Question

4. Listed below are the phenotypes of the offspring from a dihybrid testcross for leaf color (coded by the G gene) and shape (coded by the J gene). offspring phenotype # of offspring purple, jagged leaves 159 purple, pointy leaves 47 green, jagged leaves 53 green, pointy leaves 162 Which of two of these phenotypic groups are parental/made with parental gametes? Briefly explain how you knew that.

Answer 1

Dihybrid test cross: GgJj X ggjj

Purple jagged = 159

Purple pointy leaves = 47

Green jagged leaves = 53

Green pointy leaves = 162

The given dihydrid ratio = 7:1:1:7

Here, the dominant alleles are segregating together and recessive alleles are segregating together.

This phenomenon is known as linkage.

This was first identified by Bateson and he named it as coupling.

Two dominant alleles or two recessive alleles coming from different parents tend to remain separate (Repulsion).

Purple jagged and green pointy are the two parental gametic combinations as they are the predominant progeny.