Question

How does a monohybrid cross differ from a dihybrid cross?

Answer 1

In monohybrid cross only one character is considered; whereas in dihybrid cross two characters are considered simultaneously.

Explanation:

The difference in monohybrid and dihybrid cross can easily be explained by Mendel's experiments on pea plant.

Mendel crossed a pure breeding tall plant with pure breeding dwarf plant. All the plants in `F1` generation were tall and in the `F2` generation tall and dwarf plants were produced in the ratio of 3:1. In this experiment, only height of the plant is taken into consideration. This is monohybrid cross.

In another series of experiments, he crossed pure breeding pea plant with round seeds having yellow coloured cotyledons with pure breeding plant with wrinkled seeds having green coloured cotyledons.

All the plants in `F1` generation were having round seeds and yellow coloured cotyledons. In `F2` generation plants with round seeds and yellow cotyledons, wrinkled seed and yellow cotyledons, round seeds and green cotyledons and wrinkled seed and green cotyledons in the ratio of 9:3:3:1.

In these experiments inheritance of colour of cotyledons and the shape of seed are considered simultaneously. This is dihybrid cross .

Mendel's law of seggrgation and Mendel's law of independent assortment were proposed on the basis of experiments conducted by him in monohybrid and dihybrid cross , respectively