Deck 3: Biological Molecules: the Carbon Compounds of Life

Question 1

Probably the most abundant carbohydrate on Earth, which unbranched chain of b-glucose subunits is the primary structural fiber in plant cell walls?

A) chitin
B) amylopectin
C) cellulose
D) glycogen
E) amylose

Answer 1

C

Question 2

Figure 3.3
The disaccharide in the accompanying figure is ____.

A) lactose
B) fructose
C) maltose
D) cellulose
E) sucrose

Answer 2

A

Question 3

Figure 3.2
The disaccharide in the accompanying figure is ____.

A) cellulose
B) galactose
C) maltose
D) sucrose
E) lactose

Answer 3

D

Question 4

Suppose that an equal amount of each polysaccharide was placed in a landfill. Which polysaccharide should last the longest before it is decomposed?

A) chitin
B) amylopectin
C) cellulose
D) glycogen
E) amylose

Question 5

Which functional group acts as an organic base?

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

Question 6

Reactions that remove the equivalent of a water molecule when subunits are joined to make a larger molecule are called ____ reactions.

A) equilibrium
B) hydration
C) hydrolysis
D) redox
E) dehydration synthesis

Question 7

Monosaccharides and disaccharides are types of ____.

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

Question 8

Which functional group forms the highly reactive part of aldehydes and ketones?

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

Question 9

When molecules are referred to as D- or L- (for example D-forms of sugars and L-forms of amino acids), the D- and L- designations refer to the specific ____.

A) functional group
B) structural isomer
C) covalent bond
D) secondary structure
E) stereoisomer

Question 10

Which of these hydrocarbons has a double bond in its structure?

A) C₃H₈
B) C₂H₆
C) CH₄
D) C₂H₄
E) C₂H₂

Question 11

Structural isomers differ from each other ____.

A) in the arrangement of their covalent bonds
B) in their molecular formulas
C) by being mirror images that cannot be superimposed on each other
D) by having double covalent bonds instead of single bonds
E) by having different atomic isotopes in their molecules

Question 12

Reactions that use the equivalent of a water molecule to break a molecule into smaller subunits are called ____ reactions.

A) equilibrium
B) hydration
C) hydrolysis
D) redox
E) dehydration synthesis

Question 13

Figure 3.5
The molecule in the accompanying figure is mannose, an example of a ____ sugar.

A) triose
B) hexose
C) pentose
D) heptose
E) tetrose

Question 14

Amylose is a polymer made up of glucose monomers joined by ____.

A) b(1-4) linkages
B) b(1-6) linkages
C) a(1-4) linkages
D) a(1-6) linkages
E) both b(1-4) and a(1-6) linkages

Question 15

The linkage commonly found between subunits in a chain of monosaccharides is called a ____ bond.

A) phosphodiester
B) disulfide
C) glycosidic
D) hydrogen
E) peptide

Question 16

Figure 3.1
The accompanying figure illustrates the synthesis of ____.

A) sucrose
B) maltose
C) lactose
D) cellulose
E) fructose

Question 17

Isomers are two or more molecules with ____ chemical formula and ____ molecular structures.

A) a different; different
B) the same; different
C) a different; the same
D) the same; the same
E) a structural; theoretical

Question 18

Figure 3.4
The molecule in the accompanying figure is glyceraldehyde, an example of a ____ sugar.

A) triose
B) hexose
C) pentose
D) heptose
E) tetrose

Question 19

Which functional group is polar and a key component of alcohols?

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

Question 20

Which polysaccharide is a chain of glucose units that are modified by having nitrogen-containing groups, is the main structural fiber in the external skeletons of arthropods, and also a structural material in the cell walls of fungi?

A) chitin
B) amylopectin
C) cellulose
D) glycogen
E) amylose

Question 21

Glycerol forms the backbone of ____.

A) triglycerides only
B) polysaccharides and nucleic acids
C) nucleic acids only
D) polypeptides only
E) triglycerides and phospholipids

Question 22

The molecule in the accompanying figure is ____, and has ____.

