Question

1. for another set of parents, rraa and rraa, what proportion of their children will be left - handed and attached lobed? a. 1 of 4 b. 2 of 4 c. 3 of 4 d. 4 of 4 e. none of these are correct

Explanation:

Step1: Analyze R - r gene inheritance

For the R - r gene, the cross is Rr x Rr. Using a Punnett - square, the genotypes and their ratios are RR:Rr:rr = 1:2:1. The probability of having the recessive genotype (rr) which may be related to left - handedness (assuming rr is for left - handedness) is $\frac{1}{4}$.

Step2: Analyze A - a gene inheritance

For the A - a gene, the cross is AA x aa. All of the offspring will have the genotype Aa. Since the question only asks about the proportion related to the left - handedness (determined by the R - r gene in this assumed model), and the A - a gene cross does not affect the left - handedness trait in terms of proportion calculation.

Answer:

A. 1 of 4