When growth takes place only by increase in volume of existing cells, it is called

Options

A. Auxetic growth
B. Multiplication growth
C. Accretionary growth
D. Differentiated cells

Answer

To solve the question "When growth takes place only by increase in volume of existing cells, it is called," we need to analyze the options provided and identify the correct term that describes this specific type of growth.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a specific type of growth that occurs solely through the increase in volume of existing cells, rather than an increase in the number of cells.

2. **Evaluate the Options**:
- **Option 1: Auxetic Growth**: This type of growth occurs when there is an increase in the volume of existing cells without an increase in cell number. This matches the definition provided in the question.
- **Option 2: Multiplicative Growth**: This type of growth involves an increase in the number of cells, not just the volume of existing cells. Therefore, this option does not fit the description.
- **Option 3: Excretionary Growth**: This type of growth involves secretion processes that increase the volume of extracellular spaces, which is not the same as increasing the volume of existing cells.
- **Option 4: Differentiated Cells or Differential Growth**: This refers to the formation of different types of cells and does not pertain to the increase in volume of existing cells.

3. **Select the Correct Answer**: Based on the evaluation, the correct answer is **Option 1: Auxetic Growth**, as it specifically refers to the increase in volume of existing cells.

4. **Conclusion**: The term that describes growth occurring only by the increase in volume of existing cells is "Auxetic Growth."

### Final Answer:
When growth takes place only by increase in volume of existing cells, it is called **Auxetic Growth**.