Answer:
Option C, traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.
Explanation:
Complete question-
Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that
Select one:
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. the traits were lost in the F1 due to dominance of the parental traits.
e. members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait.
Solution -
In the Mendel’s experiment, some traits which were absent in the F1 generation appeared in the second generation cross. By this he concluded, that the traits exressed in the F1 generation were dominant and hence they capped the expression of traits associated witl recessive allele. He classified the traits in F2 generation as recessive, because these traits can occur only when they are in pair i.e they form individuals with homozygous recessive genotype.
For instance – If “R” is allele for dominant red color trait and “r” is the allele for recessive white color trait, then the cross between true breeding red flowers and white flowers will produce following offspring
RR * rr
Rr, Rr, Rr, Rr
Thus, in F1 generation all the offspring are heterozygous red
F2 generation-
Rr * Rr
RR, Rr, Rr, rr
The recessive trait of white colored flower reappears in second generation.
Hence, option C is correct
