Biochem

Question 1

Glucose and fructose are examples of
A. double sugars
B. disaccharides
C. single sugars
D. polysaccharides

Answer 1

c

Question 2

(CH2O)n is the molecular formula for
which type of macromolecules?
A. Proteins
B. Lipids
C. Carbohydrates
D. Nucleic Acid

Answer 2

c

Question 3

Which of the following is NOT a
polysaccharide?
A. Glycogen
B. Starch
C. Sucrose
D. Cellulose

Answer 3

c

Question 4

What are used in animals as a source of
quick energy that can be stored in the
liver and muscles ？
A. Proteins
B. Nucleic acids
C. Carbohydrates
D. Lipids

Answer 4

c

Question 5

Sugars, starches, and cellulose belong
to which major class of biological
molecules?
A. Nucleic acids
B. carbohydrates
C. lipids
D. polypeptides

Answer 5

b

Question 6

Plants like sugar cane and sugar beets store
the energy as simple sugars. Other plants,
like corn and potatoes, store the energy as
more complex sugars called?
A. carbohydrates
B. calories
C. starches
D. cellulose

Answer 6

c

Question 7

Which macromolecule does not
dissolve in water?
A. proteins
B. lipids
C. carbohydrates
D. nucleic acids

Answer 7

b

Question 8

What are the monomers of lipids?
A. Amino acids
B. Simple sugars
C. Fatty acids and glycerol
D. Nucleic acids

Answer 8

c

Question 9

Lipids are used by the body to perform all
of the following functions EXCEPT:
A. membrane structural material.
B. enzyme action.
C. insulation.
D. a rich energy source.

Answer 9

b

Question 10

What type of organic substances are
fats?
A. nucleic acid
B. carbohydrate
C. protein
D. lipids

Answer 10

d

Question 11

Fats that have fatty acids with only single
covalent bonds in their carbon skeletons
are
A. saturated
B. unsaturated
C. found in plants instead of animals
D. liquid at room temperature

Answer 11

a

Question 12

Which of the following is a polymer?
A. nucleic acid
B. fatty acid
C. Amino acid
D. Glycerol

Answer 12

a

Question 13

This biological macromolecule is
responsible for controlling the activity of the
cell, and it stores and transports genetic
information.
A. Carbohydrate
B. Nucleic acid
C. Water
D. Glucose

Answer 13

b

Question 14

What are described as the “building
blocks of Protein”?
A. Fiber
B. Lipids
C. Amino Acids
D. Nutrients

Answer 14

c

Question 15

Proteins are ___ made of amino
acid _____ .
A. monomers; polymers
B. polymers; polypeptides
C. polymers; monomers
D. monomers; molecules

Answer 15

c

Question 16

In this type of structure, most of carbonyl
groups of peptide bonds forms a hydrogen
bond with the amide nitrogen of another
peptide bond four amino acids further down
the polypeptide chain:
A. Alpha-helix
B. Beta-sheet
C. Beta-turn
D. Quaternary

Answer 16

a

Question 17

The isoelectric point of an amino acid is defined
as the pH
A. where the molecule carries no electric charge
B. where the carboxyl group is uncharged
C. where the amino group is uncharged
D. of maximum electrolytic mobility

Answer 17

a

Question 18

When the amino acid alanine (Rgroup is CH3) is added to a solution
with a pH of 7.3, alanine becomes
A. a cation
B. nonpolar
C. a zwitterions
D. an anion

Answer 18

d

Question 19

The term “SALTING IN” refers to?
A.Changes in an amino acid’s isoelectric
point.
B.Increasing the solubility of a protein in
solution by adding ions.
C.The use of a liquid bridge in an
electrochemical cell.
D. The ionization of a strong acid.

Answer 19

b

Question 20

The local spatial arrangement of a
polypeptide’s backbone atoms without regard
to the conformation of its side chains can be
called as
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure

Answer 20

b

Question 21

Which of the following amino acids are
more likely to be found in a protein’s
interior away from aqueous solvent
molecules?
A. Val, Leu, Ile, Met, and Phe
B. Ser, Thr, Asn, Gln, and Tyr
C. Arg, His, Lys, Asp, and Glu
D. All of the above.

