Work in a small group or alone to solve this "mating mystery." Then answer the questions that follow. Mister Poppleton, a cat enthusiast who breeds cats and competes on the Cat Fancier's Association competitiveshow circuit, has just received quite a shock! His award-winning cat, Emeline, has given birth to some surprising kit-tens. Of her five kittens, four have black fur, and one has an unexpected coat of fur that is a patchwork of black andorange, known as a tortoiseshell pattern. Mister Poppleton was breeding Emeline with an award-winning male cat, named Barnaby, but he is now worriedthat Emeline may have been having secret sexual relations with a neighborhood stray cat, named Hugo. Mister Pop-pleton consults with his veterinarian, Dr. Doolittle, for some expert advice. Dr. Doolittle explains: In cats, there are several genes that determine fur color. One of those genes is found onthe X chromosome and codes for whether a cat has orange fur or black fur. Because it is a sex-linked gene, it isexpressed a bit differently in males than in females. In males:.If a male cat has the orange allele on his X chromosome, he will have orange fur. If a male cat has the black allele on his X chromosome, he will have black fur. In females:.If a female cat has the orange allele on both of her X chromosomes, she will have orange fur. If a female cat has the black allele on both of her X chromosomes, she will have black fur. If a female cat has the orange allele on one of her X chromosomes and the black allele on the other X chro-mosome, she will have a tortoiseshell coat.