Question

The probability of a cross-over occurring between two genes on the same chromosome is ______.

Options

• unrelated to the distance between them

• increased if they are closer together on the chromosome

• increased if they are farther apart on the chromosome

• impossible

Answer 1

The probability of a cross-over occurring between two genes on the same chromosome is increased if they are farther apart on the chromosome.

Explanation:

The probability of a crossover occurring between two genes on the same chromosome is directly proportional to the distance between them. The farther apart two genes are, the higher the chance that a crossover event will occur between them during meiosis. This relationship is the basis for chromosomal mapping, where crossover frequency is used as an index of physical distance between genes. Therefore, genes that are closer together have a lower probability of crossover, while those farther apart have a higher probability.