Question 1

Which of the following best explains why lipids do NOT have a classic monomer-to-polymer construction like proteins or nucleic acids?

Accepted Answer

Lipids are defined by their hydrophobic properties rather than a specific repeating subunit.

Question 2

A hydrocarbon chain differs from a fatty acid chain in that a fatty acid chain:

Accepted Answer

Has a carboxyl group ($\mathrm{–COOH}$) at one end.

Question 3

Which of the following best describes the structure of a triglyceride?

Accepted Answer

Three fatty acid chains covalently bonded to a glycerol molecule via ester linkages.

Question 4

During the formation of a triglyceride, which type of chemical reaction occurs and what is the name of the bond formed?

Accepted Answer

Dehydration synthesis; ester bond

Question 5

Which of the following statements about saturated and unsaturated fats is CORRECT?

Accepted Answer

Saturated fats have only single bonds between carbon atoms, making them solid at room temperature.

Question 6

Phospholipids are considered amphipathic molecules because:

Accepted Answer

They contain both a hydrophilic phosphate head and hydrophobic fatty acid tails.

Question 7

Which of the following best describes the structure of cholesterol?

Accepted Answer

A molecule with four fused hydrocarbon rings and a short hydrocarbon tail.

Question 8

What is the primary function of cholesterol in animal cell membranes?

Accepted Answer

It increases membrane fluidity at low temperatures and decreases it at high temperatures.

Question 9

The 'fluid mosaic model' of the plasma membrane refers to:

Accepted Answer

A dynamic structure with proteins and lipids able to move laterally within the bilayer.

Question 10

Which of the following factors would INCREASE membrane fluidity?

Accepted Answer

A higher proportion of unsaturated fatty acids in the phospholipids.

Question 11

Which of the following best describes the function of integral membrane proteins?

Accepted Answer

They span the lipid bilayer and are involved in transport and signaling.

Question 12

A red blood cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

Water will enter the cell, causing it to swell and possibly burst (lyse).

Question 13

Which of the following is TRUE about facilitated diffusion?

Accepted Answer

It requires a transport protein and moves substances down their concentration gradient.

Question 14

The sodium–potassium pump is an example of:

Accepted Answer

Primary active transport, because it uses ATP to move ions against their concentration gradients.

Question 15

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

The cell engulfs specific molecules after they bind to receptors on the cell surface.

Question 16

Which of the following statements about osmosis is CORRECT?

Accepted Answer

Osmosis is the diffusion of water across a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Question 17

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

Accepted Answer

The cell will lose water, and the plasma membrane will pull away from the cell wall (plasmolysis).

Question 18

Which of the following best explains why phospholipid bilayers are selectively permeable?

Accepted Answer

Their hydrophobic core prevents passage of most polar and charged molecules, while allowing small nonpolar molecules to diffuse.

Question 19

Which of the following is an example of secondary active transport (cotransport)?

Accepted Answer

The use of the sodium gradient established by the sodium–potassium pump to drive glucose uptake into the cell.

Question 20

Which of the following would most likely DECREASE the permeability of a cell membrane to water?

Accepted Answer

A decrease in the number of aquaporin proteins.

Lipids, Membranes, and Cellular Transport: Study Guide

Study Guide - Practice Questions