Questions: Select the phrases that describe the plasma membrane. - creates a barrier between the inside and outside of the cell - maintains the correct ion concentration inside the cell

The phrases that describe the plasma membrane are:

1. Creates a barrier between the inside and outside of the cell: The plasma membrane is a selective barrier that separates the interior of the cell from the external environment, controlling the movement of substances in and out of the cell.

2. Maintains the correct ion concentration inside the cell: The plasma membrane contains various proteins that help regulate the concentration of ions inside the cell, ensuring proper cellular function.

Explanation for each option:

• Provides a rigid structure that allows the cell to hold its shape: This is incorrect. The plasma membrane is flexible and not rigid. The cell's shape is primarily maintained by the cytoskeleton, not the plasma membrane.

• Creates a barrier between the inside and outside of the cell: This is correct. The plasma membrane acts as a selective barrier, controlling the exchange of materials between the cell and its environment.

• Creates a barrier between DNA and other intracellular structures: This is incorrect. The plasma membrane does not separate DNA from other intracellular structures. In eukaryotic cells, the nuclear envelope (a double membrane) surrounds the DNA, while in prokaryotic cells, DNA is located in the cytoplasm without a surrounding membrane.

• Maintains the correct ion concentration inside the cell: This is correct. The plasma membrane contains ion channels and pumps that regulate the concentration of various ions inside the cell, which is crucial for maintaining cellular homeostasis.

Summary: The correct phrases that describe the plasma membrane are:

• Creates a barrier between the inside and outside of the cell
• Maintains the correct ion concentration inside the cell