Deck 3: The Chemical Building Blocks of Life

Question 1

This atom in its unbound state has four valence electrons.These electrons readily form single, double, and even triple bonds among themselves to become stable.This atom is:

A)carbon.
B)hydrogen.
C)oxygen.
D)nitrogen.

Answer 1

A

Question 2

The biological macromolecule that is least soluble in water is a(n):

A)lipid.
B)nucleic acid.
C)protein.
D)carbohydrate.

Answer 2

A

Question 3

A DNA molecule containing 32% thymine would contain how much cytosine?

A)18%
B)32%
C)36%
D)64%

Answer 3

A

Question 4

The simplest and the most common monosaccharide is a six-carbon sugar called:

A)galactose.
B)lactose.
C)cellulose.
D)glucose.

Question 5

Proteins are polymers formed of structural units called:

A)fatty acids.
B)amino acids.
C)nucleotides.
D)phosphate groups.

Question 6

Organic molecules have a carbon backbone and _____ such as -OH and -NH₂ that affect their chemical properties.

A)chemical groups
B)R groups
C)extension groups
D)functional groups

Question 7

These biological compounds are non-polar and insoluble in water:

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

Question 8

This type of lipid is found in pigments such as chlorophyll, in the visual pigment retinal, and in rubber:

A)steroid.
B)wax.
C)prostaglandin.
D)terpene.

Question 9

Lipids are the only class of macromolecules that contain:

A)amino acids.
B)nucleotides.
C)fatty acids.
D)phosphate groups.

Question 10

Macromolecules that are used by most organisms to store hereditary information are called:

A)proteins.
B)transfer RNA molecules.
C)ribosomal RNA molecules.
D)DNA molecules.

Question 11

Humans are unable to get metabolic energy from cellulose because:

A)cellulose contains very little chemical energy.
B)cellulose is not part of a normal diet.
C)cellulose digesting enzymes are absent from the human gut.
D)cellulose does not taste good.

Question 12

Chitin, a modified form of cellulose, is not only cross-linked with proteins but its glucose units are modified with atoms of:

A)nitrogen.
B)hydrogen.
C)oxygen.
D)sulfur.

Question 13

A double stranded DNA strand contains 26 pyrimidines.How many purines will the copied strand contain?

A)0
B)13
C)26
D)52

Question 14

DNA and RNA contain functional units known as:

A)peptides.
B)enzymes.
C)amino acids.
D)nucleotides.

Question 15

Relatively small organic molecules with a central carbon atom which is bonded to a carboxyl group, an amino group, a carbon containing group, and a hydrogen atom are called:

A)amino acids.
B)fatty acids.
C)enzymes.
D)peptides.

Question 16

A modified form of cellulose found in the exoskeletons of insects and crustaceans is known as:

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

Question 17

Macromolecules are broken down to monomers in ___

A)dehydration reactions.
B)denaturation reactions.
C)hydrolysis reactions.
D)anabolic reactions.

Question 18

The covalent bonds connecting monomer units in sugars can be formed by the removal of a water molecule.This reaction is referred to as: rev: 09_11_2014_QC_53628

A)a hydrolysis reaction.
B)an oxidation-reduction reaction.
C)a dehydration reaction.
D)a hydration reaction.

Question 19

Amino acids are linked together by peptide bonds in a ____

A)starch.
B)polypeptide.
C)polysaccharide.
D)nucleic acid.

Question 20

Three fatty acids bonded together with a glycerol are found in a(n):

A)enzyme.
B)chlorophyll pigment.
C)phospholipid.
D)triglyceride.

Question 21

You recently identified a novel protein that contains several membrane-spanning domains.You would predict that the amino acids embedded in the membrane would have ____ side groups.

A)nonpolar
B)negatively charged
C)polar uncharged
D)positively charged

Question 22

Proteins are created with:

A)phosphodiester bonds.
B)peptide bonds.
C)triglycerides.
D)polysaccharides.

Question 23

Which of the following reactions is a dehydration reaction?

