What are restriction enzymes used for?

Correct answer: Cutting DNA at specific sites

Direct answer: Option A is correct. Restriction enzymes are biological enzymes used to cut DNA at particular recognition sequences. They act like molecular scissors: an enzyme recognises a specific short DNA sequence and breaks the DNA backbone at or near that site. In genetic engineering, this allows scientists to remove a selected fragment, open a vector such as a plasmid, and join compatible DNA pieces using other enzymes. Option A gives the essential use. Option B is wrong because converting DNA information into protein is mainly the work of gene expression, involving transcription and translation, not restriction enzymes. Option C is wrong because restriction enzymes do not give light to cells; light production, when engineered, involves different genes and proteins. Option D is wrong because ribosomes are made through cellular processes involving ribosomal RNA and proteins, not by cutting DNA with restriction enzymes. Memory cue: restriction enzymes recognise and cut; they are molecular scissors, not protein-making machines.