Question

Which of the following is correct regarding monohybrid cross?

• A. It involves crossing between parents which differ in a single character
• B. The genotypic ratio of the offspring in $F_2$ generation is 1 : 2 : 1
• C. The phenotypic ratio of the offspring in $F_2$ generation is 3 : 1
• D. All of the above

Answer 1

The correct option is D All of the above

A monohybrid cross is defined as a cross between two parents which are similar in all characters except for one character.

They have contrasting traits for one of the characters.

Example- a cross between two pea plants, one of which yields round seeds and one of which yields wrinkled seeds, is known as a monohybrid cross.

Some more examples of monohybrid cross conducted by Mendel.

$\begin{array}{ccc}\text{Character}& \text{Trait in parent 1 (in}& \text{Trait in parent 2 (in}\\ & \text{monohybrid cross)}& \text{monohybrid cross)}\\ \text{Height}& \text{Tall}& \text{Dwarf}\\ \text{Seed colour}& \text{Yellow}& \text{Green}\\ \text{Pod shape}& \text{Inflated}& \text{Constricted}\\ \text{Pod colour}& \text{Green}& \text{Yellow}\\ \text{Flower colour}& \text{Violet}& \text{White}\\ \text{Flower position}& \text{Axial}& \text{Terminal}\end{array}$

Let us understand monohybrid cross considering seed shape.

Genotypic ratio in $F_2$ generation:
RR : Rr : rr = 1 : 2 : 1

Phenotypic ratio in $F_2$ generation:
Round seeds producing plants: Wrinkled seeds producing plants = 3 : 1