Which of the following is not related to the chromosomes theory of inheritance ?

Options

A. Chromosomes as well as genes occur in pairs .
B. Behaviour of chromosomes is parallel to the behaviour of genes.
C. The two alleles of genes pair are located on homologous sites on homologous chromosomes .
D. Pairing and separation of a pair of chromosomes would lead to the segregation of a factor they carried.

Answer

To solve the question "Which of the following is not related to the chromosomes theory of inheritance?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Chromosomal Theory of Inheritance**:
- The chromosomal theory of inheritance states that genes are located on chromosomes, and the behavior of chromosomes during meiosis explains the inheritance patterns of traits.

2. **Analyzing Each Option**:
- **Option A**: "Chromosome as well as genes occurs in pairs."
- This statement is correct. Chromosomes exist in pairs (homologous chromosomes), and genes also come in pairs (alleles).

- **Option B**: "Behavior of chromosomes is parallel to the behavior of genes."
- This statement is also correct. The segregation and independent assortment of chromosomes during meiosis parallel the behavior of genes.

- **Option C**: "The two alleles of a gene pair are located on homologous sites on homologous chromosomes."
- This statement is correct. Each homologous chromosome carries one allele of a gene at the same locus.

- **Option D**: "Pairing and separation of a pair of chromosomes would lead to the fact that they carried."
- This statement is incomplete and misleading. It should state that "pairing and separation of a pair of chromosomes would lead to the segregation of the factors they carried." Therefore, this option is not correctly related to the chromosomal theory of inheritance.

3. **Conclusion**:
- The option that is not related to the chromosomal theory of inheritance is **Option D**.

### Final Answer:
**Option D** is not related to the chromosomes theory of inheritance.

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