$$\text{Glycerol} + 3\ \text{Fatty Acids} \rightarrow \text{Fat} + 3\ \text{H}_2\text{O}$$

Question 1

Which of the following best describes the amphipathic nature of phospholipids and its significance in biological membranes?

Accepted Answer

Phospholipids have both hydrophilic and hydrophobic regions, enabling them to form bilayers that act as selective barriers.

Question 2

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

Accepted Answer

Water will move out of the cell, causing it to shrink, because the solute concentration is higher outside.

Question 3

Which equation best represents the process of dehydration synthesis in the formation of a fat molecule?

Accepted Answer

$$	ext{Glycerol} + 3\ 	ext{Fatty Acids} ightarrow 	ext{Fat} + 3\ 	ext{H}_2	ext{O}$$

Question 4

Which of the following molecules would cross a phospholipid bilayer most rapidly?

Accepted Answer

Oxygen, a small nonpolar molecule

Question 5

What is the primary function of the sodium-potassium pump ($$	ext{Na}^+/	ext{K}^+-$$ATPase) in animal cells?

Accepted Answer

To actively transport sodium ions out of the cell and potassium ions into the cell using ATP.

Question 6

Which structural feature distinguishes steroids from other types of lipids?

Accepted Answer

Bulky, four-ring structure with various functional groups attached.

Question 7

A patient is given intravenous fluids that are hypotonic relative to their blood plasma. What is the likely effect on their red blood cells?

Accepted Answer

Red blood cells will swell as water enters the cells.

Question 8

Which of the following statements about membrane proteins is correct according to the fluid-mosaic model?

Accepted Answer

Some proteins span the membrane, with segments facing both the interior and exterior surfaces.

Question 9

Which of the following best explains why highly unsaturated lipids are liquid at room temperature?

Accepted Answer

Double bonds create kinks in the hydrocarbon chains, preventing tight packing.

Question 10

Which of the following is a real-world example of facilitated diffusion?

Accepted Answer

Glucose entering a muscle cell via the GLUT-1 transporter.

Question 11

Which equation best represents the movement of water during osmosis?

Accepted Answer

$$	ext{Water moves from low solute concentration} ightarrow 	ext{high solute concentration}$$

Question 12

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

Accepted Answer

Synthesizing proteins for the cell.

Question 13

Which of the following best describes the role of electrochemical gradients in secondary active transport?

Accepted Answer

Electrochemical gradients provide potential energy to power the movement of another molecule against its gradient.

Question 14

Which of the following statements about the movement of phospholipids in a membrane is correct?

Accepted Answer

Phospholipids are in constant lateral motion but rarely flip to the other side of the bilayer.

Question 15

Which of the following is a characteristic of channel proteins in membranes?

Accepted Answer

They are highly selective, allowing only particular ions or molecules to pass.

Question 16

Which of the following best describes the process of passive transport?

Accepted Answer

Substances move down their concentration gradient without energy input.

Question 17

Which of the following is a plausible explanation for why foods containing lipids with double bonds are considered healthier?

Accepted Answer

Double bonds in lipids reduce the risk of cardiovascular disease by preventing tight packing.

Question 18

Which of the following best describes the function of carrier proteins in facilitated diffusion?

Accepted Answer

Carrier proteins selectively pick up solute on one side of the membrane and drop it on the other side via structural changes.

Question 19

Which of the following is a plausible scenario for the origin of the first cells according to the study materials?

Accepted Answer

Simple vesicle-like structures called protocells formed lipid bilayers that contained nucleic acids.

Lipids, Membranes, and the First Cells: Structure, Function, and Transport

Study Guide - Practice Questions