Question

the frequency of crossing over between genes on a chromosome over can be used to determine which gene is recessive. to determine which gene is dominant. to make chromosome maps

Explanation:

Crossing - over frequency between genes on a chromosome is used in genetic mapping. Chromosome maps (genetic maps) are created based on the recombination (crossing - over) frequencies. The higher the crossing - over frequency between two genes, the farther apart they are on the chromosome. Dominance or recessiveness of a gene is determined by observing the phenotype of an organism (e.g., in a monohybrid cross), not by crossing - over frequency.

Answer:

C. to make chromosome maps