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

According to the question, the +++- parent would give two types of gametes: +- and ++
The +--- parent would give two types of gametes= +- and --
The cross between then gives genotypic ratio: 1+++-: 1 ++--: 1 +-+-: 1 +---
So, the fraction of progeny distinct from parental generation= 2/4 (1/2 ++-- and 1/2 +-+-) i.e. 1/2