Within a certain species of plant there can be orange red or

Within a certain species of plant there can be orange, red or white flowers. In a mating of white flower and orange flower parents, all F1 progeny had red flowers. Two F1 progeny were crossed to produce the following F2 phenotypes: How many bi-allelic genes control flower color? What are the expected phenotypic counts under your hypothesis? Use chi square goodness of fit test to evaluate your hypothesis. Give generalized genotypes for the F1 mates and F2 progeny (i.e. use an underline to designate any ambiguous parts of a genotype, like A_ to correspond to the genotype determining a dominant phenotype).

Solution

In mating of white flower and organe flower plant , all f1 progeny had red flowers

Orange -------genotype=RR

White -------genotype=rr

Red -------genotype= Rr

Orange -------genotype=RR    X     White -------genotype=rr

F1-OFFSPRING-------- Red -------genotype= Rr

F1-OFFSPRING Rr     X      F1-OFFSPRING Rr    

gametes

R

r

R

RR    Orange

Rr      Red

r

Rr     Red

rr       White

observed

Expected

(o-e)

(o-e)^2/e

RR    Orange

160

207.5

-47.5

10.87

Rr     Red

460

415

-45

4.87

rr       White

210

207.5

2.5

0.03

830

15.77

Answer : incomplete dominance , two alleles

Null hypothesis: Flower color is controlled by two allele

Alternative hypothesis : Flower color is not controlled by two allele

Calculate x value is more than table value at 5% level of significane

Hence accept alternative hypothesis

gametes	R	r
R	RR    Orange	Rr      Red
r	Rr     Red	rr       White