Deck 20: Lipids

Question 1

Which of the following is true of the London dispersion forces in fatty acids?

A) The London dispersion forces are maximum in unsaturated fatty acids.
B) The London dispersion forces are minimum in saturated fatty acids.
C) The London dispersion forces are higher for cis unsaturated fatty acids.
D) The London dispersion forces act over shorter segments of hydrocarbon chains.

Answer 1

D

Question 2

Which of the following statements is true of the calorific value of fats compared with that of carbohydrates?

A) The burning of both fatsand carbohydrates produces about 4 kcal/g of energy.
B) The burning of both fatsand carbohydrates produces about 9 kcal/g of energy.
C) The burning of carbohydrates produces about 4 kcal/g, whereasthe burning of fatsproduces about 9 kcal/g of energy.
D) The burning of carbohydrates produces about 9 kcal/g, whereas the burning of fats produces about 4 kcal/g of energy.

Answer 2

C

Question 3

In addition to fatty acids, which of the following compounds is found in triglycerides?

A) glycol
B) glycerol
C) acetone
D) propanone

Answer 3

B

Question 4

Which of the following is a naturally occurring unsaturated fatty acid?

A) lauric acid
B) palmitic acid
C) linoleic acid
D) myristic acid

Question 5

Which of the following fatty acids is the least abundant in higher plants and animals?

A) palmitic acid
B) stearic acid
C) oleic acid
D) linolenic acid

Question 6

Which of the following are secondary messengers?

A) prostaglandins
B) thromboxanes
C) both prostaglandins and thromboxanes
D) prostaglandins nor thromboxanes

Question 7

Which of the following is a characteristic of fatty acids?

A) Most fatty acids have an odd number of carbon atoms.
B) Trans isomers of unsaturated fatty acids are common.
C) Unsaturated fatty acids have lower melting points than saturated fatty acids.
D) None of these are a characteristic of fatty acids.

Question 8

What is the molecular formula of arachidic acid?

A) CH₃(CH₂)₁₅COOH
B) CH₃(CH₂)₁₈COOH
C) CH₃(CH₂)₁₀COOH
D) CH₃(CH₂)₁₄COOH

Question 9

Which of the following fatty acids has the lowest melting point?

A) stearic acid
B) oleic acid
C) linoleic acid
D) linolenic acid

Question 10

Which of the following unsaturated fatty acids has four double bonds?

A) lauric acid
B) myristic acid
C) arachidonic acid
D) palmitoleic acid

Question 11

Which of the following statements is true of fatty acids?

A) They are amphipathic compounds.
B) They have a hydrophobic carboxyl group.
C) They have a hydrophilic hydrocarbon tail.
D) They are soluble in polar solvents such as water.

Question 12

Which of the following statements is true of lipids?

A) They have a specific functional group.
B) They are the least diverse class of biomolecules.
C) They are soluble in diethyl ether.
D) They are mostly defined by their structure.

Question 13

Which fatty acid has the simple designation ?

A) stearic acid
B) oleic acid
C) linoleic acid
D) linolenic acid

Question 14

Which of the following statements best explains the insolubility of lipids in water?

A) The structure of lipids includes hydrophilic molecules.
B) The polar portion of lipids is much larger than the nonpolar portion.
C) The polar portion of lipids is much smaller than the nonpolar portion.
D) The polar and nonpolar portions of lipids are of the same size.

Question 15

Which of the following are primary messengers?

A) prostaglandins
B) steroid hormones
C) thromboxanes
D) all of these

Question 16

What is the function of secondary messengers such as prostaglandins?

A) to carry messages from one part of a cell to another part of the same cell
B) to deliver signals from one part of the body to another part
C) to mediate hormonal responses
D) none of these

Question 17

What is the function of primary messengers such as steroid hormones?

A) to mediate hormonal responses
B) to deliver signals from one part of the body to another part
C) both of these
D) none of these

Question 18

How many different triglycerides can be formed when one molecule of glycerol combines with one molecule of oleic acid, one molecule of palmitic acid, and one molecule of stearic acid?

