DNA fragments produced with restriction enzymes are separated in gel mainly on what basis?

Correct answer: Size

The direct answer is A: size. In gel electrophoresis, DNA fragments are placed in a gel and an electric field is applied. DNA has a negative charge, so it moves toward the positive electrode through the gel. The gel acts like a mesh. Step by step: restriction enzymes cut DNA into fragments; the fragments are loaded into wells; the electric field makes them move; smaller fragments pass through the gel pores more easily and usually travel farther, while larger fragments move more slowly and remain nearer the wells. Therefore the separated bands mainly indicate fragment length or size. Option A is correct. Option B, taste, is not a physical property used in electrophoresis. Option C, smell, has no role because DNA bands are not separated by odour. Option D, sound, is unrelated to the electric movement of charged DNA. In a careful laboratory setting, migration can also be affected by gel concentration, voltage, and DNA shape, but for this school question the main basis is size. Exam cue: in gel electrophoresis, small DNA fragments run farther than large ones.