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:

• P generation: The true - breeding recessive plant in the parental generation ($P$ generation) shows the recessive trait.
• F₁ generation: When a true - breeding dominant ($AA$) is crossed with a true - breeding recessive ($aa$), the $F_1$ generation has a genotype of $Aa$. Since the dominant allele ($A$) masks the recessive allele ($a$), the recessive trait is not visible in the $F_1$ generation.
• F₂ generation: When $F_1$ individuals ($Aa\times Aa$) are self - crossed, using the Punnett square:

Gametes of Parent 1	Gametes of Parent 2
$A$	$AA$ (dominant)	$Aa$ (dominant)
$a$	$Aa$ (dominant)	$aa$ (recessive)

The genotypic ratio is $AA:Aa:aa = 1:2:1$, and the phenotypic ratio is 3 (dominant) : 1 (recessive). So, the recessive trait is visible in the $F_2$ generation.

Answer:

P generation and F₂ generation