Deck 20: Biochemistry: the Compounds of Life

Question 1

An $\alpha$ -amino acid is one in which the amine group and the carboxylic acid group are attached to ________

A) different carbon atoms.
B) different nitrogen atoms.
C) the same carbon atom.
D) the first and third carbon of the molecule.
E) neighboring carbon atoms.

Answer 1

the same carbon atom.

Question 2

Which one of the following is not an amino acid?

A)
B)
C)
D)
E)

Answer 2

Question 3

Which statement is not correct? A chiral molecule ________

A) is an enantiomer.
B) rotates the plane of polarized light.
C) has four different groups bonded to the same carbon atom.
D) has properties different from those of its mirror image.
E) can be superimposed on its mirror image.

Answer 3

can be superimposed on its mirror image.

Question 4

Which one of the following is best associated with proteins?

A) amino acids
B) saccharides
C) hydrocarbon chains
D) phosphate linkages
E) hydrocarbon rings

Question 5

This molecule is ________

A) a lipid.
B) a fatty acid.
C) an amino acid.
D) a nucleic acid.
E) a saccharide.

Question 6

Which statement about chirality is not correct?

A) A molecule is chiral if it has a carbon atom bonded to four different groups.
B) A molecule is chiral if it cannot be superimposed on its mirror image.
C) Almost all amino acids are chiral.
D) In an amino acid, the $\alpha$ -carbon is the chiral center.
E) Chiral amino acids each have three enantiomers.

Question 7

Which of the following are amino acids?
I.
II.
III.
IV.

A) III and IV
B) I and II
C) I only
D) II only
E) III only

Question 8

Amino acids bond together via ________ bonds.

A) ionic
B) coordinate covalent
C) hydrogen
D) peptide
E) van der Waals

Question 9

A peptide bond is the result of a condensation reaction between ________

A) two carboxylic acid groups on different amino acids.
B) an amino group on one amino acid and the carboxylic acid group on another.
C) two amino groups on different amino acids.
D) an amino group and a carboxylic acid group on the same amino acid.
E) an amino group and a carboxylic acid group, producing a zwitterion.

Question 10

Which statement about amino acid enantiomers is not correct?

A) An enantiomer cannot be superimposed on its mirror image.
B) Enantiomers are examples of stereoisomers.
C) A solution of an enantiomer rotates the plane of polarized light.
D) Enantiomers are designated by the prefixes D and L.
E) All the chiral amino acids in our bodies are mixtures of enantiomers.

Question 11

An oligopeptide consists of up to ________ amino acids that bond together.

A) 5
B) 20
C) 10
D) 15
E) 50

Question 12

At a physiological pH of 7.4, amino acids exist as zwitterions. At a very low pH (in an acid solution), both the amine group and the carboxylic acid group on an amino acid are protonated. Therefore, the following must be true: the pK_a of the ________ group is larger than the pK_a of the ________ group.

A) protonated amine group; carboxylic acid group
B) carboxylic acid group; protonated amine group
C) amine group; carbonate group
D) hydronium ion group; hydroxyl ion group
E) carbonate group; amine group

Question 13

Which of the following are not amino acids?
I.
II.
III.
IV.

A) III and IV
B) I and II
C) I only
D) II only
E) III only

Question 14

An amino acid is composed of ________

A) ammonia and a carboxylic acid group.
B) an amine and a carboxylic acid group.
C) an amine and an alcohol group.
D) an amine and a sulfonic acid group.
E) an amide and a hydrochloric acid group.

Question 15

Isomers that cannot be superimposed on their mirror images are called ________

A) geometric isomers.
B) structural isomers.
C) enantiomers.
D) isotopes.
E) constitutional isomers.

Question 16

Aspartame exists as a zwitterion with a ________ amine group and a ________ carboxylic acid group.

A) deprotonated; protonated
B) protonated; deprotonated
C) protonated; protonated
D) deprotonated; deprotonated
E) functionalized; defunctionalized

Question 17

At a physiological pH of 7.4, amino acids exist as zwitterions because the pK_a of the -NH₃⁺ group is ________ 7.4, and the pK_a of the -COOH group is ________ 7.4.

A) greater than; less than
B) less than; greater than
C) greater than; greater than
D) less than; less than
E) equal to; equal to

Question 18

At a physiological pH of 7.4, amino acids exist as zwitterions. At a very low pH (in an acid solution), both the amine group and the carboxylic acid group on an amino acid are protonated. Which acid group is the stronger acid?

A) -NH₂
B) -NH₃⁺
C) -COOH
D) -COO^-
E) -H₃O⁺

Question 19

Which of the following compounds is an $\alpha$ -amino acid?

