Generally, only female cats have the tortoiseshell phenotype for fur colour. Which of the following statements explains this phenomenon?
A) A male inherits only one allele of the X-linked gene controlling hair colour.
B) The Y chromosome has a gene blocking orange colouration.
C) Only males can have Barr bodies.
D) Multiple crossovers on the Y chromosome prevent orange pigment production.

Question

Quizplus · Accepted Answer

The tortoiseshell fur colour is controlled by an X-linked gene, meaning that the gene is located on the X chromosome. Females have two X chromosomes, so they can inherit two different alleles of this gene, one from each parent. In contrast, males have only one X chromosome and one Y chromosome, so they can inherit only one allele of the gene controlling hair colour. Thus, only female cats can exhibit the tortoiseshell phenotype because it requires two different alleles of an X-linked gene.

Generally, Only Female Cats Have the Tortoiseshell Phenotype for Fur