Deck 7: Energy and Enzymes

Question 1

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

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

Answer 1

A

Question 2

Living systems must work to remain ordered. They pass off their disorder in the form of

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

Answer 2

C

Question 3

Which of the following is either consumed or synthesized in virtually every cellular reaction?

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

Answer 3

D

Question 4

The metabolism of living organisms is made up of a series of reactions. These reactions are carefully controlled so that the organism

A) releases less carbon dioxide into the atmosphere.
B) has time to react to its environment.
C) doesn't use up its food source too quickly.
D) can capture as much of the released energy as possible.

Question 5

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 says that all cells have the same energy transfer system.
C) The breaking of 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.

Question 6

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

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

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

In photosynthesis, the carbon used to make sugars is

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

Question 9

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

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

Question 10

Which of the following compounds is the least oxidized?

A) C6H11O6
B) CO2
C) CH4
D) HCOOH

Question 11

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

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

Question 12

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 while promoting anabolic reactions.
D) causing substrate molecules to collide more often.

Question 13

In the reaction CH₂O + O₂ ® CO₂ + H₂O,

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 14

When ATP breaks down into ADP and a phosphate group,

A) energy is absorbed by ADP and transferred to enzymes.
B) energy is released and can 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 15

This graph depicts the amount of energy involved over the course of a chemical reaction.
The graph indicates that

A) the products of this reaction have more energy that the substrates.
B) this reaction requires an input of energy to convert glucose and O2 to H2O and CO2.
C) this reaction can only run in one direction (from left to right on the graph).
D) this reaction only occurs in the presence of an enzyme.

Question 16

A molecule of sugar slowly "burns" in one of your cells. The products of these catabolic reactions are ___________ than the original sugar molecules.

A) less stable and have more energy
B) more stable and have more energy
C) more stable and have less energy
D) less stable and have less energy

Question 17

_______ reactions use energy to build complex molecules.

A) Catabolic
B) Anabolic
C) Photosynthetic
D) Redox

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 reduces the amount of photosynthesis that can occur.
B) The biosynthetic reactions that occur 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

The second law of thermodynamics states that

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

Question 20

In the reaction X + Y ® Z, Z is the

A) substrate.
B) product.
C) enzyme.
D) carbon molecule.

Question 21

You observe that a solution turns from red to green very slowly. If you place a small piece of platinum in the solution, the change occurs much more rapidly, yet the platinum remains unchanged. Which of the following best explains this experimental result?

A) The platinum provided activation energy.
B) The platinum is an enzyme.
C) The platinum is a catalyst.
D) The platinum is an oxidizing agent.

Question 22

COX-2 inhibitors like Vioxx control inflammation without affecting COX-1, but patients taking these drugs are more susceptible to heart attack and stroke. Which of the following is a possible explanation of this side effect?

A) These newer COX-2 inhibitors must still interact with COX-1.
B) In creating these specific COX-2 inhibitors, scientists have changed the shape of aspirin so much that it no longer interacts with COX-2 at all.
C) In addition to controlling fever and inflammation, COX-2 plays a role in the maintaining the proper function of the circulatory system (heart and blood).
D) Inhibiting both COX-1 and COX-2 is necessary to prevent inflammation.

Question 23

A calorie represents

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

Question 24

Biosynthetic reactions require many things, including

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

Question 25

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

A) locating enzymes used in the same biochemical pathway near each other in the cytoplasm
B) having certain reactions occur within a specific organelle
C) embedding more enzymes in the plasma membrane
D) producing heat to increase the frequency of molecular collisions

Question 26

What do catalysts and enzymes have in common?

A) They decrease the number of collisions between substrate molecules.
B) They increase the amount of activation energy required.
C) They increase the amount of substrate that is available.
D) They decrease the amount of activation energy required.

Question 27

In a human cell,

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

Question 28

Enzymes can catalyze a reaction only

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

Question 29

Some kinds of drain cleaners use enzymes rather than strong, more dangerous chemicals. These enzymes must be 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) allow excess heat to be passed off into the environment.

Question 30

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

A) Special metabolic pathways exist just for the production of heat.
B) Mitochondria produce heat in the form of ATP.
C) Plants store up 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.

