1. What Is A Dihybrid Cross?

A dihybrid cross is a breeding experiment between two organisms that are identical hybrids for two traits. This type of cross examines the inheritance of two different traits simultaneously, following Mendel's principle of independent assortment.

2. Understanding The 9:3:3:1 Ratio

The classic 9:3:3:1 ratio represents the phenotypic ratio in a dihybrid cross:

Where:

• 9 — Dominant for both traits
• 3 — Dominant for first trait, recessive for second
• 3 — Recessive for first trait, dominant for second
• 1 — Recessive for both traits

Explanation: This ratio occurs when two heterozygous individuals (AaBb × AaBb) are crossed and the genes assort independently.

3. How To Use This Calculator

Instructions: Enter the genotypes of both parents using standard notation (e.g., AaBb). The calculator will determine the expected phenotypic ratio of their offspring.

4. Applications In Genetics

Details: Dihybrid crosses are fundamental in genetics research, plant and animal breeding, and understanding inheritance patterns of multiple traits in medical genetics.

5. Frequently Asked Questions (FAQ)

Q1: What does the 9:3:3:1 ratio represent?
A: It represents the expected phenotypic ratio when crossing two heterozygous individuals for two independently assorting genes.

Q2: When does this ratio not apply?
A: When genes are linked on the same chromosome or when there's epistasis (gene interaction).

Q3: How is this different from a monohybrid cross?
A: A monohybrid cross examines one trait (3:1 ratio), while a dihybrid cross examines two traits simultaneously.

Q4: Can this calculator handle incomplete dominance?
A: This calculator assumes complete dominance. Different ratios apply for incomplete dominance or codominance.

Q5: What's the genotypic ratio in a dihybrid cross?
A: The genotypic ratio is more complex: 1:2:1:2:4:2:1:2:1 for AABB:AABb:AAbb:AaBB:AaBb:Aabb:aaBB:aaBb:aabb.