Answer to Question #274378 in Genetics for Niyah

Question

Black fur (B) is dominant to white fur (b) in guinea pigs. An F1 cross was conducted and resulted in 100% heterozygous guinea pigs (Bb). What is the genotypic ratio outcome of the F2 generation which would cross two heterozygotes?

Answer 1

If black was crossed with white and all offspring were black, then the parents were pure lines and their genotypes were BB and bb.

When the F1 are selfed in this case; the F2 genotypic ratio will be 1BB: 2Bb:1bb

One can use genetic crosses, Punnet square, or product law(rule) of probability to show this.