Question 1

Which of the following best describes the function of the plasma membrane in a typical animal cell?

Accepted Answer

It separates the intracellular environment from the extracellular environment and regulates the movement of substances in and out of the cell.

Question 2

A red blood cell is placed in a hypertonic solution. What will happen to the cell, and why?

Accepted Answer

The cell will shrink because water leaves the cell to the area of higher solute concentration.

Question 3

Which of the following is a function of membrane proteins that distinguishes them from phospholipids?

Accepted Answer

Acting as enzymes to catalyze chemical reactions at the membrane

Question 4

A patient receives an intravenous solution that is hypotonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

Cells will swell and may burst due to water entering the cells.

Question 5

Which of the following best explains why steroid hormones can diffuse directly through the plasma membrane?

Accepted Answer

They are nonpolar and lipid-soluble, allowing them to pass through the hydrophobic core of the membrane.

Question 6

Which equation correctly represents the relationship between osmotic pressure ($$\Pi$$), molar concentration ($$C$$), the gas constant ($$R$$), and temperature ($$T) $$for a solution?

Accepted Answer

$$\Pi = CRT$$

Question 7

Which type of cell junction would you expect to find between cells lining the stomach, and why?

Accepted Answer

Tight junctions, because they prevent leakage of digestive enzymes and fluids between cells.

Question 8

A glucose molecule is transported into a cell against its concentration gradient, coupled with the movement of sodium ions down their gradient. Which transport mechanism is responsible?

Accepted Answer

Secondary active transport (symport)

Question 9

Which of the following statements about the Na$$^+/K$^+$$ pump is correct?

Accepted Answer

It moves 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions into the cell per ATP hydrolyzed.

Question 10

Which of the following best describes the role of the glycocalyx on the plasma membrane?

Accepted Answer

It serves as a marker for cell-cell recognition and communication.

Question 11

Which process is responsible for the uptake of cholesterol into cells via specific surface receptors?

Accepted Answer

Receptor-mediated endocytosis

Question 12

A scientist observes that a certain molecule crosses the plasma membrane only when a specific protein is present, and the process does not require ATP. Which transport mechanism is most likely involved?

Accepted Answer

Facilitated diffusion

Question 13

Which of the following best explains why water moves into a cell placed in a hypotonic solution?

Accepted Answer

Water moves toward the area of higher solute concentration inside the cell.

Question 14

Which of the following is a characteristic of the fluid mosaic model of the plasma membrane?

Accepted Answer

Phospholipids and proteins can move laterally within the layer, giving the membrane flexibility.

Question 15

Which of the following best describes the function of gap junctions?

Accepted Answer

They allow direct passage of ions and small molecules between adjacent cells.

Question 16

Which of the following is true regarding the resting membrane potential (RMP) of a typical animal cell?

Accepted Answer

The RMP is established primarily by the Na$$^+/K$^+$$ pump and differential permeability to K$$^+$$ and Na$$^+.$$

Question 17

Which of the following scenarios best illustrates the concept of contact signaling?

Accepted Answer

Two immune cells recognize each other by direct interaction of their membrane proteins.

Question 18

Which of the following is the correct sequence of events in G protein-coupled receptor (GPCR) signaling?

Accepted Answer

Ligand binds GPCR → G protein activated → Effector protein activated → Second messenger produced

Question 19

Which of the following best describes the movement of oxygen across the plasma membrane of a lung cell?

Accepted Answer

Oxygen moves by simple diffusion down its concentration gradient.

Question 20

Which of the following is a real-life example of phagocytosis?

Accepted Answer

A white blood cell engulfing a bacterium.

Cells: The Living Units – Plasma Membrane Structure & Function

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