A: Polypeptide sequence are dictated by DNA and represented by mRNA.
R: Sequence of amino acids in a polypeptide can be predicted by the exact sequence of nucleotides on the mRNA and template DNA.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark
B. If both Assertion & Reason are true and the reason is not the correct explanation of the assertion , then mark
C. If Assertion is ture statement but Reason is false, then mark.
D. If both Assertion and Reason are false statements, then mark.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that polypeptide sequences are dictated by DNA and represented by mRNA.
- This is true because DNA contains the genetic information that is transcribed into mRNA, which then serves as a template for protein synthesis.

2. **Understanding the Reason (R)**:
- The reason states that the sequence of amino acids in a polypeptide can be predicted by the exact sequence of nucleotides on the mRNA and the template DNA.
- This statement is partially true but misleading. While the sequence of amino acids is determined by the mRNA, the template DNA does not directly predict the amino acid sequence due to the presence of introns in the initial RNA transcript (pre-mRNA).

3. **Central Dogma of Molecular Biology**:
- The central dogma explains the flow of genetic information: DNA → RNA → Protein.
- DNA is transcribed into mRNA, and then mRNA is translated into a polypeptide (protein).

4. **Role of mRNA**:
- mRNA is the mature transcript that contains only the coding sequences (exons) after splicing, which removes non-coding sequences (introns).
- Therefore, the amino acid sequence is directly derived from the mRNA, not the original DNA sequence.

5. **Conclusion**:
- The assertion (A) is true because DNA does dictate the polypeptide sequence through mRNA.
- The reason (R) is false because the sequence of amino acids cannot be accurately predicted from the template DNA due to the presence of introns in the pre-mRNA.

### Final Answer:
- Assertion (A) is true, and Reason (R) is false.