AP BIOLOGY

Detailed explanation-1: -A male has an X chromosome from his mother and a Y chromosome from his father. Females may get the defective gene either from her mother’s defective X, or, if her father has the disorder, from her father. In either case, the girl will be a carrier and will probably pass the defect to her offspring.

Detailed explanation-2: -A male who has an X linked recessive condition will always pass on the changed gene to his daughter, who will then be a carrier. However if he has an X linked dominant condition his daughter will be affected. A male will never pass on a changed gene to his son.

Detailed explanation-3: -X-linked recessive inheritance refers to genetic conditions associated with mutations in genes on the X chromosome. A male carrying such a mutation will be affected, because he carries only one X chromosome. A female carrying a mutation in one gene, with a normal gene on the other X chromosome, is generally unaffected.

Detailed explanation-4: -In X-linked recessive inheritance, a daughter inherits a single mutated gene on the X chromosome from one of her parents. The X chromosome she inherits from the other parent will usually cancel the effect of the mutation, and she most likely will not have the genetic condition.

Detailed explanation-5: -The X chromosome in human follows criss-cross inheritance wherein father transmits its only X chromosome to the daughters while mother passes both X chromosomes to her sons. Thus, the X-linked genes, present on X-chromosomes, cannot be transmitted from father to son.