Which of the following proved an exception to Mendel's principles?

Options

A. dominance
B. linkage
C. independent assortment
D. purity of gametes/segregation

Answer

To answer the question regarding which of the following proved an exception to Mendel's principles, we need to analyze the principles established by Gregor Mendel and identify any exceptions that have been discovered in genetics.

### Step-by-Step Solution:

1. **Understand Mendel's Principles**: Mendel's principles include the Law of Segregation, the Law of Independent Assortment, and the Law of Dominance. These principles explain how traits are inherited from one generation to the next.

2. **Identify Exceptions**: Various genetic phenomena have been identified that do not conform to Mendel's principles. Some of these exceptions include:
- **Linkage**: Genes that are located close to each other on the same chromosome tend to be inherited together, which violates the Law of Independent Assortment.
- **Incomplete Dominance**: In some cases, the dominant allele does not completely mask the effect of the recessive allele, leading to a phenotype that is a blend of both traits.
- **Codominance**: Both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive.
- **Polygenic Inheritance**: Traits that are controlled by multiple genes do not follow simple Mendelian inheritance patterns.

3. **Conclusion**: Based on the exceptions identified, linkage is a significant exception to Mendel's principles, particularly the Law of Independent Assortment.

### Final Answer:
Linkage is an exception to Mendel's principles.

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