Which of these are an incorrect matched pair of the post - mendelian phenomenon and its example ?

Options

A. Incomplete dominance - Antirrhinum majus
B. Co - dominance - The type of wings in Drosophila
C. Pleiotropy - Sickle cell anemia gene
D. Polygenes - wheat kernel colour

Answer

To solve the question regarding the incorrect matched pair of post-Mendelian phenomena and their examples, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Incomplete Dominance:**
- Incomplete dominance is a phenomenon where the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.
- Example: In the case of the four o'clock plant (Mirabilis jalapa), crossing red (RR) and white (rr) flowers results in pink (Rr) flowers. The phenotypic ratio in the F2 generation is 1:2:1 (RR:Rr:rr).
- **Conclusion:** This example is correctly matched with incomplete dominance.

2. **Understanding Codominance:**
- Codominance occurs when both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits.
- Example: The ABO blood group system in humans is a classic example of codominance, where individuals with AB blood type express both A and B antigens.
- The mention of "type of wings in Drosophila" is incorrect as it does not represent codominance; instead, the ABO blood grouping does.
- **Conclusion:** This example is incorrectly matched with codominance.

3. **Understanding Pleiotropy:**
- Pleiotropy refers to a single gene affecting multiple phenotypic traits.
- Example: Sickle cell anemia is caused by a mutation in a single gene that affects hemoglobin, leading to multiple symptoms (e.g., sickle-shaped RBCs, pain crises, etc.).
- **Conclusion:** This example is correctly matched with pleiotropy.

4. **Understanding Polygenic Inheritance:**
- Polygenic inheritance involves multiple genes contributing to a single trait.
- Example: Human skin color is influenced by multiple genes (A, B, C), leading to a continuous range of phenotypes.
- **Conclusion:** This example is correctly matched with polygenic inheritance.

### Final Answer:
The incorrect matched pair of the post-Mendelian phenomenon and its example is **option number 2** (Codominance with type of wings in Drosophila).