Question

In guinea pigs, short hair, S, is dominant to long hair, s.

One Homozygous short hair and one long hair guinea pig mate. Write the genotype ratio

Answer 1

In guinea pigs, short hair (S) is dominant to long hair (s). If one parent is homozygous for short hair, its genotype is SS, and the other parent has long hair with a genotype of ss.

When these two guinea pigs mate, the possible gametes they can produce are:

- The homozygous short hair parent (SS) can only produce gametes with the allele S.
- The long hair parent (ss) can only produce gametes with the allele s.

Now, let's set up a Punnett square to illustrate the crossing:

```
S | S
---------------
s | Ss | Ss
---------------
s | Ss | Ss
```

All offspring will have the genotype Ss, which means they will all have short hair since the allele for short hair (S) is dominant.

Thus, the genotype ratio for the offspring is:

- **100% Ss** (or 4:0 when expressed as a ratio against other possible genotypes, though there are none in this case).
- The phenotype ratio is 100% short hair.