#Question id: 18225
#Unit 7. System Physiology – Animal
#Question id: 10703
#Unit 10. Ecological Principles
Keystone predators can maintain species diversity in a community if they
#Question id: 4104
#Unit 3. Fundamental Processes
Consider following statements for catalytic mechanism of RNA polymerase
A. RNA synthesis by RNA polymerase. The reaction involves two Mg2+ ions, coordinated to the phosphate groups of the incoming nucleoside triphosphates (NTPs)
B. Three Asp residues, which are highly conserved in the RNA polymerases of all species. One Mg2+ ion facilitates attack by the 39-hydroxyl group on the phosphate of the NTP; the other Mg2+ ion facilitates displacement of the pyrophosphate, and both metal ions stabilize the pentacovalent transition state.
C. About 17 bp of DNA are unwound at any given time. RNA polymerase and the transcription bubble move from left to right along the DNA as shown, facilitating RNA synthesis. Movement of an RNA polymerase along DNA tends to create negative supercoils (overwound DNA) ahead of the transcription bubble and positive supercoils (underwound DNA) behind it.
D. The RNA polymerase is in close contact with the DNA ahead of the transcription bubble as well as with the separated DNA strands and the RNA within and immediately behind the bubble. A channel in the protein funnels new NTPs to the polymerase active site. The polymerase footprint encompasses about 35 bp of DNA during elongation.
#Question id: 15985
#Unit 12. Applied Biology
#Question id: 10343
#Unit 6. System Physiology – Plant
In many plants, nitrate is assimilated in the root as well as in the shoot according to their native place. Some of the given statements about nitrate assimilation;
a) If plants native to temperate region assimilate NO3- at root
b) If plants native to temperate region assimilate NO3- at shoot
c) Plants native to tropical or subtropical region assimilate NO3- at root
d) Plants native to tropical or subtropical region assimilate NO3- at shoot
Which of the following combination from above statements is correct?