Deck 3: Carbon and the Molecular Diversity of Life

Question 1

Which of the following is a correct monomer/polymer pairing?

A) monosaccharide/polypeptide
B) amino acid/polysaccharide
C) amino acid/polypeptide
D) glycerol/triglyceride

Answer 1

C

Question 2

Amino acids are acids because they always possess which functional group?

A) amino
B) carbonyl
C) carboxyl
D) phosphate
E) hydroxyl

Answer 2

C

Question 3

A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water, it

A) will function only as an acid because of the carboxyl group.
B) will function only as a base because of the amino group.
C) will function as both an acid and a base.
D) will function as neither an acid nor a base.

Answer 3

C

Question 4

Which of the following chemical equations describes a dehydration reaction?

A) monosaccharide + monosaccharide disaccharide + H₂O
B) monosaccharide + monosaccharide + H₂O disaccharide
C) disaccharide monosaccharide + monosaccharide + H₂O
D) disaccharide + H₂O monosaccharide + monosaccharide

Question 5

How many electron pairs does carbon share in order to complete its valence shell?

A) 1
B) 2
C) 3
D) 4
E) 8

Question 6

When two carbon atoms are joined by a double bond, the atoms joined to the carbons form a

A) sphere.
B) cube.
C) tetrahedron.
D) line.
E) plane.

Question 7

Which of the following functional groups may be used to form polymers via dehydration reactions?

A) only hydroxyl groups
B) only carbonyl groups
C) only carboxyl groups
D) either hydroxyl or carboxyl groups
E) either carbonyl or carboxyl groups

Question 8

Which of the following is a monomer used to build a biological polymer?

A) amino acid
B) disaccharide
C) triglyceride
D) DNA

Question 9

Which of the following functional groups is hydrophobic?

A) amino
B) methyl
C) carboxyl
D) hydroxyl

Question 10

Which of the following will result in changing the orientation of bonds between carbon and other atoms from a tetrahedral configuration to a planar configuration?

A) the presence of single covalent bonds with oxygen atoms
B) the presence of single covalent bonds with nitrogen atoms
C) the presence of double covalent bonds between the carbon atom and other atoms
D) the presence of polar covalent bonds between carbon and other atoms

Question 11

Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers, that is, molecules that

A) have identical chemical formulas but differ in the branching of their carbon skeletons.
B) are mirror images of one another.
C) exist in either linear chain or ring forms.
D) differ in the arrangement of atoms around their double bonds.

Question 12

When carbon forms single covalent bonds with four other atoms, the atoms joined to the carbon form a

A) sphere.
B) cube.
C) tetrahedron.
D) line.
E) plane.

Question 13

Which of the following chemical equations describes a hydrolysis reaction?

A) monosaccharide + monosaccharide disaccharide + H₂O
B) monosaccharide + monosaccharide + H₂O disaccharide
C) disaccharide monosaccharide + monosaccharide + H₂O
D) disaccharide + H₂O monosaccharide + monosaccharide

Question 14

Which two functional groups are always found in amino acids?

A) hydroxyl and carboxyl
B) carbonyl and amino
C) ketone and amino
D) carboxyl and amino

Question 15

When two carbon atoms are joined by a double bond, how many electron pairs are shared between the two carbons?

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

Question 16

The primary functional groups in a common macromolecule are hydroxyl groups. Which of the following statements regarding this macromolecule is true?

A) It lacks an asymmetric carbon, and it is probably a fat or lipid.
B) It will not dissolve in water.
C) It will dissolve in a nonpolar solvent.
D) It will form hydrogen bonds with water.

Question 17

Which functional group can act as a base?

A) amino
B) phosphate
C) hydroxyl
D) carboxyl
E) methyl

Question 18

Which of the following will dissolve in water?

A) organic hydrocarbons
B) organic molecules with hydroxyl groups
C) carbon skeletons bound to hydrogen
D) fats

Question 19

What is a common chemical reaction mechanism by which cells make polymers from monomers?

A) decreasing the pH
B) hydrolysis reactions
C) dehydration reactions
D) the formation of disulfide bridges between monomers

Question 20

A carbon atom is most likely to form which of the following bonds with other atoms?

A) ionic bonds
B) hydrogen bonds
C) covalent bonds
D) covalent bonds and hydrogen bonds

Question 21

Which of the following is true of both starch and cellulose?

A) They are both polymers of glucose.
B) They are cis-trans isomers of each other.
C) They can both be digested by humans.
D) They are both used for energy storage in plants.
E) They are both structural components of the plant cell wall.

Question 22

Which of the following is the smallest carbohydrate?

A) lactose
B) glycogen
C) chitin
D) cellulose
E) starch

Question 23

Which of the following classes of biological molecules consist of both small molecules and macromolecular polymers?

