6. What is the approximate percentage of repetitive DNA sequences in human DNA?

A. 10 to 20%
B. 20 to 30%
C. 30 to 40%
D. 40 to 50%

7. The replication of a linear DNA molecule in a eukaryotic chromosome creates a problem which is reported to be sorted out by

A. using enzyme called telomerase
B. shortening of the double stranded replicated portion
C. using RNA as a template
D. none of the above

8. The rapid appearance of HIV-1 strains that are resistant to AIDS drugs is due in part to which of the following property of its reverse transcriptase?

A. AZT (zidovudine) is too expensive to be taken in effective doses
B. The RNase H domain of p66 causes error prone synthesis
C. It lacks a proofreading exonuclease
D. It has low affinity for the correct dNTP’s

9. The packing ratio of nucleosomes is about

A. 6
B. 8
C. 7
D. 9

10. After one replication in ¹⁵N, how many bands should be observed in a cesium chloride gradient?

A. One
B. Two
C. Three
D. A smear