The B and C gene are very close to each other on chromosome

The B and C gene are very close to each other on chromosome 21 and therefore so tightly linked that no recombination ever occurs. If bC/bC crosses with Bc/Bc, followed by a cross between those offspring, what are the genotypes and phenotypes of the F2 generation?

Solution

Answer:

bC/bC X Bc/Bc----------Parents

bC Bc -----------Gametes

bC/Bc -----------------F1

F1 X F1

bC/Bc X   bC/Bc

bC, Bc   bC, Bc--------------F1 gametes

As there is no recombination each F1 progeny produces two types of gametes only, bC & Bc

F2:

bC/bC : Bc/bC : Bc/Bc = 1:2:1