Select the incorrect statement from the following .

Options

A. Cistron is segment of DNA coding for a polypeptide.
B. The coding sequence or expressed sequences are defined as exons
C. Introns or intervening sequences appears in mature or processed RNA
D. Split gene arrangement is present in eukaryotes.

Answer

To solve the question of selecting the incorrect statement, we will analyze each option provided.

### Step-by-Step Solution:

1. **Analyze the First Statement**:
- **Statement**: "Cistron is the segment of DNA coding for a polypeptide."
- **Evaluation**: This statement is correct. A cistron refers to a segment of DNA that contains the information necessary to produce a polypeptide (protein).

**Hint**: Remember that a cistron is synonymous with a gene, which codes for proteins.

2. **Analyze the Second Statement**:
- **Statement**: "The coding sequence or expressed sequence are defined as the exons."
- **Evaluation**: This statement is also correct. Exons are the parts of a gene that are expressed and translated into proteins.

**Hint**: Exons are the coding regions of genes, while introns are non-coding regions.

3. **Analyze the Third Statement**:
- **Statement**: "Introns or intervening sequences appear in the mature or the processed RNA."
- **Evaluation**: This statement is incorrect. Introns are non-coding sequences that are removed during RNA processing. Therefore, they do not appear in the mature or processed RNA.

**Hint**: Focus on the process of RNA splicing, where introns are removed to produce mature mRNA.

4. **Analyze the Fourth Statement**:
- **Statement**: "Split Gene Arrangement is present in eukaryotes."
- **Evaluation**: This statement is correct. Split genes, which contain both exons and introns, are characteristic of eukaryotic organisms.

**Hint**: Split genes are a key feature of eukaryotic gene structure, distinguishing them from prokaryotic genes.

### Conclusion:
The incorrect statement among the options provided is the third statement: "Introns or intervening sequences appear in the mature or the processed RNA."

### Final Answer:
**The incorrect statement is the third one.**