What best defines a dihybrid cross?

What best defines a dihybrid cross?

• A. Cross involving more than one trait
• B. Cross between identical twins
• C. Cross that yields a 1:1:1:1 ratio
• D. Cross that uses single gene with complete dominance

Answer: (A)

Dihybrid crosses study two traits at the same time, using two genes (each with two alleles) to see how they segregate and whether they assort independently. That focus on more than one trait is what defines it. For example, crossing plants for seed shape and seed color with each parent heterozygous for both traits (RrYy x RrYy) reveals how the two genes segregate together and independently, often showing the classic 9:3:3:1 phenotypic ratio when there’s complete dominance and independent assortment. A cross between identical twins isn’t about examining two different traits in a single organism, and a cross that uses a single gene describes a monohybrid cross. The ratio you might see (such as 1:1:1:1) can happen in some specific crosses, but it doesn’t define the dihybrid concept. The key idea is a cross involving more than one trait.

Dihybrid crosses study two traits at the same time, using two genes (each with two alleles) to see how they segregate and whether they assort independently. That focus on more than one trait is what defines it. For example, crossing plants for seed shape and seed color with each parent heterozygous for both traits (RrYy x RrYy) reveals how the two genes segregate together and independently, often showing the classic 9:3:3:1 phenotypic ratio when there’s complete dominance and independent assortment. A cross between identical twins isn’t about examining two different traits in a single organism, and a cross that uses a single gene describes a monohybrid cross. The ratio you might see (such as 1:1:1:1) can happen in some specific crosses, but it doesn’t define the dihybrid concept. The key idea is a cross involving more than one trait.