What can happen if too much DNA is added in restriction digestion?

Correct answer: Enzyme may become insufficient and give incomplete digestion

The direct answer is A: too much DNA can make the available enzyme insufficient and lead to incomplete digestion. Restriction digestion depends on a suitable ratio between DNA amount and active enzyme units, together with the correct buffer, temperature, and time. Step by step: the enzyme has a limited catalytic capacity; if the DNA amount is increased greatly while enzyme units and reaction time remain unchanged, not every recognition site may be cut; undigested or partially digested molecules can then remain. Option A is correct. Option B is wrong because adding more DNA does not make the enzyme double; enzyme quantity does not increase automatically. Option C is wrong because restriction digestion does not convert DNA into protein; protein formation is a separate gene-expression process involving transcription and translation. Option D is wrong because buffer does not simply vanish when DNA is added, although an unsuitable DNA or sample volume can disturb the reaction conditions. Use the recommended DNA mass, enzyme units, buffer, and incubation time. A useful cue is to balance substrate, enzyme, and conditions rather than assuming that more DNA always gives a stronger result.