AP BIOLOGY

Detailed explanation-1: -Females will have two X-linked alleles (because females are XX), whereas males will only have one X-linked allele (because males are XY). Most X-linked traits in humans are recessive. One example of an X-linked trait is red-green colorblindness.

Detailed explanation-2: -Men have one X chromosome and one Y chromosome, while women have two X chromones. To experience color blindness, the genetic mutation for colorblindness must be present on the X chromosome, but for women, this means it must be present on both X chromones.

Detailed explanation-3: -Most commonly, color blindness is inherited as a recessive trait on the X chromosome. This is known in genetics as X-linked recessive inheritance. As a result, the condition tends to affect males more often than females (8% male, 0.5% female).

Detailed explanation-4: -Based upon these results, we would expect 50% of their male children to exhibit red-green colorblindness, while none of the female children would be colorblind (although 50% of these female children would be carriers for the allele).

Detailed explanation-5: -As females possess two X-chromosomes, they can “carry” a red-green colour vision deficiency – that is, one of their L/M gene arrays encodes a colour vision defect. In fact, some 15% of women are heterozygous carriers of colour vision deficiency.