Deck 6: Metabolism: Energy and Enzymes

Question 1

The reason an increase in substrate concentration will not increase the reaction rate indefinitely is because

A)eventually the enzyme will no longer recognize the substrate.
B)the active site will become saturated with substrate and the enzyme will not be able to go any faster.
C)another enzyme will take advantage of the excess substrate and use it for a different reaction.
D)enzymes cannot be used over and over in a reaction.
E)the enzyme will become denatured.

Answer 1

B

Question 2

Which energy association is correct?

A)Kinetic energy is energy of motion.
B)Water stored behind a dam is an example of kinetic energy.
C)Energy in the chemical bonds of a molecule is kinetic energy.
D)Potential energy must be used immediately or it is lost.
E)Light energy is a form of chemical energy.

Answer 2

A

Question 3

Most cells use a tremendous amount of ATP,

A)so our bodies therefore produce and maintain a huge amount of ATP in storage.
B)but only a little ATP is needed because it is an enzyme and does not participate in a reaction.
C)but the amount of stored ATP is not great because our body constantly generates ATP from ADP + P.
D)mainly because ATP is not very efficient as an energy currency.
E)but only for chemical work; transport and mechanical work must use transport and mechanical molecules.

Answer 3

C

Question 4

The addition of an enzyme will change the end result of a reaction.In other words,a particular reaction will result in a different product if an enzyme is used.

Question 5

During an enzymatic reaction,what happens to the enzyme?

A)It becomes the product.
B)It becomes the substrate.
C)It is used up.
D)The enzyme and the substrate form a permanent complex.
E)The enzyme and the substrate form a temporary complex.

Question 6

Enzymes are specific.This means that they

A)have a preferred pH.
B)have a preferred temperature.
C)have a particular substrate.
D)are only in certain cells.
E)require ATP and cofactors in order to work properly.

Question 7

What is a metabolic reaction called that involves one reaction releasing energy to provide energy for a second reaction that requires energy?

A)an endergonic reaction
B)an exergonic reaction
C)a coupled reaction
D)a reversible reaction
E)anabolism

Question 8

Which is true about energy of activation?

A)Energy of activation is measured as the energy that is released after a reaction occurs.
B)Adding the correct enzyme can lower the energy of activation.
C)In any one metabolic pathway,all steps will have the same energy of activation.
D)Energy of activation is the difference between the energy of the reactant and the energy of the product.
E)The energy of activation is always lower than the energy of the reactant.

Question 9

Each enzyme has a particular substrate because enzymes

A)increase the energy of activation.
B)decrease the productivity of the cell.
C)always require coenzymes.
D)have active sites complementary in shape to their substrates.
E)are named for their substrate.

Question 10

ATP can be broken down into

A)ADP.
B)ADP plus phosphate.
C)ADP plus phosphate plus energy.
D)pyruvate.
E)lactate.

Question 11

Ultimately,humans get their energy from the sun.

Question 12

Which is NOT a correct attribute of a metabolic pathway?

A)Reactants are the input molecules.
B)Reactants act as substrates for specific enzymes.
C)The product of one reaction can become the reactant for the next.
D)If several metabolic pathways have a molecule in common,one pathway can lead to several others.
E)A constant supply of new enzymes must be produced to keep the metabolic pathway active.

Question 13

Which of the following statements is true about enzymes?

A)Their 3D shape can vary and still be active.
B)Boiling temperatures do not affect their activity.
C)They catalyze only one specific type of reaction.
D)They can associate with a wide variety of substrates.
E)They are unaffected by changes in pH.

Question 14

Because the inside of a cell is more organized than the outside,the inside of the cell has increased entropy.

Question 15

All of the energy that a plant stores in the bonds of glucose are available to an animal to power its muscles.

Question 16

Which of the following statements most accurately describes the first law of thermodynamics?

A)One usable form of energy cannot be completely converted into another usable form.
B)One usable form of energy can be completely converted into another usable form.
C)Energy cannot be created or destroyed.
D)Energy can be neither created nor destroyed but it can be changed from one form to another.
E)Energy cannot be transformed.

Question 17

A reactant will always produce the same type of product,regardless of the enzymes present.

Question 18

If an enzymatic reaction was controlled by feedback inhibition,we would expect it to stop

A)only if the substrate was exhausted.
B)when the cofactors are exhausted.
C)when the product changed the pH.
D)as soon as a critical level of end product builds up.
E)only if a metabolic poison is added.

Question 19

Which of the following molecules is NOT an enzyme?

A)lipase
B)maltase
C)urease
D)lactose
E)ribonuclease

Question 20

Which statement most accurately describes the second law of thermodynamics?

