4-D

  4. BAP


Correct Option: B
Explanation:

Naphthaleneacetic acid (NAA) is a type of synthetic auxin, plant hormone. It is a growth regulator. It acts as rooting agent. Zeatin a type of naturally occurring cytokinin, the plant hormone. It was first discovered in Zea maize. A 2, 4-D is a type of synthetic auxin, plant hormone. It acts as weedicide. BAP (Benzylaminopurine) is a type of synthetic cytokinin, a plant hormone. It is involved in various physiological processes of plants like cell division.

Thus, the correct answer is option B.

Cytokinins which have specific effect in cytokinesis are modified forms of

  1. Cytosine

  2. Adenine

  3. Guanine

  4. Thiamine


Correct Option: B
Explanation:

Cytokinin is a plant hormone. It has the specific effect in cytokinesis in plants. It is modified form of adenine. Kinetin, zeatin, and 6-benzylaminopurine are adenine type cytokinins. It is adenine molecule that is modified by the addition of 5-carbon sidechains off the 6 position.

Thus, the correct answer is option B.

Plant hormones used for inducing morphogenesis in plant tissue culture is

  1. Gibberellins

  2. Ethylene

  3. Cytokinins

  4. ABA


Correct Option: C
Explanation:

Morphogenesis is the process of development of shape of an organism. Cytokinins which is present at the site where rapid cell division occurs like root apices, developing shoot buds it helps in plant growth and attaining its shape. So it will help the plant to maintain its shape in tissue culture.

So the correct option is 'Cytokinins'.

State whether the following statements are true or false.
The plant ageing process, senescence, is prevented by cytokinins.

  1. True

  2. False


Correct Option: A
Explanation:

Cytokinin is a plant growth hormone that is basic in nature and is responsible for cell division. This results in cell elongation, growth, and development of plants, they work similar to auxins. Cytokinins are helpful in delaying and stopping the senescence of leaves thus resulting in the process of aging to stop by the mobilization of nutrients in the required part of the plant.

So, the correct statement is 'True'.

Cytokinins helps to produce all except

  1. New leaves

  2. Chloroplast in leaves

  3. Lateral short growth and adventitious shoot formation

  4. Rooting on cut stem


Correct Option: D
Explanation:

 Cytokinins are plant hormones that cause increased cell division by stimulating the process of mitosis. They help in the production of new leaves, formation of chloroplasts in leaves, lateral shoot growth and adventitious shoot formation. They do not have any role in root formation. So, the correct option is 'Rooting on the cut stem'.

Hormone primarily concern with cell division is

  1. IAA

  2. NAA

  3. Cytokinin

  4. Gibberellic acid.


Correct Option: C
Explanation:

Cytokinin helps in cytokinesis. Cytokinin induces cell division in the shoots. Cytokinin positively regulates cell cycle along with auxin.

Thus, the correct answer is 'Cytokinin.'

Ageing is retarted by

  1. ABA

  2. CKN

  3. GA

  4. C2H4


Correct Option: B
Explanation:

Ageing is retarded by the CKN. 

Ageing is the process in which the human being progressively more likely to die. So, Ageing is retarded by CKN.
Hence, option B is correct.

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