A `N_(2-)` base together with pentose sugar and phosphate froms (or) building-block unit of nucleic acid is :-

Options

A. Nucleoside
B. Polypeptide
C. Nucleotide
D. Aminoacid

Answer

To solve the question regarding the building block unit of nucleic acids formed by a nitrogenous base, pentose sugar, and phosphate, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Components**:
- The question mentions three components: a nitrogenous base, a pentose sugar, and a phosphate group.

2. **Understand Nucleic Acids**:
- Nucleic acids, such as DNA and RNA, are polymers made up of smaller units called nucleotides.

3. **Define Nucleotide**:
- A nucleotide is defined as a molecule that consists of a nitrogenous base (which can be adenine, thymine, cytosine, guanine for DNA, and uracil for RNA), a pentose sugar (ribose in RNA and deoxyribose in DNA), and one or more phosphate groups.

4. **Evaluate the Options**:
- **Nucleoside**: This is a molecule that consists of just a nitrogenous base and a sugar, but it does not include a phosphate group.
- **Polypeptide**: This is a chain of amino acids and is not related to nucleic acids.
- **Nucleotide**: This includes a nitrogenous base, a pentose sugar, and a phosphate group, making it the correct answer.
- **Amino Acid**: This is the building block of proteins, not nucleic acids.

5. **Conclusion**:
- Based on the definitions and components, the correct answer is **nucleotide**.

### Final Answer:
The building block unit of nucleic acids formed by a nitrogenous base, pentose sugar, and phosphate is **nucleotide**.

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