How many different diploid genotypes are possible for a gene

How many different diploid genotypes are possible for a gene that exists in seven allelic forms?

Solution

Ans. Given,

            Ploidy = diploid

            Number of alleles of gene = n = 7

For a diploid organism, number of genotypes = [ (n) (n+1) ] / 2

                                                            Where, n = number of alleles        

Or, number of genotypes = [7 x (7+1)] / 2

                                                = 28

Also,

Number of genotypes = sum of all number from n to 1

                                    = (7 + 6+ 5+ 4+ 3+ 2+ 1) = 28