Deck 4: Enzymes and Energy

Question 1

Biological catalysts

A)decrease reaction rates.
B)alter a reaction product.
C)remain unchanged at the end of the reaction.
D)All of these choices are correct.

Answer 1

C

Question 2

During a chemical reaction, a catalyst increases the rate at which the reaction occurs.

Answer 2

True

Question 3

Which of the following statements about enzymes is NOT true?

A)Enzymes increase chemical reaction rates.
B)Enzymes are consumed during a chemical reaction.
C)Enzymes decrease the free energy of activation of specific reactions.
D)Enzymes have unique pH and temperature optima.

Answer 3

B

Question 4

Ribozymes are RNA molecules that act as

A)hormones.
B)cofactors.
C)enzymes.
D)inhibitors.

Question 5

The process that yeast uses to make alcohol from glucose is

A)fermentation.
B)aerobic respiration.
C)photosynthesis.
D)catalysis.

Question 6

Enzymes are specific for a given substrate.

Question 7

The level of protein structure primarily involved in determining enzyme activity is the

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

Question 8

The rate at which a chemical reaction can be increased is by either ______________ the temperature or ______________ the activation energy.

A)increasing, increasing
B)increasing, decreasing
C)decreasing, decreasing
D)decreasing, increasing

Question 9

Most enzymes are lipids.

Question 10

Cell extracts from which organism that could carry out fermentation caused vitalism to be questioned?

A)yeast
B)bacteria
C)amoebae
D)paramecia

Question 11

The model that describes how an enzyme can adjust its shape to fit the shape of the substrate is the

A)lock-and-key model.
B)enzyme-substrate model.
C)induced-fit model.
D)conformational model.

Question 12

Which of the following is NOT a characteristic of a catalyst?

A)is not changed itself at the end of the reaction
B)does not change the nature of the reaction
C)can change the final result of the reaction
D)increases the rate of the reaction

Question 13

Catalysts increase reaction rates by lowering the activation energy of a reaction.

Question 14

An enzyme elevated in the plasma of men with prostate cancer is

A)alkaline phosphatase.
B)catalase.
C)creatine kinase.
D)acid phosphatase.

Question 15

The model that explains how an enzyme and substrate fit together is the

A)enzyme-substrate model.
B)lock-and-key model.
C)conformational model.
D)None of these choices are correct.

Question 16

When an enzyme catalyzes a chemical reaction

A)the enzyme binds to the substrate's active site.
B)the enzyme's active site binds the product.
C)amino acids in the substrate allow for interaction with the product.
D)amino acids in the enzyme's active site interact with substrate molecules.

Question 17

Enzymes ______________ the rate of a specific chemical reaction.

A)decrease
B)increase
C)have no effect on

Question 18

In some instances RNA can act as an enzyme.

Question 19

The substrate binds to the ______________ of the enzyme.

A)allosteric site
B)acidic site
C)neutral site
D)active site

Question 20

Elevated plasma aldolase could be indicative of

A)muscular dystrophy.
B)pancreatitis.
C)pernicious anemia.
D)prostate cancer.

Question 21

The pH optima for all digestive enzymes are approximately equal to the pH of blood.

Question 22

Digestive enzymes which remove hydrogen atoms from their substrates are referred to as

A)dehydrogenases.
B)hydrolases.
C)catalases.
D)peroxidases.

Question 23

Abnormally high concentration of the BB form of creatine phosphokinase is associated with a myocardial infarction.

Question 24

Addition of phosphate groups to a particular molecule is catalyzed by

A)transaminases.
B)phosphatases.
C)isomerases.
D)kinases.

Question 25

Isomers are different forms of an enzyme.

Question 26

In general, decreased body temperature causes the rate of enzymatic reactions to decrease.

Question 27

Reactant molecules of enzyme action are called

A)substrates.
B)allosteric inhibitors.
C)cofactors.
D)products.

