Question

In Mendel's pea plants, how did he know that each F1 generation contained two alleles encoding different characteristics?

1) The F1 generation had a blended phenotype of the two parental phenotypes.
2) Both parental phenotypes reappeared in the F2 generation.
3) Each F1 plant had a different phenotype.
4) The F1 plants did not have two alleles.
5) None of the above.

Answer 1

Mendel knew that each F1 generation plant contained two different alleles because both parental phenotypes reappeared in the F2 generation, demonstrating a 3:1 dominant-recessive ratio.

Step-by-step explanation:

In Mendel's pea plants, he knew that each F1 generation contained two alleles encoding different characteristics because both parental phenotypes reappeared in the F2 generation. Therefore, the correct answer is: 2) Both parental phenotypes reappeared in the F2 generation.

When Mendel crossed plants that were homozygous for different traits, all resulting F1 offspring were heterozygous and exhibited the dominant trait. However, not until the F1 plants self-pollinated and produced the F2 generation, did the various combinations of characteristics appear, which included both recessive and dominant traits. This 3:1 dominant-recessive ratio in the F2 generation revealed the presence of two different alleles in the F1 generation: one from each parent.