Mendel's law of dominance states that in a heterozygous genotype (having two different alleles), the dominant allele will mask the effect of the recessive allele. If we consider a typical monohybrid cross between a homozygous dominant plant with purple flowers (PP) and a homozygous recessive plant with white flowers (pp), all of the offspring (F1 generation) would be heterozygous (Pp) and exhibit the dominant trait (purple flowers).
When these F1 plants are self-crossed (Pp x Pp) in the F2 generation, we would expect the following genotype ratio:
- 25% homozygous dominant (PP)
- 50% heterozygous (Pp)
- 25% homozygous recessive (pp)
Since only the homozygous recessive genotype (pp) would express the white flowers, we would expect 25% of the offspring to have white flowers.
So, the answer is: B 25
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