Question

if mendel had crossed a true breeding dominant plant with a true breeding recessive plant, in which of the three generations is the recessive trait visible?
f₁ generation only
p generation only
f₁ generation and f₂ generation
p generation and f₂ generation

Explanation:

1. Understand Generations: The P (parental) generation has one true - breeding dominant (e.g., AA) and one true - breeding recessive (e.g., aa) plant. The recessive trait is visible in the P generation's recessive plant.
2. Analyze F₁ Generation: When AA (dominant P) and aa (recessive P) are crossed, the F₁ generation has the genotype Aa. Since the dominant allele (A) masks the recessive allele (a), the recessive trait is not visible in the F₁ generation.
3. Analyze F₂ Generation: When F₁ (Aa) plants are self - crossed (Aa × Aa), the genotypes of the F₂ generation are AA, Aa, and aa in a 1:2:1 ratio. The aa genotype shows the recessive trait, so the recessive trait is visible in the F₂ generation.
4. Evaluate Options:

• Option "F₁ generation only" is wrong as F₁ has Aa and no visible recessive trait.
• Option "P generation only" is wrong as F₂ also has visible recessive traits.
• Option "F₁ generation and F₂ generation" is wrong as F₁ has no visible recessive trait.
• Option "P generation and F₂ generation" is correct because the P generation's recessive parent shows the recessive trait and the F₂ generation has aa individuals that show the recessive trait.

Answer:

D. P generation and F₂ generation (assuming the options are labeled as A: F₁ generation only, B: P generation only, C: F₁ generation and F₂ generation, D: P generation and F₂ generation)