Short hair (L) is dominant to long hair (l). Suppose a short-haired animal of unknown genotype is crossed with a long-haired animal and they produce one long-haired and one short-haired offspring. What do these results indicate?
A)The short-haired animal was homozygous.
B)The short-haired animal was heterozygous.
C)The long-haired animal was heterozygous.
D)Both the long-haired and short haired animals were heterozygous.
E)None of these can be determined with these two offspring.

Question

Quizplus · Accepted Answer

The fact that the cross produced both long-haired and short-haired offspring indicates that the short-haired animal must have been heterozygous (Ll) and the long-haired animal must have been homozygous recessive (ll). The offspring inherited one copy of the recessive allele (l) from the long-haired parent and one copy of either the dominant (L) or recessive (l) allele from the short-haired parent. Therefore, the short-haired parent must have had one dominant allele (L) and one recessive allele (l).

Short Hair (L) Is Dominant to Long Hair (L)