Choose the incorrect statement :-

Options

A. Nitrogenous base have heterocyclic ring
B. DNA is a genetic material in cellular organisms
C. Adenylic acid is nucleoside
D. Cytidine is a nucleoside

Answer

To solve the question "Choose the incorrect statement," we will analyze each statement one by one to determine which one is incorrect.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- The first statement claims that "nitrogenous bases have heterocyclic rings."
- Nitrogenous bases, such as adenine, guanine, cytosine, and thymine, indeed contain heterocyclic rings.
- **Conclusion:** This statement is correct.

2. **Analyze the Second Statement:**
- The second statement states that "DNA is the genetic material in cellular organisms."
- DNA (deoxyribonucleic acid) is indeed the primary genetic material in all cellular organisms, including prokaryotes and eukaryotes.
- **Conclusion:** This statement is correct.

3. **Analyze the Third Statement:**
- The third statement says "adenylic acid is a nucleoside."
- Adenylic acid (also known as AMP) is formed from adenine (a nitrogenous base) and ribose sugar, and it contains a phosphate group.
- Since it contains a phosphate group, it is classified as a nucleotide, not a nucleoside.
- **Conclusion:** This statement is incorrect.

4. **Analyze the Fourth Statement:**
- The fourth statement claims that "cytidine is a nucleotide."
- Cytidine is formed from cytosine and ribose sugar and does not contain a phosphate group, which makes it a nucleoside, not a nucleotide.
- **Conclusion:** This statement is correct.

### Final Conclusion:
- The incorrect statement is the third one: "adenylic acid is a nucleoside." It is actually a nucleotide.