Which of the following functions holds true for plasma membrane?

Options

A. It protects and gives structural support to cells
B. It contains the genetic material
C. It regulates substances moving in and out of cells
D. It maintains the shape of cells

Answer

To determine which function holds true for the plasma membrane, we will analyze each option provided in the question step by step.

### Step 1: Analyze the first option
- **Option 1:** "It protects and gives structural support to cells."
- The plasma membrane does provide some protection, but the primary structure that provides protection and structural support to plant cells is the cell wall. Therefore, this option is **incorrect**.

**Hint:** Consider the role of the cell wall in plant cells versus the plasma membrane.

### Step 2: Analyze the second option
- **Option 2:** "It contains the genetic material."
- The genetic material (DNA) is housed within the nucleus of the cell, not in the plasma membrane. Thus, this option is also **incorrect**.

**Hint:** Recall where genetic material is located in eukaryotic cells.

### Step 3: Analyze the third option
- **Option 3:** "It regulates substances moving in and out of the cell."
- This statement is true. The plasma membrane is selectively permeable, meaning it controls what substances can enter or exit the cell, thus regulating the internal environment of the cell. This option is **correct**.

**Hint:** Think about the selective permeability of the plasma membrane.

### Step 4: Analyze the fourth option
- **Option 4:** "It maintains the shape of the cell."
- While the plasma membrane contributes to the overall shape of the cell, it is not primarily responsible for maintaining cell shape. The cytoskeleton and cell wall (in plants) play a more significant role in maintaining the shape of the cell. Therefore, this option is **incorrect**.

**Hint:** Consider the structures that contribute to cell shape beyond the plasma membrane.

### Conclusion
After analyzing all the options, the only function that holds true for the plasma membrane is that it regulates substances moving in and out of the cell. Thus, the correct answer is **Option 3**.