In cattle, the polled (hornless) condition (H) is dominant over horned (h) phenotype. A particular polled bull is bred to three cows. Cow A, which is horned, produces a horned calf; a polled cow B produces a horned calf; and horned cow C produces a polled calf. What are the genotypes of the bull and the three cows, and what phenotypic ratios do you expect in the offspring of these three matings

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podgorica podgorica · Answer 1 · 2020-04-25T21:23:23+02:00

Answer:

A)

Hh * hh

Hh, Hh, hh, hh

Out of four two calves are horned. Thus ratio of horned calves is [tex]\frac{1}{2}[/tex]

B)

Hh * Hh

HH, Hh, Hh, hh

Out of four one calf is horned. Thus ratio of horned calf is [tex]\frac{1}{4}[/tex]

C)

Hh * hh

Hh, Hh,hh, hh

Out of four two are polled . Thus ratio of polled calves is [tex]\frac{1}{2}[/tex]

Explanation:

Allele for dominant polled /hornless cattle is H

Allele for recessive horned cattle is h

A) Polled bull X horned Cow A ----> horned calf

This signifies that the polled bull is heterozygous with genotype Hh

Hh * hh

Hh, Hh, hh, hh

Out of four two calves are horned. Thus ratio of horned calves is [tex]\frac{1}{2}[/tex]

B) Polled bull X polled Cow B ----> horned calf

Both Bull ad cow are heterozygous with genotype Hh

Hh * Hh

HH, Hh, Hh, hh

Out of four one calf is horned. Thus ratio of horned calf is [tex]\frac{1}{4}[/tex]

C) Polled bull X horned Cow C ----> polled calf

Hh * hh

Hh, Hh,hh, hh

Out of four two are polled . Thus ratio of polled calves is [tex]\frac{1}{2}[/tex]