Question 1

Which of the following best describes the primary function of the Na+/K+ ATPase pump as shown in the provided image?

Accepted Answer

It uses ATP to move Na+ and K+ against their concentration gradients, maintaining high intracellular K+ and low intracellular Na+.

Question 2

A patient receives an intravenous solution of 0.9% NaCl. Which statement best explains why this solution is considered isotonic to human blood?

Accepted Answer

It has the same osmolarity as blood plasma, approximately $$300\ 	ext{mOsm/L}$$, preventing net water movement across cell membranes.

Question 3

Which of the following is a key difference between open ion channels and carrier proteins, as depicted in the images?

Accepted Answer

Open channels create a continuous pore, while carriers never form an open channel between both sides of the membrane.

Question 4

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 possibly burst because water enters the cell due to a higher concentration of solutes inside.

Question 5

Which of the following best describes secondary active transport?

Accepted Answer

It uses the energy stored in the gradient of one molecule (often Na+) to drive the movement of another molecule against its gradient.

Question 6

Which type of membrane transport protein is responsible for moving two different substances in opposite directions across the membrane?

Accepted Answer

Antiporter

Question 7

A patient with renal failure is undergoing hemodialysis. Which principle of membrane transport is most relevant to the removal of waste products from the blood during this process?

Accepted Answer

Simple diffusion across a semi-permeable membrane, driven by concentration gradients.

Question 8

Which of the following is a characteristic of facilitated diffusion but NOT simple diffusion?

Accepted Answer

Requirement for a membrane protein to assist the movement of specific molecules

Question 9

Which of the following best explains why the lipid bilayer of the cell membrane is considered semi-permeable?

Accepted Answer

It allows only small, nonpolar molecules to diffuse freely, while restricting ions and large polar molecules.

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 an example of long-distance cell-to-cell communication?

Accepted Answer

Hormonal signaling via the bloodstream

Question 12

Which of the following best describes the role of G-protein coupled receptors (GPCRs) in signal transduction?

Accepted Answer

They activate intracellular second messengers such as $$cAMP or$$ $$IP_3$$ after ligand binding.

Question 13

Which of the following is a second messenger commonly involved in intracellular signaling cascades?

Accepted Answer

cAMP

Question 14

A drug acts as an antagonist at a membrane receptor. What is the most likely effect of this drug?

Accepted Answer

It blocks the receptor, preventing the natural ligand from activating it.

Question 15

Which of the following best explains why down-regulation of receptors can lead to drug tolerance?

Accepted Answer

Fewer receptors are available, so the same dose of drug produces a smaller effect.

Question 16

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

Accepted Answer

Water moves by osmosis, from areas of low solute concentration to high solute concentration.

Question 17

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

Accepted Answer

They allow direct electrical and chemical communication between adjacent cells.

Question 18

Which of the following is a property shared by both facilitated diffusion and active transport?

Accepted Answer

Both exhibit specificity, competition, and saturation.

Question 19

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

Accepted Answer

The cell shrinks due to water efflux.

Cell Membrane Structure, Transport Mechanisms, and Cell Communication

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