A) lipids
B) carbohydrates
C) proteins
D) nucleic acids

Question 24

Which of the following polymers lacks nitrogen?

A) protein
B) RNA
C) glycogen
D) chitin

Question 25

On food packages, to what does the term insoluble fiber refer?

A) cellulose
B) polypeptides
C) starch
D) glycogen

Question 26

A molecule with the chemical formula C₆H₁₂O₆ is probably a

A) hydrocarbon.
B) lipid.
C) monosaccharide
D) glycerol.

Question 27

Polysaccharides, triacylglycerols, and proteins are similar in that they

A) are synthesized from monomers by hydrolysis reactions.
B) are synthesized from subunits by dehydration reactions.
C) are synthesized through the formation of peptide bonds between monomers.
D) are broken down into their subunits by dehydration reactions.

Question 28

The molecular formula for glucose is C₆H₁₂O₆. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?

A) C18H36O18
B) C18H32O16
C) C6H10O5
D) C18H30O15
E) C16H36O16

Question 29

Which of the following polymers contains nitrogen?

A) starch
B) glycogen
C) cellulose
D) chitin

Question 30

Which of the following compounds are formed by dehydration reactions?

A) triacylglycerols
B) monosaccharides
C) amino acids
D) fatty acids

Question 31

How many molecules of water are needed to completely hydrolyze a polysaccharide that is 10 monomers long?

A) 12
B) 11
C) 10
D) 9

Question 32

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

A) as a pentose
B) as a hexose
C) as a monosaccharide
D) as a disaccharide
E) as a polysaccharide

Question 33

Humans can digest starch but not cellulose because

A) the monomer of starch is glucose, whereas the monomer of cellulose is glucose modified by the addition of a nitrogen-containing group.
B) humans have enzymes that can hydrolyze the β glycosidic linkages of starch but not the α glycosidic linkages of cellulose.
C) humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose.
D) humans harbor starch-digesting bacteria in the digestive tract, but not cellulose-digesting bacteria.

Question 34

Which of the following is an example of a dehydration reaction?

A) the reaction of two monosaccharides, forming a disaccharide with the release of water
B) the reaction of two amino acids, forming a peptide bond with the consumption of water
C) the reaction of a fat with glycerol, forming fatty acids with the release of water
D) the reaction of a fat, forming glycerol and fatty acids with the release of water

Question 35

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

A) Dehydration reactions split water molecules and add hydroxyl groups to polymers, and hydrolysis reactions remove hydroxyl groups from polymers.
B) Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.
C) Dehydration reactions create monomers, and hydrolysis reactions assemble polymers.
D) Dehydration reactions break down polymers, and hydrolysis reactions create monomers.

Question 36

Which of the following is an example of a hydrolysis reaction?

A) the reaction of two monosaccharides, forming a disaccharide with the release of water
B) the synthesis of two amino acids, forming a peptide bond with the release of water
C) the reaction of a fat with glycerol, forming fatty acids with the release of water
D) the reaction of a fat, forming glycerol and fatty acids with the consumption of water

Question 37

Which of the following is true of cellulose?

A) It is a polymer composed of enantiomers of glucose.
B) It is a primary structural component of plant cell walls.
C) It is digestible by bacteria in the human gut.
D) It is a storage polysaccharide for energy in plant cells.
E) It is a polymer of glucose joined by α glycosidic linkages.

Question 38

DNase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNase?

A) The two strands of the double helix would separate.
B) The phosphodiester bonds between deoxyribose sugars would be broken.
C) The bases would be separated from the deoxyribose sugars.
D) Oxygen atoms would be removed from the deoxyribose sugars.

Question 39

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down?

A) starch
B) cellulose
C) chitin
D) starch and chitin

Question 40

The biochemical reaction that joins two amino acids to form a dipeptide is accompanied by

A) the addition of a water molecule.
B) the release of a carbon dioxide molecule.
C) the addition of a nitrogen atom.
D) the release of a water molecule.

Question 41

Which of the following large biological molecules will self-assemble into a bilayer when mixed with water?

A) proteins
B) triacylglycerols
C) cellulose
D) phospholipids

Question 42

Why are hydrocarbons insoluble in water?

A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages.
B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
C) They are hydrophilic.
D) They exhibit considerable molecular complexity and diversity.

Question 43

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. How do these molecules differ from each other?

A) Testosterone and estradiol are structural isomers but have the same molecular formula.
B) Testosterone and estradiol are cis-trans isomers but have the same molecular formula.
C) Testosterone and estradiol have different functional groups attached to the same carbon skeleton.
D) Testosterone and estradiol are enantiomers of the same organic molecule.

