Read the following statements and choose the correct option (with reference to Mendel's monohybrid cross).
Statement 1: Only one of the parental traits was expressed in the F1 generation.
Statement 2: In the F2 stage both the traits were expressed in the ratio 3:1.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both the statements are correct.
A monohybrid cross follows one character, for example a cross between tall and dwarf pea plants. The first generation is F1; F1 plants self-pollinated give F2.
Statement 1: Only one of the parental traits was expressed in the F1 generation. — True. All F1 plants were tall, like one parent; none were dwarf. The trait seen in F1 is the dominant one.
Statement 2: In the F2 stage both the traits were expressed in the ratio 3:1. — True. The dwarf trait came back in F2. Three-fourths of the plants were tall and one-fourth dwarf, a 3:1 ratio.
NCERT Extract:
Inheritance of One Gene – “… Mendel then self-pollinated the tall F1 plants and to his surprise found that in the Filial2 generation some of the offspring were ‘dwarf’; the character that was not seen in the F1 generation was now expressed. The proportion of plants that were dwarf were 1/4th of the F2 plants while 3/4th of the F2 plants were tall. … Similar results were obtained with the other traits that he studied: only one of the parental traits was expressed in the F1 generation while at the F2 stage both the traits were expressed in the proportion 3:1.”