The F₁ generation differed from the F₂ in Mendel's experiments in that __________.

• A. all of the F₁ showed the dominant phenotype, whereas only one-half of the F₂ did
• B. all of the F₁ showed the dominant phenotype, and all of the F₂ showed the recessive phenotype
• C. one-half of the F₁ showed the dominant phenotype, and three-quarters of the F₂ did
• D. none of the F₁ showed the dominant phenotype, but one-half of the F₂ did
• E. all of the F₁ showed the dominant phenotype, but only three-quarters of the F₂ did

Answer: (E)

Verified step by step guidance

1. Understand Mendel's experiments: Mendel's experiments with pea plants involved crossing two true-breeding plants, one with the dominant trait and one with the recessive trait, to produce the F1 generation.
2. Analyze the F1 generation: In Mendel's experiments, the F1 generation is the first filial generation obtained by crossing the parent plants. All F1 offspring exhibit the dominant phenotype because they inherit one dominant allele from one parent and one recessive allele from the other, making them heterozygous.
3. Examine the F2 generation: The F2 generation is produced by self-pollinating the F1 generation. When F1 plants (heterozygous) are crossed, the resulting F2 generation shows a phenotypic ratio of 3:1, where three-quarters exhibit the dominant phenotype and one-quarter exhibit the recessive phenotype.
4. Compare F1 and F2 generations: In the F1 generation, all individuals show the dominant phenotype. In contrast, in the F2 generation, only three-quarters show the dominant phenotype, while one-quarter show the recessive phenotype.
5. Conclude the difference: The key difference between the F1 and F2 generations in Mendel's experiments is that all F1 individuals show the dominant phenotype, whereas in the F2 generation, only three-quarters show the dominant phenotype, confirming Mendel's 3:1 phenotypic ratio.