Question

The two genes f and g, code for body size and aggressiveness, respectively. The F allele is dominant over f, and codes for a larger body size. The G allele is dominant over g, and codes for more aggressive ants. You perform a Mendelian dihybrid cross (NOT a test cross) on these traits. If there is no recombination between these genes (recombination frequency = 0.00), what ratio should you see phenotypes in in the offspring? (note that the parent generation was made up of large aggressive ants and small docile ants.)

A. 9 large aggressive:3 large docile:3 small aggressive: 1 small docile
B. 1 large aggressive:1large docile:1small aggressive:1small docile
C. 12 large aggressive:4 small docile (i.e. 3 large aggressive:1small docile)
D. None of the above

Answer 1

The correct answer is option C.

Step-by-step explanation:

As it is given that, a Mendelian cross is performed between two parents resulted by cross the parents. This suggests that the parents or P generation has zero recombination hence the genotype of Parents would be AA and aa in nature. Therefore, all the F1 generation offspring were Aa in nature. The selfing of the F1 offspring will be:

A a

A AA Aa

a Aa aa

Genotype: AA: Aa: aa :: 1:2:1

Phenotype: Dominant: recessive :: 3:1