Arithmetic growth can be observed in :

Options

A. Trichoderma colony
B. Yeast colony
C. Bacteria colony
D. Root elongation

Answer

To answer the question about where arithmetic growth can be observed, we can break it down into a step-by-step solution:

### Step-by-Step Solution:

1. **Understand the Types of Growth**:
- **Arithmetic Growth**: This is characterized by a constant addition of a certain number of units over time. For example, if one cell divides and one of the daughter cells differentiates into a permanent cell, the growth is slower and more linear.
- **Geometric Growth**: This involves exponential growth where the population doubles at regular intervals. For instance, if one cell divides into two, then those two can divide into four, and so on.

2. **Identify Examples of Each Growth Type**:
- **Arithmetic Growth**: Typically observed in structures like roots where there is a region of meristematic activity. In this region, cells divide but some differentiate and do not continue to divide.
- **Geometric Growth**: Commonly seen in microbial colonies such as yeast, bacteria, and fungi (like trichoderma), where the population doubles continuously.

3. **Focus on the Question**: The question specifically asks where arithmetic growth can be observed. Based on the understanding from the previous steps, we can conclude that:
- The root system exhibits arithmetic growth due to the presence of a constant number of dividing cells in the meristematic region, while other organisms listed (like yeast and bacteria) show geometric growth.

4. **Select the Correct Option**:
- From the options provided, the correct answer is that arithmetic growth can be observed in the **root**.

### Final Answer:
Arithmetic growth can be observed in the **root**.

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