Given three possible phenotypes for parents showing dominance (aa, aa, aa), which combination would produce a 1: 2: 1 ratio of genotypes and a 3: 1 ratio of phenotypes? i. aa x aa ii. aa x aa iii. heterozygous x heterozygous iv. aa x aa v. homozygous dominant x heterozygous

The correct answer is-

III. Heterozygous x Heterozygous  and

IV. Aa x Aa.

Genotypic ratio corresponds to the ratio of different genotype produced for the trait ( that depicts the genetic makeup with respect to the trait). On the other hand, phenotypic ratio corresponds to the ratio of phenotypes ( such as tall and dwarf in case of height of pea plant) produced in a generation.

Dominant trait ( depicted by allele with capital letter, such as AA and Aa) masks the expression of recessive trait ( depicted by small letter, such as aa)

Aa and Aa represents heterozygous dominant genotype, which will produce three different genotypes and two different phenotypes in the ratio 1:2:1 and 3:1 respectively.

Refer punnett square.

the median of the data is 4.5.