Is it possible for twp alleles to produce four phenotypes?

Question

This is a seventh grade science question and we don't know if the punnett square could be used to solve it.

Answer 1

generally 2 alleles will only produce 2 phenotypes. A dominant and recessive.  In some circumstances you can have what is called co-dominence where the phenotype expresses both alleles.  For example. Let's say yellow flowers are dominent over blue flowers.  You have a dominant and receissive gene

A - Dominant

a - Recessive

genotypes could be

Aa, AA, aA or aa

normally anything with at 1 or 2 big A alleles displays the dominant trait.  The recessive trait is only displayed when both alleles are recessive

Genotype	Phenotype
AA	yellow flowers
Aa	yellow flowers
aA	yellow flowers
aa	blue flowers

In the case of co-dominence both alleles are displayed

Genotype	Phenotype
AA	yellow flowers
Aa	green flowers
aA	green flowers
aa	blue flowers

So two alleles could potentially produce 3 different phenotypes if co-dominence occurs in a particular species.