Question 1

Which of the following best describes the structure of the plasma membrane in human cells?

Accepted Answer

A double layer of phospholipids with embedded proteins

Question 2

Which property of the plasma membrane allows it to regulate the movement of substances into and out of the cell?

Accepted Answer

Selective permeability

Question 3

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The cells will shrink as water leaves the cells

Question 4

Which of the following best explains why ions such as Na$$^+$$ and K$$^+$$ require facilitated diffusion or active transport to cross the plasma membrane?

Accepted Answer

They are charged and hydrophilic, so they cannot pass through the hydrophobic core of the membrane

Question 5

Which of the following is a function of membrane proteins?

Accepted Answer

Facilitating communication with the environment

Question 6

A cell is placed in a solution and begins to swell. Which of the following best describes the tonicity of the solution relative to the cell?

Accepted Answer

Hypotonic

Question 7

Which type of membrane transport requires energy directly from ATP hydrolysis?

Accepted Answer

Primary active transport

Question 8

The sodium-potassium pump moves Na$$^+$$ and K$$^+$$ ions across the plasma membrane. Which of the following best describes its action?

Accepted Answer

It moves Na$$^+$$ out of the cell and K$$^+$$ into the cell using ATP

Question 9

Which of the following best describes the role of aquaporins in the plasma membrane?

Accepted Answer

They form channels that allow water to move rapidly across the membrane

Question 10

A cell is exposed to a toxin that inhibits all ATP production. Which of the following transport processes would be most directly affected?

Accepted Answer

Primary active transport of Na$$^+$$

Question 11

Which of the following best explains why the resting membrane potential (RMP) of a typical cell is negative?

Accepted Answer

There is a greater diffusion of K$$^+$$ out of the cell than Na$$^+$$ into the cell

Question 12

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

Accepted Answer

Na$$^+-$$glucose symport using the Na$$^+$$ gradient established by the Na$$^+/K$^+$$ pump

Question 13

Which of the following best describes the function of desmosomes?

Accepted Answer

They anchor adjacent cells together and distribute tension

Question 14

A researcher observes that a certain molecule can cross the plasma membrane only when a specific protein binds to it and changes shape. Which transport mechanism is most likely involved?

Accepted Answer

Carrier-mediated facilitated diffusion

Question 15

Which of the following best describes the process of phagocytosis?

Accepted Answer

The cell engulfs solid particles by extending pseudopods

Question 16

Which of the following equations correctly represents the relationship between osmolarity, solute concentration, and water movement across a membrane?

Accepted Answer

$$Osmolarity = \frac{	ext{Number of solute particles}}{	ext{Volume of solution}}$$

Question 17

Which of the following best explains why facilitated diffusion is considered a passive process?

Accepted Answer

It moves substances down their concentration gradient without using cellular energy

Question 18

A cell in the kidney is responsible for reabsorbing glucose from the filtrate against its concentration gradient. Which transport mechanism is most likely used?

Accepted Answer

Secondary active transport coupled to Na$$^+$$ movement

Question 19

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

Accepted Answer

They form pores that allow ions and small molecules to pass directly between adjacent cells

Question 20

Which of the following best describes the role of cell adhesion molecules (CAMs) in the plasma membrane?

Accepted Answer

They anchor cells, assist in movement, and act as mechanical sensors

Cell Structure and Function: The Smallest Units of Life

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