$$\text{Osmolarity} = 150\ \text{mM} \times 2 = 300\ \text{mOsm/L}$$

Question 1

Which of the following best describes the structural property of the cell membrane that allows selective permeability?

Accepted Answer

A double layer of phospholipids with embedded proteins

Question 2

A patient receives an intravenous solution of 0.9% NaCl. Which property makes this solution suitable for maintaining normal cell volume?

Accepted Answer

It is isotonic, matching the osmolarity of plasma

Question 3

Which equation correctly calculates the osmolarity of a 150 mM NaCl solution, assuming complete dissociation?

Accepted Answer

$$	ext{Osmolarity} = 150\ 	ext{mM} 	imes 2 = 300\ 	ext{mOsm/L}$$

Question 4

Which of the following transport mechanisms requires energy input from ATP and moves substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 5

A red blood cell is placed in a solution containing 15 mM NaCl. What will happen to the cell and why?

Accepted Answer

It will swell because the solution is hypotonic

Question 6

Which of the following best explains why K$$^+ is $$found in higher concentrations inside the cell compared to Na$$^+$$?

Accepted Answer

The Na$$^+/K$^+$$ ATPase actively transports K$$^+$$ into the cell and Na$$^+$$ out

Question 7

Which of the following is a feature of facilitated diffusion?

Accepted Answer

It uses membrane proteins to move molecules down their concentration gradient

Question 8

A patient with renal failure is undergoing hemodialysis. Which principle allows removal of excess solutes from the blood?

Accepted Answer

Diffusion of solutes down their concentration gradient across a semi-permeable membrane

Question 9

Which of the following best describes the role of gap junctions in cell-to-cell communication?

Accepted Answer

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

Question 10

Which of the following scenarios best illustrates the concept of tonicity?

Accepted Answer

A cell placed in a solution with equal concentrations of non-penetrating solutes inside and outside remains unchanged

Question 11

Which of the following is true regarding secondary active transport?

Accepted Answer

It couples the movement of one molecule down its gradient to move another against its gradient

Question 12

Which equation best represents the Nernst equation for calculating the equilibrium potential of an ion?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 13

Which of the following is a characteristic of carrier-mediated transport?

Accepted Answer

It can become saturated at high substrate concentrations

Question 14

Which of the following best describes the effect of a hypertonic solution on a cell?

Accepted Answer

Water moves out of the cell, causing it to shrink

Question 15

Which of the following is a direct result of ligand binding to a G-protein coupled receptor?

Accepted Answer

Activation of intracellular second messengers

Question 16

A cell is exposed to a drug that blocks Na$$^+/K$^+$$ ATPase. What is the most likely immediate effect?

Accepted Answer

Increase in intracellular Na$$^+$$ and decrease in intracellular K$$^+$$

Question 17

Which of the following is an example of vesicle-mediated transport?

Accepted Answer

Endocytosis

Question 18

Which of the following best explains the concept of receptor down-regulation in cellular signaling?

Accepted Answer

Decrease in the number of receptors on the cell surface in response to prolonged stimulation

Question 19

Which of the following is true about the movement of water across cell membranes?

Accepted Answer

Water moves by osmosis through aquaporins

Electrolyte Movement and Dysregulation: Physiology and Pathophysiology

Study Guide - Practice Questions