Given below are some statements about chromosomal disorders.
1: They can be caused due to failure in process completion during chromatid separation
2: They can be caused due to failure in process completion during cytokinesis.
3: They arise only in sex chromosomes.
4: They can be inherited.
Which of the above-mentioned statements/s is/are TRUE?

Options

A. only 1
B. only 2
C. only 3 and 4
D. only 1, 2 and 4

Answer

To determine which statements about chromosomal disorders are true, let's analyze each statement step by step.

### Step 1: Analyze Statement 1
**Statement 1**: They can be caused due to failure in process completion during chromatid separation.

- Chromosomal disorders can indeed arise from errors during cell division, particularly during the separation of sister chromatids in mitosis or homologous chromosomes in meiosis. If the chromatids do not separate properly, it can lead to an abnormal number of chromosomes in the daughter cells, which is a chromosomal disorder.

**Conclusion**: Statement 1 is TRUE.

### Step 2: Analyze Statement 2
**Statement 2**: They can be caused due to failure in process completion during cytokinesis.

- Cytokinesis is the process where the cytoplasm of a parent cell divides into two daughter cells. If cytokinesis fails, it can lead to cells with an abnormal number of chromosomes (e.g., polyploidy), which is also a form of chromosomal disorder.

**Conclusion**: Statement 2 is TRUE.

### Step 3: Analyze Statement 3
**Statement 3**: They arise only in sex chromosomes.

- Chromosomal disorders can occur in both sex chromosomes and autosomes (the first 22 pairs of chromosomes). Therefore, this statement is incorrect because it limits chromosomal disorders to only sex chromosomes.

**Conclusion**: Statement 3 is FALSE.

### Step 4: Analyze Statement 4
**Statement 4**: They can be inherited.

- Many chromosomal disorders can be inherited, especially those linked to sex chromosomes (e.g., Turner syndrome, Klinefelter syndrome). Therefore, this statement is true as chromosomal disorders can indeed be passed from parents to offspring.

**Conclusion**: Statement 4 is TRUE.

### Final Conclusion
Based on the analysis:
- **True Statements**: 1, 2, and 4
- **False Statement**: 3

Thus, the true statements are 1, 2, and 4.