A)Energy cannot be changed from one form to another without a loss of usable energy.
B)One usable form of energy can be completely converted into another usable form.
C)Energy cannot be created nor destroyed but it can be changed from one form to another.
D)Energy cannot be created or destroyed.
E)Energy cannot be transformed.

Question 21

Which of the following is consistent with the laws of physics governing energy?

A)Eventually,sunlight that is absorbed on the earth returns to the atmosphere as dispersed heat.
B)You eat a "quarter-pounder" hamburger and add exactly a quarter-pound of additional weight to your body.
C)When a liter of gasoline is burned in a car engine,100% of its energy goes into moving the car along the road.
D)A calorie of sunlight becomes a calorie of plant tissue.
E)A calorie of plant tissue,which when eaten by you,becomes a calorie of muscle "power."

Question 22

Which of the following is NOT a correct statement about the second law of thermodynamics and entropy?

A)The amount of disorder in the universe is always increasing.
B)To maintain organization of a cell,a continual input of energy is required.
C)Living cells without energy would become less organized.
D)While the total amount of energy in a system is unchanged,energy lost as heat is no longer useful to the cell in doing work.
E)Carbon dioxide and water form glucose without the input of energy.

Question 23

Energy,but NOT chemicals,may cycle through living things.

Question 24

The amount of energy available to do work after a chemical reaction has occurred is called

A)entropy.
B)metabolic energy.
C)potential energy.
D)kinetic energy.
E)free energy.

Question 25

Chemical reactions that require the input of energy are

A)exergonic reactions.
B)endergonic reactions.
C)coupled reactions.
D)kinetic reactions.
E)catabolic reactions.

Question 26

Occasionally someone claims to have built a machine that can run forever,producing as much energy as it consumes.This has always been disproved because it violates

A)the first law of thermodynamics.
B)the second law of thermodynamics.
C)entropy.
D)laws preventing any conversion between types of energy.
E)coupled reaction equations.

Question 27

When heat dissipates into the environment,it is no longer usable by the individual who produced it.

Question 28

If you wished to increase enzyme activity,you would do all of the following except

A)increase the temperature moderately.
B)increase the concentration of the enzyme.
C)increase the amount of substrate.
D)change to optimum pH for the reaction.
E)decrease the temperature.

Question 29

The term "metabolism" refers to all of the chemical reactions that occur in a cell.

Question 30

A reaction is only considered an oxidation reaction when oxygen is involved.

Question 31

When a cell uses substantial energy to organize its cell contents to a greater degree than the organization that exists outside the living cell,

A)energy has been created.
B)entropy has increased.
C)entropy has decreased.
D)entropy remains the same.
E)energy has been destroyed.

Question 32

The metabolic pathways of photosynthesis and cellular respiration

A)involve the same substrates and therefore the same enzymes.
B)are exactly the same.
C)involve oxidation reactions during photosynthesis and reduction reactions during respiration.
D)involve oxidation reactions during respiration and reduction reactions during photosynthesis.
E)both involve oxidation and reduction reactions.

Question 33

Heat is not a form of energy.

Question 34

Cells are not as efficient in their use of energy as gasoline engines.

Question 35

The unique value of the ATP molecule is that when glucose is broken down during cellular respiration,all of the free energy of glucose is transformed into ATP.

Question 36

While science cannot describe "thinking" in physical terms,we are certain that the process involves metabolism inside brain cells.With positron emission tomography (PET scan),it is possible to inject short-lived isotopes and image the regions of the brain that have the most active metabolism during various mental activities.However,

A)thought cannot be linked to cell processes because energy is not related to matter.
B)since thoughts can occur over and over,the requirement for a continual input of energy to prevent entropy does not apply to this cell activity.
C)the cellular energy expended in thinking must be less than the chemical bond energy supplied in food to these brain cells.
D)"thinking" is beyond the scope of science to study.
E)"thinking" is not a cellular process and therefore does not require energy.

Question 37

We often say that we need food for energy.In a biological sense,is this correct?

A)Yes,because the smallest units inside the atoms that make up the food are simply pure energy.
B)Yes,because the food must move through the digestive system,and motion is kinetic energy.
C)Yes,because the food we eat has potential energy in its structure and this chemical energy can be converted into mechanical energy.
D)No,because food consists of matter and cannot be transformed into energy.
E)No,since all food matter stays matter,and energy remains energy.

Question 38

Where within the cell is ATP built up?

A)mitochondria
B)cytoplasm
C)nucleus
D)endoplasmic reticulum
E)Golgi body

Question 39

The change in free energy of a reaction,delta G,is calculated by

A)subtracting the free energy content of the products from that of the reactants.
B)subtracting the free energy content of the reactants from that of the products.
C)adding the free energy content of the products to that of the reactants.
D)the amount of free energy content of the reactants.
E)the amount of free energy content of the products.

