Deck 5: Energy, Metabolism, and Enzymes

Question 1

Plants and animals use different energy storage molecules,yet they both use the same mechanism to burn their stored energy.How can plants and animals both be successful,even though they burn different energy storage molecules?

A) The internal components of plant and animal cells are identical.
B) The second law of thermodynamics states that all cells have the same energy transfer system.
C) Breaking the chemical bonds of a storage molecule transfers energy,no matter what molecule is stored.
D) All organisms have the same enzymes to catalyze their energy-producing reactions.

Answer 1

C

Question 2

A decrease in potential energy between reactants and products is typical for which of the following types of chemical reactions?

A) anabolic reactions
B) catabolic reactions
C) the formation of peptide bonds
D) reactions that happen without the aid of an enzyme

Answer 2

B

Question 3

Organisms that maintain a constant body temperature rely on the heat produced by cells.Where does this heat come from?

A) Cells have special metabolic pathways that are exclusively for the production of heat.
B) Mitochondria produce heat in the form of ATP.
C) Plants store heat as they perform photosynthesis;when an organism digests a plant,that heat is released.
D) Heat is a natural by-product of most chemical reactions.

Answer 3

D

Question 4

The second law of thermodynamics states that

A) metabolic reactions must be balanced.
B) the flow of energy connects living things to their environment.
C) energy can be created but not destroyed.
D) systems tend to become more disorderly.

Question 5

During photosynthesis,light energy is converted into chemical energy,which is a type of

A) potential energy.
B) kinetic energy.
C) heat.
D) activation energy.

Question 6

A spherical rock rests at the top of a steep hill.The rock has________ energy.

A) potential
B) chemical
C) kinetic
D) no

Question 7

Photosynthetic organisms capture energy from sunlight and convert it into chemical bonds by forming

A) sugars.
B) enzymes.
C) work.
D) heat.

Question 8

The reuse of the same carbon molecules by plants,animals,and their environments over time is known as

A) activation energy.
B) a consumption tree.
C) carbon cycling.
D) the third law of thermodynamics.

Question 9

Complex molecules are built from smaller organic compounds by using energy to drive ________ reactions.

A) catabolic
B) anabolic
C) hydrolysis
D) redox

Question 10

Living systems must work to remain ordered;they pass off their disorder to the universe in the form of

A) light.
B) sound.
C) metabolic heat.
D) water.

Question 11

The term thermal energy describes the

A) orderly movement of electrons along a conductor (such as a wire).
B) movement of photons as they travel through space.
C) attractive power of two magnets toward each other.
D) random movement or vibration of the molecules of any substance (for example,water molecules in a beaker).

Question 12

Imagine a mousetrap with the spring arm set and latched,and with the level of potential energy high.This potential energy was added to the mousetrap

A) when it was first constructed.
B) as kinetic energy when the arm was pulled back and latched.
C) when the latch was released and the arm sprang forward.
D) when the various materials used to construct the mousetrap were selected.

Question 13

In the chemical reaction C₆H₁₂O₆ + 6 O₂ $\rarr$ 6 CO₂ $\rarr$ 6 H₂O,the 6 CO₂ molecules are some of the

A) substrates.
B) products.
C) enzymes.
D) reactants.

Question 14

All molecules have a combination of kinetic energy and potential energy.If an external heat source were used to increase the kinetic energy of a group of molecules,the group's potential energy would

A) decline,because the sum of kinetic energy and potential energy always equals 100 percent.
B) be unaffected,because no changes in the bonding pattern of the molecules would take place.
C) also increase,because potential energy and kinetic energy are directly proportional to each other.
D) decrease,because the potential energy is inversely proportional to the kinetic energy.

Question 15

Heat speeds up chemical reactions by

A) causing the cell to produce enzymes that lower the activation energy of the reactions.
B) decreasing the amount of oxygen available for redox reactions.
C) inhibiting catabolic reactions and promoting anabolic reactions.
D) causing reactants to collide more often.

Question 16

The heat given off by living systems can increase the likelihood that a given chemical reaction will take place.Why?

A) The enzymes that catalyze reactions in living systems increasingly work better as the temperature decreases.
B) The heat lowers the internal cellular temperature,enabling reactions to proceed more quickly.
C) The heat enables photosynthesis to happen more rapidly.
D) The heat speeds molecular movement,increasing the likelihood of collisions between an enzyme and its substrate.

