Question

In Morgan's dihybrid crosses with Drosophila, the F₂ ratio deviated from the expected 9:3:3:1 ratio. Which genes were being studied in these crosses?

Options

• Genes located on the X chromosome

• Recessive genes only

• Genes on different chromosomes

• Genes located on autosomes

Answer 1

Morgan's dihybrid crosses that showed deviation from the 9:3:3:1 ratio involved genes located on the X chromosome. The deviation from expected ratios indicated linkage—the tendency of genes on the same chromosome to be inherited together rather than assort independently.