Answer 21

a

Question 22

Which of the following is (are) true of -
turns in proteins?
A. It is a 180º turn of four amino acids.
B.Glycine and proline are frequently
found there.
C.Are used as connecting turns of -
helix
D. All of the above

Answer 22

d

Question 23

The primary stabilizing force of
protein secondary structure is:

a. Ionic bonds.
b. Covalent bonds.
c. Van der Waals forces.
d. Hydrogen bond

Answer 23

d

Question 24

Two types of beta-pleated sheets can be
called:

Answer 24

parallel and antiparallel

Question 25

Which of the following is NOT a characteristic of a globular protein? A. Polypeptide chain in extended, long sheets B. Polypeptide chains are folded in a spherical shape. C. Contains several types of secondary structure D. Typical for regulatory proteins

Answer 25

a

Question 26

The alpha helix found in myoglobin can best be described as A. Primary structure B. Secondary structure C. Tertiary structure D. Motif structure

Answer 26

b

Question 27

Some parts of a protein that have a specific chemical structure and function are called protein A. chemicals B. domains C. subunits D. enzymes

Answer 27

b

Question 28

One of the following is NOT usually a force that helps to hold the monomer units of a quaternary protein together? A. Peptide bonds B. Disulfide bonds C. Salt bonds D. Hydrophobic interactions

Answer 28

a

Question 29

If a person breathes into a paper bag, you would expect their blood CO2 to A. decrease and their blood pH to increase B. decrease and their blood pH to decrease C. increase and their blood pH to increase D. increase and their blood pH to decrease

Answer 29

d

Question 30

The quaternary structure of a protein is A.the sequence of amino acids in the polypeptide B. the coiling or folding of the polypeptide C. the intertwining of two or more polypeptides D.the 3-dimensional appearance of the polypeptide

Answer 30

c

Question 31

The action of disrupting the threedimensional shape of a protein is termed A. dehydration B. denaturation C. deamination D. hydrolysis

Answer 31

b

Question 32

At a pH >pI of a given protein, that protein becomes ______ , at the pH

Answer 32

negatively charged (an anion) positively charged (a cation)

Question 33

The imino acid found in protein structure (a) Arginine (b) Proline (c) Histidine (d) Lysin

Answer 33

b

Question 34

The bonds in protein structure that are not broken on denaturation. (a) Hydrogen bonds (b) Peptide bonds (c) lonic bond (d) Disulfide bonds

Answer 34

b

Question 35

Which of the following is not considered a pyrimidine? A. C B. T C. U D. G

Answer 35

d

Question 36

What type of sugar is found in the nucleotides of DNA? A. deoxyribose B. ribose C. glucose D. none of the above

Answer 36

a

Question 37

What is the role of hydrogen bonds in the structure if DNA? A. to code for proteins B. to synthesize proteins C. to separate the strands D. to connect the base pairs

Answer 37

d

Question 38

Nucleoside is a pyrimidine or purine base A.covalently bonded to a sugar B.ionically bonded to a sugar C.hydrogen bonded to a sugar D.none of the abov

Answer 38

a

Question 39

Nucleotide bases and aromatic amino acids absorb light respectively at A.280 and 260 nm B.260 and 280 nm C.270 and 280 nm D.260 and 270 nm

Answer 39

b

Question 40

Which of the following is found on RNA but not DNA? A.Uracil B.Deoxyribose C.Phosphate D.Adenine

Answer 40

a

Question 41

Which is true about the pairing of bases in the DNA molecule? A. purines always pair with pyrimidines B. a single ring base pairs with another single ring base C. a double ring base pairs with another double ring base D. purines pair with purines and pyrimidines with pyrimidines

Answer 41

a

Question 42

A messenger acid is 336 nucleotides long, including the initiator and termination codons. The maximum number of amino acids in the protein translated from this mRNA is: A. 999 B. 630 C. 330 D. 111 E. 110

Answer 42

d

Question 43

With what mRNA codon would the tRNA in the diagram be able to form a codon-anticodon base pairing interaction? A. 3'-AUG-5' B. 3'-GUA-5' C. 3'-CAU-5' D. 3'-UAC-5' E. 3'-UAG-5'

Answer 43

a

Question 44

What is the function of enzymes within living systems? A) structural elements B) neurotransmitters C) catalysts D) hormones

Answer 44

c

Question 45

Enzymes have names that A) always end in -ase B) always end in -in C) can end either in -in or -ase D) can end in either -in or -ogen

Answer 45

c

Question 46

The protein portion of a conjugated enzyme is called a(n) A) apoenzyme. B) coenzyme. C) holoenzyme. D) cofactor.

