Question 1

Which of the following statements best explains why lipids are classified based on their solubility rather than their chemical structure?

Accepted Answer

Lipids are highly diverse in structure, but all are soluble in nonpolar organic solvents and insoluble in water.

Question 2

Which type of lipid is primarily responsible for forming the basic structure of cell membranes?

Accepted Answer

Phospholipids

Question 3

A triacylglycerol molecule is composed of which of the following components?

Accepted Answer

Three fatty acids and one glycerol

Question 4

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids contain only carbon-carbon single bonds, while unsaturated fatty acids contain one or more carbon-carbon double bonds.

Question 5

Why do oils generally have lower melting points than fats?

Accepted Answer

Oils contain a higher proportion of unsaturated fatty acids, which introduce kinks and prevent tight packing of molecules.

Question 6

Which process is used to convert liquid vegetable oils into solid cooking fats, and what is a potential health risk associated with this process?

Accepted Answer

Hydrogenation; it can produce trans fatty acids that increase cardiovascular risk.

Question 7

Which of the following is a function of bile acids in the digestive system?

Accepted Answer

Emulsification of dietary fats to aid in their digestion and absorption.

Question 8

What is the structural feature that distinguishes phospholipids from triacylglycerols?

Accepted Answer

Phospholipids contain a phosphate group attached to the glycerol backbone, while triacylglycerols do not.

Question 9

Which of the following best describes the amphipathic nature of soap molecules and their cleaning action?

Accepted Answer

Soap molecules have a hydrophilic head and a hydrophobic tail, allowing them to surround and suspend grease in water.

Question 10

Which of the following lipids is NOT a major component of cell membranes?

Accepted Answer

Triacylglycerols

Question 11

A patient is found to have a deficiency in sphingomyelin. Which organ system is most likely to be affected?

Accepted Answer

Nervous system

Question 12

Which of the following correctly describes the structure of a wax?

Accepted Answer

A wax is an ester formed from a long-chain fatty acid and a long-chain alcohol.

Question 13

Which of the following equations represents the saponification reaction of a triacylglycerol?

Accepted Answer

$$\mathrm{Triacylglycerol} + 3\ \mathrm{NaOH} \rightarrow \mathrm{Glycerol} + 3\ \mathrm{Soap}$$

Question 14

Which of the following statements about cholesterol is TRUE?

Accepted Answer

Cholesterol is a steroid that is a component of cell membranes and a precursor for bile acids and steroid hormones.

Question 15

Which of the following best explains why cis double bonds in unsaturated fatty acids lower the melting point?

Accepted Answer

Cis double bonds introduce kinks in the hydrocarbon chain, preventing tight packing and reducing intermolecular forces.

Question 16

Which of the following is a correct description of facilitated diffusion across a cell membrane?

Accepted Answer

A solute binds to a membrane protein, which helps transport it across the membrane without using energy.

Question 17

Which of the following is a function of glycolipids in cell membranes?

Accepted Answer

Recognition and interaction with intercellular messengers.

Question 18

Which of the following correctly describes the structure of a phospholipid bilayer in cell membranes?

Accepted Answer

Two parallel layers of phospholipids with hydrophilic heads facing the aqueous environments and hydrophobic tails facing inward.

Question 19

Which of the following is a correct statement about steroid hormones?

Accepted Answer

Steroid hormones are synthesized from cholesterol and include corticoids and sex hormones.

Chapter 23: Lipids – Structure, Types, and Biological Functions

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