11. Which of the following enzymes unwind short stretches of DNA helix immediately ahead of a replication fork?

A. DNA polymerases
B. Helicases
C. Single-stranded binding proteins
D. Topoisomerases

12. During DNA replication in prokaryotes, synthesis begins on the circular chromosome

A. always at the same place
B. at any stretch of DNA that is high in AT pairs
C. randomly on the chromosome
D. at the promoter

13. DNA replication rates in prokaryotes are approximate of the order of

A. 10 bases per second
B. 1,00 bases per second
C. 1,000 bases per second
D. 10,000 bases per second

14. Which of the following lacks 3′-5′ exonuclease activity?

A. Short fragment of DNA polymerase I
B. Taq DNA polymerase
C. T4 DNA ligase
D. All of the above

15. The synthesis of DNA by DNA polymerase occurs in the

A. 3′ to 5′ direction
B. 5′ to 5′ direction
C. 5′ to 3′ direction
D. 3′ to 3′ direction