Examine a two-gene cross that follows simple Mendelian inheritance of freckles and eyebrow shape between a woman with genotype Mmpp and a man with genotype mmpp. How many phenotypes are possible in their offspring and in what ratio?

A two-gene cross that follows simple Mendelian inheritance of freckles and eyebrow shape between a woman with genotype Mmpp and a man with genotype mmpp.

                      woman                      man

Parent:            Mmpp           x         mmpp

                     Mm x pp                      m x p

                      Mp    mp        x            mp

Offspring:            Mmpp          mmpp

Two phenotypes are possible and in the ratio 1 : 1.

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There are two phenotype possible in the offspring:

i) freckles and recessive trait for eyebrow shape i.e slender

ii) no freckles and recessive for eyebrow shape.

phenotype ratio is 2:2 0r 1:1

Explanation:

Data given:

freckles are dominant trait = Mm

no freckles are recessive = mm

the couple is having recessive trait for eyebrow shape = pp

The genotype of man = Mmpp

genotype of woman = mmpp

the cross between them is shown in punnet square below:

         Mp     mp

mp    Mmpp mmpp

mp    Mmpp  mmpp

the phenotype expressed are

freckles and recessive trait for eyebrow shape i.e slender

no freckles and recessive for eyebrow shape.

phenotype ratio is

2:2

The ratio shows that there is 50% probability of  offspring having either mother's or father's genotype and phenotype.

characteristics of hydrocarbons