Question 28

The MM isoenzyme of creatine phosphokinase is found in skeletal muscle.

Question 29

Dehydration synthesis reactions are catalyzed by

A)dehydrogenases.
B)hydrolases.
C)isomerases.
D)synthases.

Question 30

The breakdown of hydrogen peroxide is catalyzed by

A)aldolase.
B)amylase.
C)catalase.
D)kinase.

Question 31

Which of the following does NOT affect the activity of an enzyme?

A)the organ the enzyme is in
B)concentration of enzyme and substrate molecules
C)concentration of cofactors and coenzymes
D)pH and temperature

Question 32

Hydrolysis reactions are catalyzed by

A)dehydrogenases.
B)hydrolases.
C)isomerases.
D)synthases.

Question 33

The pH optimum for enzymes secreted by the stomach is higher than the pH optimum for enzymes secreted by the pancreas.

Question 34

The enzyme with the lowest pH optimum is

A)acid phosphatase.
B)lipase.
C)monoamine oxidase.
D)pepsin.

Question 35

Isoenzymes bind different substrates and catalyze different chemical reactions.

Question 36

The conversion of glucose to galactose is catalyzed by an isomerase.

Question 37

An enzyme-catalyzed reaction in the body at 50 ^$\circ$ C will proceed at a faster rate than at 35 ^$\circ$ C.

Question 38

The phosphatase found in bone would have a pH optimum that is ______________ than the pH optimum of the phosphatase found in the prostate gland.

A)higher
B)lower
C)the same as

Question 39

Pyruvate dehydrogenase catalyzes the removal of hydrogen from pyruvic acid.

Question 40

Elevated plasma amylase could indicate

A)osteitis deformans.
B)a myocardial infarct.
C)obstructive jaundice.
D)a perforated peptic ulcer.

Question 41

End-product inhibition usually involves allosteric inhibition of an enzyme.

Question 42

Metal ions such as magnesium or calcium can serve as enzyme

A)coenzymes.
B)ribozymes.
C)substrates.
D)cofactors.

Question 43

In the reaction (H₂O + CO₂ -> H₂CO₃), increasing the concentration of H₂O would

A)decrease the concentration of H₂CO₃.
B)increase the concentration of H₂CO₃.
C)increase the concentration of CO₂.
D)have no effect on either CO₂ or H₂CO₃ concentrations.

Question 44

A defect in the enzyme which converts phenylalanine into tyrosine is characteristic of the disease

A)phenylketonuria.
B)albinism.
C)lactose intolerance.
D)maple-syrup disease.

Question 45

At saturation, enzyme activity is maximal.

Question 46

Active enzymes are often called zymogens.

Question 47

Regulation of a metabolic pathway by the final product of the pathway is termed

A)allosteric inhibition.
B)end-product inhibition.
C)negative feedback.
D)Both end-product inhibition and negative feedback are correct.

Question 48

The principle that reversible reactions will be driven from the side of the equation where the concentration is lower to the side where the concentration is higher is known as the law of mass action.

Question 49

Enzymes in a metabolic pathway act antagonistically to produce a final product.

Question 50

Which of the following is NOT true about enzymes?

A)As the temperature increases from 25 ^$\circ$ C to 37 ^$\circ$ C enzyme activity decreases.
B)Very few enzymes require cofactors.
C)Most enzymes are not sensitive to changes in pH.
D)All of these choices are not true.

Question 51

A deficiency of dietary copper could limit the activity of some enzymes.

Question 52

______________ are inactive forms of digestive enzymes.

A)Cofactors
B)Coenzymes
C)Zymogens
D)Both cofactors and zymogens are correct.

Question 53

Which of the following is NOT true of catalysts?

A)They are unchanged by the reaction catalyzed.
B)They allow endergonic reactions to become exergonic reactions.
C)They increase the amount of energy released by a chemical reaction.
D)All of these choices are not true.

