Question

Birds normally have dull red eyes. Some birds have white eyes due to a mutation in a gene on the X-chromosome. The white eyed phenotype is X-linked recessive. The sex chromosomes in birds are: females, normally XX; males, normally XY.

Part 1) If a red-eyed female who is a carrier of the white eyed allele (normal or wild-type phenotype) mates with a white-eyed male (mutant phenotype), what is the likelihood that their male offspring will have red eyes? Parents: red-eyed female carrier X white-eyed male

Select one:

a. 0

b. 1/4

c. 1/2

d. 1

Part 2: If a white-eyed female (mutant phenotype) mates with a red-eyed male (normal or wild-type phenotype), what is the likelihood that their female offspring will have red eyes?

Select one:

a. 0

b. 1/4

c. 1/2

d. 1

Thank u so much

Answer 1

Answer:- let the allele for red dull eye be Xr and white eyed be X+.

According to question cross is between-

Red eyed female carrier ( Xr X+) × white eyed male ( X+Y)

Gametes of Xr X+ is Xr and X+

Gametes of X+ Y is X+ and Y.

Now cross

Male/ female ( cross)	Xr	X+
X+	X+Xr (carrier female) red dull eye	X+X+ ( white eye female)
Y	XrY ( red dull eye male)	X+Y ( white eye male)

Results F1---)

Red dull eye ( carrier ) female= 1

Red dull eye normal male= 1

White eye female=1

White eye male= 1.

Hence the probability of their male offspring wil have red eye = 1/4.

Option b ) 1/4 is correct.

Q.2. Answer:-

Cross is between ---

White eyed female (X+X+) × red eyed male ( XrY)

Gametes of X+X+ is X+

Gametes of XrY is Xr and Y.

Now cross

Male/ female (cross)	X+
Xr	XrX+( red eye carrier female)
Y	X+Y ( white eye male)

Results--)

Red eye female = 1

White eye male=1

The probabilty that their female offspring will have red eye is = 1/2 .

Option c) 1/2 is correct.