A male Styracosaurs with the genotype AaBbDdEe mates with a female with the geno

Question

A male Styracosaurs with the genotype AaBbDdEe mates with a female with the genotype AaBBdd.

a) What is the probability they would have a child with short horns?

b) What percentage of their children should have red spots on their frills and short horns?

c)Why is the female's gentoype for E unknown?

d) What phenotypic ratio of the progeny would you expect if the female is homozygous dominant for the E locus?

e) What phenotypic ratio of the progeny would you expect of the female is heterozygous for the E locus?

f)What phenotypic ratio of the progeny would you expect if the female is homozygous recessive for the E locus?

Explanation / Answer

a)

Assume allele D for horns. The capital D denotes dominant trait and small d denotes recessive trait. When the given male is crossed with female who is Homozygous dominant for E, then the number of children with short horns would be 96.  When crossed with female who is heterozygous for allelle E, the number of children with short horns would be 24.

b)

Assume allele E for Red spots on frills. The captial E denotes the dominant trait that is having red spots on frills. Thus, from the punnett square we got 72 children with short horns and red spots on frills.

d)

The phenotypic ratio of the progeny we would expect if the female is homozygous dominant for the E locus is as follows:

AABBDdEE - 37.5%

AABBddEE - 37.5%

aaBBDdEE - 12.5%

aaBBDdEE - 12.5%

e)

The phenotypic ratio of the progeny we would expect if the female is heterozygous for the E locus is as follows:

AABBDdEE - 28.1%

AABBddEE/Ee - 28.1%

AABbDdee - 9.4%

AABBddee - 9.4%

aaBbDdEE - 9.4%

aaBBddEE - 9.4%

aaBBDdee - 3.1%

aabBddee - 3.1%

Thus, there are 8 distinsct phenotypes.

f)

The phenotypic ratio of the progeny we would expect if the female is heterozygous for the E locus is as follows:

Again 8 distinsct phenotypes are observed with 4 phenotyes in the ratio of 18.8% and the other 4 in the ratio of 6.3%.

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