Question

use the following information for #12-15
in mice, the ability to run normally is a dominant trait and is referred to as a running mouse. the recessive trait causes mice to run in circles and is referred to as waltzing. hair color is also inherited with black hair being dominant and brown hair being recessive.
for # 12-14, cross a heterozygous running, heterozygous black mouse with a homozygous running, homozygous black mouse.
question 12
1 pts
what are the genotypes of the parents?
○ rrbb x rrbb
○ rrbb x rrbb
○ rrbb x rrbb
○ rrbb x rrbb

Explanation:

1. Define alleles: Let running = $R$ (dominant), waltzing = $r$ (recessive); black hair = $B$ (dominant), brown hair = $b$ (recessive).
2. Heterozygous running, heterozygous black mouse has two different alleles for each trait: genotype $RrBb$.
3. Homozygous running, homozygous black mouse has two identical dominant alleles for each trait: genotype $RRBB$.
4. The parent cross is $RrBb \times RRBB$.

Answer:

B. RrBb x RRBB