chromosome, and the Y chromosome is very small and does not carry as many genes or the same type of genes. Females would need two copies of the allele, one on each X chromosome, males, however, only need one copy. Thus, in males a recessive allele on the X chromosome will be expressed because there is no other allele to affect it. Sex- linked genes are often written using the sex chromosomes to denote that they are sex- linked. An example is color blindness. Normal vision is dominant to the color blind allele. Xc normal vision allele XE colorblindness allele (the lower case 'c' is underlined for clarity) Genotype Phenotype XCXC normal vision female XCXc normal vision female XQX; color blind female XCY normal vision male XcY color blind male Question 17. Color blindness is caused by a recessive allele found on the X chromosome. Normal vision is dominant over color blindness. XC : normal vision X: : color blindness Two parents have the following genotypes: XCXc and XCY a). What is the phenotype of the mother in regards to vision? b). What is the phenotype of the father in regards to vision? c). Could they produce a color blind female child? d). Could they produce a color blind male child? e). In general, does the color blindness allele occur more often in females or males? f). Provide the phenotypes + genotype of two parents that could produce a color blind female child