Question

gel electrophoresis separates dna for profiling based on the
gender of the individual.
number of chromosomes.
number of pcr products.
size (length).
shape of the double helix.

Explanation:

Gel electrophoresis uses an electric field to move DNA fragments through a gel matrix. Smaller DNA fragments move faster and farther through the gel than larger ones. So, it separates DNA based on size (length). It has nothing to do with gender, chromosome number, PCR - product number, or double - helix shape for the separation principle.

Answer:

size (length)