You are monitoring the diffusion of a coloured molecule across a membrane, Which of the following will result in the fastest rate of diffusion?

Options

A. An internal concentration of 5% and an external concentration of 60%
B. An internal concentration of 35% and an external conc. of 40%
C. An internal concentration of 60% and an external concentration of 5%
D. a and c are correct

Answer

To determine which scenario results in the fastest rate of diffusion of a colored molecule across a membrane, we need to analyze the concentration gradients in each option provided. The rate of diffusion is directly proportional to the concentration gradient, which is the difference in concentration between the internal and external environments.

### Step-by-Step Solution:

1. **Understand the Concept of Concentration Gradient**:
- The concentration gradient is the difference in concentration of a substance across a membrane. A larger difference results in a faster rate of diffusion.

2. **Analyze Each Option**:
- **Option 1**: Internal concentration = 5%, External concentration = 60%
- Concentration gradient = 60% - 5% = 55%
- **Option 2**: Internal concentration = 35%, External concentration = 40%
- Concentration gradient = 40% - 35% = 5%
- **Option 3**: Internal concentration = 60%, External concentration = 5%
- Concentration gradient = 60% - 5% = 55%
- **Option 4**: States that both options A and C are correct.

3. **Compare the Concentration Gradients**:
- From the calculations:
- Option 1 has a gradient of 55%.
- Option 2 has a gradient of 5%.
- Option 3 has a gradient of 55%.
- Options 1 and 3 both have the same concentration gradient of 55%, which is significantly higher than the gradient in Option 2.

4. **Determine the Fastest Rate of Diffusion**:
- Since both Options 1 and 3 have the highest concentration gradient (55%), they will result in the fastest rate of diffusion.
- Therefore, Option 4, which states that both A and C are correct, is the correct answer.

### Final Answer:
The fastest rate of diffusion will occur in **Option 4**, as both Option 1 and Option 3 have the highest concentration gradient of 55%.

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