Question 1

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

Accepted Answer

It is a flexible boundary that selectively allows certain substances to pass while blocking others.

Question 2

Which component of the phospholipid bilayer is responsible for its selective permeability?

Accepted Answer

Hydrophobic nonpolar tails in the center of the membrane

Question 3

A patient is diagnosed with a genetic disorder that affects the function of aquaporins in kidney cells. Which physiological process will be most directly impaired?

Accepted Answer

Efficient water reabsorption and maintenance of fluid balance

Question 4

Which of the following best explains why oxygen and carbon dioxide can easily diffuse across the plasma membrane?

Accepted Answer

They are small, nonpolar molecules that are lipid-soluble.

Question 5

Which type of cell junction would you expect to find in the epithelial cells lining the intestines, and what is its primary function?

Accepted Answer

Tight junctions; they prevent most molecules from moving between cells.

Question 6

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

Accepted Answer

It will lose water and shrink because water moves out to balance solute concentration.

Question 7

Which of the following is a key difference between simple diffusion and facilitated diffusion across the plasma membrane?

Accepted Answer

Facilitated diffusion requires specific transport proteins and is saturable, while simple diffusion does not.

Question 8

The sodium-potassium pump is an example of which type of membrane transport, and what is its primary function?

Accepted Answer

Primary active transport; it maintains electrochemical gradients by moving Na	extsuperscript{+} out and K	extsuperscript{+} into the cell using ATP.

Question 9

Which of the following equations correctly represents the relationship for osmotic pressure ($$\Pi) in $$terms of solute concentration ($$C$$), gas constant ($$R$$), and temperature ($$T$$)?

Accepted Answer

$$\Pi = CRT$$

Question 10

A researcher observes that glucose transport into a cell is limited even when extracellular glucose concentration is high. Which process is most likely responsible for this limitation?

Accepted Answer

Saturation of carrier proteins during facilitated diffusion

Question 11

Which of the following best describes the role of the glycocalyx in cell recognition?

Accepted Answer

It consists of glycoproteins and glycolipids that serve as identification tags for cell-to-cell recognition.

Question 12

Which of the following factors will increase the rate of diffusion of a solute across the plasma membrane?

Accepted Answer

Increasing the concentration gradient of the solute

Question 13

Which type of membrane protein is most likely to function as a receptor for signal transduction?

Accepted Answer

Integral protein with an extracellular binding site

Question 14

A mutation causes the loss of desmosomes in cardiac muscle cells. What is the most likely physiological consequence?

Accepted Answer

Reduced stability and increased risk of tissue tearing during contraction

Question 15

Which of the following best describes secondary active transport?

Accepted Answer

It uses the energy stored in ion gradients created by primary active transport to move other substances against their gradient.

Question 16

Which of the following is TRUE regarding gap junctions?

Accepted Answer

They allow small molecules and ions to pass directly between adjacent cells.

Question 17

Which process is described by the movement of water across a selectively permeable membrane in response to solute concentration differences?

Accepted Answer

Osmosis

Question 18

Which of the following best explains why cholesterol is important in the plasma membrane?

Accepted Answer

It stabilizes the membrane by interacting with both hydrophilic and hydrophobic regions.

Question 19

A cell is actively transporting sodium ions out and potassium ions in, both against their concentration gradients. Which equation best represents the energy requirement for this process?

Accepted Answer

$$\Delta G = RT \ln \dfrac{[Na^+]_{out}}{[Na^+]_{in}}$$

Cell Structure and Membrane Transport: Study Notes for Anatomy & Physiology

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