TLS Online TPP Program

#Question id: 2888


Repressive complexes have been discovered that are composed of multiple repressing proteins bound to RNAs many kilobases in length that do not contain long open reading frames and are consequently called long noncoding RNAs or lncRNAs. Which of the following statements is correct regarding the regulation of these lncRNAs?

#Unit 2. Cellular Organization
  1. X inactivation is controlled by a roughly 100-kb domain on the X chromosome called the X-inactivation center that encodes a lncRNA known as XIST that is responsible for inactivation of the maternally derived chromosome.

  2. Depletion of a 2.2-kb noncoding RNA expressed from the HOXC locus by siRNA unexpectedly led to derepression of the HOXD locus, a roughly 40-kb region on another chromosome encoding several Hox proteins and multiple other noncoding RNAs, in these cells.

  3. HOTTIP lncRNA, which is transcribed from the 5’end of the HOXA locus, is proposed to coordinate the activation of HOXA genes by binding to a histone H3 lysine 9 methylase represents the cis activation by lnc-RNAs.

  4. In humans, but not in mice, a lncRNA called XACT has been discovered to associate with multiple sites along the full length of the active X chromosome and is postulated to contribute to repression of gene activity on that chromosome.

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TLS Online TPP Program

#Question id: 4995

#Unit 11. Evolution and Behavior

It has been found that certain proteins of the complex motor that drives bacterial flagella are modified versions of proteins that had previously belonged to plasma membrane pumps. This is evidence in support of the claim that

TLS Online TPP Program

#Question id: 4996

#Unit 11. Evolution and Behavior

An explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, insect wings could best be described as

TLS Online TPP Program

#Question id: 4997

#Unit 11. Evolution and Behavior

If one organ is an exaptation of another organ, then what must be true of these two organs?

TLS Online TPP Program

#Question id: 4998

#Unit 11. Evolution and Behavior

Many species of snakes lay eggs, but in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth is an example of

TLS Online TPP Program

#Question id: 4999

#Unit 11. Evolution and Behavior

In the 5—7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis. Both species had large brains and advanced intellects. The fact that these traits were common to both species is most easily explained by which of the following?

TLS Online TPP Program

#Question id: 5000

#Unit 11. Evolution and Behavior

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that