29. Plasmids which are maintained as multiple copy number per cell are known as
A.stringent plasmids
B.relaxed plasmids
C.cryptic plasmids
D.none of these
30. Cosmid vectors are
A.plasmids that contain fragment of λ DNA including the cos site
B.phages that lack cos site
C.plasmids that have no selection marker
D.cryptic plasmids
31. Cosmids lack
A.genes coding for viral proteins
B.origin of replication
C.marker genes coding for replication
D.cleavage site for the insertion of foreign DNA
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