#Question id: 29446
#Unit 6. System Physiology – Plant
The binding of Nod factors to the Nod factor receptors (NFRs), which contain
#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: 23185
#Unit 13. Methods in Biology
#Question id: 23072
#Unit 12. Applied Biology
#Question id: 2908
#Unit 2. Cellular Organization
The H3.H4 tetramers and H2A.H2B dimers each interact with a particular region of the DNA within the nucleosome. Which of the following statement is CORRECT regarding the characteristic binding of histones with the DNA?
I. Of the 147 bp of DNA included in the structure, the histone-fold regions of the H2A.H2B dimer interact with the central 60 bp.
II. Histone H3.H4 tetramers occupy a key position in the nucleosome by binding the middle and both ends of the DNA.
III. The amino-terminal region of H4 most proximal to the histone-fold region forms a fourth alpha helix that interacts with the final 13 bp at each end of the bound DNA.
IV. The H3.H4 tetramer associate with approximately 30 bp of DNA on either side of the central 60 bp of DNA bound by H2A.H2B dimer.
V. The two H2A.H2B dimers form the bottom part of the histone octamer located across the disc from the DNA ends.