Question 1

Which property of phospholipids is most responsible for the formation of the cell membrane's bilayer structure?

Accepted Answer

Their amphipathic nature, with both hydrophilic and hydrophobic regions

Question 2

A patient is experiencing excessive water loss from cells into the extracellular fluid. Which membrane transport process is most likely responsible for this movement?

Accepted Answer

Osmosis

Question 3

Which type of cell-cell junction is primarily responsible for preventing the passage of substances between adjacent cells, such as in the lining of the intestines?

Accepted Answer

Tight junction

Question 4

Which of the following best describes the function of desmosomes in tissues such as the skin?

Accepted Answer

They anchor cells together to resist mechanical stress

Question 5

A researcher adds a ligand to a cell culture and observes an immediate influx of Na$$^+$$ ions. Which type of membrane receptor is most likely involved?

Accepted Answer

Chemical (ligand)-gated ion channel

Question 6

Which equation best represents the relationship for osmotic pressure ($$\Pi) $$across a cell membrane?

Accepted Answer

$$\Pi = iMRT$$

Question 7

Which ion is found in highest concentration inside the cell (intracellular fluid) compared to outside (extracellular fluid)?

Accepted Answer

K$$^+ ($$potassium)

Question 8

Which type of membrane transport requires ATP hydrolysis to move substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 9

A cell is exposed to a toxin that blocks all carrier proteins. Which process will be most directly affected?

Accepted Answer

Facilitated diffusion

Question 10

Which of the following best explains why ions require membrane channels to cross the plasma membrane?

Accepted Answer

Ions are charged and cannot pass through the hydrophobic core of the lipid bilayer

Question 11

Which type of cell-matrix junction anchors epithelial cells to the underlying basement membrane?

Accepted Answer

Hemidesmosome

Question 12

A cell's membrane potential becomes more negative after the movement of K$$^+$$ ions out of the cell. What is the correct term for this change?

Accepted Answer

Hyperpolarization

Question 13

Which of the following is a major function of G-protein coupled membrane receptors?

Accepted Answer

Activation of second messenger pathways

Question 14

Which process allows a cell to take in large particles, such as bacteria, by engulfing them?

Accepted Answer

Phagocytosis

Question 15

Which of the following is TRUE regarding the ionic composition of plasma and interstitial fluid?

Accepted Answer

They have similar ionic compositions but differ from intracellular fluid

Question 16

Which type of ion channel opens in response to changes in membrane voltage?

Accepted Answer

Voltage-gated channel

Question 17

A cell uses receptor-mediated endocytosis to import cholesterol. What is the main advantage of this process over pinocytosis?

Accepted Answer

It allows selective uptake of specific molecules

Question 18

Which equation describes the Nernst potential ($$E_{ion}) $$for a given ion across a membrane?

Accepted Answer

$$E_{ion} = \dfrac{RT}{zF} \ln \left( \dfrac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 19

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

Accepted Answer

Synthesis of proteins

Cellular Level of Organization: Review of Cell Membrane Features

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