Question 17

The energy required for life processes must be extracted from an organism's

A) nucleus.
B) environment.
C) predators.
D) biosynthesis.

Question 18

When humans cut down trees for lumber to build permanent structures,what aspect of metabolic cycling is disrupted?

A) The oxidation of wood products increases the amount of photosynthesis that can occur.
B) The biosynthetic reactions that happen in the lumber cause too much catabolism to occur.
C) Carbon and other atoms tied up in wooden structures are not being recycled into other living organisms.
D) The DNA in the wood is unable to obey the first law of thermodynamics.

Question 19

In accordance with the first law of thermodynamics,the energy in a gallon of gas consumed in a mileage test is equal to the

A) amount of work performed (a calculation based on miles traveled and the weight of the vehicle).
B) amount of work performed plus the heat created from the friction of moving parts.
C) amount of work performed plus the heat from friction,plus the heat of the exhaust from the motor.
D) amount of work performed plus heat from friction,plus heat from the exhaust,plus the potential energy of combustion products in the exhaust.

Question 20

In photosynthesis,the carbon used to make sugars is

A) provided by enzymes.
B) provided by carbon dioxide.
C) extracted from DNA.
D) oxidized.

Question 21

Which of the following statements about the role of enzymes in chemical reactions is true?

A) An enzyme can be used for many different kinds of chemical reactions.
B) An enzyme is permanently changed during a chemical reaction.
C) An enzyme has a special site where the products bind before the reaction begins.
D) An enzyme lowers the activation energy of a particular reaction.

Question 22

The metabolism of living organisms comprises a series of catabolic reactions and anabolic reactions;both types of reactions are very carefully controlled,enabling the organism to

A) minimize the release of carbon dioxide into the atmosphere.
B) assess its metabolic state and respond appropriately.
C) avoid consuming its food resources too quickly.
D) capture as much of the released energy as possible.

Question 23

Which of the following statements best describes how extremes of pH often disrupt the function of enzymes?

A) They alter the monosaccharides associated with the enzyme.
B) They alter the chemistry of the enzyme's active site.
C) They destroy the substrate of the reaction.
D) They destroy the products of the reaction.

Question 24

What do catalysts and enzymes have in common?

A) They both decrease the number of collisions between substrate molecules during a reaction.
B) They both increase the amount of activation energy required for a reaction to occur.
C) They both increase the amount of substrate available for a reaction.
D) They both decrease the amount of activation energy required for a reaction to occur.

Question 25

Which of the following statements about enzymes is true?

A) In a human cell,one enzyme usually catalyzes no more than five different chemical reactions.
B) In a human cell,nearly all chemical reactions are catalyzed by enzymes.
C) In a human cell,enzymes must be constantly replaced as they are used up in the reactions they catalyze.
D) In a human cell,some enzymes are specialized to store activation energy.

Question 26

Which of the following conditions destroys the three-dimensional structure of proteins?

A) cold temperatures
B) freezing the substrate
C) the presence of cofactors
D) very high salt concentrations

Question 27

Which of the following conditions does NOT disrupt the three-dimensional shape of enzymes or alter their ability to bind to their substrates?

A) cold temperatures
B) high acidity
C) very high salt concentrations
D) high alkalinity

Question 28

Imagine a chemical reaction during which a solution turns from red to green very slowly.If a small piece of platinum is placed in the solution,the change occurs much more rapidly,yet the platinum remains unchanged;this result happens because the platinum

A) provides activation energy.
B) is an enzyme.
C) is a catalyst.
D) is an oxidizing agent.

Question 29

Sometimes enzymes need particular ions or small molecules to reach their highest activity;these ions or small molecules are called

A) inhibitors.
B) cofactors.
C) activators.
D) polyfactorials.

Question 30

An enzyme and its substrate find each other by

A) chance encounter.
B) magnetic attraction.
C) catalysis.
D) oxidative reactions.

Question 31

Some kinds of drain cleaners use enzymes rather than strong,more dangerous chemicals.These enzymes are most likely able to

A) catalyze a catabolic reaction.
B) raise the activation energy of the reaction that clears the clog.
C) create energy that can be used to break up the clog.
D) let excess heat be passed off into the environment.

Question 32

Enzymes can catalyze a chemical reaction only if

A) they encounter a molecule of ATP.
B) their active site is sufficiently oxidized.
C) they have both products in their active site at the same time.
D) they encounter a substrate that fits their active site.