Question 44

Which of the following statements concerning saturated fats is true?

A) They are more common in plants than in animals.
B) They have multiple double bonds in the carbon chains of their fatty acids.
C) They are generally solid at room temperature.
D) They contain fewer hydrogen atoms than unsaturated fats having the same number of carbon atoms.

Question 45

Hydrogenated vegetable oil is the primary ingredient in margarine. How does hydrogenated vegetable oil differ from nonhydrogenated vegetable oil?

A) Hydrogenated vegetable oil has a lower melting point than nonhydrogenated vegetable oil.
B) Hydrogenated vegetable oil is solid at room temperature, whereas nonhydrogenated vegetable oil is liquid.
C) Hydrogenated vegetable oil has more kinks in its fatty acid chains than does nonhydrogenated vegetable oil.
D) Hydrogenated vegetable oil contains more cis fatty acids than nonhydrogenated vegetable oil.

Question 46

Which of the following statements regarding saturated fatty acids is true?

A) They are the predominant fatty acid in corn oil.
B) They have double bonds between the carbon atoms of the fatty acids.
C) They are the principal molecules in lard and butter.
D) They are usually liquid at room temperature.
E) They are usually produced by plants.

Question 47

Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins?

A) hydrophobic interactions
B) ionic bonds
C) hydrogen bonds
D) peptide bonds

Question 48

Why are the vertebrate sex hormones estradiol and testosterone considered to be lipids?

A) They are essential components of cell membranes.
B) Their carbon skeletons are composed of primarily C-C and C-H bonds.
C) They are made of fatty acids.
D) They are hydrophilic compounds.

Question 49

Lactase is an enzyme composed of a single polypeptide that hydrolyzes the disaccharide lactose to produce monosaccharides. The optimal pH for lactase activity is 6. Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity, likely due to the disruption of

A) only the primary structure of the enzyme.
B) the primary and secondary structure of the enzyme.
C) the secondary and tertiary structure of the enzyme.
D) the secondary, tertiary, and quaternary structure of the enzyme.

Question 50

The α helix and β pleated sheet are examples of which level of protein structure?

A) primary
B) secondary
C) tertiary
D) quaternary
E) primary, secondary, tertiary, and quaternary

Question 51

Large organic molecules are generally synthesized by polymerization of a few types of simple subunits. Which of the following is an exception to this statement?

A) a steroid
B) cellulose
C) DNA
D) an enzyme

Question 52

Which of the following statements regarding lipids is true?

A) They generally contain nitrogen.
B) They are made from glycerol and amino acids.
C) A gram of lipid stores less energy than a gram of carbohydrate.
D) They are insoluble in water.

Question 53

A molecule with the formula C18H36O₂ is probably a

A) fatty acid.
B) carbohydrate.
C) hydrocarbon.
D) nucleic acid.

Question 54

Which of the following molecules lacks amino acids?

A) hemoglobin
B) insulin
C) antibodies
D) spider silk
E) cholesterol

Question 55

How many peptide bonds are present in a polypeptide that contains 45 amino acids?

A) 90
B) 46
C) 45
D) 44

Question 56

Which bonds maintain the primary structure of a protein?

A) disulfide bonds
B) hydrogen bonds
C) ionic bonds
D) peptide bonds

Question 57

Collagen is a protein made of three identical polypeptides composed primarily of α helix structure. The α helix is an example of

A) secondary structure stabilized by covalent bonds.
B) secondary structure stabilized by hydrogen bonds.
C) secondary structure stabilized by ionic bonds.
D) tertiary structure stabilized by covalent bonds.
E) tertiary structure stabilized by hydrogen bonds.

Question 58

There are 20 different amino acids. What makes one amino acid different from another?

A) different side chains (R groups) attached to the carboxyl carbon
B) different side chains (R groups) attached to the amino groups
C) different side chains (R groups) attached to an α carbon
D) different asymmetric carbons

Question 59

What maintains the secondary structure of a protein?

A) peptide bonds between adjacent amino acids
B) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
C) disulfide bonds between the amino group of one peptide bond and the R group of another amino acid
D) hydrogen bonds between the carboxyl group of one peptide bond and the R group of another amino acid

Question 60

Which bonds are created during the formation of the primary structure of a protein?

A) disulfide bonds
B) hydrogen bonds
C) peptide bonds
D) phosphodiester bonds

Question 61

A nucleotide is composed of

A) a nitrogenous base and a phosphate group.
B) a nitrogenous base and a pentose sugar.
C) a nitrogenous base, a phosphate group, and a pentose sugar.
D) a nitrogenous base, a phosphate group, a pentose sugar, and an amino acid.

