15. Which of the following is semi-continuous (diploid) cell line?
A.HeLa
B.HEp-2
C.WI-38
D.KB

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16. Plant viruses may be cultivated in
A.tissue culture
B.cultures of separated cells
C.whole plants
D.all of these

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17. The oncogene theory refers to
A.how chemicals inactivate viruses when applied
B.how viruses replicate in host cells
C.how viruses replicate in host cells
D.none of these

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18. In cell culture, measles virus may lead to
A.nuclear pyknosis
B.transformation of cells
C.syncytium formation
D.rounding and aggregation of cells

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19. A change from lysogeny to lysis is generally induced by
A.ultraviolet light
B.chemicals
C.irradiation
D.all of these

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20. The viral DNA is removed from the host's chromosomes and the lytic cycle occurs. The process is called
A.spontaneous induction
B.inductive infection
C.resultant induction
D.spontaneous infection

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21. The lysogenic state is governed by the activity of the regulatory region of the lambda phage genomes; this region is termed as
A.A. immunity repressor
B.immunity operon
C.operon repressor
D.none of these

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