Coat color in cats is determined by genes at several different loci. At one locu
ID: 96875 • Letter: C
Question
Coat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X^+) encodes black fur: another allele (X^0) encodes orange fur. Females can be black (X^+ X^+), orange (X^0 X^0), or a mixture of orange and black called tortoiseshell (X^+ X^0). Males are either black (X^+ Y) or orange (X^0 Y). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill's house, spends the night out, and mates with a stray male. Patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. What was the genotype of the stray cat with which Patches mated? X^+ Y X^+ X^0 X^0 Y X^0 X^+ YYExplanation / Answer
The correct answer is option c) X0Y. In this case, Bill has a female cat. Thus, the stray cat has to be a male. So, all the other options with no Y chromosome are eliminated.
The genotypes of the offsprings will be:
Orange male: X0Y
Black male: X+Y
Tortoiseshell females: X+X0
The cross that takes place is as follows:
(Patches) -> X+X0 X0Y <- (Stray Cat)
/
X+X0 , X0 X0 , X0Y, X+Y
(Kittens: Tortoiseshell females, Orange Female, Orange male and Black male respectively).