Question 54

A defect in the enzyme that catalyzes the formation of melanin from DOPA results in

A)phenylketonuria.
B)albinism.
C)lactose intolerance.
D)maple-syrup disease.

Question 55

In response to increased concentration of the final product of a metabolic pathway

A)all enzymes in the pathway become more active.
B)intermediate enzymes become more active.
C)the final product acts as an allosteric regulator of one enzyme in the pathway.
D)all enzymes in the pathway become less active.

Question 56

______________ occurs when the product of a metabolic pathway binds to an enzyme and decreases enzymatic activity.

A)Allosteric inhibition
B)End-product inhibition
C)Second messaging
D)Coupling

Question 57

Addition of substrate when enzyme reaction rate is maximal results in

A)additional product formation.
B)less product formation.
C)no change in product formation.
D)enzyme destruction.

Question 58

Most enzymatic reactions in the body are one step processes.

Question 59

Coenzymes are organic molecules that are required for proper enzyme function.

Question 60

In an enzymatic reaction, when temperature is increased past the point of "optimal temperature," the enzyme starts to

A)increase its catalytic activity.
B)reduce its catalytic activity.
C)increase its allosteric properties.
D)increase product formation.

Question 61

The greatest increase in entropy occurs

A)when starch is degraded to glucose.
B)when amylase produces maltose.
C)when glucose is converted to galactose.
D)when ATP is synthesized.

Question 62

Oxidizing agents accept electrons from molecules undergoing reduction.

Question 63

Free energy is ______________ when exergonic reactions proceed.

A)increased
B)decreased
C)unchanged

Question 64

Energy transformations increase the entropy of a system is a statement of the

A)first law of thermodynamics.
B)second law of thermodynamics.
C)law of mass action.
D)law of conservation of energy.

Question 65

Another name for the first law of thermodynamics is the law of conservation of energy.

Question 66

The flow of energy in living systems is termed

A)entropy.
B)enthalpy.
C)bioenergetics.
D)bioluminescence.

Question 67

Cellular respiration results in a(n) ______________ in entropy as glucose is broken down to form carbon dioxide.

A)increase
B)decrease
C)no change

Question 68

The reaction of adenosine diphosphate and phosphate generates adenosine triphosphate and energy.

Question 69

In bioenergetic pathways, as intermediates are acted upon by enzymes, the ultimate result is the release of

A)lactate.
B)ATP.
C)free energy.
D)enzymes.

Question 70

Endergonic reactions cause the amount of entropy in the products to be

A)increased.
B)decreased.
C)unchanged.

Question 71

______________ is the universal energy carrier.

A)Glucose
B)ATP
C)ADP
D)GTP

Question 72

A ______________ is the amount of heat required to raise the temperature of one cubic centimeter of water one degree on the Celsius scale.

A)specific heat
B)meter
C)boiling point
D)calorie

Question 73

Exergonic reactions proceed with the release of energy.

Question 74

Free energy is the only type that can be used to perform cellular work.

Question 75

The amount of entropy increases as bonds are broken to generate glucose from glycogen.

Question 76

Energy transformations result in a(n) ______________ in entropy.

A)increase
B)decrease
C)no change

Question 77

Decreased phenylalanine metabolism causes

A)albinism.
B)hypercholeteremia.
C)lactose intolerance.
D)Tay-Sachs disease.

Question 78

An inborn error in lipid metabolism may cause all of the following diseases EXCEPT

A)Tay-Sachs disease.
B)homocystinuria.
C)hypercholesteremia.
D)Gaucher's disease.

Question 79

A food calorie (Calorie) is equivalent to which metric measurement of heat?

A)calorie
B)joule
C)kilocalorie
D)watt

Question 80

Energy can change forms, but cannot be created or destroyed is a statement of the

A)first law of thermodynamics.
B)second law of thermodynamics.
C)law of mass action.
D)third law of thermodynamics.