A)
B)
C)
D)

Question 20

The molecule drawn below is an example of ________

A) a nucleic acid base.
B) a peptide.
C) a carbohydrate.
D) a fatty acid.
E) an amino acid.

Question 21

The primary structure of a protein is ________

A) the sequence of amino acids in the protein.
B) the $\alpha$ -helix structure of the protein.
C) the $\beta$ -pleated sheet structure of the protein.
D) a list of the amino acids in the protein along with the number of times each occurs.
E) the arrangement of $\alpha$ -helices and $\beta$ -pleated sheets in the protein.

Question 22

Which of the following is a monosaccharide?

A) sucrose
B) glucose
C) starch
D) cellulose
E) cellobiose

Question 23

Which functional group is not present in this tripeptide?

A) amide
B) alcohol
C) carbonyl
D) amine
E) methyl

Question 24

Glucose is to cellulose as ________

A) pure gold is to 14-karat gold.
B) a link is to a chain.
C) a leaf is to a tree.
D) a trumpet is to a tuba.
E) a tomato is to a potato.

Question 25

Glucose is to starch as ________

A) pure gold is to 14-karat gold.
B) a link is to a chain.
C) a leaf is to a tree.
D) a trumpet is to a tuba.
E) a tomato is to a potato.

Question 26

Which of the following molecular formulas identifies a monosaccharide?

A) CH₂O
B) C₆H₁₀O₅
C) C₁₂H₂₂O₁₁
D) C₂H₄O₂
E) C₆H₁₂O₆

Question 27

Which functional group links amino acids together to form proteins?

A) amide
B) ester
C) ether
D) amine
E) phosphate

Question 28

Which one of the following is best associated with carbohydrates?

A) amino acids
B) saccharides
C) hydrocarbon chains
D) phosphate linkages
E) hydrocarbon rings

Question 29

This molecule is ________

A) a lipid.
B) a fatty acid.
C) an amino acid.
D) a nucleic acid base.
E) a saccharide.

Question 30

The assembly and interaction of coils and sheets in a polypeptide to produce the overall three-dimensional shape are described by the term ________

A) primary structure.
B) secondary structure.
C) tertiary structure.
D) long-range structure.
E) quaternary structure.

Question 31

The molecule drawn below is an example of ________

A) a nucleic acid base.
B) an amino acid.
C) a carbohydrate.
D) a fatty acid.
E) a lipid.

Question 32

A carbohydrate has an empirical formula of ________

A) CH₂O.
B) C₆H₁₂O₆.
C) C₁₂H₂₂O₁₁.
D) C₂H₄O₂.
E) C₃H₆O₃.

Question 33

The cyclization of glucose forms a ________

A) four-membered ring.
B) five-membered ring.
C) six-membered ring.
D) seven-membered ring.
E) double ring.

Question 34

The following reaction produces a peptide. Which statement about this reaction is not correct?

A) The peptide shown is the only product produced by this reaction.
B) This condensation reaction produces a peptide bond.
C) An amide group is formed in this reaction.
D) An amino group reacts with a carboxylic acid group.
E) Two amino acids are linked together by this reaction.

Question 35

Which of the following is not a description of the secondary structure of a protein?

A) ( $\alpha$ -helix)
B) ( $\beta$ -pleated sheets)
C) random coil
D) sequence of amino acids in the protein
E) geometric patterns formed by amino acids

Question 36

The molecule drawn below is an example of ________

A) a nucleic acid base.
B) an amino acid.
C) a disaccharide.
D) a fatty acid.
E) a lipid.

Question 37

Which of the following molecular formulas identifies a carbohydrate?

A) CH₂O
B) C₆H₁₂O₆
C) C₁₂H₂₂O₁₁
D) $$\mathrm { C } _ { 6 } \mathrm { H } _ { 6 } \_ \mathrm { H } _ { 2 } \mathrm { O }$$
E) C₁₂H₆O₁₂

Question 38

The ordering of subunits, such as amino acids, in a polymer, is called ________

A) the primary structure.
B) the secondary structure.
C) the tertiary structure.
D) the ordering structure.
E) the quaternary structure.

Question 39

The $\alpha$ -helix and $\beta$ -pleated sheet are examples of ________

A) primary structure.
B) secondary structure.
C) tertiary structure.
D) arrangement structure.
E) quaternary structure.

Question 40

A disaccharide has a molecular formula of ________

A) CH₂O.
B) C₆H₁₀O₅.
C) C₁₂H₂₂O₁₁.
D) C₂H₄O₂.
E) C₁₂H₂₄O₁₂.

Question 41

The cyclization reaction of fructose is different from that of glucose because ________

A) a five-membered ring instead of a six-membered ring is formed.
B) a bond is formed to a carbonyl carbon instead of to a methyl carbon.
C) the aldehyde group migrates to a new position.
D) a ketone is formed.
E) fructose has 6 carbon atoms in the ring instead of 5 as in glucose.

