A multicellular organism is larger due to

Options

A. large number of cells
B. larger cells
C. smaller cells
D. surface area - volume ratio

Answer

**Step-by-Step Solution:**

1. **Understanding Multicellular Organisms**:
- Multicellular organisms are made up of many cells, unlike unicellular organisms which consist of a single cell.

2. **Cell Growth and Differentiation**:
- In multicellular organisms, cells undergo growth and differentiation. This means that a single cell can divide and develop into different types of cells that perform various functions.

3. **Size of Cells**:
- The size of the cells in multicellular organisms is generally smaller compared to unicellular organisms. This is essential for the organism's overall size.

4. **Surface Area to Volume Ratio**:
- Smaller cells have a larger surface area relative to their volume. This is crucial because a larger surface area allows for more efficient exchange of materials (like nutrients and waste) between the cell and its environment.

5. **Functionality of Cells**:
- With a larger surface area per unit volume, smaller cells can perform their functions more effectively, leading to better overall functioning of the organism.

6. **Conclusion**:
- Therefore, a multicellular organism is larger primarily due to the presence of a large number of smaller cells, which allows for efficient functioning and growth.

**Final Answer**: A multicellular organism is larger due to the presence of smaller cells.

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