Question

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

a. The F1 generation had a blended phenotype of the two parental phenotypes.
b. Both parental phenotypes reappeared in the F2 generation.
c. Each F1 plant had a different phenotype.
d. The F1 plants did not have two alleles.
e. None of the above.

Answer 1

Mendel concluded that each F1 generation contained two alleles encoding different characteristics due to the reappearance of both parental phenotypes in the F2 generation, thus confirming the presence of dominant and recessive traits.

Step-by-step explanation:

In Mendel's experiments with pea plants, he knew that each F1 generation contained two alleles encoding different characteristics because both parental phenotypes reappeared in the F2 generation. Mendel's parental pea plants (P1) were homozygous, meaning they had two identical alleles for each trait. However, when these plants were cross-fertilized, their F1 offspring were heterozygous for the given trait, possessing one dominant and one recessive allele. The F1 generation exhibited the dominant phenotype. Confirmation came when the F1 plants were self-pollinated, resulting in F2 offspring that displayed all possible combinations of the two characteristics, including the recessive trait, following a 3:1 dominant-recessive ratio. This demonstrated that the traits were not blended but rather each allele remained discrete and could express itself if the dominant allele was absent.