A) unsaturated; a carbon-carbon double bond
B) saturated; a carbon-carbon double bond
C) unsaturated; no carbon-carbon double bonds
D) saturated; no carbon-carbon double bonds
E) saturated; a carbon-carbon triple bond

Question 23

In many animals, this polysaccharide is found in large quantities in liver and muscle cells. It is highly branched, with many a(1-4) and a(1-6) linkages.

A) chitin
B) amylopectin
C) cellulose
D) glycogen
E) amylose

Question 24

Figure 3.7
The molecule shown above is a(n) ____.

A) triglyceride
B) amino acid
C) steroid
D) polysaccharide
E) phospholipid

Question 25

If three molecules of a fatty acid having the formula C₁₆H₂₂O₂are each joined to a molecule of glycerol (C₃H₈O₃) by a dehydration synthesis reaction, what will be the formula of the resulting neutral fat molecule?

A) C₄₈H₆₆O₆.
B) C₄₈H₇₂O₈.
C) C₅₁H₆₈O₆.
D) C₅₁H₇₂O₈.
E) C₅₁H₇₄O₉.

Question 26

Sterol regulatory element binding proteins (SREBPs) are involved in regulating the synthesis of ____.

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

Question 27

We would expect to find fatty acids with ____ carbons in living organisms.

A) eight
B) 13
C) 16
D) 19
E) 26

Question 28

Which molecule is the main structural component of biological membranes?

A) starch
B) triglyceride
C) protein
D) phospholipid
E) steroid

Question 29

HDL cholesterol is considered "good" cholesterol. What role does HDL play in preventing coronary heart disease?

A) HDL cholesterol inhibits LDL cholesterol synthesis
B) HDL cholesterol prevents transport of LDL cholesterol in blood
C) HDL cholesterol activates LDL cholesterol breakdown
D) HDL cholesterol prevents free radical formation in plaques
E) HDL cholesterol removes excess cholesterol from plaques

Question 30

A fatty acid has a(n)____ group at the end of a hydrocarbon chain.

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

Question 31

Figure 3.8
The molecule shown above is a(n) ____.

A) triglyceride
B) amino acid
C) steroid
D) polysaccharide
E) phospholipid

Question 32

The sex hormones of many animals are lipid molecules known as ____.

A) fatty acids
B) phospholipids
C) carotenoids
D) steroids
E) lipoproteins

Question 33

Amino acids are linked together by ____ bonds.

A) phosphodiester
B) disulfide
C) glycosidic
D) hydrogen
E) peptide

Question 34

Testosterone has important regulatory functions in humans and many other animals. Molecules with regulatory functions like testosterone are called ____.

A) phytosterols
B) enzymes
C) lipoproteins
D) hormones
E) receptors

Question 35

Figure 3.9
The molecule in the accompanying figure is ____, and has ____.

A) unsaturated; a carbon-carbon double bond
B) saturated; a carbon-carbon double bond
C) unsaturated; no carbon-carbon double bonds
D) saturated; no carbon-carbon double bonds
E) saturated; a carbon-carbon triple bond.

Question 36

Figure 3.6
The molecule in the accompanying figure is a(n) ____.

A) triglyceride
B) amino acid
C) steroid
D) polysaccharide
E) phospholipid

Question 37

Waxy coatings, such as those found on skin, hair, and feathers of some animals and the cuticle of some plants, are commonly used by living organisms for protection against water loss and for lubrication. Such waxes are considered to be a type of ____.

A) triglyceride
B) steroid
C) neutral lipid
D) phospholipid
E) fatty acid

Question 38

Proteins are polymers of ____.

A) amino acids
B) monosaccharides
C) steroids
D) nucleotides
E) phospholipids

Question 39

Which class of molecule is the most diverse in terms of structure and roles played in cells?

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

Question 40

Why are trans fats more harmful for consumption than saturated fats?

