Question

Chinese Shar Peis
Chinese Shar Peis are dogs that are selectively bred by humans specifically for their wrinkly fur coat, small triangular ears, and broad muzzle. These traits are recessive and must be brought out by breeding similar dogs with the desired traits. Dominant Shar Peis are becoming less desirable, as the rare traits become more in demand.



Two-Part Question
Part A
Multiple Select Question
Which statement best describes how humans select for wrinkly skin in Chinese Shar Peis?
A.
By mating a very wrinkly female and non-wrinkly male so they have the best chance of passing on the gene for wrinkly skin.
B.
By mating a wrinkly female and wrinkly male so they have the best chance of passing on the gene for wrinkly skin.
C.
By inserting a gene for wrinkly skin into every Shar Pei puppy.
D.
By mutating the DNA of one Shar Pei, hoping they will pass on the mutated trait to their offspring.
Part B
Multiple Select Question
Chinese Shar Peis are selectively bred for their recessive trait, the wrinkly coat. The genotypic relationship of (rr) represents pure recessive genes. What would the alleles of the parents need to be in order to pass those traits to at least 25% of the offspring? Select three that apply:
A.
RR, RR
B.
Rr, Rr
C.
RR, rr
D.
Rr, rr
E.
rr, rr

Answer 1

**Part A:**
The best statement that describes how humans select for wrinkly skin in Chinese Shar Peis is:
- **B. By mating a wrinkly female and wrinkly male so they have the best chance of passing on the gene for wrinkly skin.**

**Part B:**
To pass the recessive trait (rr) to at least 25% of the offspring, the alleles of the parents would need to be:
- **B. Rr, Rr** (this would produce 25% rr offspring)
- **D. Rr, rr** (this would produce 50% rr offspring)
- **E. rr, rr** (this would produce 100% rr offspring)

Thus the correct answers for Part B are **B, D, and E.**