Question 1

These biological compounds are nonpolar and insoluble in water:

Accepted Answer

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

Question 2

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

Accepted Answer

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. B

Question 3

Biological membranes contain bilayers containing mostly ________.

Accepted Answer

A)  phospholipids
B)  oils
C)  prostaglandins
D)  triglycerides
E)  cholesterol A

Question 4

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

Accepted Answer

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

Question 5

A polysaccharide that is composed of modified glucose subunits and that is found in the exoskeletons of insects and crustaceans is known as:

Accepted Answer

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

Question 6

What polysaccharide forms the long,tough fibers found in plant cell walls?

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

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?

Accepted Answer

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 9

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?

Accepted Answer

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 10

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

Accepted Answer

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

Question 11

Which of the following reactions is a dehydration reaction?

Accepted Answer

A)  A + H2O → B + C
B)  A + B → C + H2O
C)  A + B + H2O → C
D)  A → B + C+ H2O

Question 12

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

Accepted Answer

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

Question 13

Lipids are the only class of macromolecules that contain:

Accepted Answer

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

Question 14

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

Accepted Answer

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

Question 15

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?

Accepted Answer

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

Question 16

Macromolecules are broken down to monomers in ________

Accepted Answer

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

Question 17

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.

Accepted Answer

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

Question 18

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:

Accepted Answer

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

Question 19

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

Accepted Answer

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

Question 20

Which amino acid is least soluble in water?

Accepted Answer

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

Exam 3: The Chemical Building Blocks of Life