1. What is Dihybrid Cross Ratio?

The dihybrid cross ratio (9:3:3:1) describes the phenotypic ratio expected from crossing two heterozygous individuals for two different traits. This ratio demonstrates Mendel's principle of independent assortment.

2. How Does the Calculator Work?

The calculator uses the classic dihybrid cross ratio:

Where:

• 9 — Dominant for both traits
• 3 — Dominant for trait 1, recessive for trait 2
• 3 — Recessive for trait 1, dominant for trait 2
• 1 — Recessive for both traits

Explanation: This ratio occurs because the inheritance of one trait is independent of the inheritance of the other trait.

3. Importance of Dihybrid Cross

Details: Dihybrid crosses are fundamental in genetics for understanding how multiple traits are inherited simultaneously and for demonstrating Mendel's law of independent assortment.

4. Using the Calculator

Tips: Enter the observed phenotype counts for each combination. The calculator will show the expected values based on the 9:3:3:1 ratio and the total number of offspring.

5. Frequently Asked Questions (FAQ)

Q1: What is a dihybrid cross?
A: A dihybrid cross is a breeding experiment between two organisms that are heterozygous for two different traits.

Q2: Why is the ratio 9:3:3:1?
A: This ratio results from the independent assortment of two gene pairs during gamete formation.

Q3: When does the 9:3:3:1 ratio apply?
A: It applies when both parents are heterozygous for both traits and the genes are on different chromosomes (unlinked).

Q4: What if the observed ratio differs from 9:3:3:1?
A: Significant deviations may indicate linked genes, gene interaction, or other genetic phenomena.

Q5: How is this different from monohybrid cross?
A: Monohybrid cross involves one trait (3:1 ratio), while dihybrid cross involves two traits (9:3:3:1 ratio).