In each of the scenarios, an individual heterozygous for the indicated gene or genes is crossed with an identical heterozygous individual. Predict the number of different phenotypes that would be observed among the progeny of such a cross?

Explanation:

Lets take a single gene for one character,

Two identical heterozygous individuals  for single gene or two genes

Aa and Aa   or iAiB,   iAiB,

scenario-1, if , A is completely dominant on a.

scenario 2 if, iA and iB  are co-dominant,

scenario 3,  if both are recessive,

scenario 4 , if they are incompletely dominant.

Here cross is,

Between Aa And Aa= AA, Aa ,Aa  aa.

iAiB and iAiB=   iAiA, iAiB, iAiB, iBiB

Their phenotype depends on the type of allele, if it dominant, recessive, co-dominant, or incomplete dominant.