Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that _____
A) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1
B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants
C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1
D) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait
Answer:
C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1
Explanation:
Mendel observed that the F1 generation obtained by crossing two pure breeding plants expressed only one trait. Here, the two parents differ from each other with respect to one genetic trait. F1 progeny expressed the phenotype identical to one parent plant while the trait expressed by the other parent plant was not present in the F1 progeny. However, the self crossing of two F1 plants obtained the F2 progeny and 1/4 F2 plants expressed the trait that was absent in the F1 progeny.
He concluded that the trait which was masked in the F1 was recessive and the alternating trait that appeared in the F1 was dominant. The presence of the allele for the dominant trait did not allow the expression of the allele for the recessive trait in the F1 generation.
