In a dihybrid cross, what is the expected phenotypic ratio? (2023)

₹0.0

Question: In a dihybrid cross, what is the expected phenotypic ratio? (2023)

Options:

Correct Answer: 9:3:3:1

Exam Year: 2023

Solution:

The expected phenotypic ratio in a dihybrid cross is 9:3:3:1.

In a dihybrid cross, what is the expected phenotypic ratio? (2023)

In a dihybrid cross, what is the expected phenotypic ratio? (2023)

Step 1: Understand what a dihybrid cross is. It involves two traits, each with two alleles.
Step 2: Identify the possible combinations of alleles for each trait. For example, if we have traits A (dominant) and a (recessive) and B (dominant) and b (recessive), the combinations are AB, Ab, aB, and ab.
Step 3: Create a Punnett square to visualize the combinations of the two traits. You will have a 4x4 grid for the combinations of alleles from each parent.
Step 4: Fill in the Punnett square with the combinations of alleles from both parents.
Step 5: Count the resulting phenotypes from the filled Punnett square. You will find 9 with both dominant traits, 3 with the first dominant and second recessive, 3 with the first recessive and second dominant, and 1 with both recessive traits.
Step 6: Write down the phenotypic ratio based on your counts. The ratio will be 9:3:3:1.

Dihybrid Cross – A genetic cross between individuals that differ in two traits, typically involving two pairs of alleles.
Phenotypic Ratio – The ratio of different phenotypes that appear in the offspring from a genetic cross.
Mendelian Genetics – The principles of inheritance established by Gregor Mendel, including the law of segregation and the law of independent assortment.