Question 62

Which of the following statements about the 5' end of a polynucleotide strand of RNA is correct?

A) The 5' end has a hydroxyl group attached to the number 5 carbon of ribose.
B) The 5' end has a phosphate group attached to the number 5 carbon of ribose.
C) The 5' end has phosphate attached to the number 5 carbon of the nitrogenous base.
D) The 5' end has a nitrogenous base attached to the number 5 carbon of ribose.

Question 63

If cells are grown in a medium containing radioactive 32P, which of these molecules will be radioactively labeled?

A) triacylglycerols
B) nucleic acids
C) fatty acids
D) starch

Question 64

A disulfide bridge is an example of which type of bond?

A) ionic bond between R groups
B) hydrophobic interaction between R groups
C) hydrogen bond between R groups
D) covalent bond between R groups

Question 65

Changing a single amino acid in a protein consisting of 433 amino acids would

A) always alter the primary structure of the protein but never alter its tertiary structure or function.
B) always alter the primary structure of the protein and sometimes alter its tertiary structure or function.
C) always alter the primary and tertiary structure of the protein but never alter its function.
D) sometimes alter the primary and tertiary structure of the protein but always alter its function.

Question 66

Which of the following are purines?

A) cytosine and guanine
B) guanine and adenine
C) adenine and thymine
D) thymine and uracil
E) uracil and cytosine

Question 67

How will brief heating (to 95°C) affect macromolecular structures in aqueous solution?

A) Unsaturated fatty acid tails will become saturated.
B) Proteins will unfold (denature).
C) Starch will hydrolyze into monomeric sugars.
D) Proteins will hydrolyze into amino acids.

Question 68

One of the primary functions of RNA molecules is to

A) transmit genetic information to offspring.
B) function in the synthesis of proteins.
C) make a copy of itself, thus ensuring genetic continuity.
D) act as a pattern or blueprint to form DNA.

Question 69

If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?

A) polysaccharides
B) proteins
C) DNA
D) RNA
E) both DNA and RNA

Question 70

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA

A) is a six-carbon sugar and the sugar in RNA is a five-carbon sugar.
B) is a five-carbon sugar and the sugar in RNA is a six-carbon sugar.
C) is in the α configuration and the sugar in RNA is in the β configuration.
D) contains one less oxygen atom than the sugar in RNA.

Question 71

In a normal cellular protein, where would you expect to find a hydrophilic amino acid such as asparagine?

A) in the interior of the folded protein, away from water
B) on the exterior surface of the protein, interacting with water
C) in the transmembrane portion interacting with lipid fatty acid chains
D) on the exterior surface of the protein, interacting with water, or in a transmembrane portion interacting with lipid fatty acid chains

Question 72

Which of the following are pyrimidines?

A) adenine and thymine
B) adenine and guanine
C) cytosine and uracil
D) cytosine and guanine

Question 73

If cells are grown in a medium containing radioactive 35S, which of these molecules will be radioactively labeled?

A) phospholipids
B) nucleic acids
C) proteins
D) starch

Question 74

The side chain (R group) of the amino acid serine is -CH2-OH. The side chain of the amino acid leucine is -CH2-CH-(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?

A) Serine would be on the exterior, and leucine would be in the interior of the globular protein.
B) Serine would be in the interior, and leucine would be on the exterior of the globular protein.
C) Both serine and leucine would be in the interior of the globular protein.
D) Both serine and leucine would be on the exterior of the globular protein.

Question 75

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of

A) 120 adenine and 120 uracil molecules.
B) 120 adenine and 120 guanine molecules.
C) 120 cytosine and 120 thymine molecules.
D) 120 thymine and 120 adenine molecules.

Question 76

If a DNA sample were composed of 15% adenine, what would be the percentage of guanine?

A) 15
B) 30
C) 35
D) 50

Question 77

If a DNA sample were composed of 15% adenine, what would be the percentage of thymine?

A) 15
B) 30
C) 35
D) 50

Question 78

The tertiary structure of a polypeptide is the

A) linear sequence of amino acids in a polypeptide.
B) localized region of a polypeptide chain that forms an α helix or β pleated sheet.
C) overall three-dimensional shape of a fully folded polypeptide.
D) overall three-dimensional shape of a protein composed of more than one polypeptide.

Question 79

Interactions between the side chains (R groups) in a polypeptide are most important in stabilizing which of the following?

A) primary structure
B) secondary structure
C) tertiary structure
D) quaternary structure

Question 80

Normal hemoglobin is a tetramer, consisting of two molecules of β-globin and two molecules of α-globin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits

A) altered primary structure.
B) altered secondary structure.
C) altered tertiary structure.
D) altered quaternary structure.
E) altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.