Understanding the Genetics
* Long hair is recessive: This means an offspring needs to inherit two copies of the recessive allele (let's call it "l") to have long hair.
* Short hair is dominant: This means an offspring only needs one copy of the dominant allele (let's call it "L") to have short hair.
Analyzing the Offspring
* 25% long hair: This tells us that 25% of the offspring received two "l" alleles.
* 75% short hair: This tells us that 75% of the offspring received at least one "L" allele.
Determining Parental Genotypes
To get a 25% chance of long hair, both parents must be carriers of the recessive "l" allele. This means the only possible parental genotypes are:
* Parent 1: Ll (Heterozygous - one dominant and one recessive allele)
* Parent 2: Ll (Heterozygous - one dominant and one recessive allele)
Punnett Square Explanation
Here's how the Punnett Square for this cross would look:
```
L l
L LL Ll
l Ll ll
```
* LL: Short hair (dominant)
* Ll: Short hair (dominant)
* ll: Long hair (recessive)
As you can see, this results in a 1:2:1 ratio of genotypes (LL:Ll:ll), which translates to a 3:1 ratio of phenotypes (short hair:long hair).
Conclusion
The most probable genotypes of the parent guinea pigs are both Ll (heterozygous).