Deck 6: Energy Flow in the Life of a Cell

Question 1

Why is photosynthesis considered an endergonic reaction?

A) Low-energy reactants are converted to high-energy products.
B) Photosynthesis does not comply with the physical laws of the universe.
C) Sugar has less energy than does the sun.
D) Protein catalysts are not needed.
E) Activation energy is not required.

Answer 1

A

Question 2

How is your body able to work against the effects of entropy?

A) Sunbathing
B) Regular work
C) Eating a balanced diet and proper nourishment
D) Regular exercise

Answer 2

C

Question 3

In exergonic chemical reactions,

A) energy is stored by the reactions.
B) the reactants have more energy than do the products.
C) the reactants and products have equal amounts of energy.
D) the reactants have less energy than do the products.

Answer 3

B

Question 4

In the liver, the polysaccharide glycogen is broken down into glucose monomers. The glucose molecules are then released into the blood when blood sugar levels need to be raised. This process is an example of a(n)________ reaction.

A) endergonic
B) exergonic
C) potential
D) kinetic

Question 5

When solid sodium hydroxide is added to water, the solution gets hot. This is an example of a(n)

A) release of activation energy.
B) conversion of kinetic energy to potential energy.
C) endergonic process.
D) exergonic process.
E) enzyme-catalyzed process.

Question 6

Which of the following has the greatest amount of kinetic energy?

A) A hot car engine
B) A moving car
C) A tank of gasoline
D) The cool air surrounding the car engine
E) An unlit firecracker

Question 7

Activation energy is necessary for all ________reactions.

A) coupled
B) endergonic
C) chemical
D) exergonic

Question 8

All of the following statements are true of the first law of thermodynamics EXCEPT

A) the amount of useful energy decreases when energy is converted from one form to another.
B) the total amount of energy within a closed system remains the same.
C) one form of energy may be converted to a different form of energy.
D) the first law of thermodynamics is often called the law of the conservation of energy.

Question 9

During photosynthesis, plants convert light energy to chemical energy. This is an example of

A) the first law of thermodynamics.
B) the second law of thermodynamics.
C) increasing entropy.
D) chemical equilibrium.
E) a spontaneous reaction.

Question 10

In an isolated system, all of the following are true of the second law of thermodynamics EXCEPT

A) there is a natural tendency toward greater disorder in the organization of matter (increase in entropy).
B) the amount of useful energy decreases.
C) reactions cause energy to be converted from more useful to less useful forms.
D) all chemical reactions release more energy than they consume.

Question 11

Energy that is not converted to useful energy is usually given off as

A) entropy.
B) light.
C) radioactivity.
D) heat.
E) electricity.

Question 12

Similar to a car, a human body is about________ efficient in converting chemical energy to movement.

A) 25%
B) 75%
C) 1%
D) 95%

Question 13

What is the ultimate source of energy for almost all forms of life on Earth?

A) Thermal energy
B) Solar energy
C) Nuclear energy
D) Chemical energy
E) Heat energy

Question 14

Each of the following requires 12 carbon atoms. Which of the arrangements of carbon atoms has the greatest entropy?

A) 1 molecule of the disaccharide maltose, C₁₂H₂₂O₁₁
B) 4 molecules of the monosaccharide pyruvate, C₃H₄O₃
C) 12 molecules of carbon dioxide, CO₂
D) 2 molecules of the monosaccharide glucose, C₆H₁₂O₆

Question 15

A(n)________ chemical reaction releases energy, whereas a(n)________ reaction requires an input of energy.

A) exergonic; endergonic
B) equilibrium; exergonic
C) enzymatic; endergonic
D) endergonic; enzymatic
E) endergonic; exergonic

Question 16

Entropy is a measure of an increase in

A) randomness.
B) high-level energy.
C) kinetic energy.
D) organization.
E) potential energy.

Question 17

Which of the following does NOT have much potential energy?

A) A water droplet at the top of a waterfall
B) A glucose molecule
C) A diver on a springboard
D) A ball that has rolled downhill and stopped
E) A 9-volt battery

Question 18

How is it possible for living organisms to comply with the second law of thermodynamics?

A) Chemical reactions inside cells mostly cause an increase in high -level energy.
B) Living organisms are unique in that they do not require energy for survival.
C) Organisms are able to function efficiently on heat energy alone.
D) Sunlight functions as an ultimate source of energy for most forms of life on Earth.
E) Living organisms are totally isolated systems that are not subject to the laws of physics.

