Question

In a monohybrid cross, the phenotypic ratio is 9:3:3:1.true or false
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Answer 1

In a monohybrid cross, the phenotypic ratio is 9:3:3:1. is false.

Explanation:

A monohybrid cross is defined as the cross between only one pair of contrasting characters or alleles.

In a monohybrid cross, Mendel selected pure tall(TT) and dwarf pea plants(tt). He made a cross between these two plants. In $F_{1}$ generation, all the pea plants were tall(Tt). Again, he self-pollinated the $F_{1}$ generation plant and get  $F_{2}$  generation in which 75% of plants were tall and 25% of plants were dwarf. So, the ratio of tall and dwarf is 3:1 phenotypically.

But,  genotypically it was found that 25% of plants were pure tall(TT), 50% were hybrid tall(Tt) and 25% were pure dwarf(tt). So, the ratio of pure tall, hybrid tall, and pure dwarf plants is 1:2:1.

Answer 2

The phenotypic ratio is 1:2:1 so it is false