In wheat kernel color is determined by additive alleles at t

In wheat, kernel color is determined by additive alleles at two unlinked loci. If two plants, one with dark red kernels (+++- genotype), and one with light red kernels (+---genotype), are crossed, what fraction of the offspring is expected to have phenotypes distinct from parental colors? 1/4 4/16 6/16 1/2 10/16

Solution

Answer: 10/16

Explanation:

+++- X +---

Take first two allele of the first parent and the first two alleles of the second parent, then the below ratio comes

++ x +- = ++ (1/2) & +- (1/2)

Take second two allele of the first parent and the second two alleles of the second parent, then the below ratio comes

+- X -- = +-(1/2) & -- (1/2)

The probability of the first parent, +++- = 1/2 * 1/2 =1/4

The probability of the second parent, +--- = 1/2 * 1/2 =1/4

Total parental probability = 1/4 + 1/4 = 2/4

In dihybrid cross, total 16/16 progeny will be produced. It the parental progeny is substracted from the total progeny, then we get real recombinant probability.

16/16 -2/16 = 10/16