Question

Which of the following statements correctly describes how Mendel accounted for the observation that traits had disappeared in the F1 generation and then reappeared in the F2 generation?

A) Traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.
B) New mutations were frequently generated in the F2 progeny, causing traits that had been lost in the F1 to reappear in the F2.
C) Members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait.
D) The mechanism controlling the appearance of traits was different between the F1 and the F2 plants.

Answer 1

Mendel described traits that disappeared in the F1 generation and reappeared in the F2 generation as dominant or recessive. The recessive traits were hidden by the dominant ones in the F1, but could reappear in the F2 when the hybrid F1 plants were crossed.

Step-by-step explanation:

The correct statement that describes how Mendel accounted for the observation that traits had disappeared in the F1 generation and then reappeared in the F2 generation is: "Traits can be dominant or recessive, and the recessive traits were 'hidden' by the dominant ones in the F1." This is because Mendel observed that when plants with different traits were crossed, the dominant trait appeared in all the F1 hybrid offspring, while the recessive trait appeared to disappear. However, the recessive trait reappeared in the F2 generation when the F1 plants were self-crossed or intercrossed. Mendel proposed that traits were determined by heritable "factors," now known as genes, which came in pairs. If an organism had at least one dominant factor, the dominant trait would be expressed. The observation of a recessive trait in the F2 generation indicated that the organism lacked any dominant factors for that characteristic.

Answer 2

A) Traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.

Step-by-step explanation:

Mendel discovered the fundamental theory of heredity: that inheritance involves the passing of genes (he called it discrete units of inheritance), from parents to offspring. Those genes are with two alleles in the genotype, one inherited from the father and other inherited from the mother.

When he cross-bred pure-bred parent (always produced offspring identical to the parent) plants dominant traits were always seen in the offspring, while recessive traits were hidden until the first-generation (F1) hybrid plants were left to self-pollinate. Mendel also noticed that in second-generation (F2) of the offspring 3:1 was ratio of dominant to recessive traits.