Absorption of diffusible ions by cells concentration gradient is called :

Options

A. Passive absorption
B. Active absorption
C. Osmosis
D. Donnan equilibrium

Answer

**Step-by-Step Solution:**

1. **Understanding the Process**: The question asks about the absorption of diffusible ions by cells in relation to the concentration gradient. It is important to understand what is meant by "diffusible ions" and "concentration gradient".

2. **Defining Concentration Gradient**: A concentration gradient refers to the difference in concentration of a substance (in this case, ions) across a space or a membrane. Ions tend to move from an area of higher concentration to an area of lower concentration.

3. **Types of Transport**: There are two main types of transport mechanisms in cells: passive transport and active transport.
- **Passive Transport**: This does not require energy and occurs when substances move along the concentration gradient (from high to low concentration).
- **Active Transport**: This requires energy (usually in the form of ATP) and occurs when substances move against the concentration gradient (from low to high concentration).

4. **Identifying the Correct Term**: Since the question specifies the absorption of ions against the concentration gradient, we are looking for a term that describes this process.
- Passive absorption would not be correct as it involves movement along the gradient.
- Active absorption is the correct term as it involves energy expenditure to move ions against the concentration gradient.

5. **Conclusion**: Therefore, the absorption of diffusible ions by cells against the concentration gradient is called **active absorption**.

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