Pheno and geno

Asked by SSHHII | 18th Sep, 2009, 02:11: PM

Expert Answer:

In plants like 4-0-clock (Mirabilis jalapa) and snapdragon (Antirrhinum) ,if red flowered plants are crossed with white flowered ones, F1 produces all pink flowers. Dominance thus appears to be partial or incomplete. In F2, we get red, white and pink flowers.

Parents                          RR (red)                         ×                rr(white)

 

      Gametes                         R                            ×                 r       

                                             │­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­________________________│

                                                                           

    F1                                                                   Rr(pink)

 

Selfing                              Rr                              ×                   Rr

 

                                                                                                                                    

Male gametes→

 

Female gametes↓                

R

r

R

RR(red)

Rr(pink)

r

Rr(pink)

rr(white)

 

 

 

 

 

 

 

In F2 generation, the phenotypic ratio of red:pink:white flowers = 1:2:1.

The genotypic ratio is RR:Rr:rr = 1:2:1. Thus it can be seen that phenotypic and genotypic ratios are same.  

Answered by  | 24th Sep, 2009, 03:27: PM

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