explain the dihybrid cross with suitable cross diagrams and phenotypic ratio tables
Answers
A dihybrid cross is a cross between two individuals that are both heterozygous for two different traits. As an example, let's look at pea plants and say the two different traits we're examining are color and height. In other words, each plant has:
One dominant allele F for purple color and one recessive allele f for white color and
One dominant allele H for height and one recessive allele h, which produces a dwarf pea plant
Answer:
Dihybrid Cross and Inheritance of Two Genes
“Dihybrid cross is the cross between two different genes that differ in two observed traits.”
Introduction
Gregor Johann Mendel was the first person who discovered the basic principles of heredity during the mid-19th century. Hence, he is known as the “Father of Modern Genetics”. He conducted experiments in his garden on pea plants and observed their pattern of inheritance from one generation to the next generation.
Mendel laid the basic groundwork in the field of genetics and eventually proposed the laws of inheritance. Law of Segregation, Law of Independent Assortment and Law of Dominance are the three laws of inheritance proposed by Gregor Mendel. These laws came into existence from his experiments on pea plants with a variety of traits.
Mendel first studied the inheritance of one gene in the plant through monohybrid cross. He considered only a single character (plant height) on pairs of pea plants with one contrasting trait. Later, he studied the inheritance of two genes in the plant through dihybrid cross.
Mendel studied the following seven characters with contrasting traits:
Stem height: Tall/dwarf
Seed shape: Round/wrinkled
Seed colour: Yellow/green
Pod colour: Green/yellow
Pod shape: Inflated/constricted
Flower colour: Violet/white
Flower position: Axial/terminal
Also Read: Difference between Monohybrid and Dihybrid Cross
Dihybrid Cross
A dihybrid cross is a breeding experiment between two organisms which are identical hybrids for two traits. In other words, a dihybrid cross is a cross between two organisms, with both being heterozygous for two different traits. The individuals in this type of trait are homozygous for a specific trait. These traits are determined by DNA segments called genes.
In a dihybrid cross, the parents carry different pair of alleles for each trait. One parent carries homozygous dominant allele, while the other one carries homozygous recessive allele. The offsprings produced after the crosses in the F1 generation are all heterozygous for specific traits.

Visualisation of dihybrid cross using a Punnett square
Dihybrid Cross Examples
Mendel took a pair of contradicting traits together for crossing, for example colour and the shape of seeds at a time. He picked the wrinkled-green seed and round-yellow seed and crossed them. He obtained only round-yellow seeds in the F1 generation. This indicated that round shape and yellow colour of seeds are dominant in nature.
Meanwhile, the wrinkled shape and green colour of seeds are recessive traits. Then, F1 progeny was self-pollinated. This resulted in four different combinations of seeds in the F2 generation. They were wrinkled-yellow, round-yellow, wrinkled-green seeds and round-green in the phenotypic ratio of 9:3:3:1.
During monohybrid cross of these traits, he observed the same pattern of dominance and inheritance. The phenotypic ratio 3:1 of yellow and green colour and of round and wrinkled seed shape during monohybrid cross was retained in dihybrid cross as well.
Consider “Y” for yellow seed colour and “y” for green seed colour, “R” for round shaped seeds and “r” for wrinkled seed shape. Thus, the parental genotype will be “YYRR” (yellow-round seeds) and “yyrr” (green-wrinkled seeds).