What is the fraction of the homozygous offspring for both recessive characters in a dihibited cross RrCc x RrCc?
1 Answer
The offsprings homozygous for both the recessive alleles( rrcc ) will be 1/16 of the total.
Explanation:
Both the plants crossed in a dihybrid cross ( RrCc X RrCc ) have genotype RrCc.
Each plant will produced 4 types of gametes :
RC, Rc, rC and rc .
Each of the 4 types of the gametes produced by one plant have equal chances to fuse with each of the 4 gametes produced by the other plant.
The possible combination of the genotypes resulting from the cross can be calculated by checker board method. There will be 16 different genotypes resulting by the chance fusion between 4 types of gametes produced by two plants crossed. Out of these only one combination will be homozygous for both the recessive alleles (rrcc).
Thus the offspring homozygous for both recessive alleles will be 1 out of 16 or 1/16 as calculated. It may be emphasized that actually observed results are approximatley closer tothe calculated values and that too when large data is taken as these calculations are based on the law of probability.