A) Trans fats increase LDL cholesterol levels more than saturated fats.
B) Trans fats decrease HDL cholesterol levels more than saturated fats.
C) Saturated fats prevent LDL transport more than trans fats.
D) Trans fats are often consumed with other food additives that increase fat absorption in the gut.
E) Saturated fats are more natural, and better digested in the gut.

Question 41

In his experiments, Anfinsen treated a protein with a chemical that broke disulfide bonds and then removed the chemical to see how this would affect the function of the molecule. What did he conclude from these experiments?

A) The information for determining the three-dimensional shape of ribonuclease lies in its amino acid sequence.
B) The disulfide bonds are essential for quaternary, but not tertiary, protein structure.
C) Protein conformation is maintained when disulfide bonds are disrupted.
D) Altering the three-dimensional shape of the protein is irreversible.
E) Disulfide bonds are unnecessary for proper protein function.

Question 42

Which molecules are the most important for a cell to protect from damage if the cell is to stay alive and reproduce?

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

Question 43

In proteins, structural segments called ____ provide flexibility that allow parts of the protein to bend, fold, or move.

A) random coils
B) peptide bonds
C) b sheets
D) a helices
E) b polysaccharides

Question 44

Figure 3.16
The molecule in the accompanying figure is the pyrimidine ____, which is typically found in DNA but not RNA.

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

Question 45

The unique sequence of monomer subunits in a protein is the ____ structure of the protein.

A) primary
B) secondary
C) tertiary
D) quaternary
E) linear

Question 46

The sugar in DNA is comprised of ____ carbons.

A) three
B) four
C) five
D) six
E) seven

Question 47

After a long period of gradual evolution of protein domains, a period of explosive change (the "big bang") in protein domain complexity occurred at roughly the same time as the three taxonomic domains were undergoing rapid diversification. In which taxonomic domain was this diversification most extensive?

A) Eukarya
B) Protista
C) Archaea
D) Animalia
E) Bacteria

Question 48

Figure 3.12
The two amino acids in the accompanying figure both have side chains ( R groups) that are ____.

A) acidic and polar
B) uncharged and nonpolar
C) basic and polar
D) acidic and nonpolar
E) uncharged and polar

Question 49

A hydrogen bond between the amino acid side chains ( R groups) of two different polypeptide chains in a multichain protein would be considered part of the ____ structure of the protein.

A) primary
B) secondary
C) tertiary
D) quaternary
E) linear

Question 50

Figure 3.11 (Question 41)
The two amino acids in the accompanying figure both have side chains ( R  groups) that are ____.

A) acidic and polar
B) uncharged and nonpolar
C) basic and polar
D) acidic and nonpolar
E) uncharged and polar

Question 51

Excessive heat or extremes of pH often cause denaturation of proteins, which means that the proteins ____.

A) have fallen apart into individual monomer subunits
B) are no longer biological molecules
C) have broken into many separate domains
D) are no longer in a functional three-dimensional conformation
E) are highly reactive

Question 52

In an elegant set of experiments, which protein did Anfinsen study in order to understand how the three-dimensional structure of proteins is determined?

A) ovalbumin
B) chaperonin
C) ribonuclease
D) insulin
E) hemoglobin

Question 53

Figure 3.18
The molecule shown above is the purine ____.

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

Question 54

Figure 3.13
The two amino acids in the accompanying figure both have side chains ( R groups) that are ____.

A) acidic and polar
B) uncharged and nonpolar
C) basic and polar
D) acidic and nonpolar
E) uncharged and polar

Question 55

Figure 3.17
The molecule in the accompanying figure is the pyrimidine ____, which is typically found in both DNA and RNA.

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

Question 56

Chaperonins assist with ____.

A) proteins synthesis
B) assembly of DNA strands
C) polysaccharide synthesis
D) protein folding
E) forming the DNA double helix

Question 57

Which amino acid can be involved in special covalent "disulfide bridges" that, when present, help to stabilize the tertiary and quaternary structure of proteins?

