#Question id: 11808
#Unit 6. System Physiology – Plant
In addition to the free bases, which are the only active
forms, active cytokinin levels are decreased through;
a) Addition of sugar molecule to the 3, 7, or 9 nitrogen of
the purine ring, called glycosylation-mediated inactivation
b) cis-trans isomerisation of zeatin
c) Irreversible cleavage by cytokinin oxidases.
Which of the following is incorrect?
#Question id: 11809
#Unit 6. System Physiology – Plant
Shortly after the discovery of kinetin, it was observed that
the differentiation of cultured callus tissue derived from tobacco pith
segments into either roots or shoots depends on the ratio of auxin to cytokinin
in the culture medium. Whereas
a) high auxin:cytokinin ratios stimulated the formation of
roots
b) high auxin:cytokinin ratios stimulated the formation of
shoots
c) low auxin:cytokinin ratios led to the formation of shoots
d) low auxin:cytokinin ratios stimulated the formation of
roots
which of the following combination is correct about the ratio of auxin to cytokinin
#Question id: 11810
#Unit 6. System Physiology – Plant
An experiment was done to see the effect of auxin: cytokinin ratios on morphogenesis can also be seen in crown gall tumors by mutation of the T-DNA of the Agrobacterium Ti plasmid,
I) Mutating the ipt gene (the tmr locus) of the Ti plasmid blocks zeatin biosynthesis in the infected cells
II) mutating either of the genes for auxin biosynthesis (tms locus)
Given some results about these above mutations ,
a) equal auxin to cytokinin ratio form undifferentiated callus tissue
b) high auxin:cytokinin ratio in the tumor cells causes the proliferation of roots instead of undifferentiated callus tissue
c) lowers the auxin:cytokinin ratio and stimulates the proliferation of shoots
What would be the result of these two mutation ?
#Question id: 11811
#Unit 6. System Physiology – Plant
The expression of IPT gene in the stress is driven by___
#Question id: 11812
#Unit 6. System Physiology – Plant
The nitrogens at the 3, 7, and 9 positions of the adenine ring of cytokinins can be conjugated to glucose residues, Alanine can also be conjugated to the nitrogen at the 9 positon, forming
#Question id: 11813
#Unit 6. System Physiology – Plant
Cytokinin-overproducing plants exhibit several
characteristics that point to roles played by cytokinin in plant physiology and
development:
a) shoot apical meristems of cytokinin-overproducing plants
produce more leaves.
b) Adventitious shoots may form from unwounded leaf veins
and petioles.
c) Leaf senescence is retarded.
d) more extreme cytokinin-overproducing plants are stunted,
with greatly shortened internodes.
e) Apical dominance is greatly increased
Which of the following statements of above given overproducing cytokinin plants is correct?