Question 1

Which property of the plasma membrane is most responsible for its ability to control the movement of substances into and out of the cell?

Accepted Answer

Its selective permeability

Question 2

A phospholipid molecule in the plasma membrane is described as amphipathic. What does this mean?

Accepted Answer

It has both hydrophilic and hydrophobic regions

Question 3

Which of the following best explains why membranes with unsaturated hydrocarbon tails remain fluid at lower temperatures?

Accepted Answer

Kinks in the tails prevent tight packing of phospholipids

Question 4

If a cell is placed in a hypotonic solution, what will happen to the cell due to osmosis?

Accepted Answer

Water will enter the cell, causing it to swell

Question 5

Which equation best represents the net movement of water across a selectively permeable membrane during osmosis?

Accepted Answer

$\Delta \Psi = \Psi_{inside} - \Psi_{outside}$

Question 6

Which of the following statements about membrane proteins is correct?

Accepted Answer

Some membrane proteins move laterally within the membrane

Question 7

A scientist observes that a cell is able to move glucose against its concentration gradient. Which process is most likely responsible?

Accepted Answer

Active transport

Question 8

Which of the following is a function of cholesterol in animal cell membranes?

Accepted Answer

It helps maintain membrane fluidity at varying temperatures

Question 9

Which type of transport protein is directly involved in cotransport?

Accepted Answer

A symporter

Question 10

During exocytosis, which of the following occurs?

Accepted Answer

Vesicles fuse with the plasma membrane to release contents outside the cell

Question 11

Which stage of cell signaling involves the binding of a signaling molecule to a receptor protein?

Accepted Answer

Reception

Question 12

A mutation causes a cell to produce a plasma membrane with only saturated fatty acids. What is the most likely effect on the cell at low temperatures?

Accepted Answer

The membrane will become more rigid and less fluid

Question 13

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

Accepted Answer

Proteins are embedded in or attached to a bilayer of phospholipids

Question 14

Which process requires energy input from the cell to move substances against their concentration gradient?

Accepted Answer

Active transport

Question 15

A cell is exposed to a toxin that blocks all transport proteins. Which of the following processes will be most directly affected?

Accepted Answer

Facilitated diffusion

Question 16

Which equation describes the rate of diffusion ($J$) across a membrane according to Fick's law?

Accepted Answer

$J = -D \frac{dC}{dx}$

Question 17

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

Accepted Answer

Synthesizing DNA

Question 18

A cell uses a second messenger in its signaling pathway. Which of the following is most likely to be a second messenger?

Accepted Answer

cAMP

Question 19

Which of the following best explains why the plasma membrane is described as 'life at the edge'?

Accepted Answer

It separates the living cell from its surroundings and controls all inbound and outbound traffic

Question 20

Which process allows cells to communicate with each other by releasing molecules that bind to receptor proteins on neighboring cells?

Accepted Answer

Local signaling

Cell Membrane Structure and Function: Life at the Edge

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