For the genetic cross RrYy The probability of YellowRound or

For the genetic cross RrYy: The probability of Yellow/Round or Green/Wrinkled as the first offspring is?

and the probability of Yellow/Wrinkled or Green/Round as the second is?

R=Yellow r=Green Y=round y=wrinkled

Please explain any reasoning/ratios.

I understand how to do the branching method and got 9/16 + 1/16 for the first question, is the final answer then 10/16 aka 5/8?

I got 6/16 for the second answer, but just wanted to verify.

Thanks in advance, Max

Solution

Assume that the gene coding for round is R and the gene coding for wrinkled is r; R is dominant over r. Similarly, the gene coding for yellow is Y and the gene coding for green is y; Y is dominant over y.

RrYy* RrYy --à R_ Y_ (9/16, round and yellow), R_ yy (3/16, round, green), rr Y_ (3/16, wrinkled, yellow), rr yy (1/16, wrinkled, green)

To calculate the probability of occurrence of A or B, we use the “addition” rule.

Thus, the probability of yellow/round or green/wrinkled is = 9/16+ 1/16 = 5/8

The the probability of Yellow/Wrinkled or Green/Round is = 3/16 + 3/16 = 3/8