3.21 Genetic Probabilities

a) Predicting the probabilities of outcomes from monohybrid crosses

-the chance of offspring from one type of gene

Parents : red petal flower x white petal flower ( red is dominant )

Genotype : RR x rr

Through meiosis all genotypes os the offspring half of each of the parent alleles, which in this case is R and r.

Producing four heterozygotes

Genotype of offspring is all Rr

Phenotype of offspring is all red

When a homozygous red petaled flower is crossed with a homozygous white petaled flower the genotype of the offspring produced is Rr therefore the phenotype has a probability of 100% red.

b) crossing F1 offsprings

Parent phenotype : red x red

Parent genotype : Rr x Rr

Both Parents are heterozygotes

Through Meiosis all genotypes of the offspring will include half of each parents alleles.

 

Genotypes of offspring:                      RR   :  2Rr  : rr

Phenotype ratio of offspring(F2):     Red : Red : White    

                                                                         1   :   2    :    1

                                                                         3         :          1

                                                                         75%    :       25%