A)A + H₂O $\rightarrow$ B + C
B)A + B + H₂O $\rightarrow$ C
C)A $\rightarrow$ B + C+ H₂O
D)A + B $\rightarrow$ C + H₂O

Question 24

Phospholipids are made up of:

A)a glycerol and three fatty acids.
B)four fused carbon rings.
C)a phosphate, two fatty acids and a glycerol.
D)five-carbon rings with two nonpolar tails.

Question 25

The specific amino acid sequence of a protein is its ____.

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

Question 26

L-lysine is an essential amino acid and must be supplied in the diet.By comparison, the stereoisomer D-lysine is not biologically active.Why can your body only utilize one form?

A)Since the L form and D form are enantiomers, they will bind together and inhibit utilization of the D form.
B)Since the L form and D form are chiral molecules, they will bind together and inhibit utilization of the D form.
C)Antibodies recognize the D form and destroy it before your body can use it for nutritional purposes.
D)Enzymes can only recognize a single, specific stereoisomer.

Question 27

The nitrogenous base that is only found in RNA and not DNA is:

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

Question 28

A low fat cookie with 2 grams of fat, 10 grams of carbohydrate, and 2 grams of protein contains:

A)14 calories
B)56 calories
C)66 calories
D)126 calories

Question 29

The DNA sequence capable of pairing with 5' CGATTAGT 3' is:

A)5' CGATTAGT 3'.
B)5' GCTAATCA 3'.
C)3' CGATTAGT 5'.
D)3' GCTAATCA 5'.

Question 30

The types of bonds found in nucleic acids are:

A)phosphodiester bonds.
B)peptide bonds.
C)ionic bonds.
D)non-polar covalent bonds.

Question 31

People who are lactose intolerant can often consume some products made from milk such as cheese and yogurt because microorganisms in their digestive system consume the lactose.By comparison, people with a true milk allergy, which involves an immune response to milk protein, cannot consume milk or products made from milk.Given this information, what can you conclude about milk?

A)The protein that causes a true milk allergy is lactose.
B)All people who are lactose intolerant are also allergic to milk.
C)Yogurt contains live and active cultures of Lactobacillus acidophilus bacteria and therefore prevents an allergic response in people with a true milk allergy.
D)Lactose is a carbohydrate, not a protein and is therefore not the cause of true milk allergies.

Question 32

Carbohydrates are composed of:

A)amino acids.
B)fatty acids and glycerol.
C)nucleotides.
D)monosaccharides.

Question 33

A candy bar contains 108 calories per serving.There are 4 grams of carbohydrate, 5 grams of protein, and 8 grams of fat in a serving.How many of the calories come from fat?

A)72
B)16
C)18
D)20

Question 34

Denaturation disrupts the secondary and tertiary structure of proteins.However, denaturation is not strong enough to disrupt what interaction that is relevant to protein structure?

A)ionic bonds
B)hydrophobic exclusion
C)peptide bonds
D)van der Waals attraction

Question 35

A nucleic acid contains uracil, allowing you to conclude that:

A)this nucleic acid is DNA.
B)this nucleic acid is RNA.
C)this nucleic acid could be either DNA or RNA.

Question 36

Which of the following reactions is a hydrolysis reaction?

A)A + B + H₂O $\rightarrow$ C
B)A $\rightarrow$ B + C+ H₂O
C)A + B $\rightarrow$ C + H₂O
D)A + H₂O $\rightarrow$ B + C

Question 37

Enzymes function to:

A)react with other enzymes to form a product.
B)catalyze chemical reactions.
C)transport molecules and ions across membranes.
D)regulate messages between cells.

Question 38

Egg whites consist primarily of water and the protein albumin.When you fry an egg, why does the egg white turn from clear to white?

A)The protein becomes dissociated.
B)The protein acquires tertiary structure.
C)The protein becomes denatured.
D)The protein becomes dehydrated.

Question 39

The nitrogenous base that is only found in DNA and not in RNA is: rev: 02_22_2014_QC_45858

A)cytosine.
B)uracil.
C)adenine.
D)thymine.

Question 40

What is the difference in the bonding between alpha-helix and beta sheets?

