8. Due to which of the following DNA repair mechanisms, one is able to distinguish newly synthesized DNA strands from older one?
A.New strands do not contain cytosine bases
B.New strands are lower in molecular size
C.Old strands are methylated while new strands are not
D.New strands are methylated while old strands are not
9. Which of the following bacterial genome was sequenced first?
A.E. coli
B.S. pneumoniae
C.H. influenzae
D.S. thermophilus
10. A nonsense mutation may result into
A.an abnormal elongation of a polypeptide
B.a large deletion within the reading frame of a gene
C.a premature termination of the synthesis of a polypeptide
D.modification of mRNA
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
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