Which of the following represents a germ layer?
a. blastula
b. inner cell mass
c. ectoderm
d. zygote
c. ectoderm
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Actin filaments have polarity. This means that the two ends can be identified due to structural differences. The plus end is the end to which subunits are added more rapidly, or the end of polymerization
Which of the following would enable you to identify the plus end of actin filaments? A) Add radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization. B) Add radiolabeled actin subunits to a mixture of actin filaments in which conditions favor depolymerization. C) Determine the ionic charge of the ends of the actin filaments.
Smallpox is an enveloped virus with a DNA genome. We have eliminated this once deadly virus through an aggressive worldwide vaccination program. Why might a vaccine be successful with smallpox, but not with HIV?
A. DNA genomes mutate less rapidly than RNA genomes. B. Host cells have RNA in them, and thus do not raise antibodies against RNA. C. RNA is more stable than DNA, and is less likely to be destroyed by the vaccine. D. Viruses with DNA genomes must replicate inside a host cell. E. Smallpox is an enveloped virus.
Proteins are often regulated by phosphorylation by enzymes called
a. protein phosphatases. b. phosphoproteases. c. protein phosphorylases. d. protein kinases.
Stabilizing selection occurs more often than disruptive selection.
a. true b. false