Question

during meiosis in males, how are the x and y chromosomes able to pair and separate properly?
a. crossing over occurs across the entire y chromosome.
b. small homologous regions at the chromosome ends, called pseudoautosomal regions (pars), allow pairing.
c. they are fully homologous along their entire length.
d. the x chromosome duplicates the ys genes before meiosis.

Explanation:

During meiosis, the X and Y chromosomes pair and separate properly due to small homologous regions at the chromosome ends, known as pseudoautosomal regions (PARs). These PARs allow for the necessary pairing. Crossing over does not occur across the entire Y chromosome. The X chromosome does not duplicate the Y's genes before meiosis. And the X and Y chromosomes are not fully homologous along their entire length.

Answer:

B. Small homologous regions at the chromosome ends, called pseudoautosomal regions (PARs), allow pairing.