Sunday, 2 October 2011

3.21 Genetic Probabilities

Predict probabilities of outcomes from monohybrid crosses.
(a)
Here we are calculating the chances or probability of offspring from monohybrid cross (crosses involving just the one gene):
[this had already been covered in detail in 3.19]

Parents(phenotype)-        Red Petals          x           White Petals
           (genotype)-               RR                 x             rr                                  R(dominant)>r(recessive)

The next stage involves meiosis in plants, its where they produce the pollen grains.

This shows us:
So there is a 100% chance that the offspring will have red petals (phenotype).

(b)
 Lets breed two heterozygous flowers with red petals together.
   Rr            x               Rr
 
the genotype of the random fertilisation is 25% RR, 25% rr, 50% Rr
the phenotype of the outcome is 25% white petals and 75% red petals.


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