Question

how does the monohybrid cross prove that the traits are dominant or recessive

Answer 1

the phenotypic ratio is 3 1 means there must be one allele that would be dominant over the other.

Answer 2

Traits are dominant or recessive in Monohybrid Cross – Prove:

The monohybrid cross prove that the traits are dominant or recessive in the following ways,

Matting the individuals with different alleles of one gene it is called as monohybrid cross.  

For example: Yellow (YY) and yy (green) are different alleles coding in the genes for the color.  

When these two alleles are matted with each other, in the F1 generation it can be found that all the produced offspring are dominant in nature as they have dominant allele’s expression in them.  

When the F1 generations off springs are self mated, it leads to the progeny in the ratio of 3:1, where 3 progeny are dominant in nature and 1 is recessive.