Q: The sodium-potassium pump moves Na$^+$ and K$^+$ ions across the plasma membrane. Which equation best represents the stoichiometry of this pump?

$3 \mathrm{Na}^+ \text{ out}, 2 \mathrm{K}^+ \text{ in}$

Question 1

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

Accepted Answer

A mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.

Question 2

A cell is placed in a solution and begins to swell until it bursts. Which type of solution is the cell most likely in?

Accepted Answer

Hypotonic solution

Question 3

Which of the following molecules can most easily cross the lipid bilayer of a plasma membrane without the aid of a transport protein?

Accepted Answer

O$_2$

Question 4

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

Accepted Answer

Facilitate the diffusion of water

Question 5

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Unsaturated hydrocarbon tails increase membrane fluidity.

Question 6

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell undergoes plasmolysis.

Question 7

Which type of membrane protein is most likely to be involved in signal transduction?

Accepted Answer

Integral protein

Question 8

Which process requires energy input from the cell and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 9

The sodium-potassium pump moves Na$^+$ and K$^+$ ions across the plasma membrane. Which equation best represents the stoichiometry of this pump?

Accepted Answer

$3 \mathrm{Na}^+ 	ext{ out}, 2 \mathrm{K}^+ 	ext{ in}$

Question 10

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

Accepted Answer

DNA replication

Question 11

Familial hypercholesterolemia is caused by defective receptor proteins. Which cellular process is directly affected?

Accepted Answer

Receptor-mediated endocytosis

Question 12

Which of the following best explains why a Paramecium caudatum living in freshwater must have a contractile vacuole?

Accepted Answer

To pump excess water out of the cell

Question 13

Which of the following is an example of bulk transport across the plasma membrane?

Accepted Answer

Exocytosis of insulin

Question 14

Which type of cell signaling involves hormones traveling through the bloodstream to reach distant target cells?

Accepted Answer

Endocrine signaling

Question 15

During osmosis, water moves across a selectively permeable membrane. Which direction does water move?

Accepted Answer

From the region of lower solute concentration to higher solute concentration

Question 16

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient.

Question 17

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

Accepted Answer

The membrane will solidify more easily.

Question 18

Which of the following best describes the role of membrane carbohydrates in cell-cell recognition?

Accepted Answer

They are covalently bonded to lipids or proteins and vary among species and individuals.

Question 19

Which of the following is a correct sequence of the three stages of cell signaling?

Accepted Answer

Reception, Transduction, Response

Question 20

A nerve cell releases neurotransmitters that diffuse across a synapse to a target cell. What type of signaling is this?

Accepted Answer

Synaptic signaling

Membrane Transport and Cell Signaling – Study Notes (Campbell Biology in Focus, Chapter 5)

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