Answer 46

a

Question 47

Which of the following could be a component of a conjugated enzyme? A) coenzyme B) cofactor C) apoenzyme D) more than one correct response E) no correct response

Answer 47

d

Question 48

Enzyme cofactors that bind covalently at the active site of an enzyme are referred to as . (a) cosubstrates. (b) prosthetic groups. (c) apoenzymes. (d) vitamin

Answer 48

b

Question 49

Which of the following statements concerning the effect of temperature change on an enzyme-catalyzed reaction is correct? A) An increase in temperature can stop the reaction by denaturing the enzyme. B)An increase in temperature can increase the reaction rate by increasing the speed at which molecules move. C)An increase in temperature to the optimum temperature maximizes reaction rate. D) more than one correct response E) no correct response

Answer 49

d

Question 50

A catalyst can promote product formation during a chemical reaction by . (a) lowering the activation energy barrier. (b) stabilizing the transition state. (c) positioning reactants in the correct orientation. (d) bringing reactants together. (e) all of the above

Answer 50

e

Question 51

Which of the following is characteristic of an enzyme catalyst? (a) It positions reactants in the correct orientation. (b) It lowers the activation energy barrier. (c) It binds the transition state tighter than the substrate. (d) all of the above

Answer 51

d

Question 52

An enzyme active site is the location in the enzyme where A) protein side groups are brought together by bending and folding to form a site for interactions with substrates B) the catalyst interactions with the enzyme C) catalyst molecules are generated D) the substrate creates the catalyst molecules

Answer 52

a

Question 53

An enzyme active site is the location in an enzyme where substrate molecules A) are generated. B) become catalysts. C) undergo change. D) more than one correct response E) no correct response

Answer 53

c

Question 54

For the enzyme reaction A+ B = C + D, Delta Go ' = + 1 kcal/mol. This reaction will proceed spontaneously in a forward direction if: A. The concentration of C is increased one-hundred fold B. The concentration of A is increased one-hundred fold C. The concentration of B is lowered one-hundred fold D.The concentration of both A and D are increased onehundred fold

Answer 54

b

Question 55

Which of the following statements about enzymes or their function is true? A.Enzymes do not alter the overall change in free energy for a reaction B. Enzymes are proteins whose three-dimensional form is key to their function C.Enzymes speed up reactions by lowering activation energy D. All of the above

Answer 55

d

Question 56

What is the optimal temperature range for the majority of enzymes? A. 40-55 ℃ B. 35-40 ℃ C. 25-30 ℃ D. 15-20 ℃

Answer 56

b

Question 57

An allosteric activator A. increases the binding affinity B. decreases the binding affinity C. stabilizes the R state of the protein D. both (a) and (c)

Answer 57

d

Question 58

Reactants of an enzyme-catalyzed reaction are known as A. products B. substrates C. proteins D. complex

Answer 58

b

Question 59

The location on an enzyme where binding occurs is known as the A. action point B. enzyme C. binding location D. active site

Answer 59

d

Question 60

Enzymes catalyze reactions by A.Increasing the free energy of the system so that the change in free energy is positive B.Increasing the free energy of the substrate so that it is greater than the free energy of the product C. Changing the equilibrium constant for the reaction D. Decreasing the free energy of activation

Answer 60

d

Question 61

An apoenzyme A. Includes non-protein compounds such as metal ions B.Consists of complex organic structures which may be classified as activation-transfer coenzymes or oxidationreduction coenzymes C.Is the protein portion of the enzyme without the cofactors D. None of the above

Answer 61

c

Question 62

NAD+, FAD, and FMN are all cofactors for: A. Oxidoreductases B. Transferases C. Hydrolases D. Ligases

Answer 62

a

Question 63

At the end of a chemical reaction A. an enzyme's structure is altered B.an enzyme is detached from the product, has its original structure, and can catalyze more chemical reactions C.the enzyme loses its ablity to catallyze other chemical reactions D.the enzyme remains attached to the products

Answer 63

b

Question 64

Glycolytic pathway regulation involves A. allosteric stimulation by ADP B. allosteric inhibition by ATP C. feedback, or product, inhibition by ATP D. all of the above

Answer 64

d

Question 65

Why does the glycolytic pathway continue in the direction of glucose catabolism? A. There are essentially three irreversible reactions that act as the driving force for the pathway B. High levels of ATP keep the pathway going in a forward direction C. The enzymes of glycolysis only function in one direction D. Glycolysis occurs in either direction

