Question

If you crossed the round-seeded plants obtained in the F1 generation with a truebreeding

strain of wrinkle-seeded plants, how many round-seeded plants would
you expect to obtain in the next generation? (See Figure Q19-38.)
(a) 25%
(b) 50%
(c) 75%
(d) 100%

Answer 1

When crossing F1 generation round-seeded plants with true-breeding wrinkled-seeded plants, 50% of the offspring are expected to be round-seeded due to Mendelian monohybrid cross genetics.

Step-by-step explanation:

If you cross the F1 generation round-seeded plants with a true-breeding strain of wrinkled-seeded plants, you can expect to obtain 50% round-seeded plants in the next generation. The F1 generation is heterozygous (Rr), having received one round allele (R) from the round-seeded parent and one wrinkled allele (r) from the wrinkled-seeded parent. When crossed with a true-breeding wrinkled-seeded plant (rr), the offspring would have the genotypes Rr (round-seeded) and rr (wrinkled-seeded) in equal proportions. Since R (round) is dominant over r (wrinkled), half of the offspring, those with the Rr genotype, would have round seeds. This follows Mendelian genetics where the monohybrid cross of a heterozygous organism (Rr) with a homozygous recessive organism (rr) results in a 1:1 phenotypic ratio.