What of the following is incorrect about the chromosomal theory of inheritance ?

Options

A. It was proposed by Sutton and Boveri in 1902.
B. The pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried.
C. The behaviour of chromosomes was non - parallel to the behaviour of genes and used chromosome movement to explain Mendel's laws
D. Sutton united the knowledge of chromosomal segregation with Mendelian principles and celled it the chromosomal theory of inheritance .

Answer

To determine which statement is incorrect about the chromosomal theory of inheritance, we can analyze each of the provided statements step by step.

### Step 1: Understand the Chromosomal Theory of Inheritance
The chromosomal theory of inheritance states that chromosomes are the vehicles of inheritance. This theory was proposed by scientists Sutton and Boveri in 1902. It explains how genetic information is transmitted from parents to offspring through chromosomes.

**Hint:** Remember that the chromosomal theory connects the behavior of chromosomes with Mendelian genetics.

### Step 2: Analyze Each Statement
1. **Statement 1:** "They are proposed by Sutton and Boveri in 1902."
- This statement is correct. The chromosomal theory of inheritance was indeed proposed by Sutton and Boveri in 1902.

**Hint:** Verify the historical context of the theory to confirm its origin.

2. **Statement 2:** "Pairing and the separation of the pair of chromosomes will lead to segregation of pair factors."
- This statement is also correct. The pairing and separation of chromosomes during meiosis lead to the segregation of alleles (factors) as described by Mendel.

**Hint:** Consider how meiosis contributes to genetic diversity through segregation.

3. **Statement 3:** "The behavior of chromosomes was non-parallel."
- This statement is incorrect. The chromosomal theory emphasizes that the behavior of chromosomes is parallel to the behavior of genes (factors). They both segregate and assort independently during gamete formation.

**Hint:** Recall the key principles of the chromosomal theory that highlight the similarities between chromosome behavior and gene behavior.

4. **Statement 4:** "Sutton united the knowledge of chromosomal segregation with the Mendelian principle."
- This statement is correct. Sutton integrated the principles of Mendelian genetics with the understanding of chromosomal behavior, forming the basis of the chromosomal theory of inheritance.

**Hint:** Think about how Sutton's work bridged the gap between cytology and genetics.

### Step 3: Identify the Incorrect Statement
After analyzing all the statements, we find that:
- Statement 3 is the only incorrect statement as it contradicts the fundamental idea of the chromosomal theory of inheritance.

### Conclusion
The incorrect statement about the chromosomal theory of inheritance is:
**Option 3: "The behavior of chromosomes was non-parallel."**

**Final Answer:** Option 3 is incorrect.