Biology Regents Practice #7

What genetic mutation is responsible for the ginger color in domestic cats?

• A DNA deletion on the X chromosome

• A mutation on the Y chromosome

• A gene duplication on the X chromosome

• A mutation in the Arhgap36 gene itself

Explain how the location of the ginger color gene on the X chromosome results in differences between male and female cats’ fur colors.

Why are most completely orange cats male?

• Males have one X chromosome, so the mutation is fully expressed

• Females have two X chromosomes, so the mutation is not expressed

• The mutation is only present in male cats

• Male cats have a different gene that causes orange fur

Based on the article, why do most calico and tortoiseshell cats tend to be female?

• Use evidence from the passage to analyze how X chromosome inheritance and gene activity create these color patterns.

How does the DNA deletion affect the pigment production in cats?

• It stops genes needed to make brown-black pigment, leading to yellow-red pigment production

• It increases the production of brown-black pigment

• It has no effect on pigment production

• It changes the pigment to blue-green

Apply the concepts discussed in the passage to a real-world scenario. Compare the way the Arhgap36-associated deletion impacts pigment production in cats with how coat color is determined in another mammal, such as tigers or dogs.

• What does this suggest about the uniqueness of the mutation in domestic cats?

Imagine you are a breeder who wants a litter of fully orange kittens. Using your knowledge of X chromosome inheritance, which parents should you select, and why?

• Apply genetic principles to determine the most likely breeding pair for this outcome.