Membrane transport

The video tutorial by Dr. Morton covers the permeability of the cell membrane, focusing on the concentration of ions like sodium and potassium. It explains diffusion, including simple and facilitated diffusion, and the role of membrane proteins in these processes. The tutorial also discusses osmosis and active transport, highlighting primary and secondary active transport mechanisms, such as the sodium-potassium pump. The content is designed to help students understand how substances move across cell membranes and the physiological significance of these processes.

What is the primary reason for the higher concentration of sodium ions outside the cell compared to inside?

• Sodium ions are actively transported out of the cell.

• The cell membrane is more permeable to sodium ions.

• Sodium ions are attracted to the cell's exterior by electrical forces.

• Sodium ions are produced in higher quantities outside the cell.

Which type of molecules can diffuse rapidly across the cell membrane without the need for transport proteins?

• Large polar molecules

• Small nonpolar molecules

• Charged ions

• Proteins

What is the role of ion leak channels in facilitated diffusion?

• They block ions from entering the cell.

• They change the shape of ions to facilitate movement.

• They allow specific ions to move down their concentration gradient.

• They actively transport ions against their concentration gradient.

Which of the following is an example of a molecule that uses facilitated diffusion to cross the cell membrane?

• Sodium ions

• Glucose

• Water

• Oxygen

How does osmosis differ from simple diffusion?

• Osmosis occurs only in plant cells.

• Osmosis moves particles against their concentration gradient.

• Osmosis requires energy, while simple diffusion does not.

• Osmosis involves the movement of water, while simple diffusion involves solutes.

What happens to a cell when it is placed in a hypertonic solution?

• The cell shrinks as water leaves the cell.

• The cell becomes more permeable to ions.

• The cell swells and bursts.

• The cell remains unchanged.

What is the main energy source for primary active transport?

• ATP

• Glucose

• Oxygen

• Sodium ions

Which of the following best describes the sodium-potassium pump?

• It only functions in the presence of glucose.

• It allows sodium and potassium to passively diffuse across the membrane.

• It uses ATP to move sodium out of the cell and potassium into the cell.

• It moves sodium and potassium ions down their concentration gradients.

In secondary active transport, what is the role of a symporter?

• It only transports ions.

• It moves two particles in opposite directions.

• It moves one particle down its gradient and another against its gradient in the same direction.

• It uses ATP to move particles against their gradient.

What distinguishes an antiporter from a symporter in secondary active transport?

• An antiporter only transports ions, while a symporter transports molecules.

• An antiporter requires ATP, while a symporter does not.

• An antiporter moves particles in opposite directions, while a symporter moves them in the same direction.

• An antiporter moves particles in the same direction, while a symporter moves them in opposite directions.