Question

(Problem 66a) Male house cats are either black or orange; females are black, orange, or calico. If these coat-color phenotypes are governed by a sex-linked gene, how can these observations be explained?

A.The gene is on the X chromosome and three alleles must be involved.
B.Calico males die before birth
C.In males, orange is always dominant over calico.
D. The gene is on the X chromosome and heterozygous females display the calico phenotype.	.
E.Calico males are sterile.

(Problem 66 B)Male house cats are either black or orange; females are black, orange, or calico. Assuming these coat-color phenotypes are governed by a sex-linked gene, determine the phenotypes expected in the progeny of a cross between an orange female and a black male.

A.All cats are black.

B.All cats are orange.

C.All cats are calico.

D.Female cats are orange; male cats are black

E.Female cats are calico; male cats are orange.

(Problem 66 C)Male house cats are either black or orange; females are black, orange, or calico; these coat-color phenotypes are governed by a sex-linked gene. Half the females produced by a certain kind of mating are calico, and half are black; half the males are orange, and half are black. What colors are the parental males and females in this kind of mating?

father is black; mother is calico
	A.father is black; mother is orange
	B.father is orange; mother is orange
	C.father is orange; mother is black
	D.father is orange; mother is calico

(Problem 66d) Male house cats are either black or orange; females are black, orange, or calico; these coat-color phenotypes are governed by a sex-linked gene. A certain kind of mating produces progeny in the following proportions: one-fourth orange males, one-fourth orange females, one-fourth black males, and one-fourth calico females. What colors are the parental males and females in this kind of mating?

A.father is black; mother is calico
	B.father is black; mother is orange
	C.father is orange; mother is orange
	D.father is orange; mother is black
	E.father is orange; mother is calico

Answer 1

Answer:

66a).

D. The gene is on the X chromosome and heterozygous females display the calico phenotype.

Explanation:

XRXR = Orange female

XRXr = Caico female

XrXr = black female

XRY = Orange male

XrY = black male

66b). E.Female cats are calico; male cats are orange.

Explanation:

Orange female (XRXR)x (XrY) black male ---Paretsn

	Xr	Y
XR	XRXr (caico female)	XRY (orange male)

66c). A. Father is black; mother is calico

Explanation:

Calico mother (XRXr) x Black father (XrY)---Parents

	Xr	Y
XR	XRXr (caico female)	XRY (orange male)
Xr	XrXr (black female)	XrY (black male)

66d). E.father is orange; mother is calico

Explanation:

Calico mother (XRXr) x orange father (XRY)---Parents

	XR	Y
XR	XRXR (orange female)	XRY (orange male)
Xr	XRXr (calico female)	XrY (black male)