The grade of organisation in sponges is

Options

A. cellular grade
B. cell-tissue grade
C. protoplasmic grade
D. organ-system grade

Answer

To solve the question regarding the grade of organization in sponges, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the grade of organization in sponges. We need to identify the correct classification from the given options: cellular grade, cell tissue grade, protoplasmic grade, and organ system grade.

2. **Identify Characteristics of Sponges**: Sponges are simple multicellular organisms that lack true tissues and organs. Their body structure is primarily made up of a network of cells.

3. **Define the Grades of Organization**:
- **Protoplasmic Grade**: Found in unicellular organisms (protozoans) where all life processes occur within a single cell.
- **Cellular Grade**: Characterized by a collection of similar cells that perform specific functions but do not form true tissues. This is typical of sponges.
- **Cell Tissue Grade**: Found in organisms like cnidarians (e.g., jellyfish), where cells are organized into tissues.
- **Organ System Grade**: Present in more complex organisms (e.g., vertebrates) where organs work together as systems.

4. **Analyze the Options**:
- Since sponges have a cellular organization where cells perform various functions but do not form true tissues, they fit into the **cellular grade**.
- The other options (cell tissue grade, protoplasmic grade, organ system grade) do not accurately describe the organization of sponges.

5. **Conclude the Answer**: Based on the analysis, the grade of organization in sponges is **cellular grade**.

### Final Answer:
The grade of organization in sponges is **cellular grade**.