A) 1
B) 2
C) 3
D) 4

Question 19

Which of the following is a function of lipids?

A) They store energy within cells.
B) They serve as chemical messengers.
C) They serve as components of cell membranes.
D) All of these are functions of lipids.

Question 20

What is the IUPAC name of glycerol?

A) 1,2-ethanediol
B) 1,2-propanediol
C) 1,3-propanediol
D) 1,2,3-propanetriol

Question 21

Which of the following linkages can be found in sphingolipids?

A) sphingosine−serine−phosphate
B) sphingosine−phosphate−choline
C) phosphate−sphingomyelin−choline
D) none of these

Question 22

Why is coconut oil liquid at room temperature (77^oF)?

A) because of the presence of high amounts of unsaturated fatty acids
B) because of the presence of essential fatty acids
C) because of the presence of low-molecular-weight saturated fatty acids
D) because of the presence of high-molecular-weight saturated fatty acids

Question 23

Which of the following triglycerides is most likely to be a fat?

A) one that contains short-chain, saturated fatty acids
B) one that contains short-chain, unsaturated fatty acids
C) one that contains long-chain, saturated fatty acids
D) one that contains long-chain, unsaturated fatty acids

Question 24

Which of the following compounds is found in all types of complex lipids?

A) a fatty acid
B) glycerol
C) a phosphate group
D) all of these

Question 25

If a triglyceride contains linoleic, linolenic, and stearic acids, then how many moles of hydrogen are required to fully hydrogenate one mole of this triglyceride?

A) 3
B) 4
C) 5
D) 6

Question 26

What is an essential fatty acid?

A) A fatty acid that the body can synthesize from precursor molecules
B) A fatty acid that must be a part of our diet since we cannot synthesize it
C) Both of these
D) None of these

Question 27

Which of the following chemical compounds is found in glycolipids but not in other complex lipids?

A) a carbohydrate group
B) a fatty acid
C) a sphingosine molecule
D) none of these

Question 28

What is the minimum number of double bonds that must be present in a polyunsaturated fatty acid?

A) 2
B) 3
C) 4
D) 5

Question 29

Which of the following alcohols can be found in glycerophospholipids?

A) choline
B) serine
C) inositol
D) all of these

Question 30

Which of the following statements is true of trans fats?

A) They are produced by condensation reactions.
B) They tend to increase serum cholesterol if consumed in large amounts.
C) They are classified under "generally recognized as safe" compounds.
D) They are more common than their cis counterparts.

Question 31

Which of the following reactions is the source of trans fatty acids found in certain processed foods?

A) condensation
B) dehydration
C) hydrogenation
D) hydrolysis

Question 32

To which class of compounds do waxes belong?

A) alcohols
B) carboxylic acids
C) esters
D) ethers

Question 33

In glycerophospholipids, what is the position of the phosphate group that is linked to glycerol?

A) It is present on the central carbon atom.
B) It is present on the terminal carbon atom.
C) It is present either on the central or on the terminal carbon atom.
D) It is present on both the central and the terminal carbon atoms.

Question 34

According to the FDA, to which of the following categories do trans fats belong?

A) bioactive compounds
B) food additives
C) "generally recognized as safe" compounds
D) flavor enhancers

Question 35

If a triglyceride contains linoleic, linolenic, and oleic acids, then how many moles of hydrogen are required to fully hydrogenate one mole of this triglyceride?

A) 3
B) 4
C) 5
D) 6

Question 36

Which of the following includes all the components of glycerophospholipids?

A) glycerol, one fatty acid, two phosphate groups, and an alcohol
B) glycerol, two fatty acids, a phosphate group, and an alcohol
C) either of these
D) none of these

Question 37

Which of the following linkages is found in glycerophospholipids?

A) glycerol-fatty acid-phosphate
B) glycerol-phosphate-fatty acid
C) phosphate-glycerol-glucose
D) none of these

Question 38

Identify a polyunsaturated fatty acid.

A) arachidonic acid
B) palmitoleic acid
C) stearic acid
D) oleic acid

Question 39

Which of the following statements is true of linoleic acid?

