Question 1

Which of the following best describes the function of receptor proteins in the plasma membrane?

Accepted Answer

They bind signaling molecules and trigger cellular responses.

Question 2

According to the fluid-mosaic model of the cell membrane, which statement is correct?

Accepted Answer

Phospholipids and proteins can move laterally within the layer.

Question 3

A small, nonpolar molecule such as $$O_2 is $$most likely to cross the plasma membrane by which process?

Accepted Answer

Simple diffusion through the lipid bilayer

Question 4

Which of the following best defines a concentration gradient?

Accepted Answer

A difference in concentration across a space

Question 5

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

Accepted Answer

It will shrink because water moves out of the cell.

Question 6

Which of the following statements about active transport is correct?

Accepted Answer

It requires energy, often in the form of ATP.

Question 7

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Active transport

Question 8

Which of the following best describes the role of second messengers such as cAMP in cell signaling?

Accepted Answer

They relay signals from receptors to target molecules inside the cell.

Question 9

A cell receives a signal via a G protein-coupled receptor (GPCR). Which of the following is the correct sequence of events?

Accepted Answer

Ligand binds GPCR → GPCR activates G protein → G protein activates enzyme → Second messenger produced

Question 10

Which of the following is an example of negative feedback in the endocrine system?

Accepted Answer

Rising blood glucose triggers insulin release, lowering blood glucose levels.

Question 11

Which of the following best explains why water-soluble hormones cannot pass through the plasma membrane?

Accepted Answer

They are hydrophilic and cannot cross the hydrophobic core of the lipid bilayer.

Question 12

Which of the following is a function of cell recognition proteins?

Accepted Answer

They help cells identify each other, such as in the immune system.

Question 13

A neuron receives a stimulus that causes depolarization. What is the likely effect on the membrane potential?

Accepted Answer

The membrane potential becomes less negative (moves toward zero).

Question 14

Which of the following best describes the difference between paracrine and endocrine signaling?

Accepted Answer

Paracrine signals act locally between nearby cells; endocrine signals travel long distances via the bloodstream.

Question 15

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses channel or carrier proteins to move substances down their concentration gradient.

Question 16

Which of the following best describes the function of the sodium-potassium pump in neurons?

Accepted Answer

It maintains the electrochemical gradient by pumping 3 Na$$^+$$ out and 2 K$$^+ in $$using ATP.

Question 17

Which of the following is a correct statement about the role of Schwann cells?

Accepted Answer

They form the myelin sheath around axons in the peripheral nervous system.

Question 18

A cascade in signal transduction is best described as:

Accepted Answer

A multi-step process where a signal is relayed through a series of proteins, often amplifying the response.

Question 19

Which of the following is an example of a real-world application of membrane transport concepts?

Accepted Answer

Administering intravenous fluids: a hypotonic IV solution can cause red blood cells to swell and burst due to osmosis.

Question 20

Which of the following best explains why the same signaling molecule can produce different responses in different cell types?

Accepted Answer

Different cells have different sets of receptors and intracellular proteins, leading to different responses.

Cell Membranes, Transport, Cell Signaling, and the Endocrine System: Study Notes

Study Guide - Practice Questions