What principle is demonstrated by a dihybrid cross showing independent assortment?

• A. The Law of Independent Assortment
• B. The Law of Dominance
• C. The Law of Segregation
• D. The Principle of Reciprocal Crossing

Answer: (A)

The principle shown is Mendel's Law of Independent Assortment. In a dihybrid cross like AaBb x AaBb, each parent can produce four kinds of gametes (AB, Ab, aB, ab). During meiosis, the gene loci for the two traits assort into gametes independently due to the random orientation of homologous chromosome pairs. This means the alleles for one gene mix freely with the alleles for the other gene in gametes, so all combinations occur with equal likelihood. When fertilization occurs, offspring display the characteristic variety of trait combinations, often summarized by the 9:3:3:1 phenotypic ratio under complete dominance and when the genes are unlinked. The other terms refer to different inheritance concepts (dominance relationships for a single gene, segregation of alleles for a single gene, or a crossing method) and do not capture the specific idea that two genes assort independently during gamete formation.