What are the alleles for a 2x2 punnet square, two heterozygous guinea pigs, 75% offspring will have short hair and 25% offspring will have long hair?

Answer 1

In the case of guinea pigs, the trait for hair length can be represented by the alleles "S" for short hair (dominant) and "s" for long hair (recessive). Since both parent guinea pigs are heterozygous for this trait, their genotypes are both Ss.

When you set up a 2x2 Punnett square for two heterozygous parents (Ss x Ss), you will get the following combinations for the offspring:

       S        s
     -------------
S |    SS     |  Ss  |
     -------------
s |    Ss     |  ss  |

From this Punnett square, the possible genotypes for the offspring are:

• SS: Homozygous dominant (short hair)
• Ss: Heterozygous (short hair)
• ss: Homozygous recessive (long hair)

Now, let's look at the expected ratios:

• Short hair (SS or Ss): 3 offspring out of 4
• Long hair (ss): 1 offspring out of 4

Thus, the expected phenotypic ratio is 75% short hair and 25% long hair, which matches your observation.

In summary, the alleles are:

• S (short hair)
• s (long hair)

And both parent guinea pigs are heterozygous (Ss).