Determine whether the statements below are true or false. If a...

Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.

If a dihybrid cross is performed, the expected genotypic ratio is 9:3:3:1.

Accepted Answer

Hi, everyone. Let's take a look at this practice problem together assuming simple dominance and independent assortment the Gina typical ratio of the big A little A big B, little B and big a little A big B little B cross will be the answer options are a to 1 B 9 to 3 to 3 to 1 C, 1 to 1 to 2 to 2 to 1 to 1 and D 1 to 2 to 1 to 2 to 4 to 2 to 1 to 2 to one. So this question is asking us to solve a simple di hybrid cross with one dominant a little and one recessive a little. First, let's determine the possible gametes that each parent can produce. Now, since there Gina types are identical, this means their possible gametes will be identical as well. Now note that each parent has four different alleles, big a little A big B and little B. The reason I point this out is with this type of problem, I just want to give you a heads up to be extra careful when filling out the pun it square due to the many combinations that are possible. It's very easy to miss even just one a lil. And then that could result in you getting an incorrect answer. So let's fill out a small punnett square together to determine the possible gametes of the parents on the screen is the punnett square results. The first trait alleles are in the top row. So big a little A and the second trait alleles are in the first column. Big B, little B, the possible gametes are big A big B, big, a little B, little A big B and little A little B. Now, we know that these gametes are produced both by parent one and parent too. So we can fill out the larger punnett square. The results of that punnett square are on the screen on the top row. The first row is the first parents possible gametes that we just solved for. And in the first column is the 2nd parents gam ease. You can see I've already filled in each of the possible combinations and note that there are 16 total offspring. Now, I'm going to remove this punnett square and post up another one. The results are exactly identical. The only difference is in this punnett square, I've highlighted the different gina types. So let's review those gina types together. We have one offspring with genotype, big A big A big B big B highlighted in pink, two offspring with genotype, big a big a big b little b highlighted in orange, one offspring with a big A big A little B little B highlighted in purple. Two offspring with genotype big a little A big B big B in blue. Four offspring with genotype big a little A big B little B highlighted in green. Two offspring with genotype big a little A little B little B highlighted in this maroon color. One offspring with genotype little a little A big B big B highlighted in the light purple. two offspring with genotype little a little a big b little b highlighted in gray and one offspring with genotype little a little A little B little B. This means the correct answer is option D, the 1 to 2 to 1 to 2 to 4 to 2 to 1 to 2 to one ratio D is the correct answer. Alright, everyone, I hope you found this helpful and I'll see you soon for the next practice problem.

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.
If a dihybrid cross is performed, the expected genotypic ratio is 9:3:3:1.

Key Concepts

Dihybrid Cross

Genotypic Ratio

Mendel's Laws of Inheritance

Watch next