Deck 6: Metabolism: Energy and Enzymes

Question 1

A living organism represents stored energy in the form of chemical compounds.When an organism dies,what happens to this stored energy?

A)All chemicals immediately lose their high-energy bonds.
B)All molecules immediately degrade into basic elements.
C)All energy immediately leaves,and that is one manifestation that the organism is dead.
D)The chemical compounds in cells lose their organization over time because there is no longer an input of energy to maintain the organized state.
E)The chemical compounds remain exactly intact and ready to start up again unless digested by a consumer or decay organism.

Answer 1

D

Question 2

Which of these statements is NOT a consequence of the second law of thermodynamics?

A)While the total amount of energy is unchanged,the energy lost as heat is no longer useful to the cell in doing work.
B)Reactions that occur spontaneously are those that increase the amount of useful energy in a system.
C)The amount of disorder in the universe is always increasing.
D)To maintain organization of a cell,a continual input of energy is required.

Answer 2

B

Question 3

Which best describes the first law of thermodynamics?

A)Energy can be created or destroyed and it cannot be changed from one form of energy to another.
B)Energy is not created nor destroyed,but it can change from one energy form to another.
C)Energy can be created from matter or used to produce matter.
D)Some useful energy is lost as heat whenever an energy transfer occurs.
E)Energy transfers are always 100% efficient in changing energy from one useful form to another.

Answer 3

B

Question 4

Which of the following is a true statement about enzyme inhibition?

A)In competitive inhibition,the inhibitor binds to the active site of the enzyme.
B)In noncompetitive inhibition,the inhibitor binds to the allosteric site of the enzyme.
C)In irreversible inhibition,a poison binds to the enzyme so that it can never work again.
D)Most inhibitors act in a reversible fashion.
E)All of the statements are true.

Question 5

ATP is considered to be

A)an enzyme used widely in all kinds of cells.
B)a coenzyme used to inhibit or activate different enzymes.
C)a molecule that carries a great deal of chemical energy in a chemical bond.
D)the precursor of a high-energy membrane-bounded protein.

Question 6

The activity of an enzyme might be increased by all of the following except

A)an increase in substrate concentration.
B)a vitamin.
C)a two to four degree increase in temperature.
D)the presence of other enzymes.

Question 7

All of the following would denature a protein except

A)heating to temperatures above 100°C.
B)addition of a strong acid.
C)addition of a strong base.
D)a missing coenzyme.

Question 8

Which of the following is NOT a form of potential energy?

A)food
B)water in a dam
C)a muscle contracting
D)All of the above.

Question 9

Which best describes the second law of thermodynamics?

A)Energy is not created nor destroyed,but it can change into matter.
B)Energy is not created nor destroyed,but it can change from one energy form to another.
C)Energy can be created from matter or used to produce matter.
D)Some useful energy is lost as heat whenever an energy transfer occurs.
E)Energy transfers are always 100% efficient in changing energy from one useful form to another.

Question 10

A coenzyme is

A)an inorganic ion that interacts with an enzyme to allow it to work.
B)a protein-based organic molecule that interacts with an enzyme to allow it to work.
C)a nonprotein organic molecule that interacts with an enzyme to allow it to work.
D)an inorganic ion that interacts with an enzyme to inhibit it.

Question 11

Endergonic reactions

A)release energy.
B)have a negative ΔG and occur spontaneously.
C)can only occur if there is an input of energy.
D)have products with less free energy than the reactants.
E)All of the choices are correct.

Question 12

Which statement describes the currently accepted theory of how an enzyme and its substrate fit together?

A)When the product binds to the enzyme,the substrate changes shape to accommodate the reaction.
B)The enzyme is like a key that fits into the substrate,which is like a lock.
C)The active site is permanently changed by its interaction with the substrate.
D)As the substrate binds to the enzyme,the shape of the active site changes to accommodate the reaction.

Question 13

The sum of the chemical reactions in a cell constitute

A)coupling reactions.
B)free energy.
C)endergonic reactions only.
D)exergonic reactions only.
E)metabolism.

Question 14

Energy coupling of endergonic and exergonic reactions within cells

A)permits energetically favorable and unfavorable reactions to occur in the same place,at the same time.
B)uses energy released by one reaction to fuel the other reaction.
C)utilizes ATP to carry energy between the energetically favorable and unfavorable reactions.
D)All of the choices are correct.

Question 15

Which organelles are involved in a redox cycle?

A)Golgi complexes and lysosomes
B)mitochondria and chloroplasts
C)endoplasmic reticulum and vesicles
D)vacuoles and vesicles
E)mitochondria and endoplasmic reticulum

Question 16

Which form of energy is NOT correctly associated with the related example?

A)kinetic energy: fat molecules
B)kinetic energy: movement of muscles
C)chemical energy: glucose
D)potential energy: water held behind a dam
E)potential energy: ATP

Question 17

The subunits from which ATP is made are

A)ADP and phosphate.
B)FAD and NAD⁺.
C)FAD and NADPH.
D)ADP and FAD.
E)ADP and NAD⁺.

