Question

Mendel made 2 different types of of cross-monohybrid and dihybrid . Why did he obtain different type of ratios in his experiments ?​

Answer 1

Dear student,

In the first experiment of Mendel, which involved Monohybrid cross in Garden pea,in which a cross involving contrasting traits of only one character was done, i.e., in order to study inheritance of plant height, a pure breeding tall tree plant was crossed with pure breeding dwarf plant. All other traits were ignored here. Hence, the phenotypic ratio obtained in F2 generation was 3:1 and the genotypic ratio obtained was 1:2:1.

On the other hand, inheritance of two pair of alleles through a number of generation was studied by Mendel through Dihybrid cross. It involved cross between plants with round and yellow seeds and plants with green and wrinkled seeds. Thus here two contrasting traits were studied and hence the ratios obtained was more diverse than the monohybrid cross. The phenotypic ratio obtained was 9:3:3:1 whereas the genotypic ratio obtained was 1:2:1:2:4:2:1:2:1.

Regards.