Given below are two columns. In Column I is the list of four enzymes and in Column II is the list of functions of the given enzymes. Which one of the following options shows the enzymes matched with their respective functions correctly ?

The correct option is P-iii, Q-i, R-ii, S-iv.

Based on the table provided in the image, we can match each enzyme in Column I with its correct biological function in Column II as follows:

1. P. DNA Ligase → iii. Joins the DNA fragments
DNA ligase is a crucial molecular gluing enzyme. It catalyzes the formation of a phosphodiester bond between the adjacent 3'-hydroxyl and 5'-phosphate ends of DNA fragments (such as Okazaki fragments during DNA replication), effectively joining the DNA strands together.

2. Q. Restriction exonuclease → i. Removes nucleotides from ends of DNA
Exonucleases are nucleolytic enzymes that cleave nucleotides one at a time from the free ends (either the 5' or 3' ends) of a polynucleotide chain. Therefore, restriction exonucleases remove nucleotides from the terminal ends of a DNA molecule.

3. R. Taq polymerase → ii. Extends primer on a DNA template
Taq polymerase is a thermostable DNA polymerase extracted from the thermophilic bacterium Thermus aquaticus. In techniques like Polymerase Chain Reaction (PCR), it functions to synthesize new DNA strands at high temperatures by adding nucleotides to extend the primers along the template DNA strand.

4. S. Restriction endonuclease → iv. Cuts DNA at a specific position
Unlike exonucleases, endonucleases cleave phosphodiester bonds internally within the DNA molecule. Restriction endonucleases make precise cuts at specific nucleotide sequences, known as recognition or restriction sites, within double-stranded DNA. This property makes them indispensable tools in recombinant DNA technology.

Thus, matching all components correctly yields: P-iii, Q-i, R-ii, S-iv.