Movement of hydrophilic substances according to the concentration gradient with the help of membrane proteins without expenditure
of energy is called

Options

A. osmosis
B. simple diffusion
C. passive transport
D. Facilitated diffusion

Answer

To solve the question, "Movement of hydrophilic substances according to the concentration gradient with the help of membrane proteins without expenditure of energy is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Key Terms**:
- **Hydrophilic Substances**: These are substances that are attracted to water and can dissolve in it.
- **Concentration Gradient**: This refers to the difference in concentration of a substance across a space. Substances tend to move from an area of higher concentration to an area of lower concentration.
- **Membrane Proteins**: These are proteins that are embedded in the cell membrane and assist in the transport of substances across the membrane.

2. **Identify the Type of Transport**:
- The question specifies that the movement occurs **without expenditure of energy**, indicating that it is a type of passive transport.

3. **Evaluate the Options**:
- **Osmosis**: This is the movement of water across a semipermeable membrane, but it does not involve membrane proteins for the transport of water.
- **Simple Diffusion**: This is the movement of substances across a membrane without the assistance of proteins, also along the concentration gradient.
- **Passive Transport**: This is a broad category that includes both osmosis and diffusion but does not specifically involve membrane proteins.
- **Facilitated Diffusion**: This is the process where hydrophilic substances move across the membrane with the help of specific membrane proteins, along the concentration gradient, and without the use of energy.

4. **Select the Correct Answer**:
- Based on the definitions and characteristics of each option, the correct answer is **Facilitated Diffusion**. This is because it specifically involves the movement of hydrophilic substances through membrane proteins along the concentration gradient without energy expenditure.

### Final Answer:
**Facilitated Diffusion**

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