In Mendelian genetics, what is the expected genotypic ratio in a dihybrid cross F2 generation?
Show answer & explanation
Correct answer: B
Explanation
Answer — 9:3:3:1.
Explanation —
According to Mendelian genetics, a dihybrid cross is a hybridization experiment in which the inheritance of two distinct traits (such as seed shape and color) is studied.
When self-pollination is performed on plants of the F1 generation (e.g., those with round and yellow seeds; RrYy), the phenotypic ratio observed in the resulting F2 generation is 9:3:3:1.
In this ratio, 9 plants exhibit both dominant traits (round-yellow), 3 plants exhibit one dominant and one recessive trait (round-green), 3 plants exhibit the other dominant and recessive trait (wrinkled-yellow), and 1 plant exhibits both recessive traits (wrinkled-green).
This result validates Mendel's 'Law of Independent Assortment.'
Additional Points —
Monohybrid Cross: In this type of cross, the phenotypic ratio in the F2 generation is 3:1, and the genotypic ratio is 1:2:1.
Punnett Square: Invented by Reginald C. Punnett, this tool is used to calculate potential genotypes.
Potential Exam Questions and Answers —
Question: Which plant did Mendel select for his experiments?
Answer: The garden pea.
Question: Who is known as the 'Father of Genetics'?
Answer: Gregor Johann Mendel.