Question

9. In guinea pigs, rough coat is dominant (R) to smooth coat (r) and black coat (B) is dominant to white coat (b). A rough black guinea pig bred with a rough white one produces 29 rough black offspring, 31 rough white offspring, 11 smooth black and 9 smooth white. Give the genotypes of the parents, the probability for the offspring, and the actual number of each kind of offspring you would expect. ________ Genotype of the rough, black parent

Answer 1

The genotype of the rough, black parent is RrBb. The probability for the offspring is 25% rough black, 25% rough white, 25% smooth black, and 25% smooth white. The expected number of each kind of offspring would be 25% of the total number of offspring produced.

Step-by-step explanation:

The genotypes of the parents can be determined based on the phenotypic ratios of the offspring. Let's analyze the given information:

The rough black guinea pig produces 29 rough black offspring, which means it must be heterozygous for both the rough coat (Rr) and the black coat (Bb).

The rough white guinea pig produces 31 rough white offspring, which means it must be heterozygous for the rough coat (Rr) and homozygous recessive for the white coat (bb).

Therefore, the genotype of the rough, black parent is RrBb.

The probability for the offspring can be calculated using Punnett squares:

There is a 25% chance of getting a rough black guinea pig (RRBB or RrBB).

There is a 25% chance of getting a rough white guinea pig (Rrbb).

There is a 25% chance of getting a smooth black guinea pig (RrBb).

There is a 25% chance of getting a smooth white guinea pig (Rrbb).

Therefore, you would expect 25% rough black offspring, 25% rough white offspring, 25% smooth black offspring, and 25% smooth white offspring.

Answer 2

the genotype of the parent guinea pigs are as follows:

RrBb (rough, black) and Rrbb (rough, white)

Step-by-step explanation:

Since the phenotype of smooth coat is present in the offspring, the parent genotype cannot have RR alleles for their coat. Similarly, the rough, black parent cannot have BB alleles in its genotype because that will not yield a white coat color in its offspring.

After making the dihybdrid cross, the probability obtained for each phenotype is given below:

rough black:
`(3)/(8)`

rough white:
`(3)/(8)`

smooth black:
`(1)/(8)`

smooth white:
`(1)/(8)`

Hope that answers the question, have a great day!