Quiz 2

Question 1

All of the following are polysaccharides except:
a) chitin
b) amylopectin
c) glycogen
d) lactose
e) cellulose

Answer 1

d) lactose

Question 2

What aspects of protein structure are stabilized or assisted by hydrogen bonds?

Answer 2

secondary, tertiary and quaternary statutes, but not primary structure

Question 3

Which of the four classes of biological molecule is not a polymer? (Lipid, carb, protein, nucleic acid)

Answer 3

Lipid

Question 4

If cells are grown in a medium containing radioactive 35S, which these molecules will be labelled?
a) amylose
b) proteins
c) nucleic acids
d) phospholipids
e) both proteins and nucleic acids

Answer 4

b) proteins

Question 5

Why are sex hormones considered to be lipids?

Answer 5

They are not soluble in water.

Question 6

One of the primary functions of RNA molecules is to?

Answer 6

Function in the synthesis of proteins

Question 7

Dehydration rxns are used in forming which of the following compounds?

Answer 7

triglycerides, polysaccharides and proteins

Question 8

The bonding of two amino acid molecules to form a larger molecule requires which of the following?
a) formation of hydrogen bond
b) removal of H2O
c) addition of H2O

Answer 8

b) removal of H2O

Question 9

Polysaccharides, triglycerides and proteins are similar in that they..?

Answer 9

Are synthesized from subunits by dehydration rxns

Question 10

Which of the following is an example of hydrolysis?
a) synthesis of two amino acids, forming a peptide with H2O release
b) the rxn of fat, forming glycerol and fatty acids with H2O release
c) synthesis of a nucleotide from a phosphate, pentose sugar, and nitrogenous base with production of H2O molecule
d) the rxn of a fat, forming glycerol and fatty acids with consumption of H2O

Answer 10

d) the rxn of a fat, forming glycerol and fatty acids with consumption of H2O

Question 11

What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptides specific 3D shape?

Answer 11

Disulphide bond

Question 12

At which level of protein structure are interactions between side chains (R groups) most important?
a) tertiary
b) quaternary
c) secondary
d) primary

Answer 12

a) tertiary

Question 13

What is the structural feature that allows DNA to replicate?

Answer 13

Complimentary pairing of nitrogenous bases

Question 14

The bonding of two amino acid molecules to form a larger molecule requires..?
a) release of NO
b) release of H2O
c) addition of H2O
d) addition of N
e) release of CO2

Answer 14

b) release of H2O

Question 15

What maintains the secondary structure of a protein?
a) hydrogen bonds between the R groups
b) hydrogen bonds between the amino group of one peptide bond and the carboxyl of another peptide bond
c) peptide bonds
d) disulphide bonds

Answer 15

b) hydrogen bonds between the amino group of one peptide bond and the carboxyl of another peptide bond

Question 16

Humans can digest starch but not cellulose because..?

(hint: enzymes)

Answer 16

Humans have enzymes that can hydrolyze the alpha glycosidic linkages of starch but not the beta glycosidic linkages of cellulose

Question 17

Which of the following is true of both starch and cellulose?
a) they are cis-trans isomers of each other
b) they are both structural components of the plant cell wall
c) they are both polymers of glucose

Answer 17

c) they are both polymers of glucose

Question 18

All of the following are amino acids except:
a) insulin
b) cholesterol
c) antibodies
d) enzymes
e) hemoglobin

Answer 18

b) cholesterol

Question 19

Which class of biological molecules are grouped together because they are hydrophobic?
a) carbs
b) lipids
c) proteins
d) nucleic acids

Answer 19

b) lipids

Question 20

Which of the following statements is true for the class of biological molecules known as lipids?
a) They are insoluble in water.
b) They contain less energy than proteins and carbohydrates.
c) They are made from glycerol, fatty acids, and phosphate.
d) They contain nitrogen.
e) They are made by dehydration reactions.

Answer 20

a) They are insoluble in water.

Question 21

Which modifications of fatty acids will best keep triglycerides solid at warmer temperatures?
a) adding cis double bonds and trans double bonds to the fatty acids
b) creating cis double bonds to the fatty acids
c) creating trans double bonds to the fatty acids
d) adding hydrogens or trans double bonds to the fatty acids
e) adding hydrogens to the fatty acids

Answer 21

d) adding hydrogens or trans double bonds to the fatty acids

Question 22

Molecules with which functional groups may form polymers via dehydration reactions?

a) carbonyl groups
b) carboxyl groups
c) hydroxyl groups
d) either hydroxyl or carboxyl groups
e) either carbonyl or carboxyl groups

Answer 22

d) either hydroxyl or carboxyl groups

Question 23

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

a) Dehydration reactions form polymers, and hydrolysis reactions break down polymers.
b) Dehydration reactions break down polymers, and hydrolysis reactions form polymers.
c) Dehydration reactions can occur only after hydrolysis.
d) Hydrolysis forms monomers, and dehydration reactions break down polymers.

Answer 23

a) Dehydration reactions form polymers, and hydrolysis reactions break down polymers.

Question 24

Which of the following statements best summarizes the differences between DNA and RNA?

a) DNA encodes hereditary information, whereas RNA does not.
b) The bases in DNA form base-paired duplexes, whereas the bases in RNA do not.
c) DNA nucleotides contain a different sugar than RNA nucleotides.
d) DNA contains the base uracil, whereas RNA contains the base thymine.

Answer 24

c) DNA nucleotides contain a different sugar than RNA nucleotides.

Question 25

The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil? a) The hydrogenated vegetable oil has a lower melting point. b) The hydrogenated vegetable oil has fewer trans fatty acids. c) The hydrogenated vegetable oil stays solid at room temperature. d) The hydrogenated vegetable oil has more "kinks" in the fatty acid chains.