A)Hydrogen bonding between the amides only occurs in one of these two types of secondary structures.
B)Hydrogen bonding occurs between the amides of adjacent chains in the sheets instead of between the amides in different parts of the helices.
C)Sulfur bridges allow the spring like turns in alpha helices and van der Waals dispersion allows the folds in beta sheets.
D)Hydrogen bonding always occurs in the alpha helices but only occurs in parallel beta sheets.

Question 41

You arrive late to a biological seminar.However, just as you enter the room, you hear the speaker referring to the "amino end" and the "carboxyl end" of a macromolecule.Immediately, you know that they are talking about a:

A)carbohydrate.
B)protein.
C)lipid.
D)DNA.

Question 42

If all functional groups are removed from an organic molecule, leaving only a hydrocarbon chain, the molecule becomes a:

A)Lipid
B)Carbohydrate
C)Protein
D)Nucleic acid

Question 43

The formula for glucose is C₆H₁₂O₆.What is the formula for a polymer made by linking ten glucose molecules together by dehydration synthesis?

A)C₆₀H₁₁₁O₅₁
B)C₆₀H₁₂₀O₆₀
C)C₆₀H₁₀₀O₅₀
D)C₆₀H₁₀₂O₅₁

Question 44

The digestive enzyme pepsin works in the acidic environment of the stomach to hydrolyze peptide bonds.As a result, pepsin affects which macromolecule?

A)carbohydrate
B)protein
C)DNA
D)lipid

Question 45

A phosphorus shortage in soil would make it difficult for plants to produce:

A)DNA
B)starch
C)amylose
D)cellulose

Question 46

What type of monomer does ATP represent?

A)nucleotide
B)glycerol
C)fatty acid
D)monosaccharide

Question 47

Hemoglobin transports oxygen in the blood and consists of a chain of 146 amino acids.How many different types of amino acids are used to construct proteins?

A)2
B)20
C)146
D)200

Question 48

Luke sprained his ankle, tearing some of the collagen protein that forms his ligaments.Some types of collagen consist of three polypeptide chains twisted together to form a rope-like strand.What level of protein structure does this rope-like strand represent?

A)Primary
B)Secondary
C)Tertiary
D)Quaternary

Question 49

A bobcat is feeding on a white-tailed deer.It first eats the liver, which is rich in stored sugars.In what form would sugar be stored in the deer's liver?

A)Glucose
B)Maltose
C)Glycogen
D)Amylose

Question 50

Vitamin D can be synthesized by the body from a derivative of cholesterol.Given this information, predict vitamin D's solubility.

A)Vitamin D is water-soluble.
B)Vitamin D is fat-soluble.
C)Vitamin D is soluble in both water and fat.
D)Vitamin D is not soluble in either water or fat.

Question 51

Yogurt contains galactose and glucose, which are generated when bacterial enzymes act on milk sugars.What is the main source of the galactose in yogurt?

A)Maltose
B)Sucrose
C)Lactose
D)Fructose

Question 52

You arrive late to a biological seminar.However, just as you enter the room, you hear the speaker referring to the "five-prime end" and the "three-prime end" of a macromolecule.Immediately, you know that they are talking about a:

A)carbohydrate.
B)protein.
C)DNA.
D)lipid.

Question 53

Margarine is made by hydrogenating vegetable oils so that they take on the consistency of butter.Propose a chemical basis for this change from a liquid to a solid.

A)Hydrogenation of fats changes them from saturated to unsaturated, which are more solid.
B)Trans-fatty acids are changed from unsaturated to saturated, allowing them to solidify.
C)Trans fatty acids are changed from saturated to unsaturated, allowing them to solidify.
D)Hydrogenation of fats changes them from unsaturated to saturated, which are more solid.

Question 54

You have recently identified a novel protein and obtained its sequence.How could you use this sequence to predict the function of the protein?

A)By using the sequence to make antibodies against the protein.
B)By determining the secondary structure of the protein.
C)By determining the DNA sequence that could encode the protein.
D)By looking for conserved domains.

Question 55

The myoglobin protein, which carries oxygen in muscle cells, has only the first three levels of protein structure.What can you infer about myoglobin?

A)Myoglobin is made of nucleic acids
B)Myoglobin lacks hydrogen bonds
C)Myoglobin is made of only one polypeptide chain
D)Myoglobin is not helical or pleated

Question 56

At the pH of most bodily fluids, which functional group will lose a proton and which functional group will accept a proton?

