Monohybrid Cross

Step 1: Setting up the Punnett square.
The genotypes of the parents are and . The Punnett square is set up as follows: Step 2: Calculating the genotypic ratio.
From the Punnett square, the offspring have the following genotypes: : 1 individual. : 2 individuals. : 1 individual. The genotypic ratio is therefore: Step 3: Explanation of options.
Option (A): Incorrect. This represents an equal distribution between two genotypes, which is not the case. Option (B): Correct. The genotypic ratio for a monohybrid cross is . Option (C): Incorrect. This represents the phenotypic ratio, not the genotypic ratio. Option (D): Incorrect. This represents the phenotypic ratio for a dihybrid cross, not a monohybrid cross.

The height of the plant is determined by a single gene with two alleles: (dominant, tall) and (recessive, dwarf). A homozygous dominant tall plant has the genotype , and a homozygous recessive dwarf plant has the genotype .
To determine the phenotypic ratio of the F1 generation, we perform a cross between the two plants using a Punnett square.
The parent can only produce gametes with the allele, and the parent can only produce gametes with the allele. The Punnett square for the cross is:
All offspring in the F1 generation have the genotype . Since the allele is dominant, all plants with the genotype will exhibit the tall phenotype.
Thus, the phenotypic ratio of the F1 generation is all tall (100% tall).