Codominance/Incomplete Dominance Practice

Question

1. Explain the difference between incomplete dominance and codominance (Include the following words: Homozygous Dominant, Homozygous Recessive, Heterozygous, Genotype, Phenotype, Blend/Mix, Both)

Codominance Problems

2. In some chickens, the gene for feather color is controlled by codominance. The allele for black is B and the allole for whito is B'. The heterozygous phenotype is known as Erminette (black and while spotted)

a. What is the genotype for a black chicken.

b. What is the genotype for a white chicken

c. What is the genotype for Erminotte chicken

3. If 2 Erminette chickens were crossed what is the probability that

a. They would have a black chick?

b. They would have a white chick?

Answer 1

1. Difference Between Incomplete Dominance and Codominance

Incomplete dominance and codominance are both forms of inheritance that describe how alleles interact in heterozygous individuals.

Incomplete Dominance occurs when the phenotype of a heterozygous individual is an intermediate blend or mix between the phenotypes of the two homozygous parents. For example, if we have a homozygous dominant red flower (RR) and a homozygous recessive white flower (rr), the heterozygous phenotype (Rr) might appear as pink. Here, the genotype is a mix (Rr) resulting in a phenotype that is a blend of the dominant (red) and recessive (white) traits.

On the other hand, Codominance occurs when both alleles in a heterozygous individual are fully expressed, resulting in a phenotype that showcases both traits simultaneously. In this case, if we have a homozygous dominant red flower (RR) and a homozygous recessive white flower (rr), the heterozygous phenotype (Rr) would show both red and white features such as spotted flowers. Here, both alleles are distinctly visible in the phenotype.

In summary, in incomplete dominance, the heterozygous phenotype is a blend/mix of the two homozygous phenotypes, whereas in codominance, the heterozygous phenotype displays both traits distinctly.

2. Codominance Problems

Let's analyze the feather color in chickens controlled by codominance.

• Alleles: B (black) and B' (white)

a. What is the genotype for a black chicken?

The genotype for a black chicken would be homozygous dominant: BB.

b. What is the genotype for a white chicken?

The genotype for a white chicken would be homozygous recessive: B'B'.

c. What is the genotype for an Erminette chicken?

The genotype for an Erminette chicken (black and white spotted) would be heterozygous: BB'.

3. Probability From Crossing Two Erminette Chickens

To determine the probabilities of various chick colors, we can set up a Punnett square for the two Erminette chickens (BB').

• Possible gametes for each Erminette chicken: B and B'

The Punnett square would look like this:

| | B | B' | |------|------|------| | B | BB | BB' | | B' | BB' | B'B' |

From the Punnett square, we can see the following genotypes of the offspring:

• BB (black chicken)
• BB' (Erminette chicken)
• B'B' (white chicken)

Now, let's calculate the probabilities:

a. Probability of having a black chick (BB):

• There is 1 BB genotype out of 4 total outcomes.
• Probability = 1/4 or 25%.

b. Probability of having a white chick (B'B'):

• There is 1 B'B' genotype out of 4 total outcomes.
• Probability = 1/4 or 25%.

The other outcomes, which are the Erminette chickens (BB'), make up the remaining probability:

• Probability of Erminette (BB') = 2/4 = 1/2 or 50%.

So, to summarize:

• Probability of a black chick: 25%
• Probability of a white chick: 25%
• Probability of an Erminette chick: 50%.

Answer 2

Can you make the first question way shorter? I only have 5 lines to write

Answer 3

1. Difference Between Incomplete Dominance and Codominance:

Incomplete dominance occurs when the phenotype of a heterozygous individual is a blend of the homozygous dominant and recessive traits. For example, in plants, red (RR) and white (rr) parents produce pink (Rr). In contrast, codominance features both traits visible in the heterozygous phenotype, such as red (RR) and white (rr) flowers producing red and white spotted (Rr) flowers. Thus, incomplete dominance mixes traits, while codominance displays both distinctly.

Answer 4

Can you make it seem like a 9th grader wrote it?

Answer 5

1. Difference Between Incomplete Dominance and Codominance:

Incomplete dominance happens when a heterozygous individual shows a mix or blend of the two homozygous traits. For example, if you cross a red flower (RR) with a white flower (rr), the offspring might be pink (Rr). Codominance, on the other hand, is when both traits are fully shown in the heterozygous individual. So if you cross a red flower (RR) with a white flower (rr), the result would be a flower with red and white spots (Rr). In short, incomplete dominance blends traits, while codominance shows both traits clearly.