HIV once only infected nonhuman primates and now infects humans as well. Likewise, the avian flu only infected birds but now infects humans. What causes the host range of a virus to increase?
A. The size of the virus changes over time
and allows the virus to infect a different host
cell.
B. The virus integrates with another virus to
gain the DNA sequences that allow infection
of a new host cell.
C. The virus gains entry into a new host cell
through random mutation of the virus's
genetic material.
D. Changes in the human genome over time
make humans more susceptible to infection
by different kinds of viruses.
E. None of the answer options is correct.
C
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Which one of the following statements describes the relationship between -galactosidase and -thiogalactoside?
A. They are synonyms for the same molecule. B. -galactosidase cleaves -thiogalactoside. C. -galactosidase is a precursor for synthesizing -thiogalactoside. D. -thiogalactoside is a precursor for synthesizing -galactosidase. E. -galactosidase binds to -thiogalactoside but is unable to cleave it.
If carrier testing determines that one parent is a heterozygous carrier of an autosomal recessive genetic defect, while
the other parent is not a carrier, then the fetus has a(n) ____________________ % chance of being affected. Fill in the blank(s) with the appropriate word(s).
Storage of energy is a MAJOR function of
A. protein. B. fats. C. steroids. D. nucleic acids.
Photosystem II generates ________, and photosystem I generates ________, both of which are required by the light reactions
Fill in the blank(s) with correct word