Question
(a) What is a dihybrid cross? (b) Explain the dihybrid cross with a checkerboard.
Answer
(a) Dihybrid cross refers to a cross between two individuals that differ in two traits that are controlled by two different genes.
(b) To find out whether one pair of alleles affects or influences the inheritance pattern of other alleles. In a dihybrid cross, Mendel considered two traits simultaneously. A cross conducted between two pure parents differing in two pairs of contrasting characters. He studied round and wrinkled seed characters along with yellow and green colours.
| Gametes | yr | yr |
| YR | YyRr | YyRr |
| YR | YyRr | YyRr |
Yellow and round are dominant alleles so in an F1 generation all plants with yellow and round are used. Above table is a punnet square for the F1 generation.
Mendel allowed self-pollination in each hybrid of F1 and collected seeds separately and obtained F2 generation. a checkerboard or punnet square for F2 generation is shown in the image. He found seeds of four types in 9:3:3:1 ratio which is a dihybrid ratio.
