Mendel’s laws

In Mendel’s monohybrid cross, a pure tall plant is crossed with a pure dwarf plant. The first-generation offspring receive one allele for each form of the trait, but only the tall phenotype is visible. This shows that the tall allele masks the dwarf allele and is dominant. The dwarf allele is not destroyed; it remains present in the hybrid genotype. Therefore option A is correct.

Let the dominant tall allele be T and the recessive dwarf allele be t. A pure tall parent is TT and a pure dwarf parent is tt. Every F1 offspring receives T from the first parent and t from the second, giving genotype Tt. Because T is dominant, all F1 plants appear tall, while the t allele remains present but hidden. Therefore option A is correct; the dwarf information was not destroyed or absent.

Mendel’s law of independent assortment states that, during gamete formation, the allele pair for one trait can separate independently of the allele pair for another trait, provided the genes are not linked in a way that prevents independence. In a dihybrid cross this produces new combinations of traits, commonly reflected in the classic 9:3:3:1 ratio under ideal conditions. Thus option A is correct.