In cats, short hair (L) is dominant to long hair (l). If a short-haired cat of unknown genotype is crossed with a long-haired animal, and they produce one long-haired kitten and one short-haired kitten, this would indicate that ____.
A) the short-haired cat was true-breeding
B) the short-haired cat was not true-breeding
C) the long-haired cat was not true-breeding
D) the long-haired cat was heterozygous
E) neither parent was true-breeding

Question

In cats, short hair (L) is dominant to long hair (l). If a short-haired cat of unknown genotype is crossed with a long-haired animal, and they produce one long-haired kitten and one short-haired kitten, this would indicate that ____.​
A) ​the short-haired cat was true-breeding
B) ​the short-haired cat was not true-breeding
C) ​the long-haired cat was not true-breeding
D) ​the long-haired cat was heterozygous
E) ​neither parent was true-breeding

Quizplus · Accepted Answer

Since the offspring include both short-haired and long-haired kittens, the short-haired parent must be heterozygous (Ll), not true-breeding (LL), because it passed the recessive long hair allele (l) to the long-haired kitten. Long hair (ll) is recessive, so the long-haired cat can only have the genotype ll, making it true-breeding for long hair.

In Cats, Short Hair (L) Is Dominant to Long Hair