Plant Growth Regulator Short Question

 59) Which phyto-hormones are responsible for callus formation in plant tissues?

 Auxins,Gibberelin and  Cytokinin

 

60) What are bound auxins and free auxins?

Auxins which  remain conjugated with sugars, sugar alcohol or proteins are called bound auxin.They remain inactive in cells.

 

Auxin which exist  as a free soluble auxin are called as free auxin.They remain active in cell and tissue.

61) Name the precursor of auxin in plants.

The major precursor of Auxin is most likely the amino acid Tryptophan.

 

62) What is basipetal  ant acropetal transport of auxin?

In shoot system auxins move downwards from the apex to the base of the tem.Such  transport of auxin is called  basipetal polar transport.

 

In root system auxins move up wards from the root tip to the base of stem.Such  transport of auxin is called  acropetal polar transport.

 

63)Write the auxin transport pattern in root?

In root system auxins move up wards from the root tip to the base of stem.Such  transport of auxin is called  acropetal polar transport.

 

64) What is anti-auxin?

Any substance that inhibits auxin by competing for the same receptors are known as antiauxin.

 

65) Name two synthetic auxins.

  Indole Butyric Acid and 2,4-Dichloro acetate

 

66) Name one hormone which delays leaf abscission.

Auxin/ cytokinin

 

67)Name one fungus which produces gibberellin.

Gibberella fujikuroi , an  endophytic fungi produce gibberellins.

 

68)Name one hormone which is able to break seed and bud dormancy.

Gibberellins

69) Name the hormones which help in development of partheno-carpic fruits.

Auxin

70) Which plant hormone is required during malting of barley?

Gibberelin

71) Name one gibberellin biosynthetic inhibitor.

Auxin

 

72) Name two naturally occuring cytokinins.

Zeatin and Kinetin

 

73)Name one synthetic compound that antagonizes cytokinin.

 

74)Which hormones are synthesized from Agrobacterium Ti plasmid?

Auxin and Cytokinin

 

75) Which plant hormones regulate cell division?

Cytokinin

 

76)Name one plant hormone which promotes ethylene biosynthesis.

Gibberelin

 

77) Which is the immediate precursor of ethylene? Mention its two  physiological functions.

ACC (1-Aminocyclopropane-1-Carboxylic acid) is the immediate precursor of ethylene.

(i) It helps in fruit ripening.    (ii)It also helps in leaf abscission.

 

78)Which hormone induces leaf senescence?

Ethylene

 

79)Mention two commercial uses of ethylene.

 

 

80)Name the hormones which control vivipary.

Gibberelin and ABA

 

81)Which hormones help in stomatal opening and closing?

ABA

 

82)What is coat imposed dormancy?

Testa

 

83)What are photohiasne and quiescent seeds?

When a seed fails to germinate due to the unfavourable environmental conditions like extreame dry or warm or cold for germination.Such seeds are called quiescent seeds.

 

84) What are microbiotic ,mesobiotic and macrobiotic seeds?

The seeds which have life span 3 years  are called microbiotic seeds.The seeds which have life-span ranges from 3–15 years  are called mesobiotic seeds.The seeds which have life-span  from 15 to more than 100 years are called macrobiotic seeds.

 

85)Name two synthetic hormone which is used as weed killer.

2,4-D  and 2,4,5-T

 

86) What is the chemical name of kinetin?

6-Furfurylamino-purine

87) Give two examples of long day plants.

Solanum tuberosum and Gossypium hirsutum

 

88) Give two examples of short day plants.

Nicotiana  tabacum and Xanthium pennsylvanicum

 

89) What is critical day length?

The photoperiod(relative length of day and night)required to induce flowering is referred to as the critical day length.

 

90) Why does cytochromc act as a good electron carrier?

Cytochrome contain Iron ion which appear as both reduced and oxidized form.Due to the inter convertion of Iron cytochromc act as a good electron carrier.

 

91) What are florigen and antiflorigen?

Florigen is the hypothesized hormone-like molecule responsible for controlling or triggering flowering in plants.Florigen is produced in the leaves, and acts in the shoot apical meristem of buds and growing tips.It is known to be graft-transmissible,and even functions between species.

 

Substances which counteract florigen or inhibit the activity of florigen, are known as antiflorigen.

 

92) What is phytochrome?

Phytochrome  is a blue proteinaceous plant pigment which perceive light stimuli and controls flowering responses in plants.

 

93) Name two phytochrome mediated photoresponses in plants.

(i)Flowering and (ii)Crop yield are  two  important phytochrome mediated photoresponses .

 

94)What is climacteric fruit?

The climacteric is a stage of fruit ripening associated with increased ethylene production and a rise in cellular respiration. Apples, bananas, melons, apricots, tomatoes (among others) are climacteric fruit. Citrus, grapes, strawberries are non-climacteric (they ripen without ethylene and respiration bursts).

 

95)Define bolting?

Bolting is the term applied to vegetable crops when they prematurely run to seed, usually making them unusable. A cold spell or changes in day length initiates this behaviour. It can affect a wide range of vegetables including lettuce, spinach and fennel.

 

96)Name the plant hormone having least molecular weight.

Ethylene

 

97)What is dormin?

Dormin is a hypothetical plant hormone which is  thought to be responsible for dormancy .

 

98)What is vernalin

Vernalin is a hypothetical plant hormone which is  thought to be responsible for vernalization.