Question 33

Which of the following compounds is the LEAST oxidized?

A) C₆H₁₂O₆
B) CO₂
C) CH₄
D) HCOOH

Question 34

A molecule of sugar slowly burns in a cell.Compared with the original sugar molecules,the products of these catabolic reactions are ________ and have ________.

A) less stable;more energy
B) more stable;more energy
C) more stable;less energy
D) less stable;less energy

Question 35

In the chemical reaction CH₂O + O₂ $\rarr$ CO₂ + H₂O,which of the following results occurs?

A) Carbon is reduced and hydrogen is oxidized.
B) Carbon is oxidized and oxygen is reduced.
C) Carbon and hydrogen are reduced.
D) Carbon and oxygen are oxidized.

Question 36

Which of the following substances is either consumed or synthesized in a large number of cellular reactions?

A) sugars
B) enzymes
C) DNA
D) ATP

Question 37

Most enzymes are members of a special class of

A) proteins.
B) nucleotides.
C) chemical bonds.
D) hormones.

Question 38

In the chemical reaction H₂O + CO₂ $\rarr$ carbonic anhydrase $\rarr$ H⁺ + HCO₃^- + carbonic anhydrase,the carbonic anhydrase is a(n)

A) reactant.
B) product.
C) enzyme.
D) active site.

Question 39

When ATP breaks down into ADP and a free phosphate group,which of the following processes occurs?

A) ADP absorbs energy and transfers it to enzymes.
B) Energy is released and can be used to power cellular activities.
C) ADP becomes the active site in an enzyme.
D) The energy in the broken bond is transferred to the phosphate group.

Question 40

Biosynthetic reactions require many things,including ________ and ________.

A) carbon dioxide;water
B) glucose;water
C) enzymes;ATP
D) sunlight;CTP

Question 41

The sequential reaction pathway A $\rarr$ B $\rarr$ C $\rarr$ D is dependent on enzymes for each separate step.If the pathway starts with A,how many different enzymes would be needed to produce D?

A) just one,used over and over for each step
B) two: one for the conversion of A to B and one for the conversion of C to D
C) three
D) four

Question 42

A calorie represents the

A) number of grams of fat in a food product.
B) number of times an enzyme can be reused before it must be replaced.
C) amount of energy needed to raise the temperature of one liter of water by 1°C.
D) temperature at which a gram of food is completely converted into carbon dioxide.

Question 43

A rotted log exemplifies the operation of the ________ law of thermodynamics.

Question 44

A catalyst is not changed during a chemical reaction,but it affects the ________ at which the reaction occurs.

Question 45

Which of the following organisms is NOT an ectotherm?

A) a snake
B) a lizard
C) most insects
D) a skunk

Question 46

The capture and use of energy by living organisms involves many chemical reactions.Collectively,these processes are known as ________.

Question 47

Carbon dioxide is one product of a metabolic process that occurs in both plants and animals;this process is called ________.

Question 48

The application of modern biological research methods has shown that the most successful strategy for permanent weight loss almost always involves

A) simply eating less and exercising more.
B) consuming BMR activators (supplements that elevate the basal metabolic rate),such as caffeine.
C) changes in body composition,particularly changing connective tissue to muscle.
D) altering the body's ratio of surface area to volume.

Question 49

Comparative studies have repeatedly shown that smaller animals have faster metabolic rates than larger animals.However,human males are larger than human females,yet men have a higher average basal metabolic rate (BMR)than women.Which of the following statements explains this variation in the pattern?

A) Men typically weigh more than women;when standardized for body weight,the average BMR is identical for both genders.
B) The large average body size of men reduces the ratio of surface area to volume;body systems elevate their metabolic rates to compensate for the change.
C) Different tissues have different metabolic rates;the male body has a higher percentage of energy-consuming muscle than the female body.
D) Compared with women,men have larger digestive systems,ingest more food per meal,and metabolize food at a higher rate to maintain body weight homeostasis.

Question 50

Almost all the chemical reactions that occur in cells are catalyzed by ________.

Question 51

When a molecule of methane burns,it produces carbon dioxide,heat,light,and water.The direction of the event is dictated by the ________ law of thermodynamics.

Question 52

The energy input needed to start a chemical reaction is called the ________.

Question 53

In a research study,physiologists monitored the metabolite concentrations generated during exercise in three groups of participants (people with poor fitness,average fitness,and exceptional fitness).Which statement best summarizes this study's findings?

