Recall that in many organisms, including humans, sex is determined by the sex chromosomes. Human females are XX, while human males are XY at their 23rd chromosome pair. The genes that occur on the sex chromosomes are considered sex-linked. The X chromosome is large and contains many genes, thus most sex linked traits are located on the X chromosome. In humans there are two genes, color vision and hemophilia (a blood clotting disease), which are found on the X chromosome and not on the Y chromosome, making them sex-linked.Normal color vision is dominant over red-green color blindness (a situation where red and green cannot be differentiated). Due to complete dominance, in order for a female to be affected by colorblindness, both of her X chromosomes must carry the colorblind allele. A female carrying only one copy of the colorblind allele has normal vision and is called a carrier. However, a male only has one X chromosome. If his single X carried the allele for colorblindness, he will be colorblind.

Using X for normal vision and XC for colorblind, calculate the Punnett square that would result from a carrier female mating with a colorblind male. Hint: the female genotype is XCX and the male genotype is XCY.