Question 19

Which of the following is part of the first law of thermodynamics?

A) Potential energy equals kinetic energy in a reaction.
B) Exergonic reactions are coupled with endergonic reactions.
C) Energy cannot be transferred or transformed.
D) Energy cannot be created or destroyed.
E) Kinetic energy is stored energy.

Question 20

When, if ever, do molecules stop moving?

A) At absolute zero (-273.15°C)
B) At the boiling point (100°C)
C) At the freezing point (0°C)
D) Never

Question 21

Which of the following statements regarding enzymes is FALSE?

A) The activity of enzymes can be regulated by factors in their environment.
B) Enzymes are highly specific for the molecules to which they attach.
C) Enzymes provide energy for the reactions they catalyze.
D) Enzymes are proteins that function as biological catalysts.
E) An enzyme may be used many times for the same specific reaction.

Question 22

Imagine that you are conducting an experiment on a yeast enzyme known as sucrase. This enzyme is used by yeast cells to break down the disaccharide sucrose into the monosaccharides glucose and fructose. What type of reaction is this?

A) Metergonic
B) Spontaneous
C) Endergonic
D) Exergonic

Question 23

ATP is an energy carrier. Where is the energy actually located?

A) Between the sugar and the phosphate
B) Attached to the phosphate group
C) In the bonds between phosphate groups
D) Attached to the nucleotide
E) Inside the phosphate

Question 24

FADH₂ is an example of a(n)

A) electron carrier molecule.
B) enzyme-substrate complex.
C) protein.
D) active site.
E) enzyme.

Question 25

When a muscle cell demands energy to perform its work of contraction, ATP

A) catalyzes the reaction.
B) is broken down and liberates energy.
C) is phosphorylated.
D) manufactures more ATP.
E) enters a metabolic pathway.

Question 26

All of the following statements about catalysts are true EXCEPT

A) catalysts increase the reaction rate.
B) biological catalysts are specific enzymes.
C) catalysts can be used repeatedly.
D) catalysts increase activation energy requirements.
E) catalysts are not permanently altered during reaction.

Question 27

Enzymes are important because they

A) bind irreversibly to substrates.
B) are structural proteins that make up bodily tissues.
C) increase the body temperature of organisms.
D) allow reactions to occur at body temperature.
E) can enable organisms to evade the laws of thermodynamics.

Question 28

Which of the following functions as a biological catalyst?

A) Steroid
B) Amino acid
C) Enzyme
D) Substrate
E) Energy-carrier molecule

Question 29

The reactant in an enzyme-catalyzed reaction is the

A) activation energy.
B) allosteric inhibitor.
C) active site.
D) product.
E) substrate.

Question 30

Most reactions in the body occur too slowly to sustain life. This is because

A) many reactions require large inputs of activation energy.
B) all reactions in the body are endergonic.
C) there is not enough ATP in body cells.
D) most biological catalysts are not active at body temperature (37°C).
E) no catalysts are present in body cells.

Question 31

Place these steps of enzyme catalysis in the correct order: 1. The substrate and enzyme change shape.
2) The substrate enters the active site.
3) The enzyme reverts to its original configuration.
4) The product is expelled.

A) 2, 3, 1, 4
B) 2, 1, 3, 4
C) 1, 3, 4, 2
D) 2, 1, 4, 3
E) 1, 2, 3, 4

Question 32

Which statement best describes the relationship between an enzyme and a reactant?

A) One enzyme typically has many reactants with which it will associate.
B) The enzyme and the reactant molecule are both permanently changed.
C) The resultant product and the enzyme are permanently bonded together.
D) The relationship is temporary.
E) Covalent chemical bonds stabilize the relationship.

Question 33

Which molecule stores energy for just a short period of time?

A) Steroids
B) Glycogen
C) Phospholipids
D) Protein
E) ATP

Question 34

Which of the following is the best description of a coupled reaction?

A) Two reactions, where the product of the first reaction is the reactant of the second reaction
B) Two reactions that occur simultaneously
C) A reaction that occurs right after another reaction
D) Reactions that occur during sexual reproduction
E) Two reactions that occur in the same organelle

Question 35

The most common energy carrier molecule in living organisms is

A) glucose.
B) NADPH.
C) DNA.
D) ADP.
E) ATP.

