Most of the mineral nutrients required by plants are absorbed by the root cells by the process -

Options

A. Phagocytosis
B. Passive transport
C. Active transport
D. Osmosis

Answer

### Step-by-Step Solution:

1. **Understanding Mineral Nutrient Absorption**: Plants require various mineral nutrients for their growth and development, and these nutrients are primarily absorbed through their root cells.

2. **Analyzing the Options**: The question provides four options regarding the process of mineral nutrient absorption:
- Option 1: Phagocytosis
- Option 2: Passive transport
- Option 3: Active transport
- Option 4: Osmosis

3. **Evaluating Each Option**:
- **Phagocytosis**: This process involves the engulfing of large particles by cells. However, plant root cells do not utilize phagocytosis for nutrient absorption, so this option is incorrect.
- **Passive Transport**: This process allows substances to move across cell membranes without energy, typically down a concentration gradient. While some minerals can be absorbed passively, it is not sufficient for all minerals, especially in the case of iron. Therefore, this option is also incorrect.
- **Osmosis**: This is the movement of water across a semi-permeable membrane. While osmosis is crucial for water uptake, it does not directly facilitate the absorption of mineral nutrients. Thus, this option is incorrect as well.
- **Active Transport**: This process requires energy to move substances against their concentration gradient. In the case of mineral nutrients like iron, which are often found in lower concentrations in the soil compared to inside the root cells, active transport is necessary to absorb them effectively.

4. **Conclusion**: The correct answer is **Option 3: Active Transport**. This process allows root cells to absorb essential minerals, such as iron, from the soil even when they are in lower concentrations outside the root cells.