Codominant and Incomplete Dominance Practice Worksheet Answer Key
This practice worksheet is designed to help students understand the concepts of codominant and incomplete dominance in genetics. The following answer key provides explanations and answers to the practice problems.
Multiple Choice Questions
- What is the result of a cross between two parents with the genotype Aa and Aa? A) AA and aa B) AA, Aa, and aa C) Aa only D) AA and Aa
Answer: B) AA, Aa, and aa
📝 Note: In a cross between two parents with the genotype Aa and Aa, the possible genotypes of the offspring are AA, Aa, and aa, following the rules of Mendelian inheritance.
- Which of the following is an example of incomplete dominance? A) Red flowers ® and white flowers ® B) Tall plants (T) and short plants (t) C) Brown eyes (B) and blue eyes (b) D) AB blood type (I^A and I^B)
Answer: A) Red flowers ® and white flowers ®
📝 Note: Incomplete dominance occurs when one allele does not completely dominate the other allele, resulting in a blend of the two traits. In this case, the cross between red flowers (R) and white flowers (r) produces pink flowers (Rr), which is an example of incomplete dominance.
Short Answer Questions
- What is codominance? Provide an example.
Answer: Codominance is a phenomenon where two alleles have an equal effect on the phenotype, resulting in a combination of the two traits. An example of codominance is the AB blood type, where the A and B alleles are codominant, resulting in the expression of both A and B antigens on the surface of red blood cells.
- Describe the difference between incomplete dominance and codominance.
Answer: Incomplete dominance occurs when one allele does not completely dominate the other allele, resulting in a blend of the two traits. In contrast, codominance occurs when two alleles have an equal effect on the phenotype, resulting in a combination of the two traits.
Problem-Solving Questions
- A cross is made between two parents with the genotype AaBb. What are the possible genotypes and phenotypes of the offspring?
Answer:
| Genotype | Phenotype |
|---|---|
| AABB | AB |
| AABb | AB |
| AaBB | AB |
| AaBb | AB |
| aaBB | aB |
| aaBb | aB |
| AAbb | Aa |
| aaBB | aa |
- A cross is made between two parents with the genotype Rr. What are the possible genotypes and phenotypes of the offspring?
Answer:
| Genotype | Phenotype |
|---|---|
| RR | Red |
| Rr | Pink |
| rr | White |
Conclusion
In conclusion, this practice worksheet has helped students understand the concepts of codominant and incomplete dominance in genetics. By working through the multiple-choice questions, short answer questions, and problem-solving questions, students have demonstrated their ability to apply these concepts to real-world scenarios.
What is the difference between codominance and incomplete dominance?
+Codominance occurs when two alleles have an equal effect on the phenotype, resulting in a combination of the two traits. Incomplete dominance occurs when one allele does not completely dominate the other allele, resulting in a blend of the two traits.
What is an example of codominance?
+An example of codominance is the AB blood type, where the A and B alleles are codominant, resulting in the expression of both A and B antigens on the surface of red blood cells.
What is the result of a cross between two parents with the genotype Aa and Aa?
+The possible genotypes of the offspring are AA, Aa, and aa, following the rules of Mendelian inheritance.
