### Step-by-Step Solution:
1. **Understanding the Question**: The question asks us to identify the incorrect statements regarding biomolecules, specifically focusing on nucleotides and nitrogenous bases.
2. **Analyzing the First Statement**:
- The first statement mentions that nitrogen bases (n bases) AGCTU have heterocyclic rings.
- **Evaluation**:
- Purines (adenine and guanine) have two heterocyclic rings.
- Pyrimidines (cytosine, thymine, and uracil) have one heterocyclic ring.
- Since the statement implies that all bases (AGCTU) have heterocyclic rings, it is misleading because while purines have two rings, pyrimidines only have one. Therefore, the statement is incorrect.
3. **Analyzing the Second Statement**:
- The second statement claims that DNA is the genetic material in cellular organisms.
- **Evaluation**:
- This statement is mostly correct as DNA is indeed the primary genetic material in most cellular organisms, although there are exceptions where RNA can serve as genetic material (e.g., in some viruses). However, the statement does not specify these exceptions, making it generally accepted as correct.
4. **Analyzing the Third Statement**:
- The third statement states that adenylic acid is a nucleoside and cytidine is a nucleoside.
- **Evaluation**:
- Adenylic acid (AMP) is actually a nucleotide, which consists of a nitrogenous base (adenine), a sugar (ribose), and a phosphate group.
- Cytidine, however, is a nucleoside (it consists of a nitrogenous base, cytosine, and a sugar, but no phosphate).
- Therefore, this statement is incorrect because it misclassifies adenylic acid as a nucleoside.
5. **Conclusion**:
- The incorrect statements identified are:
- The first statement about nitrogen bases having heterocyclic rings is misleading.
- The third statement incorrectly classifies adenylic acid as a nucleoside.
### Final Answer:
The incorrect statements are:
1. "N base AGCTU have heterocyclic rings" (misleading).
2. "Adenylic acid is a nucleoside" (incorrect classification).