Question 36

A ʺhigh-energyʺ bond in an ATP molecule is located between

A) ribose and the first phosphate group.
B) adenine and the first phosphate group.
C) adenine and ribose.
D) two phosphate groups.

Question 37

Why is photosynthesis a coupled reaction?

A) The exergonic reaction occurs in the plant, and the endergonic reaction occurs in the soil.
B) Photosynthesis requires two reactants: carbon dioxide and water.
C) Sunlight energy enters a plant and is ultimately lost as heat.
D) The exergonic reaction occurs in the plant, and the endergonic reaction occurs in the sunlight.
E) An exergonic reaction occurs in the sunlight, and an endergonic reaction occurs in the plant.

Question 38

Which of the following lowers the activation energy of a biochemical reaction?

A) High concentration of products
B) Presence of a catalyst
C) High temperature
D) Low concentration of reactants
E) Altering pH to 7

Question 39

When a high-energy bond in ATP is broken, what primarily happens to the released energy?

A) It functions as a second messenger.
B) It converts inorganic phosphates to energy-carrier molecules.
C) It polarizes the cell.
D) It is lost as light energy.
E) It provides the energy needed to drive endergonic reactions in the cell.

Question 40

Which of the following is NOT a commonly used energy carrier in the cell?

A) ATP
B) H₂O
C) NAD
D) FAD

Question 41

Which of the following will bind to the active site of an enzyme?

A) Competitive inhibitor only
B) Substrate only
C) Both substrate and competitive inhibitor
D) Allosteric inhibitor only
E) Noncompetitive inhibitor only

Question 42

The law of conservation of energy states that although the form of energy used remains the same, the total amount of energy changes.

Question 43

All of the following are ways in which enzymes are regulated by the cell EXCEPT

A) by feedback inhibition.
B) a gene coding for the enzyme may be turned off.
C) a heavy metal (such as lead) may block the enzymes non -active site.
D) by first synthesizing the enzyme in an inactive form.

Question 44

All of the following are examples of noncompetitive inhibitors EXCEPT

A) arsenic.
B) nerve gas.
C) mercury.
D) lead.

Question 45

Preservatives such as citric acid are added to foods to interfere with bacterial growth. This creates an acidic pH in the food. Why does this affect the bacteria that are present?

A) An acidic environment increases the activation energy more quickly in bacteria.
B) An acidic environment causes bacterial enzymes to fail or work less efficiently.
C) An acidic environment causes the bacteria to grow more rapidly.
D) An acidic environment encourages endergonic reactions in the bacterial cells.

Question 46

Competitive and noncompetitive enzyme inhibitors differ with respect to

A) their pH.
B) the temperature at which they work best.
C) their energies of activation.
D) the precise location on the enzyme to which they bind.

Question 47

The optimum reaction rate of a particular enzyme occurs at pH 7.3 at 37°C. This reaction would probably proceed faster by

A) increasing both temperature and pH.
B) decreasing the pH and increasing the temperature.
C) increasing the pH and maintaining the temperature at 37°C.
D) increasing the temperature to 38°C and keeping the pH at 7.3.

Question 48

The burning of sugar is an example of an endergonic reaction, and photosynthesis is an example of an exergonic reaction.

Question 49

The addition of a competitive inhibitor slows down a particular reaction. What could be done to increase the rate of the reaction, even in the presence of the inhibitor?

A) Add more inhibitor.
B) Add more substrate.
C) Lower the temperature of the reaction.
D) Allow the reaction to reach equilibrium.
E) Add a coenzyme.

Question 50

Sulfa antibiotics damage bacteria by affecting a certain bacterial enzyme. The sulfa antibiotic looks similar to a substrate normally required by the bacterial cells to live. The sulfa antibiotic occupies the active site of the required enzyme and blocks entry of its normal substrate. This prevents the bacteria from making nucleotides that are required for their reproduction and survival. Based on this information, the action of sulfa antibiotics is an example of

A) activation energy.
B) competitive inhibition.
C) denaturing of proteins.
D) electron carriers.

Question 51

The photosynthetic reaction is considered an endergonic reaction.

Question 52

The end product of a biosynthetic pathway often acts to block the initial step in that pathway. This phenomenon is called

A) denaturation.
B) feedback inhibition.
C) irreversible inhibition.
D) allosteric activation.
E) substrate activation.

