Activators can recruit factors needed for polymerase to initiate or elongate transcription. In all of these functions, the activator is merely recruiting proteins to the promoter. In bacteria, RNA polymerase is the only protein that needs to be recruited; this is not the case in eukaryotes. Indeed, in eukaryotes, a given activator might work in all three ways:

1.    Recruitment of nucleosome modifiers and remodelers	i.     “open” the promoter
2.    Recruitment of general transcription factors and mediators	ii.      That stimulate Pol II initiation and elongation
3.       Recruitment of protein complexes	iii.     To recruit PTEFb/SEC

#Question id: 3422

#Unit 9. Evolution & Diversity of Life Forms

Micro-evolution is the term used for changes in allele frequencies that occur over time.

A) It gives rise to changes in the gene pool, which results in few changes in the same species

B) It occur above species level

C) New addition, deletion in the genetic structure, resulting in the formation of new species

D) It changes occurs over short time scales

Which of the following combinations is correct?

#Question id: 3423

#Unit 9. Evolution & Diversity of Life Forms

Following statement regarding divergent evolution?

A- Spreading of same species to different and isolated environments which blocks the gene flow among the distinct populations

B. vertebrate limb of whale and elephant is one example of divergent evolution

C- Both orthologous genes and paralogous genes can be said to display divergent evolution

D- Sympatric speciation leads to divergence of one species in to two are more descendant species

Which of the following combination of above statement are correct?

#Question id: 3424

#Unit 9. Evolution & Diversity of Life Forms

Which of the following statement is correct? 

A. Darwin, theory of natural selection based on better-adapted organisms would acquire more resources and leave more offspring.

B. When population sizes become too small, individuals accumulate deleterious (harmful) mutations, and survival of offspring is threatened

C. Inbreeding is more likely to take place in nature when population size becomes very small and the number of mates is limited.

D. Effective population size can be reduced by harem mating structures

E. The movement of a few individuals between populations can counteract the effects of genetic drift

#Question id: 3425

#Unit 9. Evolution & Diversity of Life Forms

Many evolutionary forces are operating in population. In study, within population increase genetic variation due to -----A-----while decrease genetic variation due to ------B-----. Between populations increase genetic variation due to -----C-----while decrease genetic variation due to ------D-----.

#Question id: 3426

#Unit 9. Evolution & Diversity of Life Forms

Fitness of three different genotypes is given in population I and II, under natural selection which of the following statement are correct?

#Question id: 3427

#Unit 9. Evolution & Diversity of Life Forms

Natural selection can alter the frequency of distribution allele and heritable trait in different following way

A- Accumulation of those mutation that increase fitness of population in changing environment

B- Check accumulation of mutation that lower the fitness of species in unchanging environment

c- occur when population is subjected to divergent selection