Which one is not connected with transport across the cell membrane

Options

A. Osmosis
B. Active transport
C. Diffusion
D. Surface tension

Answer

To determine which option is not connected with transport across the cell membrane, we can analyze each option provided:

1. **Osmosis**: This is the movement of water molecules from an area of higher water concentration (or lower solute concentration) to an area of lower water concentration (or higher solute concentration) across a semi-permeable membrane. This process is directly related to transport across the cell membrane.

2. **Active Transport**: This process involves the movement of molecules against their concentration gradient (from lower concentration to higher concentration) and requires energy in the form of ATP. Active transport is also directly connected to transport across the cell membrane.

3. **Diffusion**: This is the movement of molecules from an area of higher concentration to an area of lower concentration, and it occurs without the need for energy. Diffusion is another process that is directly related to transport across the cell membrane.

4. **Surface Tension**: This refers to the cohesive forces between liquid molecules at the surface of a liquid, which causes the liquid to behave as if its surface is covered with a stretched elastic membrane. Surface tension does not involve the movement of substances across a cell membrane.

Based on this analysis, the correct answer is **Surface Tension**, as it is not connected with transport across the cell membrane.

### Step-by-Step Solution:
1. **Identify the processes listed**: Osmosis, Active Transport, Diffusion, Surface Tension.
2. **Define each process**:
- **Osmosis**: Movement of water across a semi-permeable membrane.
- **Active Transport**: Movement of molecules against their concentration gradient using energy.
- **Diffusion**: Movement of molecules from high to low concentration without energy.
- **Surface Tension**: Cohesive forces at the surface of a liquid.
3. **Analyze the connection to cell membrane transport**:
- Osmosis, Active Transport, and Diffusion are all processes that involve the movement of substances across cell membranes.
- Surface Tension does not involve the transport of substances across cell membranes.
4. **Conclude the answer**: The process that is not connected with transport across the cell membrane is **Surface Tension**.