Humans may have Rh blood or Rh- blood. A person who is Rh (R) has a certain type of protein on the red blood cells. A person who is Rh- (r) does not have this particular protein. In humans, Rh dominates Rh-. Normal insulin (I) production dominates abnormal insulin production (i) (diabetes). If both parents are heterozygous for both Rh and normal insulin production, what phenotypes would they produce in their offspring

- Rh, normal insulin

- Rh, no insulin

- Rh-, normal insulin

- Rh-, no insulin.

Explanation:

This question involves two genes; one coding for Rhesus factor and insulin product. The allele for Rh blood and normal insulin dominates that of Rh- and no insulin.

According to this question, if both parents are heterozygous for both Rh and normal insulin production and cross, i.e. RrIi × RrIi, the following phenotype of offsprings will be produced (see punnet square):

- Rh, normal insulin (R_I_)

- Rh, no insulin (R_ii)

- Rh-, normal insulin (rrI_)

- Rh-, no insulin (rrii)