Question 40

Which hypothesis,based on the two laws of thermodynamics as applied to cells,would determine if something is a living cell or not?

A)If something uses energy to make itself more organized,then it is alive.
B)If something is organized,then it is alive.
C)If something moves,then it is alive.
D)If something loses heat,then it is alive.
E)If something uses energy to move,then it is alive.

Question 41

Since enzymes are not used up during a reaction,they do not play any role in the reaction.

Question 42

Enzymes maintain their same shape when they bind to a substrate.

Question 43

While eating a container of yogurt,you have to leave,so you store the yogurt in the refrigerator.A day later you return and find the surface of the yogurt is no longer smooth but has broken into several liquified products.You correctly guess that enzymes from your saliva,via the spoon,have continued digesting the yogurt in your absence.What will happen over time?

A)The reaction has probably stopped because the amount of saliva is small and you would have to add more saliva to continue the degradation.
B)The reaction will continue indefinitely since the enzyme is not consumed by the reaction.
C)The reaction will continue until half is digested and then stop because the reaction between substrate and product will be balanced.
D)The reaction has probably stopped because the yogurt has denatured the enzyme.
E)As long as the enzyme is not denatured by environmental conditions,the reaction will continue until all of the substrate is used up.

Question 44

The high energy bond in ATP is found in or between

A)the adenine base.
B)the adenine and the ribose.
C)the ribose sugar.
D)the adenine and the phosphates.
E)the phosphate groups.

Question 45

Less energy is needed to bring about a reaction when an enzyme is present.

Question 46

Most enzymes are

A)lipid molecules.
B)carbohydrate molecules.
C)protein molecules.
D)DNA molecules.
E)ATP molecules.

Question 47

A forest contains vegetation that is in constant battle with the many insect caterpillars that eat the vegetation.Which of the following strategies would not be a driving force in this evolutionary battle?

A)Plants are selected that evolve strong chemicals (plant alkaloids)that are toxic to the caterpillar and for which the caterpillars lack digestive enzymes.
B)Caterpillars are selected that evolve new enzymes to digest or detoxify the plant alkaloids.
C)Plants are selected that evolve chemicals that slow down or inhibit the digestive enzymes in the caterpillars so that ingested leaf material passes through before much nutrition can be gained.
D)The caterpillars are selected that eat the least leaf material.
E)Caterpillars are selected that evolve enzymes to break down the chemicals that interrupt their digestive enzymes.

Question 48

ATP contains

A)an adenine base and one phosphate group.
B)an adenine base and two phosphate groups.
C)an adenine base and three phosphate groups.
D)an adenine base,a ribose sugar,and two phosphate groups.
E)an adenine base,a ribose sugar,and three phosphate groups.

Question 49

The main reason that ATP is considered the energy currency in cells is because it

A)is a small molecule.
B)carries a positive charge.
C)contains accessible energy in phosphate bonds.
D)contains an adenine base.
E)contains a sugar ring.

Question 50

The function of an enzyme is to

A)provide the energy for metabolic reactions.
B)increase the rate of a metabolic reaction.
C)change the direction of metabolic reactions.
D)act as a buffer in metabolic reactions.
E)raise the energy of activation for a reaction.

Question 51

If A has a free energy of 38 units,and C has a free energy of 45 units,and the reaction is exergonic,based on the calculation of free energy,which is the substrate and which is the product?

A)A is the substrate and C is the product.
B)C is the substrate and A is the product.
C)It is impossible to tell with this information.
D)Both A and C are the products.
E)Both A and C are the substrates.

Question 52

Which of the following is an example of chemical work within a cell?

A)catabolism
B)anabolism
C)moving glucose across the cell membrane
D)the beating of cilia
E)the contraction of muscle fibers

Question 53

The various uses of ATP include all of the following except

A)being a structural component of the cell membrane.
B)chemical work.
C)mechanical work.
D)transport work.
E)moving substances into a cell.

Question 54

If there are 12 different intermediate products produced during production of a molecule in a cell,we can expect that there

A)is one enzyme that carries this process through all 12 stages to the end product.
B)are about 12 enzymes,at least one responsible for each step in the metabolic pathway.
C)is one enzyme for degradation and another enzyme for synthesis.
D)there may not be any enzymes involved if this is a natural cell product.
E)must be 12 different raw materials combined in the cell by one enzyme.

Question 55

Enzymes,coenzymes,and cofactors provide a mechanism for a cell to regulate the metabolism of a large amount of cell products using small quantities of chemicals.

