Mendel’s experiments discovered that one parent's trait disappeared in the F1 generation, only to reappear in 25% of the F2 generation. Which of the following best explains this pattern of inheritance?
A. The two genes of a given trait segregate during gamete production
B. There are alternative forms of genes that account for variation in inherited characteristics.
C. If the two alleles of an inherited pair differ, then one determines the organism's appearance and is the dominant allele.
D. For each characteristic, an organism inherits two alleles, one from each parent
Answer (2)
The best explanation for the observed pattern in Mendel's experiments is that one allele determines an organism’s appearance and is dominant over the other. In the F1 generation, the recessive trait disappeared due to dominance, and reappeared in the F2 generation when two recessive alleles were present. The correct answer is option C.
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To understand the pattern of inheritance observed in Mendel's experiments, let's break down the options:
A. The two genes of a given trait segregate during gamete production.
B. There are alternative forms of genes that account for variation in inherited characteristics.
C. If the two alleles of an inherited pair differ, then one determines the organism's appearance and is the dominant allele.
D. For each characteristic, an organism inherits two alleles, one from each parent.
Gregor Mendel's experiments with pea plants in the mid-19th century laid the foundation for the field of genetics. In his experiments, Mendel observed that when he cross-pollinated purebred plants (plants that were homozygous for a specific trait), the trait from one of the parents disappeared in the F1 generation (first filial generation), but then reappeared in approximately 25% of the F2 generation (second filial generation).
This was explained by Mendel's Principle of Segregation, which states that during the formation of gametes (sperm and egg cells), the two alleles for each trait separate, so that each gamete carries only one allele for each trait. This principle explains why a recessive trait can disappear in the F1 generation and then reappear in the F2.
Option A, 'The two genes of a given trait segregate during gamete production,' best explains this pattern of inheritance. According to this principle, each parent contributes one of two alleles for a trait, and these alleles segregate (or separate) during the formation of gametes, leading to the observed ratios in the offspring.
Therefore, the correct answer is A.
