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: 11610

#Unit 6. System Physiology – Plant

Environmental factors such as photoperiod and temperature can alter the levels of active gibberellins by affecting gene transcription for specific steps in the biosynthetic pathway such as;

a) Promotion of germination by light has been shown to be due to increases in GA1 levels resulting from a light-induced increase in the transcription of the gene for GA3ox, which converts GA20 to GA1

b) level of GA20-oxidase occurs in the highest amount in shoot tips and elongating stems, is increased under long-day conditions.  The fact that GA 20-oxidase is the enzyme that converts GA53 to GA20

c) Giving cold treatment  of Thlaspiarvense and a return to high temperatures, the ent-kaurenoic acid is converted to GA9, the most active gibberellin for stimulating the flowering response

d) Potato plants overexpressing the GA20ox gene showed tuberization, whereas transformation with the antisense gene for GA20ox inhibited tuberization

Which of the following from the given above statements is correct?

#Question id: 11611

#Unit 6. System Physiology – Plant

Given below are names of phytohormones in column I and their associated features/effects/ functions in column II.

Which of the following combination from the above statements is  correct? 

#Question id: 11612

#Unit 6. System Physiology – Plant

AMO-1618, which blocks GA biosynthesis at the cyclization step, what would be the A, B and C represents. where, the control shows no inhibitor;

#Question id: 11613

#Unit 6. System Physiology – Plant

Gibberellin can induce auxin biosynthesis and that auxin can induce gibberellin biosynthesis. If the pea plants are decapitated, leading to  a cessation in stem elongation, which one of the following prediction about this experiment is correct?

#Question id: 11614

#Unit 6. System Physiology – Plant

During the biosynthesis of GA many stages will be involved in this pathway, one of which is takes place in the plastids is GGPP is converted into the ent-kaurene via  two steps of pathway involving enzymes known as

#Question id: 11615

#Unit 6. System Physiology – Plant

Biosynthesis of GA including various enzyme which are belong to______I_________ and are localized in the ______II__________.