18. A particular breed of dog can have long hair or short hair. When true-breeding long-haired animals were crossed to true-breeding short-haired animals, the offspring all had long hair. The F2 generation consisted of a 3:1 ratio of long - to short-haired animals. A second gene affects the texture of the hair. The two variants are wiry hair and straight hair. F1 offspring from a cross of these two varieties all had wiry hair, and F2 offspring showed a 3:1 ratio of wiry - to straight-haired puppies. Recently, a breeder of the short-, wiry-haired dogs discovered a female puppy that was albino. Similarly, another breeder of the long-, straight-haired dogs found a male puppy that was albino. The albino trait is due to a recessive allele. The two breeders got together and mated the two dogs. Surprisingly, all the puppies in the litter had black hair. How would you explain this result

Question

Biology

Amira

3 September, 20:15

18. A particular breed of dog can have long hair or short hair. When true-breeding long-haired animals were crossed to true-breeding short-haired animals, the offspring all had long hair. The F2 generation consisted of a 3:1 ratio of long - to short-haired animals. A second gene affects the texture of the hair. The two variants are wiry hair and straight hair. F1 offspring from a cross of these two varieties all had wiry hair, and F2 offspring showed a 3:1 ratio of wiry - to straight-haired puppies. Recently, a breeder of the short-, wiry-haired dogs discovered a female puppy that was albino. Similarly, another breeder of the long-, straight-haired dogs found a male puppy that was albino. The albino trait is due to a recessive allele. The two breeders got together and mated the two dogs. Surprisingly, all the puppies in the litter had black hair. How would you explain this result

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Answers (1)

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Dawson · Answer 1

All the puppies have black hair because albino alleles are found in two different genes.

If we let the letters A and B represent the two different pigmentation genes, the one of the dogs is AAbb, and the other is aaBB.

Their offspring are AaBb and so there are not albinos because they have one dominant copy of each gene.