A) It is an essential saturated fatty acid.
B) It is an essential unsaturated fatty acid.
C) It is not an essential fatty acid but is a saturated fatty acid.
D) It is not an essential fatty acid but is an unsaturated fatty acid.

Question 40

Which of the following statements is true of pure fats and oils?

A) They have characteristic color but lack odor and taste.
B) They have characteristic odor but lack color and taste.
C) They have characteristic taste but lack odor and color.
D) They are colorless, odorless, and tasteless substances.

Question 41

Which of the following is true of all lecithins?

A) They are composed of only saturated fatty acids.
B) They are composed of only unsaturated fatty acids.
C) They always have a choline group in carbon 3 of the glycerol backbone.
D) They always have an unsaturated fatty acid bound to carbon 1 of the glycerol backbone.

Question 42

Lecithin is a major component of egg yolk. What is the role of lecithin in egg yolk?

A) It increases the protein content of yolk.
B) It acts as a natural emulsifying agent.
C) It decreases the trans fat content of yolk.
D) It acts as an excellent antioxidant.

Question 43

Cell membranes are composed of _____.

A) lipid bilayers
B) protein bilayers
C) lipid trilayers
D) protein trilayers

Question 44

Which of the following is choline?

A) HOCH₂CH₂NH₂
B)
C) [HOCH₂CH₂N(CH₃)₃] ⁺
D) none of these

Question 45

Which of the following is a function of unsaturated fatty acids in membranes?

A) They provide fluidity to membranes and allow transport of biochemical products.
B) They provide a site for chemical reactions to occur.
C) Both of these are functions of unsaturated fatty acids.
D) None of these are functions of unsaturated fatty acids.

Question 46

Some glycerophospholipids are commonly called lecithins. Which of the following is found in all lecithins?

A) choline
B) ethanolamine
C) inositol
D) serine

Question 47

What is the nature of the cholesterol found in cell membranes?

A) amphipathic
B) hydrophobic
C) hydrophilic
D) amphiprotic

Question 48

Which of the following is found in cephalins?

A) choline
B) ethanolamine
C) inositol
D) none of these

Question 49

How are polar molecules transported through a membrane?

A) by active transport
B) through specific channels
C) by both of these methods
D) by none of these methods

Question 50

Which of the following statements is true of membrane proteins?

A) They are suspended on the surface of the membrane.
B) They are partly embedded in the bilayer.
C) They span across the bilayer and project from both sides.
D) Any of these are true, depending on the specific membrane protein.

Question 51

Which components of a sphingolipid are collectively known as a ceramide?

A) a fatty acid and a phosphate group
B) a fatty acid and a sphingosine molecule
C) a phosphate group and a choline group
D) a phosphate group and a sphingosine molecule

Question 52

Which of the following diseases is associated with sphingomyelins?

A) Alzheimer's disease
B) Parkinson's disease
C) multiple sclerosis
D) none of these

Question 53

Which of the following is true of all glycerophospholipids?

A) They are composed of only saturated fatty acids.
B) They are composed of only unsaturated fatty acids.
C) Their backbone is composed of the trihydric alcohol glycerol.
D) Their third group is esterified by a nitrate group, which is also esterified to an alcohol.

Question 54

Which mechanism is involved in the transport of nonpolar molecules through a membrane?

A) active transport
B) diffusion
C) osmosis
D) all of these

Question 55

In sphingomyelin, which type of bond exists between the -NH₂ group of sphingosine and a fatty acid?

A) an amide bond
B) an azide bond
C) a hydrogen bond
D) an anhydride bond

Question 56

Which of the following are glycerophospholipids?

A) cephalins
B) lecithins
C) phosphatidylinositols
D) all of these

Question 57

To which class of complex lipids does myelin, the coating of nerve axons, belong?

A) glycerophospholipids
B) glycolipids
C) sphingolipids
D) none of these

Question 58

How are the hydrophilic heads and hydrophobic tails of complex lipids distributed in the lipid bilayer?

