Dihybrid ratio 9:3:3:1 in F2 results due to independent assortment of :

The dihybrid ratio of 9:3:3:1 in the F₂ generation results from the independent assortment of alleles (not chromosomes directly). Explanation: Mendel's Law of Independent Assortment states that: Alleles of different genes separate independently during gamete formation (meiosis), provided they are located on different chromosomes or are far apart on the same chromosome. Chromosomes vs. Alleles: Chromosomes carry many genes, but independent assortment refers specifically to the separation of alleles of different genes, not whole chromosomes. For example, in a dihybrid cross (e.g., AaBb × AaBb), the alleles A/a and B/b assort independently, leading to the 9:3:3:1 ratio. Exception (Linkage): If two genes are linked (on the same chromosome very close together), they do not assort independently, and the 9:3:3:1 ratio is disrupted