The process by which hydrophilic molecule move across the membrane by proteins is known as

Options

A. osmosis
B. facilitated diffusion
C. active transport
D. plasmolysis

Answer

To solve the question regarding the process by which hydrophilic molecules move across the membrane by proteins, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Membrane Structure**:
- The plasma membrane is primarily composed of a lipid bilayer, which is hydrophobic (water-repelling). This structure allows hydrophobic molecules to easily pass through.

**Hint**: Remember that the lipid bilayer's hydrophobic nature is crucial for understanding how different types of molecules interact with it.

2. **Identifying Hydrophilic Molecules**:
- Hydrophilic molecules are those that are attracted to water and cannot easily cross the hydrophobic lipid bilayer. Examples include ions and polar molecules.

**Hint**: Think about the properties of molecules and how they interact with water to classify them as hydrophilic or hydrophobic.

3. **Role of Proteins in Transport**:
- Since hydrophilic molecules cannot pass through the lipid bilayer directly, they require assistance from proteins embedded in the membrane. These proteins facilitate the movement of these molecules across the membrane.

**Hint**: Consider the function of membrane proteins and how they assist in transporting substances that cannot cross the membrane freely.

4. **Defining the Transport Process**:
- The specific process by which hydrophilic molecules move across the membrane with the help of proteins is known as **facilitated diffusion**. This process does not require energy and occurs along the concentration gradient (from high to low concentration).

**Hint**: Recall that "facilitated" implies assistance, and "diffusion" refers to the movement of molecules from an area of higher concentration to an area of lower concentration.

5. **Eliminating Other Options**:
- **Osmosis**: This specifically refers to the movement of water, not all hydrophilic molecules.
- **Active Transport**: This process requires energy (ATP) and moves molecules against their concentration gradient, which is not applicable here.
- **Plasmolysis**: This is the process of cell shrinkage due to water loss and does not pertain to the movement of molecules across the membrane.

**Hint**: When answering multiple-choice questions, systematically eliminate options that do not fit the criteria outlined in the question.

### Final Answer:
The correct answer is **Facilitated Diffusion**.