biology punnett

Question

5a) Red roan hair colour in some horses is due to codominance of the white allele and the red allele. If a red roan horse mates with a white horse, indicate the genotypic and phenotypic ratios that would result.

5b) Snapdragons show incomplete dominance in flower colour. A cross between red flowers and white flowers will produce pink flowers. If a white flower is crossed with a pink flower, what is the probability of producing a pink flower?

do it by hand

Answer 1

Red roan x White (Rr x rr)

1/2 R x 1 r = 1/2 Rr

1/2 r x 1 r = 1/2 rr

genotypic ratio: 1 Rr : 1 rr

phenotypic ratio: 1 Red roan : 1 White

Red flower x White flower (RR x rr)

1 R x 1 r = 1 Rr

All pink.

Pink flower x White flower (Rr x rr)

1/2 R x 1 r = 1/2 Rr

P(Rr) = P(Pink flower) = 1/2= 0.5