Deck 9: Introduction to Metabolism

Question 1

For the reaction A + B $\rightarrow$ C + D, the equilibrium constant (Keq) is defined as

A) [A][B]/[C][D].
B) [C][D]/[A][B].
C) [A][D]/[B][C].
D) [B][C]/[A][D].

Answer 1

[C][D]/[A][B].

Question 2

Cells carry out three major types of work; which of the following involves energy for cell motility and the movement of structures within cells?

A) Chemical work.
B) Transport work.
C) Mechanical work.
D) None of the above.

Answer 2

C

Question 3

The __________ law of thermodynamics states that energy can be neither created nor destroyed.

A) first
B) second
C) third
D) fourth

Answer 3

A

Question 4

The most commonly used practical form of energy used in cells is adenosine diphosphate.

Question 5

The amount of heat energy needed to raise 1 gram of water from 14.5 $\degree$ C to 15.5 $\degree$ C is called a(n)

A) joule.
B) calorie.
C) erg.
D) thermal unit.

Question 6

__________ is a measure of the randomness or disorder of a system.

A) Entropy
B) Enthalpy
C) Free energy
D) Synergy

Question 7

A reaction in which the forward rate is equal to the reverse rate is said to be at __________.

Question 8

__________ is the total energy change that accompanies a chemical reaction.

A) Entropy
B) Enthalpy
C) Free energy
D) Synergy

Question 9

In thermodynamic studies, energy changes are analyzed in a collection of matter called a __________. All other matter in the universe is called the __________.

Question 10

__________ reactions capture energy from the organisms' energy source.

Question 11

Cells carry out three major types of work; which of the following involves the synthesis of macromolecules as well as the breakdown of substances for their energy?

A) Chemical work.
B) Transport work.
C) Mechanical work.
D) None of the above.

Question 12

The __________ law of thermodynamics states that physical and chemical processes occur in such a way that randomness (disorder) increases to a maximum.

A) first
B) second
C) third
D) fourth

Question 13

The change in __________ is the amount of energy in a system that is available to do work.

A) entropy
B) enthalpy
C) free energy
D) synergy

Question 14

________ reactions build new organic molecules from smaller inorganic and organic compounds.

Question 15

_________ is the total of all chemical reactions occurring in the cell.

Question 16

A reaction that releases energy is __________.

A) exergonic
B) endergonic
C) impossible
D) none of the choices

Question 17

Energy can be redistributed within a collection of matter (called a system) or can be redistributed between the system and its surroundings.

Question 18

Cells carry out three major types of work; which of the following involves nutrient uptake and waste elimination?

A) Chemical work.
B) Transport work.
C) Mechanical work.
D) None of the above.

Question 19

__________ is the science that analyzes energy changes in a collection of matter.

Question 20

The numerical value of the free energy change indicates how fast a reaction will reach equilibrium.

Question 21

Which of the following is used as an electron carrier by living organisms?

A) NAD⁺
B) NADP⁺
C) ubiquinone
D) all of the choices

Question 22

Disruption of an enzyme's structure with loss of activity caused by extremes of pH, temperature, or other factors is called _________.

Question 23

In order for the cell to be able to input energy into necessary endergonic reactions, energy-generating processes such as photosynthesis, fermentation, and respiration are used to produce __________.

Question 24

Which of the following is not true about enzymes?

A) Enzymes are catalysts that speed up reactions.
B) Enzymes are proteins that can be denatured by changes in pH or temperature.
C) Enzymes are highly specific for the substrates they react with and catalyze only one or a limited set of possible reactions with those substrates.
D) all of the choices

Question 25

The reacting molecules in an enzyme-catalyzed reaction are called __________.

Question 26

A molecule that binds noncovalently to an enzyme at the active site and thereby prevents a substrate from binding and reacting is a(n) __________ inhibitor.

Question 27

A complex formed during a reaction that resembles both the substrates and the products is called the __________ state complex.

Question 28

One of the components used during photosynthetic electron transport is ferredoxin, a nonheme iron protein.

Question 29

Cells must efficiently transfer energy from their energy-trapping systems to the systems actually carrying out work and also use various metabolic processes to replace the energy used in doing work. This is called the __________.

Question 30

A molecule that binds to an enzyme at a location other than the active site and thereby alters the enzyme's shape, making it inactive or less active is a(n) __________ inhibitor.

Question 31

The __________ is the electron donor in a redox reaction.

A) reductant
B) oxidant
C) enzyme
D) product

Question 32

An chemical reaction that requires an input of energy in order to proceed is __________.

A) exergonic
B) endergonic
C) impossible
D) one of the choices

Question 33

The molecules formed by an enzyme-catalyzed reaction are called __________.

Question 34

The electron transport chain is based on the principle that redox couples with more positive reduction potentials will donate electrons to couples with more negative potentials.

Question 35

The standard reduction potential of a redox reaction is a measure of the tendency of the __________ to __________ electrons.

A) reductant; gain
B) reductant; lose
C) oxidant; gain
D) oxidant; lose

Question 36

The __________ __________ is the substrate concentration needed for an enzyme to achieve half maximal velocity.

Question 37

The equilibrium constant for a redox reaction is called the standard reduction potential.

