Which of the following phylum possess multicellular, organ grade level of organisation?
1. Platyhelminthes
2. Porifera
3. Nematode
4. Protozoa

Options

A. 1,2 and 3 are correct
B. 1 and 2 are correct
C. 2 and 4 are correct
D. 1 and 3 are correct

Answer

To determine which of the following phyla possess a multicellular, organ-grade level of organization, we need to analyze each option based on their biological characteristics.

### Step-by-Step Solution:

1. **Understanding Levels of Organization**:
- The levels of biological organization in animals include:
- **Cellular Level**: Individual cells perform all functions (e.g., Protozoa).
- **Tissue Level**: Groups of similar cells work together (e.g., Porifera).
- **Organ Level**: Tissues combine to form organs (e.g., Platyhelminthes and Nematoda).
- **Organ System Level**: Organs work together to perform complex functions.

2. **Analyzing Each Phylum**:
- **Porifera**: Commonly known as sponges, they exhibit a cellular level of organization. They are multicellular but lack true tissues and organs.
- **Protozoa**: These are unicellular organisms, meaning they have a cellular level of organization. They do not possess tissues or organs.
- **Platyhelminthes**: Also known as flatworms, they exhibit an organ-grade level of organization. They have tissues and organs, making them multicellular with a more complex structure.
- **Nematoda**: Known as roundworms, they also possess an organ-grade level of organization. Like Platyhelminthes, they have tissues and organs.

3. **Identifying the Correct Answer**:
- From the analysis, we see that both **Platyhelminthes (1)** and **Nematoda (3)** possess multicellular, organ-grade level of organization.
- Therefore, the correct answer to the question is **1 and 3**.

### Final Answer:
The phyla that possess multicellular, organ-grade level of organization are **Platyhelminthes (1)** and **Nematoda (3)**.

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