Question 1

Which of the following best describes the main function of the plasma (cell) membrane?

Accepted Answer

It acts as a selective barrier, regulating the movement of substances into and out of the cell.

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will swell and may burst because water moves into the cell.

Question 3

Which of the following molecules can most easily cross the plasma membrane by simple diffusion?

Accepted Answer

Oxygen ($\mathrm{O_2}$)

Question 4

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What effect will this have on their red blood cells?

Accepted Answer

The cells will shrink due to water leaving the cells.

Question 5

Which of the following best explains why glucose requires a carrier protein to cross the plasma membrane?

Accepted Answer

Glucose is large and water-soluble, so it cannot pass through the lipid bilayer without assistance.

Question 6

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It requires ATP to function and moves 3 $\mathrm{Na^+}$ out and 2 $\mathrm{K^+}$ into the cell.

Question 7

A cell is placed in an isotonic solution. What will happen to the cell's volume and why?

Accepted Answer

The cell's volume will remain unchanged because there is no net movement of water.

Question 8

Which of the following is an example of secondary active transport?

Accepted Answer

Glucose being transported into the cell along with sodium ions using the sodium gradient established by the sodium-potassium pump

Question 9

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of solutes from high to low concentration through a protein channel or carrier, without using ATP

Question 10

A neuron releases acetylcholine, which binds to a receptor on a muscle cell and opens a sodium channel. What type of membrane transport is this an example of?

Accepted Answer

Facilitated diffusion via a gated channel

Question 11

Which of the following best explains why osmosis is important for cell function?

Accepted Answer

It maintains the proper balance of water and solutes, preventing excessive swelling or shrinking of cells.

Question 12

Which of the following statements about endocytosis is correct?

Accepted Answer

It involves the formation of vesicles to bring large substances into the cell.

Question 13

A cell uses ATP to move calcium ions ($\mathrm{Ca^{2+}}$) from a region of low concentration to a region of high concentration. Which type of transport is this?

Accepted Answer

Primary active transport

Question 14

Which of the following best describes the role of integral proteins in the plasma membrane?

Accepted Answer

They act as channels, carriers, receptors, and enzymes.

Question 15

Which of the following is true regarding the distribution of sodium ($\mathrm{Na^+}$) and potassium ($\mathrm{K^+}$) ions across the plasma membrane?

Accepted Answer

$\mathrm{Na^+}$ is higher outside the cell and $\mathrm{K^+}$ is higher inside.

Question 16

A patient with diabetes has high blood glucose levels. Insulin is released and binds to its receptor on target cells. What is the immediate effect of insulin binding?

Accepted Answer

It stimulates glucose transporters to move to the cell membrane, increasing glucose uptake.

Question 17

Which of the following best describes the process of exocytosis?

Accepted Answer

Release of large molecules from the cell by fusion of vesicles with the plasma membrane.

Question 18

Which of the following scenarios best illustrates secondary active transport?

Accepted Answer

Glucose entering a cell along with sodium ions, using the sodium gradient established by ATP-driven pumps.

Question 19

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Storing genetic information

Question 20

A cell is exposed to a solution with a much higher solute concentration than its cytoplasm. Which equation best represents the direction of water movement due to osmosis?

Accepted Answer

$	ext{Water moves from low solute concentration (high water) to high solute concentration (low water)}$

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