Question

the illustration below shows two adult rabbits and their offspring.

in rabbits, the allele for spots is dominant to the allele for solid color. what is the most likely genotype of the parent rabbits in the illustration?

• rr x rr
• rr x rr
• rr x rr
• rr x rr

10 multiple choice
a genetic cross involving two unlinked genes is represented.
hhee x hhee

Explanation:

Step1: Analyze the cross \(rr\times rr\)

If both parents are \(rr\) (homozygous recessive), all offspring will be \(rr\) (solid - colored). But the illustration shows both spotted and solid - colored offspring, so this option is incorrect.

Step2: Analyze the cross \(Rr\times Rr\)

Using the Punnett square:

Gametes	R	r
r	Rr	rr

The genotypic ratio is \(RR:Rr:rr = 1:2:1\), and the phenotypic ratio (assuming \(R\) - spotted, \(r\) - solid) is \(3\) (spotted):\(1\) (solid). This is consistent with the presence of both spotted and solid - colored offspring.

Step3: Analyze the cross \(Rr\times rr\)

Using the Punnett square:

Gametes	R	r

The genotypic ratio is \(Rr:rr=1:1\), and the phenotypic ratio is \(1\) (spotted):\(1\) (solid). But the illustration shows more spotted than solid - colored offspring (a \(3:1\) - like ratio is more likely visually), so this option is less likely.

Step4: Analyze the cross \(RR\times rr\)

Using the Punnett square:

Gametes	R	R

All offspring will be \(Rr\) (spotted). But the illustration shows solid - colored offspring, so this option is incorrect.

Answer:

B. \(Rr\times Rr\)