The diffusion rates depend on

Options

A. Gradient of concentration
B. Permeability of membrane
C. Temperature
D. All these factors

Answer

### Step-by-Step Solution:

1. **Understanding Diffusion**:
- Diffusion is the process through which substances move from an area of higher concentration to an area of lower concentration. This process is essential for the transport of minerals and organic compounds in plants.

2. **Identifying the Factors Affecting Diffusion**:
- To determine what affects the rate of diffusion, we need to analyze the given options.

3. **Option 1: Gradient of Concentration**:
- The concentration gradient refers to the difference in concentration between two areas. A steeper gradient (larger difference) will result in a faster diffusion rate. Therefore, this is a factor that affects diffusion.

4. **Option 2: Permeability of Membrane**:
- Permeability is the ability of a membrane to allow substances to pass through it. If a membrane is highly permeable, it allows more substances to diffuse across it, thus increasing the diffusion rate. Hence, this is also a factor.

5. **Option 3: Temperature**:
- Temperature affects the kinetic energy of particles. Higher temperatures increase the movement of particles, which in turn increases the rate of diffusion. Therefore, temperature is another factor that affects diffusion.

6. **Option 4: All of These**:
- Since all the previously mentioned factors (concentration gradient, permeability of the membrane, and temperature) influence the rate of diffusion, we can conclude that the correct answer is option 4, which states that all of these factors help in increasing the rate of diffusion.

### Final Answer:
The diffusion rates depend on **all of the above factors**: gradient of concentration, permeability of the membrane, and temperature.

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