7. Assume that the trihybrid cross AA bb CC aa BB cc is made in a plant species

Question

7. Assume that the trihybrid cross AA bb CC aa BB cc is made in a plant species where A and C are dominant but there is incomplete dominance between B and b. Consider the F2 progeny from the cross, and assume independent assortment. (a) How many phenotypic classes are expected? (b) What is the probability of the parental aa BB cc genotype in the F2 progeny? (c) What proportion would be expected to be homozygous for all three genes? (d) What proportion would be expected to be heterozygous for all three genes?

8. Mendel’s cross of homozygous round yellow with homozygous wrinkled green peas yielded the phenotypes 9/16 round yellow, 3/16 round green, 3/16 wrinkled yellow, and 1/16 wrinkled green in the F2 progeny. If he had testcrossed the round green progeny individually, what proportion of them would have yielded some progeny with round yellow seeds? (a) 1/4 (b) 1/3 (c) 1/2 (d) 3/4 (e) 0

Explanation / Answer

7 Answer:

P: AA bb CC x aa BB cc

F1=AaBbCc

A-B-CC
A-B-Cc
A-B-cc
A-bbCC
A-bbCc
A-bbcc
aaB-CC
aaB-Cc
aaB-cc
aabbCC
aabbCc
aabbcc

2x2x3=12.

b) 1/4x1/4x1/4=1/64

c) 1/8

d) 1/4

8) Answer: The answer is option e) o.

The test cross is round green and wrinkled green, and green is the phenotype of homozygous recessive.

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