Question 42

What is the linkage that forms between two monosaccharides in a polysaccharide?

A) C- CH₂ - C
B) C- O - O - C
C) C- O - C
D) C- C
C
C
E) C - N - C

Question 43

Glucose and fructose undergo a(n) ________ reaction in the formation of sucrose.

A) sugarization
B) precipitation
C) condensation
D) neutralization
E) addition

Question 44

The cyclization of fructose forms a ________

A) four-membered ring.
B) five-membered ring.
C) six-membered ring.
D) seven-membered ring.
E) double ring.

Question 45

Which statement is not correct? Sucrose ________

A) is used for table sugar.
B) is a disaccharide.
C) consists of glucose and fructose with a glycosidic bond.
D) is formed in a condensation reaction that eliminates water.
E) is a synonym for glucose.

Question 46

Converting renewable biomass into fuel to reduce our need to import petroleum and release carbon dioxide from fossil fuels is a great idea. But, to be viable, the process must be cost-effective, not subsidized by taxpayer support, and not reduce our supply of food! It also must be recognized that the amount of energy produced through biomass conversion will always be small compared to our total needs. In any case, Professor Popsnorkle's research students at PC University have projects dealing with these issues. Amy's project deals with $\alpha$ -glucoside hydrolysis of starches, and Brad's project deals with $\beta$ -glucoside hydrolysis of cellulose. What do you see as the value of these projects and why?

A) Amy's is more valuable because improving the efficiency of starch hydrolysis will increase the effectiveness of our edible corn for fuel program and reduce the need for taxpayer subsidies.
B) Brad's is more valuable because the hydrolysis of cellulose, which is not edible, to produce glucose and ethanol currently is not economically viable.
C) Both are valuable because anything we can do along these lines merits equitable support.
D) Neither is valuable because these ideas are promoted only to enrich farmers in the Midwest.
E) I have a neutral position on the value of these projects because I do not know enough about these issues.

Question 47

The active ingredient, sucralose, in an artificial sweetener, Splenda, is shown below. Sucralose is advertised as being made from table sugar. What is the main difference between sucrose (table sugar) and sucralose?

A) Sucralose is a disaccharide, while sucrose is a monosaccharide.
B) Sucralose has a six-membered and a five-membered ring, unlike the two six-membered rings in sucrose.
C) Sucralose has a glycosidic bond between the two saccharide units, unlike the C-C bond in sucrose.
D) Some hydroxyl groups in sucrose are replaced by chlorine atoms in sucralose.
E) Sucralose has a six-membered and a five-membered ring, unlike the two five-membered rings in sucrose.

Question 48

Mountain folk in Kentucky and Tennessee were sometimes stereotyped for their "corn liquor" stills that they hid from the "revenue-ers." What is the first step in making corn liquor (ethanol) from corn?

A) fermentation
B) distillation
C) hydrolysis
D) intoxication
E) celebration

Question 49

In its linear form, which functional groups are present in glucose?

A) aldehyde and alcohol
B) aldehyde and carboxyl
C) alcohol and ketone
D) amino and alcohol
E) amino and aldehyde

Question 50

To produce ethanol from corn (i.e., starch) to use as fuel or drink, the starch first must be decomposed to glucose through a process called ________

A) fermentation.
B) distillation.
C) hydrolysis.
D) combustion.
E) oxidation.

Question 51

Which one of the following statements about biomolecules is not correct?

A) Table sugar (sucrose) is a disaccharide made of glucose and fructose.
B) Starch and cellulose are polysaccharides made from glucose.
C) A glycosidic linkage in polysaccharides is an ether group.
D) Cellobiose is a disaccharide composed of two glucose monomers.
E) Maltose is a disaccharide composed of two fructose monomers.

Question 52

In its ring structure, which functional groups are present in glucose?

A) ether and alcohol
B) aldehyde and carboxyl
C) alcohol and ketone
D) amino and alcohol
E) amino and aldehyde

Question 53

Which statement is not correct? Starch and cellulose ________

A) are polysaccharides.
B) have monosaccharides joined by glycosidic bonds.
C) are equally easily hydrolyzed to produce glucose.
D) are stereoisomers made from glucose monomers.
E) are a major source of biomass.

Question 54

An ether linkage connects monomers in ________

A) proteins.
B) nucleic acids.
C) carbohydrates.
D) lipids.
E) steroids.

Question 55

Table sugar is ________

A) glucose.
B) fructose.
C) cellobiose.
D) a monosaccharide.
E) a disaccharide.

