11. Which of the following mutation affects only a single nucleotide?
A. Aerial mutation
B. Site mutation
C. Point mutation
D. Regional mutation
12. When mutations involve vital functions so that the mutants are nonviable, it is a
A. nonsense mutation
B. lethal mutation
C. transversion
D. none of these
13. A mutagen is defined as
A. an enzyme that repairs mutations
B. a chemical or physical agent that induces mutations
C. an inhibitor of gene modification
D. a molecule which stabilizes DNA thus prevents mutations from occurring
14. The DNA sequences of rRNA genes can be used to
A. assess relatedness of eukaryotes but not prokaryotes
B. obtain a tentative identification of a new microorganism
C. predict the pulsed field gel pattern of a microorganism
D. predict whether a bacteria will be gram-positive or gram-negative
15. A nonsense mutation introduced into the DNA sequence of a gene may
A. cause premature termination of the mRNA
B. shorten the length of the protein encoded by the gene
C. have no effect on the transcript or protein made
D. cause a shift in reading frame