Why are Type II restriction enzymes more useful in laboratories?

Correct answer: They cut at or near recognition sites

Direct answer: Option A, they cut at or near recognition sites. Type II restriction enzymes recognize short, specific DNA sequences and usually cleave at a defined position within that sequence or very close to it. This predictable relationship between recognition and cutting makes the fragment sizes reproducible. Researchers can therefore use these enzymes in gene cloning, restriction mapping, and recombinant-DNA construction. Option A is correct. Option B, working only in leaves, is false because these enzymes are not limited to leaf cells and are commonly used in purified laboratory reactions. Option C, not recognizing DNA, contradicts their defining function. Option D, always joining proteins, is false because restriction enzymes cut DNA rather than join proteins; DNA ligase is the enzyme associated with sealing DNA fragments. Memory cue: Type II means a predictable recognition site and cut, making it convenient for laboratory work.