Final answer:
It is b) false that all cells have a cell wall; not all cells possess one. The cell membrane, which is found in all cells, is selectively permeable and plays a key role in maintaining homeostasis by controlling the movement of substances in and out of the cell.
Step-by-step explanation:
To address the student's question: It's false that all cells have a cell wall that regulates the passage of molecules into and out of the cell. Not all cells possess a cell wall. It's important to understand that the cell membrane is a common feature of all cells, which serves as the selective barrier, but the cell wall is an additional rigid structure found only in certain organisms like plants, bacteria, fungi, and some archaea. The cell membrane is selectively permeable due to its structure, which allows some molecules to pass freely while regulating the movement of others. For instance, small, non-charged molecules like oxygen, carbon dioxide, and water can pass through the cell membrane without assistance. In contrast, larger or charged molecules typically require specific transport mechanisms to cross the membrane. Additionally, the cell membrane plays a critical role in maintaining the cell's homeostasis, which involves the balance of substances inside and outside the cell critical for its survival and function.