Question 18

Which statement is NOT true about how various conditions will affect the activity of an enzyme?

A)Higher temperatures generally increase the activity of an enzyme up to a point.
B)Above a certain range of temperatures,the protein of an enzyme is denatured.
C)A change in pH can cause an enzyme to be inactivated.
D)An enzyme's activity is generally reduced by an increase in substrate concentration.
E)When sufficient substrate is available,the active site will nearly always be occupied.

Question 19

ATP is considered a high-energy compound because under cellular conditions,7.3 kcal per mole of energy is released when a bond is broken between

A)the base adenine and the sugar ribose.
B)the adenosine and the phosphate groups.
C)the base adenine and the phosphate groups.
D)the adenosine diphosphate and the third phosphate.
E)All of the bonds release energy as ATP is completely broken down.

Question 20

Coupling occurs when the energy released by an exergonic reaction is

A)used to drive another exergonic reaction.
B)used to drive an endergonic reaction.
C)lost as nonusable heat to the environment.
D)used to decrease the entropy of the universe.
E)All of the choices are correct.

Question 21

In the reaction NAD → NADH,the NAD is ________,while the NADH is ________.

A)reduced; oxidized
B)oxidized; oxidized
C)reduced; reduced
D)oxidized; reduced

Question 22

Astrophysicists explain that eventually the sun will swell to become a red giant,engulf the earth,and "burn out" with all forms of energy dispersing in a final "heat death." Compared with conditions today,the entropy of the universe then will

A)have increased greatly.
B)have decreased greatly.
C)remain the same because energy cannot be created or destroyed.
D)remain the same because new energy will replace the energy destroyed.

Question 23

What does this graph reveal about the rate of reaction of the two different enzymes? What are the implications of this finding?

Question 24

If there are twelve different intermediate products produced in the stages of a metabolic pathway within a cell,we can expect that there

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

Question 25

B → C is

A)exergonic.
B)endergonic.
C)No answer choice is correct.

Question 26

In living cells,the hydrolysis of ATP to ADP + P is the main supply of energy.ATP releases its energy in areas of the cell where some work is being carried out.If ATP underwent hydrolysis spontaneously,anywhere and at any time within a cell,would life as we know it be possible?

Question 27

Study the graph shown here.The letter "B" depicts the ________,while "C" depicts ________.

A)energy of activation; energy of the product
B)energy of the product; energy of activation
C)energy of the reactant; energy of the product
D)reactant concentration; activation energy

Question 28

Which of the following is consistent with the laws of thermodynamics' governing energy?

A)When a liter of gasoline is burned in a car engine,100% of its energy goes into moving the car along the road.
B)You eat a "quarter-pounder" hamburger and assemble exactly a quarter-pound of additional body weight on your body.
C)Eventually sunlight that is absorbed on the earth returns to space as dispersed heat.
D)A calorie of sunlight becomes a calorie of plant tissue that,eaten by you,becomes a calorie of heat lost in muscle "power."
E)Chemical bonds are a case of converting energy to matter; breaking the bonds converts matter to energy.

Question 29

While science is not yet able to describe the phenomenon of "thinking" in physical terms,we can be certain that it is a process involving the metabolism of 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.For different mental functions,different regions and amounts of nerve cells become active.However,

A)the cellular energy expended in "thinking" must be less than the chemical bond energy supplied in food to these brain cells.
B)"thought" cannot be linked to cell processes because energy is not related to matter.
C)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.
D)"thinking" is beyond the scope of science to study.

Question 30

Study the figure shown here.What does the letter "A" depict?

A)energy of the reactant
B)energy of the product
C)energy of activation
D)substrate concentration

Question 31

The metabolic pathway below involves how many possible chemical reactions? A → B → C → D → E

A)five
B)six
C)one
D)four

Question 32

Lactose is milk sugar,and as infants,humans produce substantial amounts of the lactase enzyme to digest it.However,as we age,we soon lose some or even all of our lactase.In such cases,undigested lactose passes to the lower intestine where bacteria break it down into lactic acid and CO₂,causing painful gas and bloating.This problem could be avoided by

A)avoiding all dairy products containing lactose.
B)taking lactase enzyme tablets when consuming lactose products.
C)taking any enzyme tablets when consuming dairy products.
D)consuming lactose in tablet form.
E)taking lactase enzyme tablets or avoiding all dairy products.

Question 33

Analyze the graph.Label the following. A.The energy of activation of the reaction with an enzyme.
B.The energy of activation of the reaction without an enzyme.
C.The energy of the reactants.
D.The energy of the products.

Question 34

Analyze this figure to categorize the chemical reaction as a synthesis reaction or a degradation reaction.Cite evidence to support your answer.

