Sphincters
a. are circular muscles.
b. prevent backflow.
c. are smooth muscles.
d. are found at the entrance and exit of the
stomach.
e. include all of these.
Answer: e
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48. If a person is treated with a single anti-HIV drug, they often end up with a resistant strain. How does this occur?
A. The HIV wants to avoid the drug, so it becomes resistant. B. The drug causes mutations in the HIV, making them resistant to the drug. C. All of the answer choices are correct. D. The drugs kill all sensitive viruses, leaving only the preexisting resistant viruses. E. The drugs weaken the immune system, making a patient more susceptible to infection with resistant strains of HIV.
Biomagnification occurs with chemicals that
A. dissolve in only acidic solvents. B. dissolve in water. C. are not readily degraded and dissolve in fat. D. are not readily degraded and dissolve in water. E. dissolve in only basic solvents.
The enzyme terminase is responsible for
a. formation of eukaryotic centromeres. b. packaging a phage genome into its capsid. c. the decondensation of eukaryotic chromatin. d. supercoiling bacterial DNA. e. formation of eukaryotic telomeres.
When experimenting with Streptococcus pneumoniae in the 1920s, Griffith concluded that some substance from the dead S strain bacteria passed to the R strain bacteria, imparting virulence and the ability to form a capsule. Avery and others continued the search for the substance that "transformed" the R strain into the S strain.Hypothesis I:Genetic material or "transforming substance" is protein.Hypothesis II:Genetic material or "transforming substance" is RNA.Hypothesis III:Genetic material or "transforming substance" is DNA.An experiment was performed that demonstrated that RNAase failed to prevent transformation of the R strain to S strain. This finding
A. supports Hypothesis I. B. supports Hypothesis II. C. supports Hypothesis III. D. rejects Hypothesis I only. E. rejects Hypothesis II only. F. rejects Hypothesis III only. G. does not support or provide information to reject any of these hypotheses.