A) proline
B) alanine
C) leucine
D) cysteine
E) methionine

Question 58

Hereditary information in all eukaryotes, prokaryotes, and viruses is stored in ____.

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

Question 59

Figure 3.15
The image in the accompanying figure is an example of a(n) ____.

A) random coil
B) double helix
C) b sheet
D) a helix
E) b polysaccharide

Question 60

Figure 3.14
The two amino acids depicted above both have side chains ( R groups) that are ____.

A) acidic and polar
B) uncharged and nonpolar
C) basic and polar
D) acidic and nonpolar
E) uncharged and polar

Question 61

Nucleotides are joined together to make a nucleic acid strand by ____ bonds.

A) phosphodiester
B) disulfide
C) glycosidic
D) hydrogen
E) peptide

Question 62

Consider the DNA sequence 5'-GATTACA-3'. If the strand with this sequence forms a double helix with another DNA strand, the sequence on the other strand should be ____.

A) 5'-TCGGCAC-3'
B) 3'-GATTACA-5'
C) 5'- ACATTAG-3'
D) 3'-GTGCCGA-5'
E) 3'-CTAATGT-5'

Question 63

Two structural differences between a uridine monophosphate and thymidine monophosphate are ____ and ____.

A) the number of hydrogen bonds formed between it and its matching base; the presence of a hydroxyl group on the ribose
B) the presence of a methyl group on the nitrogen base; the presence of a hydroxyl group on the ribose
C) the number of hydrogen bonds formed between it and its matching base; the presence of a methyl group on the nitrogen base
D) the number of hydrogen bonds formed between it and its matching base; the location of the ribose attachment to the nitrogenous base
E) the presence of a methyl group of the nitrogen base; the location of the ribose attachment to the nitrogenous base

Question 64

Which two nucleotides also serve as transporters of chemical energy?

A) ATP and GTP
B) ATP and CTP
C) ATP and TTP
D) CTP and TTP
E) CTP and UTP

Question 65

In addition to serving as building blocks of DNA, what other function do nucleotides perform in a cell?

A) regulate cellular activity
B) regulate gene expression
C) chaperone protein folding
D) activate vesicular transport
E) trigger muscle contractions

Question 67

Describe the general structure of amino acids.

Question 68

Are saturated or unsaturated fats generally solids at room temperature? Explain why there is a difference in the fluidity of these two related molecules.

Question 69

A large molecule whose subunits consist of a sugar and a nitrogenous base is called a ____.

A) nucleoside
B) nucleotide
C) nucleic acid
D) nucleosome
E) nuclear unit

Question 70

The two strands of a DNA double helix are held to each other by ____ bonds between nitrogenous bases.

A) phosphodiester
B) disulfide
C) glycosidic
D) hydrogen
E) peptide

Question 71

Glucose and fructose, which have the same chemical formula, are considered stereoisomers .

Question 72

When DNA is heated, the hydrogen bonds break and allow the two strands of DNA to separate from one another. Which sequence of DNA would be most resistant to heating, and therefore stay double stranded longer?

A) AATTGGCC
B) ATGCATTC
C) AGGAGCTC
D) TGGCTTAG
E) TACCAATT

Question 73

Approximately how many base pairs comprise one turn of the double helix in DNA?

A) 2.5
B) 5
C) 10
D) 20
E) 50

Question 74

How many hydrogen bonds are formed between adenine and thymine?

A) one
B) two
C) three
D) four
E) six

Question 75

Using what you know about how carbohydrate monomers are linked to form polymers, explain why most animals can digest starch more easily than cellulose?

Question 76

The tertiary structure of proteins is the three-dimensional shape comprised of two or more polypeptides.

Question 77

The most abundant organic molecules in the world are nucleic acids .

Question 78

Chitin is a reinforcing fiber in the external skeleton of arthropods.

Question 79

Unsaturated fats are considered healthier than saturated fats in the human diet.

Question 80

RNA is significantly less stable than DNA. Based on the structural differences between these molecules, what is a plausible hypothesis as to why this is?