Embryonic stem cells are pluripotent. What
does this mean?
a. they can divide an unlimited amount of
times
b. they can give rise to most, but not all body
cell types
c. they can give rise to any of the body cell
types
d. they are indestructible
e. they can give rise to different, unique
individuals
C
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A scientist studying evolution of peppered moths (Biston betularia) in Michigan observed that the percentage of melanic moths increased by around 2% from 1960-1961. Has evolution occurred in this population?
A. No, because melanism wasn't adaptive at that time. B. No, because the frequency of the melanic moths did not change enough to be considered evolution. C. Yes, because the frequency of the melanic moths in the population changed over time. D. Yes, because the frequency of melanic moths decreased.
In female humans and other mammals, dosage compensation is achieved by the inactivation of one of the two X chromosomes in each cell. Which one of the following does not occur in the X-inactivation mechanism of female mammals?
A. X-inactivation begins with a small region of the X chromosome that contains a gene for an X-inactivation specific transcript (Xist). B. Xist is expressed in low levels except when an X chromosome is about to be inactivated. C. When an X chromosome is about to be inactivated, Xist RNA transcripts increase markedly and undergo splicing, but do not encode a protein. D. Xist RNA is attracted to and associates with a protein called the X-chromosome inactivation center (XIC), which becomes entirely coated with Xist. E. Xist RNA recruits factors that promote DNA methylation, histone modification, and other changes associated with transcriptional silencing.
"Mad cow" disease, also called bovine spongiform encephalopathy, is caused by a ________
a. virus b. fungus c. bacteria d. prion
The major histocompatibility complex is important in a T-cell's ability to:
A. recognize specific viruses. B. recognize self from nonself. C. recognize specific parasites. D. recognize specific bacteria.