There are five known families of enzyme complexes that actively move or displace nucleosomes, hydrolyzing ATP in the process, three of which are particularly important in transcriptional activation. Which of the following statement is/are correct regarding these nucleosome remodeling complexes?

I. SWI/SNF remodels chromatin so that nucleosomes become more irregularly spaced, and stimulate the binding of transcription factors. It includes a bromodomain near the C-terminus of the active ATPase subunit, which interacts with acetylated histone tails.

II. Some members of a family, SWR1, are involved in deposition of the H2A.Z histone variant in transcriptionally inactive chromatin. 

III. NURF, a member of the ISW1 family, remodels chromatin in ways that complement and overlap the activity of SWI/SNF. These two enzyme complexes are crucial in preparing a region of chromatin for active transcription.

#Question id: 4989

#Unit 11. Evolution and Behavior

If the malesʹ halteres have species-specific size, shape, color, and use in courtship displays, and if the speciesʹ ranges overlap, then the speciation events may have been driven, at least in part, by which of the following?

#Question id: 4990

#Unit 11. Evolution and Behavior

Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then species W and Y

#Question id: 4991

#Unit 11. Evolution and Behavior

Which of these fly organs, as they exist in current fly populations, best fits the description of an exaptation?

#Question id: 4992

#Unit 11. Evolution and Behavior

The existence of the phenomenon of exaptation is most closely associated with which of the following reasons that natural selection cannot fashion perfect organisms?

#Question id: 4993

#Unit 11. Evolution and Behavior

If the prokaryotic flagellum developed from assemblages of proteins that originally were not involved with cell motility but with some other function instead, then the modern prokaryotic flagellum is a(n)

#Question id: 4994

#Unit 11. Evolution and Behavior

In certain motile prokaryotes, dozens of different proteins comprise the motor that powers the prokaryotic flagellum. The motor has a complicated structure, and its various proteins interact to carry out its function. Based on Darwinʹs explanation for the existence of human eyes, how would he probably have explained the existence of such motors?