Question

Need an explination for this the answers are in the bottom

4. In pea plants, violet flower color is dominant over white flowers. For the following crosses, give the most probable genotype for EACH of the parents. !!! !! ! !

# of Progeny Parents violet! ! white

#1. violet X violet 82 0

#2 violet X violet 118 39

#3 white X white 0 50

#4 violet X white 89 92

and here is the answers :

4. We can let V be the dominant allele for violet, and v be the recessive allele for white.

#1 VV X VV, OR VV X Vv (either one works)

#2 Vv X Vv

#3 vv X vv

#4 Vv X vv

Answer 1

When analysing the parental genotaype we need to first think of the dominant and recessive allele. We always assume any letter which can represent the dominant and recessive trait.

So, Here V is stands for dominant allele, and v for recessive allele.

V will form violet colour flower and v white flower.

now, as V is dominant, VV or Vv both will make violet flower, and only vv will produce white flower.

Now, lets check fort the parental genotype-

1. violet X violet 82 0

here violet progeny is dominant , having 82 flower, and no white flower.

thus A cross of VV X VV will only give all violet flower.

	V	V
V	VV violet	VV violet
V	VV violet	VV violet

	V	v
V	VV violet	Vv violet
v	Vv violet	vv white

#2 violet X violet 118 39

this shows 3.1 ratio of genotype, or 3 part violet and 1 part white, which can only achieved by Vv X Vv

	V	v
V	VV violet	Vv violet
v	Vv violet	Vv white

#3 white X white 0 50

vv X vv , as there is no violet flower,

	v	v
v	vv white	vv white
v	vv white	vv white

#4 violet X white 89 92

here the ratio is 1:1

which only can be found with the cross

Vv X vv

	V	v
v	Vv violet	vv white
v	Vv violet	vv white