Question 38

The __________ is the electron acceptor in a redox reaction.

A) reductant
B) oxidant
C) enzyme
D) product

Question 39

Electron transport molecules that only transfer electrons include

A) ubiquinone.
B) NADP.
C) FAD.
D) ferredoxin.

Question 40

Some endergonic reactions can be made to proceed forward if they are coupled to hydrolysis of one or more of the phosphates of ATP.

Question 41

The energy required to bring the substrates of a reaction together in the correct way to reach the transition state is called

A) free energy.
B) activation energy.
C) enthalpy.
D) entropy.

Question 42

Enzymes function as catalysts by

A) bringing the substrates together at the active site, in effect concentrating them.
B) bringing the substrates together at the active site correctly oriented for the reaction.
C) bringing the substrates together at the active site, in effect concentrating them and bringing the substrates together at the active site correctly oriented for the reaction.
D) none of the choices

Question 43

RNA molecules that have catalytic activity are known as ____________.

Question 44

Each enzyme normally has specific pH and temperature optima at which they function best.

Question 45

Enzymes increase the rate of a reaction by increasing molecular motion, thereby providing kinetic energy to drive the reaction.

Question 46

If all available enzyme molecules are binding substrate and converting it to produce as rapidly as possible, the reaction is said to be proceeding at __________ velocity.

A) terminal
B) maximal
C) optimal
D) infinite

Question 47

Enzymes are usually named based on

A) the substrates they act on.
B) their molecular structure.
C) the type of reaction they catalyze.
D) all of the choices.
E) the substrates they act on and the type of reaction they catalyze.

Question 48

The most specific term usually used to describe a substance in a biological system that increases the rate of a reaction without being permanently changed by the reaction is a(n)

A) catalyzer.
B) catalyst.
C) enzyme.
D) rate increaser.

Question 49

Enzymes increase the rate of a reaction but do not alter equilibrium constants.

Question 50

A nonprotein component of an enzyme that is loosely attached to the protein component is referred to as a(n)

A) apoenzyme.
B) coenzyme.
C) holoenzyme.
D) prosthetic group.

Question 51

The substrate of an enzyme binds at the

A) affinity site.
B) active site.
C) determinative site.
D) reaction site.

Question 52

The nonprotein component of an enzyme that is firmly attached to the protein is called a(n)

A) apoenzyme.
B) coenzyme.
C) holoenzyme.
D) prosthetic group.

Question 53

A complete enzyme that consists of a protein component and a nonprotein component is called a(n)

A) apoenzyme.
B) heteroenzyme.
C) holoenzyme.
D) multienzyme.

Question 54

The Michaelis constant (Km) of an enzyme is the substrate concentration that produces maximum velocity.

Question 55

One important ribozyme located in mitochondria is responsible for catalyzing peptide bond formation during protein synthesis.

Question 56

Enzyme activity can be greatly affected by the pH and the temperature of the environment in which the enzyme must function.

Question 57

A(n) _______________ increases the rate of a reaction without being permanently altered by the reaction.

A) catalyzer
B) catalyst
C) enzyme
D) rate increaser

Question 58

If an enzyme consists of a protein component and a non-protein component, the protein component is referred as the

A) apoenzyme.
B) coenzyme.
C) holoenzyme.
D) prosthetic group.

Question 59

When the amount of enzyme present is held constant, the rate of a reaction will continue to increase as long as the substrate concentration increases.

Question 60

Enzymes catalyze a reaction by

A) decreasing the amount of energy released by the reaction.
B) increasing the amount of energy released by the reaction.
C) decreasing the activation energy of the reaction.
D) increasing the activation energy of the reaction.

Question 61

When the end product of a pathway inhibits catalysis of the first step of that pathway, this phenomenon is called

A) reversible covalent modification.
B) feedback inhibition.
C) metabolic channeling.
D) non-competitive inhibition.

Question 62

In metabolic channeling, the regulation of metabolic pathways is controlled by the __________ of metabolites and enzymes involved in the pathway.

A) amount
B) location
C) activity
D) all of the choices

Question 63

Which of the following is a reason for metabolic regulation?

A) maintain cell components at appropriate levels
B) conserve materials
C) ensure efficient use energy stores
D) all of the choices

Question 64

In a branched pathway with many end products, an abundance of one of the end products will usually inhibit

A) the first step in the set of pathways.
B) the first committed step in the branch of the pathway leading to the production of that particular product.
C) the last step before the branch leading to the production of that particular end product.
D) the last step in the production of that particular product.

Question 65

Isoenzymes are different enzymes that catalyze the same reaction but can be regulated independently of one another.

Question 66

Enzyme activity can be controlled by

A) allosteric regulation.
B) covalent modification.
C) feedback (end product) inhibition.
D) all of the choices

Question 67

Metabolic channeling involves the localization of __________ in different parts of a cell in order to influence the activity of metabolic pathways.

A) activators
B) repressors
C) substrates and enzymes
D) inhibitors

Question 68

In allosteric regulation, effector molecules usually bind

A) reversibly and covalently.
B) irreversibly and covalently.
C) reversibly and noncovalently.
D) irreversibly and noncovalently.