Here's why:
* Mendel's Law of Segregation: Each parent contributes one allele for each trait to their offspring.
* Dominance: One allele (the dominant one) can mask the expression of the other allele (the recessive one).
In F1 pea plants, if one parent contributes the dominant allele (e.g., for purple flower color) and the other contributes the recessive allele (e.g., for white flower color), the offspring will inherit both alleles. However, the dominant allele will be expressed, resulting in purple flowers.
The recessive allele is not gone; it is simply hidden. This becomes evident in the F2 generation when the recessive allele can be expressed again if both parents contribute the recessive allele.
To illustrate with an example:
* Parent 1: PP (purple flowers)
* Parent 2: pp (white flowers)
* F1 generation: All offspring will be Pp (purple flowers). The recessive allele (p) is present but masked by the dominant allele (P).
* F2 generation: When F1 plants self-pollinate, the following combinations are possible:
* PP (purple)
* Pp (purple)
* pP (purple)
* pp (white)
This demonstrates that the recessive allele (p) was present in the F1 generation, but only became visible in the F2 generation when paired with another recessive allele.