A) Exercise was beneficial to all three groups,but those benefits ended immediately after the exercise stopped;to have significant benefits,exercise must be done for a longer period of time.
B) The least fit participants had extremely low metabolic responsiveness;therefore,people with poor fitness are unlikely to experience benefits from exercise for at least 30 days after starting an exercise program.
C) In all three groups,exercise produced an almost immediate positive metabolic effect in which the strength of the effect was proportional to the participants' fitness levels.
D) Metabolites extracted from the blood of the least fit participants suppressed the metabolism level of cells growing in a tissue culture.

Question 54

Which of the following strategies is NOT used by cells to help enzymes and substrates find each other?

A) locating enzymes that are used in the same biochemical pathway close to each other in the cell
B) having certain reactions occur within a specific organelle
C) embedding enzymes in a membrane in a precise order
D) producing heat to increase the frequency of molecular collisions

Question 55

In an enzyme,the area that has a specialized shape and/or set of chemical properties that enables the enzyme to bind to a particular substrate is called a(n)________.

Question 56

If provided with the proper conditions,enzymes that are recovered from living tissues can be used in cell-free industrial processes.Which of the following statements is an example of such a process?

A) The addition of amylases,lipases,and proteases can improve a detergent's ability to remove wrinkles from clothing.
B) Cellulases and pectinases can digest the proteins in fruit juice,producing a clarified product that is more appealing to consumers.
C) The proteases in pineapples and papayas can tenderize meat by digesting its large fibrous proteins,such as collagen.
D) Rennin,an enzyme from the guts of cows and sheep,has been used for many years to make pasta.

Question 57

When chemical energy is converted into kinetic energy in a biological system,________ of the available energy is converted.

Question 58

In many organelles,groups of different enzymes are located on membranes in close proximity to each other.Why?

A) Attaching enzymes to the membrane prevents the cell from losing them to the surrounding environment.
B) When enzymes are in close proximity,each one can catalyze more than one type of reaction.
C) These enzymes are involved in the same metabolic pathway;keeping them closer together increases the pathway's efficiency.
D) All enzymes must act in groups to sufficiently reduce the amount of activation energy needed for a reaction to occur.

Question 59

Catabolic reactions are tightly coupled to reactions that require energy;those reactions are called ________ reactions.

Question 60

The gain of electrons by one atom from another atom is referred to as ________.

Question 61

The shape of an enzyme does not affect its activity.

Question 62

The enzyme maltase splits the disaccharide maltose into two sugar monomers.Maltose is maltase's ________.

Question 63

An insect devouring a leaf is an example of the second law of thermodynamics in action.

Question 64

Photosynthesis creates energy;cellular respiration destroys energy.

Question 65

The tiny dwarf lemur balances its energy budget by ________ and ________ by burrowing underground.

Question 66

Sugar molecules are more oxidized than carbon dioxide molecules.

Question 67

Oxygen can be reduced.

Question 68

According to the ________ model,an enzyme's active site will adjust its shape to mold around a substrate after binding to that substrate.

Question 69

The organelles where the breakdown products of food are oxidized,generating most of a cell's ATP,are called ________.

Question 70

Organisms that drop their basal metabolic rate (BMR)as cold weather arrives,enabling their body temperature to plummet,are called ________.

Question 71

In a study,researchers put human participants on a treadmill for 10 minutes and then drew blood samples.They found that blood levels of certain "exercise metabolites" increased after the participants exercised.When the researchers added these "exercise metabolites" to mouse muscle cells cultured in a lab dish,the cells increased the rate at which they were burning ________.

Question 72

During a chemical reaction,a cell uses all the chemical energy in ATP.

Question 73

Enzymes catalyze only anabolic chemical reactions.

Question 74

The first law of thermodynamics states that the total energy of a living system and its surroundings remains constant.

Question 75

High temperatures generally cause the three-dimensional configuration of most enzymes to be destroyed.Enzymes that have been affected by high temperatures in this way have been ________.

Question 76

Some enzymes need particular ions or small molecules to attain their highest activity;these enzyme "helpers" are known as ________.

Question 77

When ATP breaks down into ADP and a free phosphate group,energy is given off.

Question 78

Chemical reactions in which reactants have a lower energy content than the products can occur without the input of any energy.

Question 79

Enzymes can make reactions happen that would otherwise be impossible.

Question 80

As a molecule becomes oxidized,it loses electrons.