Question 56

A glycosidic bond links two sugar molecules in carbohydrates. This linkage could also be called an ________

A) alcohol.
B) amide.
C) ether.
D) aldehyde.
E) ester.

Question 57

Table sugar is ________

A) glucose.
B) fructose.
C) cellobiose.
D) a monosaccharide.
E) a molecule combining glucose and fructose.

Question 58

Table sugar is ________

A) glucose.
B) fructose.
C) cellobiose.
D) a monosaccharide.
E) sucrose.

Question 59

Glucose is shown below. Number the carbon atoms 1-6 from top to bottom. In the cyclization reaction, a bond is formed to C-1 by an oxygen lone pair on the OH bonded to ________

A) C-2.
B) C-4.
C) C-5.
D) C-6.
E) C-3.

Question 60

Which of the following sugars is glucose?

A)
B)
C)
D)
E)

Question 61

Triglycerides are formed between ________

A) glycerol and inorganic acids.
B) glucose and long-chain fatty acids.
C) glycerol and long-chain fatty acids.
D) glycerol and any carboxylic acid.
E) glucose, fructose, and sucrose.

Question 62

How many different nucleotides are used to create DNA and RNA?

A) 2
B) 5
C) 3
D) 4
E) 6

Question 63

The tricarboxylic acid cycle (a.k.a. Krebs cycle) ________

A) produces carbohydrates in photosynthesis.
B) is a series of chemical reactions that assists in extracting energy from glucose.
C) serves to break down cellulose to produce glucose.
D) describes how enzymes act as catalysts.
E) has one more wheel than a tricycle.

Question 64

Which of the following triglycerides would you most expect to be a liquid at room temperature?

A) saturated fat
B) trans monounsaturated fat
C) trans polyunsaturated fat
D) cis monounsaturated fat
E) cis polyunsaturated fat

Question 65

Which of the following statements is not correct? Triglycerides ________

A) have both structural isomers and stereoisomers.
B) are soluble in water.
C) are made from glycerol combining with three fatty acids.
D) are lipids.
E) have ester groups.

Question 66

A saturated fatty acid has ________

A) more than one carboxyl group.
B) a long hydrocarbon chain containing C = C and C - C bonds.
C) a long hydrocarbon chain containing only C - C bonds.
D) a long hydrocarbon chain containing only C = C bonds.
E) cis and trans isomers.

Question 67

In glycolysis, ________ is converted into pyruvic acid.

A) sucrose
B) fructose
C) galactose
D) glucose
E) glycolase

Question 68

Which one of the following is best associated with lipids?

A) amino acids
B) saccharides
C) ribose units
D) phosphate linkages
E) fatty acids

Question 69

Which of the following is not a lipid?

A) fatty acid esters
B) cholesterol
C) fats
D) cellulose
E) oils

Question 70

Hydrolysis is ________

A) any reaction involving hydrogen.
B) breaking a bond by the addition of water.
C) the process of dissolving a solute to make a solution.
D) breaking a bond to produce hydrogen gas.
E) forming a bond by adding hydrogen gas.

Question 71

Trans fats are unhealthy in foods and tend to be solid at room temperature because they have bonds that force the triglyceride to be ________

A) rigid and straight.
B) rigid and bent.
C) flexible and straight.
D) flexible and bent.
E) highly reactive.

Question 72

Which one of the following is a saturated fatty acid?

A)
B)
C)
D)

Question 73

How many different nucleic acid bases are found altogether in the nucleic acids DNA and RNA?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 74

This molecule, like cholesterol, is ________

A) a nucleic acid base.
B) an amino acid.
C) a carbohydrate.
D) a fatty acid.
E) a lipid.

Question 75

Which of the following triglycerides would you most expect to be a liquid and the most healthy to use in cooking?

A) saturated fat
B) trans monounsaturated fat
C) trans polyunsaturated fat
D) cis monounsaturated fat
E) cis polyunsaturated fat

Question 76

This molecule is ________

A) a lipid.
B) a fatty acid.
C) an amino acid.
D) a nucleic acid base.
E) a saccharide.

Question 77

This molecule is ________

A) a lipid.
B) a cis fatty acid.
C) a trans fatty acid.
D) a peptide.
E) a saccharide.

Question 78

The molecule drawn below is an example of ________

A) a nucleic acid base.
B) an amino acid.
C) a carbohydrate.
D) a fatty acid.
E) a lipid.

Question 79

Which of the following is not part of a nucleotide?

A) a five-carbon sugar
B) a phosphate group
C) a nitrogen-containing base
D) an amine group
E) a carboxylic acid group

Question 80

The molecules drawn below are examples of ________

A) nucleic acids.
B) amino acids.
C) carbohydrates.
D) fatty acids.
E) steroidal acids.