Answer 25

c) The hydrogenated vegetable oil stays solid at room temperature.

Question 26

What is the chemical reaction mechanism by which cells make polymers from monomers? a) phosphodiester linkages b) the formation of disulphide bridges between monomers c) ionic bonding of monomers d) hydrolysis e) dehydration reactions

Answer 26

e) dehydration reactions

Question 27

Which bonds are created during the formation of the primary structure of a protein? a) phosphodiester bonds b) peptide bonds c) hydrogen bonds d) disulphide bonds e) peptide bonds, hydrogen bonds, and disulphide bonds

Answer 27

b) peptide bonds

Question 28

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence..? a) 5'TGCAAT3' b) 5'UAACGU3'. c) 5'UGCAAU3'. d) 3'UAACGU5'.

Answer 28

a) 5'TGCAAT3'

Question 29

The basis for diversity, both within a species and among species, is a result of the a) fact that some individuals have mutations. b) infinite number of base molecules to build from. c) ratio of lipid to protein. d) shared structures of polymers and lipids. e) arrangement of a few base molecules into many different macromolecular combinations.

Answer 29

e) arrangement of a few base molecules into many different macromolecular combinations.

Question 30

Which of the following polymers contain nitrogen? a) starch b) amylopectin c) chitin d) glycogen e) cellulose

Answer 30

c) chitin

Question 31

The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by...? a) ionic bonds b) covalent bonds. c) hydrogen bonds. d) polar bonds. e) peptide bonds.

Answer 31

c) hydrogen bonds.

Question 32

What maintains the secondary structure of a protein? a) hydrogen bonds between the R groups b) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond c) peptide bonds d) hydrophobic interactions

Answer 32

b) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond

Question 33

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine? a) 10 b) 20 c) 80 d) 40

Answer 33

d) 40

Question 34

Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct? a) The 5' end has a phosphate group attached to the number 5 carbon of deoxyribose. b) The 5' end is the fifth position on one of the nitrogenous bases. c) The 5' end has a carboxyl group attached to the number 5 carbon of deoxyribose. d) The 5' end has a hydroxyl group attached to the number 5 carbon of deoxyribose. e) The 5' end has phosphate attached to the number 5 carbon of the nitrogenous base.

Answer 34

a) The 5' end has a phosphate group attached to the number 5 carbon of deoxyribose.

Question 35

A molecule with the chemical formula C6H12O6 is probably a a) carbohydrate and lipid only. b) carbohydrate. c) carbohydrate and monosaccharide only. d) lipid. e) monosaccharide

Answer 35

c) carbohydrate and monosaccharide only.

Question 36

Which of the following is not a polymer? a) cellulose b) chitin c) DNA d) starch e) glucose

Answer 36

e) glucose

Question 37

Which of the following descriptions best fits the class of molecules known as nucleotides? a) a nitrogenous base and a pentose sugar b) a pentose sugar and a purine or pyrimidine c) a nitrogenous base, a phosphate group, and a pentose sugar d) a phosphate group and an adenine or uracil e) a nitrogenous base and a phosphate group

Answer 37

c) a nitrogenous base, a phosphate group, and a pentose sugar

Question 38

There are 20 different amino acids. What makes one amino acid different from another? a) different side chains (R groups) attached to an α/alpha carbon b) different side chains (R groups) attached to the amino groups c) different side chains (R groups) attached to a carboxyl carbon d) different asymmetric carbons e) different structural and optical isomers

Answer 38

a) different side chains (R groups) attached to an α/alpha carbon

Question 39

Which of the following statements concerning saturated fats is not true? a) They have multiple double bonds in the carbon chains of their fatty acids. b) They are more common in animals than in plants. c) They generally solidify at room temperature. d) They contain more hydrogen than unsaturated fats having the same number of carbon atoms. e) They are one of several factors that contribute to atherosclerosis.

Answer 39

a) They have multiple double bonds in the carbon chains of their fatty acids.

Question 40

Which of the following is not a monomer/polymer pairing? a) amino acid/protein b) triglyceride/phospholipid bilayer c) ribonucleotide/RNA d) deoxyribonucleotide/DNA e) monosaccharide/polysaccharide

Answer 40

b) triglyceride/phospholipid bilayer

Question 41

Which of the following is true of cellulose? a) It is a polymer composed of enantiomers of glucose. b) It is a storage polysaccharide for energy in plant cells. c) It is a major structural component of plant cell walls. d) It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major structural component of plant cell walls. e) It is digestible by bacteria in the human gut.

Answer 41

c) It is a major structural component of plant cell walls.

Question 42

What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide's specific three-dimensional shape? a) ionic bond b) hydrogen bond c) hydrophobic interaction d) van der Waals interaction e) disulphide bond

Answer 42

e) disulphide bond

Question 43

Which of these molecules is not formed by dehydration reactions? a) DNA b) amylose c) disaccharides d) fatty acids e) protein

Answer 43

d) fatty acids

Question 44

Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures? a) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. b) Unsaturated fatty acids are more polar than saturated fatty acids. c) The double bonds result in shorter fatty acid tails and thinner membranes. d) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes. e) The double bonds block interaction among the hydrophilic head groups of the lipids.

Answer 44

a) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

Question 45

Distinguish between the glycosidic linkage found in starch and cellulose. Explain why the difference is biologically important.

Answer 45

Starch has alpha glycosidic linkages and cellulose has beta glycosidic linkage. Is important because we have an enzyme that breaks down the alpha but not the beta.

Question 46

How do different stimuli lead to different signals?

Answer 46

different shape = different binding affinity stronger binding = stronger signal = sweeter