Question 1

Which of the following changes to the phospholipid bilayer would most likely increase membrane fluidity at room temperature?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in phospholipids

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome?

Accepted Answer

The cell will swell and may burst due to water influx

Question 3

Which of the following molecules can most easily diffuse directly through the phospholipid bilayer without the help of a transport protein?

Accepted Answer

O$$_2 ($$oxygen)

Question 4

What is the primary function of cholesterol in the plasma membrane?

Accepted Answer

To stabilize the membrane by holding phospholipids together at moderate and high temperatures

Question 5

Which equation best describes the movement of water during osmosis across a semipermeable membrane?

Accepted Answer

$$\Psi_{water}$$ moves from high to low solute concentration$

Question 6

A cell is placed in a hypertonic solution. Which of the following best describes what happens to the cell?

Accepted Answer

Water leaves the cell, causing it to shrink

Question 7

Which type of membrane protein spans the entire plasma membrane and is involved in transporting substances across it?

Accepted Answer

Transmembrane (integral) protein

Question 8

Facilitated diffusion differs from active transport in that:

Accepted Answer

Facilitated diffusion moves substances down their concentration gradient without using energy

Question 9

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

Accepted Answer

They are involved in cell recognition and signaling

Question 10

Which process requires energy from ATP to move ions against their concentration gradient?

Accepted Answer

Active transport

Question 11

A plant cell placed in an isotonic solution will:

Accepted Answer

Remain flaccid, with no net movement of water

Question 12

Which of the following is a correct statement about exocytosis?

Accepted Answer

It requires the fusion of a vesicle with the plasma membrane to release contents outside the cell

Question 13

Which of the following ions is typically pumped out of the cell by the sodium-potassium pump?

Accepted Answer

Na$$^+ ($$sodium ion)

Question 14

Which of the following best explains why ions cannot easily cross the plasma membrane without a transport protein?

Accepted Answer

Ions are repelled by the hydrophobic interior of the phospholipid bilayer

Question 15

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

Accepted Answer

Movement of glucose into a cell using the sodium gradient established by the sodium-potassium pump

Question 16

Which process is described by the equation $$J = -D \frac{dC}{dx}$$, where $$J is $$the flux, $$D is $$the diffusion coefficient, and $$\frac{dC}{dx} is $$the concentration gradient?

Accepted Answer

Simple diffusion

Question 17

Which of the following best describes pinocytosis?

Accepted Answer

The cell absorbs fluid and dissolved solutes from the extracellular environment

Question 18

Which of the following is true about aquaporins?

Accepted Answer

They are channel proteins that facilitate water movement across the membrane

Question 19

Which of the following best describes the fluid-mosaic model of the plasma membrane?

Accepted Answer

A dynamic structure with proteins and other molecules embedded in a phospholipid bilayer

Question 20

Which of the following is a function of membrane proteins involved in signal transduction?

Accepted Answer

They receive chemical signals from outside the cell and transmit messages inside the cell

Structure and Function of the Plasma Membrane

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