Question 56

The location in which the enzyme and substrate complexes is called the

A)active site.
B)inhibitor site.
C)receptor site.
D)enzyme-substrate complex.
E)enzyme-inhibitor complex.

Question 57

Which of the following statements is not true concerning enzymatic activity?

A)Each enzyme has a preferred pH at which the enzyme reaction rate is highest.
B)Above a certain temperature,an enzyme will become denatured.
C)As the temperature increases,most enzymatic reactions will still proceed at the same rate.
D)Enzymatic reactions proceed quite rapidly.
E)Enzyme activity increases as substrate concentration increases until the maximum rate is achieved.

Question 58

The specificity of an enzyme to a substrate is currently best explained by

A)the "lock and key" model.
B)the induced-fit model.
C)the allosteric model.
D)the receptor model.
E)the synthase complex model.

Question 59

If A $\rightarrow$ B $\rightarrow$ C $\rightarrow$ D $\rightarrow$ E represents a metabolic pathway,then letter E would be

A)a substrate.
B)a product.
C)energy.
D)an enzyme.
E)an enzyme-substrate complex.

Question 60

In a coupled reaction,some of the energy is not released to the environment because the energy from one reaction is used to drive the other reaction forward.

Question 61

The removal of electrons and/or hydrogen atoms from a substrate is called what?

A)reduction
B)oxidation
C)phosphorylation
D)metabolism
E)an enzyme-substrate complex

Question 62

Glucose is broken down during cellular respiration so that the released energy can be stored and converted into ATP.

Question 63

Which of the following is a by-product of photosynthesis?

A)carbon dioxide
B)water
C)oxygen
D)glucose
E)energy

Question 64

Whether or not an enzyme is active and present within a cell depends on all of the following except

A)if the gene for the enzyme has been turned on and the enzyme made.
B)if the enzyme has been activated or inactivated by the addition of a phosphate group.
C)whether an inhibitor is bound to the enzyme.
D)whether the necessary cofactor is present.
E)whether the enzyme catalyzes an endergonic or exergonic reaction.

Question 65

What is the equation for photosynthesis?

A)C₆H₁₂O₆ + 6O₂ $\rightarrow$ 6CO₂ + 6H₂O + energy
B)energy + C₆H₁₂O₆ $\rightarrow$ 6CO₂ +6H₂O.
C)energy + C₆H₁₂O₆ $\rightarrow$ 6CO₂ +6H₂O
D)energy + 6CO₂ + 6H₂O $\rightarrow$ C₆H₁₂O₆ + 6O₂
E)C₆H₁₂O₆ + 6CO₂ $\rightarrow$ 6O₂ + 6H₂O + energy

Question 66

When a kinase adds phosphates to an enzyme,it will only activate the enzyme.

Question 67

Poisons are often

A)enzyme inhibitors.
B)cofactors.
C)coenzymes.
D)vitamins.
E)kinases.

Question 68

Define the first law of thermodynamics.

Question 69

In feedback inhibition of a metabolic pathway,where does the inhibitor bind?

A)to the substrate of the first reaction
B)to the product of the first reaction
C)to the enzyme of the first reaction
D)to the enzyme of the last reaction
E)to a substrate or the product of the last reaction

Question 70

Less energy is needed to bring about a reaction when an enzyme is present.

Question 71

A piece of meat and a piece of fruit are fed to both a lizard and a person.The extent to which these foods are digested by digestive enzymes along these two gastrointestinal tracts varies.Which of the following is not a reason for the variation in digestion?

A)pH of the digestive organs
B)body temperature
C)variation in enzymes produced
D)the amount of protein in the meat and fruit
E)bacteria present in the digestive tract

Question 72

Chloroplasts and mitochondria are involved in a redox cycle because

A)carbon dioxide is reduced during photosynthesis and carbohydrates are oxidized during cellular respiration.
B)both use carbon dioxide.
C)photosynthesis uses energy and cellular respiration releases energy.
D)both are required to be in all cells.
E)energy cycles between the two organelles.

Question 73

Lactose is milk sugar that is broken down by the enzyme lactase.The reason that some people are "lactose intolerant" could be because

A)the enzyme lactase only works in the laboratory,not in the human body.
B)the pH of the digestive system does not allow lactase to function properly.
C)the temperature of the digestive system does not allow lactase to function properly.
D)they drink too much milk and have inactivated the lactase in their digestive system.
E)they are missing the enzyme lactase in their digestive system.

Question 74

Explain the factors that will cause a protein to become denatured and what will occur structurally to the protein when it is denatured.

Question 75

During cellular respiration,what is reduced?

A)glucose
B)oxygen
C)carbon dioxide
D)water
E)ATP (energy)