13. Free ears in dogs are controlled by the dominant allele (F), and attached ears are controlled by the recessive allele (f). In addition, short hair in dogs is due to a dominant allele (S), and long hair is due to a recessive allele (s). Which of the following is the genotype of a dog with attached ears and short hair?
Answer: D
The genotype of a dog with attached ears and short hair is ffSs.
A dog with attached ears must possess the recessive genotype for ears, which is represented by 'ff'. Additionally, since the dog has short hair, it must have at least one dominant allele for short hair, which is 'S'. Therefore, the correct genotype is 'ffSs'.
A) FFSS
This genotype indicates a dog with free ears (FF) and short hair (SS). Since the question specifies that the dog has attached ears, this option is incorrect.
B) ffss
This genotype represents a dog with attached ears (ff) and long hair (ss). Although it correctly shows attached ears, it does not meet the requirement for short hair, making this option incorrect.
C) FfSs
In this case, the genotype indicates a dog with free ears (Ff) and short hair (SS). Since the dog is specified to have attached ears, this option is not suitable and therefore incorrect.
D) ffSs
This genotype accurately describes a dog with attached ears (ff) and short hair (S). It fulfills both criteria outlined in the question, making it the correct choice.
Conclusion
The correct answer, 'ffSs', clearly identifies a dog with attached ears and short hair by combining the recessive ear genotype with a dominant short hair allele. Options A, B, and C fail to meet the criteria for either ears or hair length, reinforcing that 'ffSs' is the only valid genotype for the described traits.