Question

You cross a true breeding pea comb chicken with a single comb chicken. What will you observe in the F2 generation?

(a) Ratio 1:2:1

(b) Ratio 3:1

(c) Ratio 9:3:3:1

(d) All pea combed

I got this question in semester exam.

My question comes from Gene Interactions topic in section Extension and Deviation from Mendelian Genetic Principles of Cytogenetics

Answer 1

The correct choice is (d) All pea combed

The best explanation: Pea comb has genotype P/P r/r and single has genotype p/p r/r. Thus the cross will give F1 P/p r/r. This is homozygous recessive at R locus so F2 will only differ in P locus giving monohybrid ratio 3:1.