In guinea pigs, black coat is dominant to albino, so that true breeding lines of
ID: 15168 • Letter: I
Question
In guinea pigs, black coat is dominant to albino, so that true breeding lines of black animals, crossed to albino animals,yield an F1, that is all black.a)if these F1 animals are crossed with each other, what will be the genotypic and phenotypic ratios in the F2 (black to albinio)?
b) What will be the genotypic ratio of the progeny of a cross between homozygous dominant and heterzygous individuals?
c)What will be the genotypic ratio of progeny of a cross between two heterozygous individuals?
d) What willbe the genotypic and phenotypic ratios of the progeny of a cross between heteroozygous and homozzygous recessive individuals?
Explanation / Answer
assigning B for black and b for albino BB * bb all Bb ie black a) Bb * Bb in F2 gives B b B BB Bb b Bb bb 1/4 BB 1/2 Bb 1/4 bb 3:1 black :albino b) homozygous dominant and heterzygous BB * Bb B B BB b Bb 1:1 is the genotypic ratio of the progeny c) two heterzygous Bb * Bb B b B BB Bb b Bb bb 1:2:1 between BB Bb bb d) bb * Bb b B Bb b bb genotype 1:1 phenotype 1:1 black :albino