Question

Which of the following is FALSE. Finding a male calico cat is :

a. Impossible, as X-chromosome inactivation happens only in XX females
b. Impossible if his genotype is XY
c. Possible as long as his genotype is XXY
d. Possible if it is heterozygous for the color allele
e. Possible but extremely rare

Answer 1

The FALSE statement is option c: Possible as long as his genotype is XXY. In cats, female cats have two X chromosomes and undergo X-chromosome inactivation, resulting in a tortoiseshell pattern when the cat has two different alleles for coat color. Male cats, having only one X chromosome, do not exhibit a tortoiseshell coat color.

Step-by-step explanation:

The FALSE statement is option c: Possible as long as his genotype is XXY.

In cats, the gene for coat color is located on the X chromosome. Female cats have two X chromosomes and undergo X-chromosome inactivation. This inactivation results in a tortoiseshell pattern when the cat has two different alleles for coat color. Male cats, having only one X chromosome, do not exhibit a tortoiseshell coat color.

Therefore, finding a male calico cat is considered impossible because male cats cannot exhibit the tortoiseshell coat color due to their genotype of XY, or one X chromosome.