The flow of molecules in and out of a cell is regulated by

Options

A. cell membrane
B. mitochondria
C. golgi body
D. nucleus

Answer

**Step-by-Step Solution:**

1. **Identify the Question:** The question asks about what regulates the flow of molecules in and out of a cell.

2. **Consider the Options Provided:**
- **Option 1: Cell Membrane**
- **Option 2: Mitochondria**
- **Option 3: Golgi Body**
- **Option 4: Nucleus**

3. **Evaluate Each Option:**
- **Cell Membrane:** The cell membrane is responsible for regulating the entry and exit of molecules. It is selectively permeable, meaning it allows certain substances to pass while blocking others. This makes it the correct answer.
- **Mitochondria:** This organelle is primarily involved in cellular respiration and energy production, not in regulating the flow of molecules in and out of the cell. Therefore, this option is incorrect.
- **Golgi Body:** The Golgi body is involved in the packaging and sorting of proteins for secretion or use within the cell, but it does not regulate the flow of molecules in and out of the cell. This option is also incorrect.
- **Nucleus:** The nucleus coordinates cell activities and houses genetic material, but it does not directly regulate the flow of molecules in and out of the cell. Thus, this option is incorrect as well.

4. **Conclusion:** Based on the evaluation, the correct answer is the **Cell Membrane** as it regulates the flow of molecules in and out of the cell.

**Final Answer:** The flow of molecules in and out of a cell is regulated by the **Cell Membrane**.

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