In guinea pigs, the allele for a rough coat (R) is dominant over the allele for a smooth coat (r). A heterozygous guinea pig (Rr) and a homozygous recessive guinea pig (rr) reproduce and have 10 offspring. Explain how all 10 offspring can have smooth coats.

All the 10 offsprings have recessive smooth coats because all the progeny are formed by recessive r allele and resulted is smooth coat. It was because one of the parents was heterozygous.

Explanation:

Rough coat R is dominant over the allele for smooth coat r

Heterozygous guinea pig Rr is crossed with homozygous recessive guinea pig rr

So from the Punette square

      r     r

R  Rr    Rr

r   rr    rr

There are chances of occurrence of 50 % each of heterozygous rough and dominant recessive smooth coats.

From the result obtained in actual, all the offspring have smooth coats because all of these offsprings have receive recessive allele from their parent and have become homozygous recessive.