A) The hydrophilic heads project to the cytoplasm, and the hydrophobic tails project to the exterior of the cell.
B) The hydrophilic heads project to the exterior of the cell, and the hydrophobic tails project to the cytoplasm.
C) Both the hydrophilic heads and the hydrophobic tails are nonuniformly arranged across the bilayer.
D) Some membranes have only hydrophilic heads, whereas other membranes have only hydrophobic tails.

Question 59

Which class of glycerophospholipids can serve as signaling molecules when phosphorylated?

A) cephalins
B) lecithins
C) phosphatidylinositols
D) all of these

Question 60

Which of the following statements is true of the fluid mosaic model of membranes?

A) Membranes have proteins present only on the outer surface.
B) The complex lipids that make up membranes are distributed evenly.
C) The fluidity of membranes increases with an increase in unsaturated fatty acids.
D) It is impossible to determine the degree of fluidity of membranes.

Question 61

Which of the following is the basic ring structure of steroids?

A)
B)
C)
D)

Question 62

Where does the synthesis of cholesterol occur in the body?

A) in the liver
B) in the pancreas
C) in the spleen
D) in the thyroid

Question 63

Which of the following is a glycolipid?

A) ceramides
B) endorphins
C) enkephalins
D) none of these

Question 64

Which of the following contain(s) free cholesterol?

A) HDL
B) gallstones
C) LDL
D) all of these

Question 65

Which of the following is a role of cholesterol?

A) to serve as a component of plasma membranes
B) to serve as a starting material for the synthesis of steroid hormones
C) to serve as a precursor for the synthesis of bile salts
D) all of these

Question 66

Which of the following is a glycolipid?

A) ceramides
B) cerebrosides
C) endorphins
D) enkephalins

Question 67

Which of the following is not found in cerebrosides?

A) an amide linkage
B) a carbohydrate
C) a hydroxyl group
D) a phosphate group

Question 68

Which of the following linkages is found between a glucose unit and the ceramide portion of a cerebroside?

A) α-1-fructosidic
B) β-1-fructosidic
C) α-1-glycosidic
D) β-1-glycosidic

Question 69

Which of the following linkages is found in cerebrosides?

A) α-1-fructosidic
B) β-1-glycosidic
C) both of these
D) neither of these

Question 70

Which of the following conditions is associated with Gaucher's disease?

A) an inability to synthesize glucocerebrosides
B) an inability to store sufficient glucocerebrosides
C) an overaccumulation of glucocerebrosides
D) any of these, depending on the patient

Question 71

How many carbon atoms are present in a steroid ring?

A) 15
B) 16
C) 17
D) 18

Question 72

In which part of the body do cerebrosides primarily occur?

A) the brain
B) the intestines
C) bones
D) skeletal tissues

Question 73

Examine the following triglyceride. If this triglyceride is subjected to hydrogenation, how many moles of H₂ will be consumed per mole of this reactant?

A) 1 mol
B) 2 mol
C) 3 mol
D) 4 mol
E) This triglyceride will not react with H₂.

Question 74

Examine the following triglyceride. To which carbon of the glycerol molecule is stearic acid bound?

A) top
B) central
C) bottom
D) Stearic acid is not present in this structure.

Question 75

Which of the following compounds are exclusively found in glycolipids?

A) carbohydrates
B) phosphate groups
C) amines
D) hydroxyl groups

Question 76

Identify the disease that is associated with the overaccumulation of galactocerebroside in the body.

A) Gaucher's disease
B) Fabry's disease
C) Krabbe's leukodystrophy
D) Niemann-Pick disease

Question 77

Which of the following lipoproteins carry the highest percentage (dry weight) of cholesterol?

A) HDLs
B) LDLs
C) VLDLs
D) chylomicrons

Question 78

How many cyclohexane rings are present in a steroid structure?

A) 3
B) 4
C) 2
D) 1

Question 79

In which of the following body structures are cerebrosides found?

A) osteocytes
B) skeletal tissues
C) nerve synapses
D) nephrocytes

Question 80

In cholesterol, to which of the following steroid rings is the hydroxyl group attached?

A) A
B) B
C) C
D) D