In Moses’s office there is a small colony of true-breeding dust bunnies. All his

Question

In Moses’s office there is a small colony of true-breeding dust bunnies. All his dust bunnies are grey and they also have coarse hair. By contrast, Dr. Howe’s office has dust bunnies which are brown and have soft hair. When we mated one of Moses’s coarse grey bunnies to one of Dr. Howe’s soft brown bunnies, all 17 offspring were soft and brown.

When these F1 bunnies were allowed to mate amongst themselves, we got a total of 923 with brown fur and soft hair, and 317 with grey fur and coarse hair.

a. What is the phenotypic ratio you observe in the F2?

b. Based on this ratio, how many genes control these characteristics?

c. Which characteristics are dominant and which are recessive?

d. Use genetic symbols to describe the crosses that were carried out.

If two parents have A type blood, is it possible to have a child with O type blood? Explain your reasoning. 1.5 pts

Explanation / Answer

Parental cross: SS X ss
F1 progeny: Ss
F1 selfing: Ss X Ss
F2 progeny: SS Ss Ss ss

a. Phenotypic ratio = 923/317 = 2.91:1 = ~3:1
b. 3:1 phenotypic ratio is a characteristic of a monohybrid cross. So, the given traits are regulated by a single gene with two alleles.
c. Since the F1 shows soft and brown bunnies, they are the dominant phenotype.
d. Soft and brown = Dominant = S and Grey and coarse = Recessive = s

e. Parental cross: AO X AO
F1 progeny: AA AO AO OO
There is 25% probability that the child can be OO.

Please rate the answer. Your efforts are highly appreciated. Thank you.

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