Question

What is the probability of producing a child that will phenotypically resemble either one of the two parents in the following four crosses? How many phenotypically different kinds of progeny could potentially result from each of the four crosses? a. Aa Bb Cc Ddx aa bb cc dd b. aa bb cc ddx AA BB CC DD c. Aa Bb cc Ddx Aa Bb cc Dd d. aa bb cc ddx aa bb cc dd

Answer 1

The best way to know the probabilities here is to do each cross and see the results.

a. Aa Bb Cc Ddx aa bb cc dd

Aa Bb Cc Dd

Aa Bb Cc Dd

aa bb cc dd

aa bb cc dd

You have 50% chances of Aa Bb Cc Dd which is phenotypically the same as one of the parents, and 50% chances of aa bb cc dd which are phenotypically the same as one of the parents.

b. aa bb cc dd x AA BB CC DD

aA bB cC dD

aA bB cC dD

aA bB cC dD

aA bB cC dD

You have 100% chances of having aA bB cC dD offspring, and it will be phenotypically the same as the AA BB CC DD because of the dominant allele.

c. Aa Bb cc Ddx Aa Bb cc Dd

AA BB cc DD

Aa Bb cc Dd

aA bB cc dD

aa bb cc dd

You have 25% chances of AA BB cc DD, 50% chances of Aa Bb cc Dd which are phenotypically the same as both the parents and 25% chances of aa bb cc dd.

d. aa bb cc dd x aa bb cc dd

aa bb cc dd

aa bb cc dd

aa bb cc dd

aa bb cc dd

You have 100% chances of having aa bb cc dd which are phenotypically the same as both the parents.