Using a Punnett square An explanation describe if an orange pet mates with another orange pet, can they have any green offspring.

It is possible if the parents are heterozygous (meaning they have a dominant AND recessive allele for the trait.

Well say the allele for orange is X and the allele for green is X.

Let’s say we have two homozygous orange parents. That means they have no trace of green.

XX

X XX XX As you can see, the Punnett

X. XX XX. Square shows that all offspring will have capital X’s, meaning only homozygous orange offspring is produced. No green babies here.

We can try the same thing with a homozygous parent and a heterozygous parent.

Xx

X XX Xx Here we can see that 50% of

X XX Xx the offspring has a lowercase x. That means they are heterozygous. They carry the green trait, but it doesn’t show because it is masked by the dominant orange allele. So no green babies here either.

Finally we can try heterozygous parents.

Xx

X XX Xx 25% of the offspring is

x Xx xx homozygous for orange. 50% of the offspring is heterozygous for orange. And 25% is homozygous for green. There must be two recessive alleles in order for green to show.

The only way to produce green offspring is to have two heterozygous parents.