Question

Which of the following statement(s) about plasmid is/are correct?

[I)] It can replicate by itself
[II)] Hybrid plasmid is introduced into bacteria by transformation
[III)] Other than bacteria, plasmid can also be found in bacteriophage

• A. I only
• B. I and II only
• C. II and III only
• D. I, II and III

Hint:

Plasmids are \textbf{self-replicating DNA vectors} used in biotechnology and are introduced into bacteria mainly by \textbf{transformation}.

Answer 1

The Correct Option is B

Step 1: Plasmids are extrachromosomal, circular DNA molecules that possess their own origin of replication. Hence, statement I is correct.
Step 2: In genetic engineering, a hybrid (recombinant) plasmid carrying foreign DNA is commonly introduced into bacterial cells by the process of transformation. Hence, statement II is correct.
Step 3: Bacteriophages are viruses that infect bacteria and contain their own viral genome. Plasmids are not found in bacteriophages; they are independent replicons mainly present in bacteria (and some eukaryotes like yeast). Hence, statement III is incorrect.