Question

In mendelian monohybrid cross, which generation is always heterozygous?

Options

• First filial generation

• Second filial generation

• Third filial generation

• Parent generation

Answer 1

First filial generation

Explanation:

When two pure-breeding parents with contrasting traits (e.g., homozygous dominant and homozygous recessive) are crossed, all offspring in the F₁ generation are heterozygous, carrying one allele from each parent. This heterozygosity results in the dominant trait being expressed in the F₁ generation, and hence this generation is always completely heterozygous in a monohybrid cross. Subsequent generations (like F₂) show segregation of alleles leading to a mixture of genotypes including homozygous one.