Question

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

Two heterozygous short hair guinea pigs mate. Write the phenotype ratio

Answer 1

In guinea pigs, if we denote the short hair trait by the allele \(S\) (dominant) and the long hair trait by the allele \(s\) (recessive), then we can analyze the genetic cross between two heterozygous short-haired guinea pigs (genotype \(Ss\)).

To find the phenotype ratio, we can set up a Punnett square for the cross:

\[
\begin{array}{c|c|c}
& S & s \\
\hline
S & SS & Ss \\
\hline
s & Ss & ss \\
\end{array}
\]

From this Punnett square, we have the following genotypes for the offspring:

- 1 \(SS\) (homozygous dominant) - short hair
- 2 \(Ss\) (heterozygous) - short hair
- 1 \(ss\) (homozygous recessive) - long hair

Now, we can summarize the phenotypes:
- Short hair (\(SS\) and \(Ss\)): 3 offspring
- Long hair (\(ss\)): 1 offspring

Thus, the phenotype ratio of short hair to long hair is:

**3 short hair : 1 long hair**.