A)sulfhydryl; carbonyl
B)Hydroxyl; amino
C)amino; carboxyl
D)carboxyl; amino

Question 57

Which amino acid is least soluble in water?

A)Alanine
B)Glutamine
C)Glycine
D)Isoleucine

Question 58

The human immunodeficiency virus (HIV) uses RNA, rather than DNA, to encode genetic information.During infection, however, HIV uses an enzyme known as reverse transcriptase to generate double-stranded DNA.Generally speaking, how would the enzyme generate a double strand of DNA from a single strand of RNA?

A)Reverse transcriptase first catalyzes the synthesis of a DNA copy from the viral RNA, and then catalyzes the synthesis of a second strand of DNA complementary to the first one.
B)Reverse transcriptase first catalyzes the synthesis of a RNA copy from the viral DNA, and then catalyzes the synthesis of a second strand of DNA complementary to the first one.
C)Reverse transcriptase first catalyzes the synthesis of a DNA copy from the viral RNA, and then catalyzes the synthesis of a second strand of DNA from the viral RNA.

Question 59

Which amino acid is most soluble in water?

A)Valine
B)Glycine
C)Leucine
D)Serine

Question 60

Seth purchased five pounds of live crayfish and realized that the outer shells were made of a tough carbohydrate similar to that used to make the carapace of a cockroach.What do you think the outer shells of the crawfish are made of?

A)Glycogen
B)Chitin
C)Amylopectin
D)Cellulose

Question 61

Benedict's reagent is a chemical that is used as a test for the presence of a free aldehyde functional group on glucose.The aldehyde is used when glucose and fructose bind together to form sucrose, and the Benedict's test is negative.Starch contains a great deal of glucose but gives a negative Benedict's test because:

A)all of the aldehyde groups on the starch are oxidized and cannot react with the Benedict's reagent.
B)glucose in starch has lost a carbon atom and cannot react with Benedict's reagent.
C)only the glucose at the end of a chain of starch will have an exposed aldehyde functional group to react with Benedict's reagent.
D)starch is not soluble in water and cannot react with Benedict's reagent.

Question 62

A polymer with the sequence 5' ACGTACGAATAG 3' is a:

A)polysaccharide.
B)protein.
C)piece of RNA.
D)piece of DNA.

Question 63

This is a nucleotide containing molecule that is commonly used to carry electrons in the cell.

A)ADP
B)ATP
C)NAD⁺
D)pyruvic acid

Question 64

How many water molecules are produced during the formation of a triglyceride from fatty acids and glycerol?

A)0
B)1
C)2
D)3

Question 65

What characteristic would the R groups of amino acids have if they are located within the interior of biological membranes?

A)The R groups would be able to form ionic bonds.
B)The R groups would be polar.
C)The R groups would hydrophobic.
D)The R groups would be hydrophilic.

Question 66

Acyclovir is an antiviral chemical that resembles a nucleotide but lacks a 3' OH group and cannot form phosphodiester bonds.Why is Acyclovir useful in treating some viral infections?

A)Acyclovir stops viral protein synthesis.
B)Acyclovir halts viral DNA replication.
C)Acyclovir blocks the assembly of viral cell capsules.
D)Acyclovir hydrolyzes viral polysaccharides.

Question 67

You label cells with a radioactive isotope of sulfur (³⁵S).The only molecules that would be radioactively labeled in these cells are:

A)Proteins
B)Carbohydrates
C)Nucleic acids
D)Lipids

Question 68

$\alpha$ - glucose is present in potatoes and $\beta$ - glucose is present in wood.Both are glucose molecules but one can be used by humans to synthesize ATP and one cannot.Based on this information, what is the best explanation on why humans can only digest one of the glucose types?

A) $\alpha$ - glucose and $\beta$ - glucose are stereoisomers with OH groups oriented differently.
B) $\alpha$ - glucose is C₆H₁₂O₆ and $\beta$ - glucose is C₅H₁₂O₆.
C)Only $\alpha$ - glucose can form polysaccharides.
D) $\alpha$ - glucose is a chain and $\beta$ - glucose is a ring.