21. Which of the following virus is enveloped?

A. Adeno
B. Herpes
C. Polio
D. None of these

22. Which of the following viruses can rescue adenovirus in simian cells?

A. Rabies
B. Vaccinia
C. Simian virus 40
D. Cytomegalovirus

23. The phage components begin to assemble into mature phages only after the synthesis of

A. structural protein
B. nucleic acid
C. Both (a) and (b)
D. amino acids

24. Which of the following bacteriophage is said to have banal symmetry?

A. T2
B. T4
C. T6
D. all of these

25. Which of the following statements is correct?

A. Up to 10% of human tumors have a viral risk factor
B. Up to 40% of human tumors have a viral risk factor
C. Up to 30% of human tumors have a viral risk factor
D. Up to 20% of human tumors have a viral risk factor