Question 35

Explain how,at a glance,it appears that life must violate the laws of thermodynamics.Provide a brief explanation on how life does NOT violate these rules.

Question 36

Which of the following labels is incorrectly identified?

A)A refers to the products.
B)B refers to the substrate-enzyme complex.
C)C refers to the reactants.
D)D refers to the product.

Question 37

An automobile engine is about 20 to 30% efficient in converting chemical energy to mechanical energy.Cells are about 39% efficient in the transformation of glucose to ATP.The rest of the energy is lost as heat.This is illustrative of the

A)first law of thermodynamics.
B)second law of thermodynamics.
C)third law of thermodynamics.
D)the cell theory.

Question 38

You are interrupted while eating some yogurt and you store the remaining 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 areas.You correctly guess that enzymes from your saliva,via the spoon,have continued digesting the yogurt in your absence.If you left the yogurt on the counter for another 24 hours,what would happen?

A)The reaction will soon stop because the amount of saliva is small,and you would have to add more saliva to continue the degradation.
B)The reaction will continue since the enzymes have plenty of substrate.Additionally,it would speed up since the enzymes are exposed to warmer temperatures.
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 will stop because you have altered the environment and denatured the enzyme.

Question 39

In living cells of all types,the hydrolysis of ATP to ADP + P is the main supply of energy.ATP releases its energy in areas of the cell where some work is being carried out.In such cases,special enzymes (ATPases)are necessary for the hydrolysis of ATP.How does the universality of ATP and the diversity of enzyme systems relate to the unity and diversity of life through evolution?

Question 40

________ represent(s)the first reactant(s)of this metabolic pathway and ________ represent(s)the end product(s)of this pathway. A → B → C → D → E

A)A; E
B)B; E
C)A; D
D)A and B; D and E

Question 41

Which of the following scenarios accurately represents the second law of thermodynamics?

A)As our body converts glucose into ATP some of the energy is given off in the form of heat.
B)The temperature of your car's engine begins to increase as you drive to work.
C)When we are cold our body shivers as a response to the decrease in body temperature.
D)All of these are consistent with the second law of thermodynamics.

Question 42

During the conversion of glucose into a free form of energy only some of the energy is converted into usable ATP.What happens to the rest of the energy?

A)The energy is converted to heat.
B)The energy is converted to CO₂.
C)The energy is released in H₂O.
D)The energy is converted into more glucose.

Question 43

Which substrate is missing: 6CO₂ + ________ + energy = C₆H₁₂O₆ + 6O₂ ?

A)6H₂O
B)4H₂O
C)4O₂
D)glucose

Question 44

What are the end products of photosynthesis?

A)glucose and oxygen
B)glucose and ATP
C)carbon dioxide and energy
D)carbon dioxide and water
E)oxygen and NADP+

Question 45

C $\rightarrow$ D is coupled with the reaction ATP $\rightarrow$ ADP.Based on this information the reaction $C \rightarrow D$ is ________. A ? B ? C ? D ? E

A)endergonic
B)exergonic
C)spontaneous
D)It cannot be determined from the information given.

Question 46

Which of the following substrates are required for cellular respiration?

A)glucose and oxygen
B)glucose and carbon dioxide
C)sunlight and oxygen
D)sunlight and glucose
E)oxygen and carbon dioxide

Question 47

Which of the following is an example of potential energy?

A)a Snickers bar
B)an apple
C)a glass of milk
D)All are examples of potential energy.

Question 48

Enzyme inhibition is the process that turns off an enzyme in a metabolic pathway.One way this can happen is for the end product of the pathway to act as an inhibitor.

Question 49

Which of the following substrates is essential to an organism that utilizes photosynthesis?

A)6H₂O
B)C₆H₁₂O₆
C)6O₂
D)6 carbon atoms

Question 50

In this pathway,B $\rightarrow$ C is coupled with ADP $\rightarrow$ ATP.Categorize the reactions as endergonic or exergonic. A ? B ? C ? D ? E

A)B $\rightarrow$ C is endergonic and ADP
$\rightarrow$ ATP is exergonic.
B)ADP $\rightarrow$ ATP is endergonic and B
$\rightarrow$ C is exergonic.
C)Both B $\rightarrow$ C and ADP
$\rightarrow$ ATP are endergonic.
D)Both B $\rightarrow$ C and ADP
$\rightarrow$ ATP are exergonic.

Question 51

In order to roll a rock down a hillside,you must first push it up the hill.Pushing the rock is analogous to the energy of activation of a chemical reaction.

Question 52

While we are sitting down to lunch,we are consuming ________ energy,which will then be converted into ________ energy as we work until dinner time.

A)potential; kinetic
B)kinetic; potential
C)kinetic; free
D)potential; stored

Question 53

If a change in pH alters an allosteric site where an inhibitor binds,it would be possible for an enzyme-controlled reaction to occur as normal.

Question 54

An enzyme is a protein that causes the rate of the reaction to slow down.