Question 31

A given enzyme

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

Question 32

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

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 and keeping them closer together increases the efficiency of the pathway.
D) all enzymes must act in groups to sufficiently reduce the amount of activation energy required for a reaction to occur.

Question 33

In the reaction H₂O + CO₂ + carbonic anhydrase® HCO₃- + H⁺+ carbonic anhydrase, carbonic anhydrase is a(n)

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

Question 34

In the figure below, E1, E2 and E3 represent three enzymes in the membrane of a mitochondrion.
Which of the following is true?

A) B is the product of the activity of E2 and the substrate of E3.
B) If E2 doesn't function properly, A will not be produced.
C) E2 is the product of E1 and the substrate of E3.
D) C is the substrate for E1.

Question 35

An enzyme and its substrate find each other by

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

Question 36

Enzymes are a special class of

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

Question 37

This image diagrams the action of an enzyme.
Notice that the enzyme is depicted as being more tightly wrapped around the substrates in step 2 than it is in step 1. Why is this?

A) When a substrate locks into the active site of an enzyme, the enzyme changes shape to mold itself around the substrates.
B) Generally, the size of a substrate is larger than the size of the active site it must fit into. When the substrate enters the active site, the active site must stretch to fit.
C) Before catalysis can occur, a substrate must change its shape so that it fits into the active site of the enzyme more precisely.
D) Most active sites are only designed to hold one substrate. In this image, two substrates enter the active site, creating a tighter fit.

Question 38

In general, smaller animals have

A) longer life spans than larger animals.
B) slower metabolic rates than larger animals.
C) faster metabolic rates than larger animals.
D) the same life spans as larger animals.

Question 39

Higher metabolic rates may shorten life spans, because

A) enzymes get used up more quickly than the cell can produce them.
B) toxic by-products build up quickly and are more likely to damage DNA.
C) cells and organs that run faster also wear out faster.
D) anabolism outpaces catabolism.

Question 40

The heat given off by living systems can increase the likelihood of a given chemical reaction's taking place. Why is this true?

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

Question 41

_______ are the organelles where the breakdown products of food are oxidized, thereby generating most of a cell's ATP.

Question 42

Catabolic reactions are tightly coupled to _______ reactions that require energy.

Question 43

_______ blocks the activity of both COX-1 and COX-2 enzymes.

Question 44

All of the chemical energy in ATP is used during a chemical reaction

Question 45

A molecule of methane burns, producing carbon dioxide, heat, light, and water. The direction of the event is dictated by the __________ law of thermodynamics.

Question 46

According to the _____ ______ model, the active site of an enzyme adjusts its shape to mold around a substrate after binding.

Question 47

The capture and use of energy by living organisms involves numerous chemical reactions. Together all of these processes are known as _______.

Question 48

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

Question 49

Carbon dioxide is the product of the metabolic process called ____________ that occurs in both plants and animals.

Question 50

A rotted log indicates that the ____________ law of thermodynamics has been operating.

Question 51

When chemical energy is converted into kinetic energy in a biological systems, _____ [more than all, less than all, or all] of the available energy is converted.

Question 52

An enzyme splits a disaccharide into two sugar monomers. The disaccharide is the _________ of this enzyme.

Question 53

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

Question 54

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

Question 55

The chemical reactions that occur in cells are catalyzed by _______ .

Question 56

Photosynthesis creates energy and cellular respiration destroys energy.

Question 57

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

Question 58

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

Question 59

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

Question 60

The _______ of an enzyme is an area with a specialized shape and/or set of chemical properties that allows the enzyme to bind with a particular substrate.

Question 61

Sugar molecules are more oxidized than carbon dioxide molecules.

Question 62

Chemical reactions can occur without the input of any energy.

Question 63

Exposing many proteins to high heat causes their three-dimensional shape to change. How might heat affect the function of an enzyme?

Question 64

Enzymes catalyze only anabolic chemical reactions.

Question 65

The shape of an enzyme does not affect its activity.

Question 66

Oxygen can be reduced.

Question 67

As a molecule becomes more oxidized, it loses electrons.

Question 68

Enzymes can make otherwise impossible reactions happen.