Which of the following pairs is wrongly matched?

Options

A. Starch synthesis in pea : Multiple alleles
B. T.H. Morgan : Linkage
C. XO type sex Determination : Grasshopper
D. ABO blood grouping : Codominance

Answer

To determine which of the following pairs is wrongly matched, let's analyze each option step by step:

1. **Star Synthesis in Pea Plants with Multiple Alleles**:
- **Understanding Multiple Alleles**: Multiple alleles refer to a situation where more than two alleles exist for a single gene, affecting the same phenotype.
- **Star Synthesis in Peas**: This phenomenon involves the synthesis of starch and is controlled by a single gene that affects the seed shape.
- **Conclusion**: Since star synthesis in pea plants is controlled by a single gene, it does not fit the definition of multiple alleles. Instead, it is an example of pleiotropy, where one gene influences multiple traits.

2. **T.H. Morgan with Linkage**:
- **Understanding Linkage**: Linkage refers to genes that are located close to each other on the same chromosome and tend to be inherited together.
- **T.H. Morgan's Contribution**: T.H. Morgan studied Drosophila melanogaster (fruit flies) and provided significant insights into the concept of linkage.
- **Conclusion**: This pair is correctly matched.

3. **Exo-type Sex Determination in Grasshopper**:
- **Understanding Exo-type Sex Determination**: In grasshoppers, sex is determined by the presence of X chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
- **Conclusion**: This pair is also correctly matched.

4. **ABO Blood Grouping with Co-dominance**:
- **Understanding Co-dominance**: Co-dominance occurs when both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits.
- **ABO Blood Grouping**: In this system, both A and B antigens can be present in the same individual (AB blood type), demonstrating co-dominance.
- **Conclusion**: This pair is correctly matched.

**Final Conclusion**:
The incorrectly matched pair is **Star Synthesis in Pea Plants with Multiple Alleles**. It should be matched with **Pleiotropy** instead.