1. A nicked RNA molecule can be ligated by

A. T4 RNA ligase
B. DNA polymerase
C. T4 DNA ligase
D. all of these

2. The tertiary structure of yeast tRNA

A. involves extensive base stacking interactions
B. resembles the 3-dimensional structure of other tRNAs
C. is maintained mostly by non-Watson-Crick base pairing
D. all of the above

3. Which of the following RNA characteristically contains unusual purines and pyrimidines?

A. rRNA
B. nRNA
C. mRNA
D. tRNA

4. The anticodon is a structure on

A. mRNA.
B. tRNA.
C. aribosome.
D. rRNA.

5. The genetic material of retroviruses such as HIV is

A. DNA
B. RNA
C. protein
D. all of these