Assertion :- The backbone of polynucleotide chain is formed due to sugar and phosphate.
Reason :- A nitrogenous base is linked to the pantose sugar through a N-glycosidic linkage to formed a nucleoside.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The backbone of polynucleotide chain is formed due to sugar and phosphate."
- In the context of nucleic acids (DNA and RNA), the backbone of the polynucleotide chain consists of alternating sugar (pentose) and phosphate groups. This is indeed correct.

2. **Understanding the Reason**:
- The reason states that "A nitrogenous base is linked to the pentose sugar through an N-glycosidic linkage to form a nucleoside."
- This is also correct. In nucleic acids, nitrogenous bases (adenine, thymine, cytosine, guanine in DNA; and uracil in RNA) are attached to the sugar molecule via N-glycosidic bonds to form nucleosides.

3. **Analyzing the Relationship**:
- Although both the assertion and reason are true, we need to determine if the reason correctly explains the assertion.
- The assertion is about the structure of the polynucleotide backbone, while the reason describes the formation of nucleosides, which is a different aspect of nucleic acid structure.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not explain the assertion, the correct answer is that both the assertion and reason are true, but the reason is not a correct explanation of the assertion.

### Final Answer:
Both the assertion and reason are true, but the reason is not a correct explanation of the assertion.

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