Plasmid has been used as vector because:
- Both ends show replication
- It has antibiotic resistance gene
- It is circular DNA which has capacity to join to eukaryotic DNA
- It can move between prokaryotic and eukaryotic cells
Answer
(3) It is circular DNA which has capacity to join to eukaryotic DNA
Solution
As per NCERT, a plasmid is an autonomously replicating circular extra-chromosomal DNA of bacteria.
⇒ When a piece of alien (eukaryotic) DNA is linked with the plasmid, it is multiplied along with the plasmid in the host cell.
∴ This ability of the circular plasmid DNA to join with foreign (eukaryotic) DNA makes it a vector.
Answer: (3)