Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic phospholipid bilayer with proteins and other molecules floating and moving within it.

Question 2

What is the primary function of cholesterol in the plasma membrane?

Accepted Answer

To stabilize the membrane and reduce its fluidity.

Question 3

A red blood cell (RBC) with an internal osmolarity of 300 mOsm is placed in a solution containing 300 mOsm NaCl and 60 mOsm urea. What will happen to the RBC after equilibrium is reached?

Accepted Answer

The cell will swell because urea diffuses into the cell, increasing intracellular osmolarity and drawing in water.

Question 4

Which type of membrane junction is most important in preventing the passage of molecules between adjacent cells in the lining of the digestive tract?

Accepted Answer

Tight junctions

Question 5

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

Accepted Answer

Synthesis of proteins for export

Question 6

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

Accepted Answer

Oxygen ($O_2$)

Question 7

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Uses carrier or channel proteins to transport molecules that are not lipid-soluble.

Question 8

Which of the following best describes the Na$^+$/K$^+$ ATPase pump?

Accepted Answer

It is an antiport that uses ATP to move Na$^+$ out of the cell and K$^+$ into the cell against their concentration gradients.

Question 9

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

Accepted Answer

Glucose transport into a cell coupled with Na$^+$ influx

Question 10

A patient with severe dehydration is given an intravenous solution of 0.45% NaCl. What is the likely effect on their red blood cells?

Accepted Answer

Cells will swell and may lyse due to water influx.

Question 11

Which of the following best explains why minor damage to the plasma membrane is usually not a problem for the cell?

Accepted Answer

The fluid mosaic nature allows lipids and proteins to move and self-heal small tears.

Question 12

Which process involves the movement of water across a semipermeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 13

Which of the following statements about desmosomes is correct?

Accepted Answer

They anchor cells together to resist mechanical stress.

Question 14

Which of the following is true regarding the glycocalyx?

Accepted Answer

It is a carbohydrate-rich area on the extracellular face of the plasma membrane involved in cell recognition.

Question 15

Which of the following is a characteristic of carrier-mediated facilitated diffusion?

Accepted Answer

It can be inhibited and shows saturation when all carriers are occupied.

Question 16

Which of the following best describes filtration across a capillary wall in the kidney?

Accepted Answer

Solutes are forced through the membrane by hydrostatic pressure.

Question 17

Which of the following is true about exocytosis?

Accepted Answer

It involves the fusion of a vesicle with the plasma membrane to release contents outside the cell.

Question 18

Which equation correctly represents the calculation of osmolarity for a solution containing 1 mM NaCl?

Accepted Answer

$	ext{Osmolarity} = 1\,	ext{mM} 	imes 2 = 2\,	ext{mOsm}$

Question 19

Which of the following best describes a solution that is isotonic to human red blood cells?

Accepted Answer

0.9% NaCl

Cell Membrane Structure and Transport Processes – ANP1105 Study Notes

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