Question 53

In cells, endergonic reactions are often coupled with exergonic reactions that store energy.

Question 54

The hydrolysis of sucrose to glucose and fructose is a spontaneous reaction inside our bodies. However, if you dissolve sucrose in water and keep the solution overnight at room temperature, there is no detectable conversion to glucose and fructose. Why not?

A) The reaction is endergonic.
B) The reaction requires a catalyst.
C) The energy of the products is higher than that of the energy of the reactants.
D) The activation energy of the reaction decreases.
E) The reaction is at equilibrium.

Question 55

Triclosan is a broad-spectrum antibacterial agent used in many household products. It is structurally similar to polychlorobiphenylol, a substrate that binds to the active site of the enzyme sulfotransferase. Based on these facts, you can conclude that triclosan most likely

A) lowers the activation energy of chemical reactions.
B) acts as a noncompetitive inhibitor.
C) is a competitive inhibitor.
D) functions as an enzyme when sulfotransferase is absent.

Question 56

To say that an enzyme has been denatured means that

A) the enzyme is working at its maximal rate.
B) the enzyme is working at an optimal temperature.
C) an inhibitor has bound the enzyme at the active site.
D) its three-dimensional structure has changed and the enzyme can no longer function properly.

Question 57

For many enzymes, the rate of product formation increases as the concentration of the substrate increases. Eventually the rate of the reaction reaches a maximum at which further increases in the concentration of the substrate have no effect. Why?

A) The enzyme is no longer specific for the substrate.
B) At high concentrations of substrate, the reaction is endergonic.
C) At high concentrations of substrate, the activation energy of the reaction increases.
D) At high concentrations of substrate, all of the enzyme active sites are being occupied by substrate molecules.
E) At high concentrations of substrate, the activation energy of the reaction decreases.

Question 58

Kinetic energy is like sitting at the top of a hill, and potential energy is like coasting down that hill on your bike.

Question 59

Energy is defined as the capacity to do work.

Question 60

Animals have enzymes that break apart starch molecules but not cellulose, despite the fact that both are made up of glucose subunits. Which enzyme characteristic best explains this?

A) Enzyme activity is regulated.
B) Enzymes are highly specific.
C) All enzymes are proteins.
D) Enzymes usually speed up chemical reactions.
E) Enzymes are not permanently changed by the reactions they promote.

Question 61

In chemical reactions, ________reactions release energy and ________reactions require an input of energy.

Question 62

In chemical reactions, the________ are converted into products.

Question 63

What is a simple definition of energy, from a biological perspective? Give some examples of how energy is used in a cell.

Question 64

Briefly describe the difference between kinetic energy and potential energy, and give an example of each.

Question 65

The molecule________ is the major energy carrier in cells.

Question 66

ATP is considered a short-term form of energy for the cell, whereas ________or________represent more stable, long-term energy stores.

Question 67

Sitting at the top of a slide, a child has ________energy; sliding down, she is using________energy.

Question 68

_____-are biological catalysts.

Question 69

The metabolism of a cell is the sum of all of its chemical reactions.

Question 70

Compare endergonic and exergonic chemical reactions using an analogy from everyday life.

Question 71

The enzyme phosphoglucoisomerase catalyzes the conversion of glucose -6-phosphate to fructose-6-phosphate. The region on phosphoglucoisomerase where glucose-6-phosphate binds is called the ________.

Question 72

AMP stores energy in its chemical bonds and is able to use that energy for work in the cell.

Question 73

Briefly describe how ATP acts as an energy carrier in cells.

Question 74

The burning of sugars as fuels for runners is an example of a(n) ________chemical reaction, whereas the production of sugars during photosynthesis is an example of a(n)________chemical reaction.

Question 75

Energy transformations are not 100% efficient. Often, energy is released in the form of________, which is in agreement with the second law of thermodynamics.

Question 76

Activation energy can be provided by the kinetic energy of moving molecules.

Question 77

Briefly explain the two laws of thermodynamics.

Question 78

The energy of movement is referred to as________ energy, and stored energy is referred to as________ energy.

Question 79

Special molecules such as NADH and FADH ₂ transport ________in cells, which can then be used as energy in the cell.

Question 80

The second law of thermodynamics states that the ________, or disorder, of the universe is constantly increasing.