AP BIOLOGY

Detailed explanation-1: -X-linked recessive diseases most often occur in males. Males have only one X chromosome. A single recessive gene on that X chromosome will cause the disease. The Y chromosome is the other half of the XY gene pair in the male.

Detailed explanation-2: -In the case of an X-linked disease, it is usually males that are affected because they have a single copy of the X chromosome that carries the disease-causing mutation. In females, the presence of a second, non-mutated copy may cause different, milder, or no symptoms of a sex-linked disorder.

Detailed explanation-3: -X-linked recessive disorders affect males, whereas female carriers are generally spared. This is due in part to the random inactivation in females of one of the two X chromosomes in all somatic cells.

Detailed explanation-4: -In humans, the alleles for certain conditions (including some forms of color blindness, hemophilia, and muscular dystrophy) are X-linked. These diseases are much more common in men than they are in women due to their X-linked inheritance pattern.