Answer 65

a

Question 66

The released energy obtained by oxidation of glucose is stored as A. a concentration gradient across a membrane B. ADP C. ATP D. NAD+

Answer 66

c

Question 67

For every one molecule of sugar glucose which is oxidized molecule of pyruvic acid are produced. A.1 B.2 C.3 D.4

Answer 67

b

Question 68

The enzymes of glycolysis in a eukaryotic cell are located in the A.intermembrane space B.plasma membrane C.cytosol D.mitochondrial matrix

Answer 68

c

Question 69

Which of the following is not true of glycolysis? A. ADP is phosphorylated to ATP via substrate level phosphorylation B.The pathway does not require oxygen C.The pathway oxidizes two moles of NADH to NAD+ for each mole of glucose that enters D.The pathway requires two moles of ATP to get started catabolizing each mole of glucos

Answer 69

c

Question 70

ATP is from which general category of molecules? A.Polysaccharides B.Proteins C.Nucleotides D.Amino acids

Answer 70

c

Question 71

Which of the following regulates glycolysis steps? A.Phosphofructokinase B.Hexose kinase C.Pyruvate kinase D.All of these

Answer 71

d

Question 72

Which of the following is not a mechanism for altering the flux of metabolites through the rate-determining step of a pathway? A. Allosteric control of the enzyme activity B. Block active sites C. Genetic control of the enzyme concentration D. Covalent modification of the enzyme

Answer 72

b

Question 73

Phosphofructokinase, the major flux-controlling enzyme of glycolysis is allosterically inhibited and activated respectively by A.ATP and PEP B.AMP and Pi C.ATP and ADP D.Citrate and ATP

Answer 73

c

Question 74

Where does glycolysis occur? A. inner membrane of mitochondria B. matrix of mitochondria C. stroma of chloroplast D. cytoplasm

Answer 74

d

Question 75

Sports physiologists wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds? A. oxygen B. ATP C. lactate D. carbon dioxide

Answer 75

c

Question 76

There are four enzymes of gluconeogenesis that circumvent the irreversible steps in glycolysis. When starting with the substrate pyruvate or lactate they are A.Hexokinase, phosphofructokinase-1, phosphofructokinase-2 and pyruvate kinase B.Pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase C.Glycerol kinase, glycerol-3-phosphate dehydrogenase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase D.Amino transferase, phosphoenolpyruvate carboxykinase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase

Answer 76

b

Question 77

The enzymes that remove phosphate groups during the process of gluconeogenesis and circumvent two of the three irreversible reactions of glycolysis are A. Pyruvate kinase and glycerol kinase B.Phosphoenolpyruvate carboxykinase and glycerol kinase C.3-Phosphoglycerate kinase and fructose-1,6- bisphosphatase D.Fructose-1,6-bisphosphatase and glucose-6- phosphatase

Answer 77

d

Question 78

The most important control step in gluconeogenesis is fructose-1,6- bisphosphatase. All of the following statements are true EXCEPT A.Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate to fructose-6-phosphate B.During times when insulin is high, fructose-1,6-bisphosphatase is inhibited by fructose-2,6-bisphosphate C.During a fast or exercise when glucagon and/or epinephrine are high, fructose-1,6-bisphosphatase is active because of the absence of fructose-2,6-bisphosphate D.Glycolysis or gluconeogenesis cannot be active at the same time. If they were is would be a futile cycle

Answer 78

a

Question 79

In the liver, glucagon will activate A. Glycolysis and glycogen synthesis B. Gluconeogenesis and glycogenolysis C. Gluconeogenesis and glycogen synthase D. Gluconeogenesis and glycogen synthesis

Answer 79

b

Question 80

Which of the following statements about hormonal levels during different states is true? A.During the time you are eating a high carbohydrate mixed meal, the insulin to glucagon ratio will decrease B.When passing from the fed to fasting state, insulin and glucagon usually decrease C. When playing basketball, epinephrine is usually low and insulin is high D.After running for 20 miles, epinephrine and glucagon are high and insulin is low

Answer 80

d

Question 81

All of the following will result in activation of glycogen phosphorylase in skeletal muscle EXCEPT A.Increased concentrations of AMP from contraction of muscle B. Increased epinephrine and cAMP C. Increased cytosolic [Ca++] D. Increased protein phosphatase E. Increased activity of glycogen phosphorylase kinase

Answer 81

d