Chapter 5

Question 1

Second Law of Thermodynamics

Answer 1

Energy tends to disperse spontaneously.

Question 2

First Law of Thermodynamics

Answer 2

Energy cannot be created or destroyed.

Question 3

Kinetic Energy

Answer 3

The energy of motion.

Question 4

Potential Energy

Answer 4

Stored energy.

Question 6

Activation Energy

Answer 6

Minimum amount of energy required to start a reaction.

Question 7

Endergonic

Answer 7

Describes a reaction that requires a net input of free energy to proceed.

Question 8

Exergonic

Answer 8

Describes a reaction that ends with a net release of free energy.

Question 9

Catalysis

Answer 9

The acceleration of a reaction by a molecule that is unchanged by participating in the reation.

Question 11

Substrate

Answer 11

A molecule that is specifically acted upon by an enzyme.

Question 12

Product

Answer 12

A molecule that remains at the end of a reaction.

Question 14

Reactant

Answer 14

A molecule that enters a reation.

Question 15

Transition State

Answer 15

Point during a reaction at which substrate bonds reach their breaking point and the reaction will run spontaneously.

Question 16

Metabolic Pathway

Answer 16

Series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule.

Question 17

Induced-Fit Model

Answer 17

The concept that substrate binding to an active site of an enzyme improves the fit between the two molecules.

Question 18

Antioxidant

Answer 18

Substance that prevents oxidation of other molecules.

Question 19

ATP

Answer 19

The nucleotide adenosine trphosphate.

Question 20

Allosteric

Answer 20

Describes a region of an enzyme that can bind a regulatory molecule and is not the active site.

Question 21

Active Site

Answer 21

Of an enzyme, pocket in which substrates bind and a reaction occurs.

Question 22

Cofactor

Answer 22

A metal ion or a coenzyme that associates with an enzyme and is necessary for its function.

Question 23

Phosphorylation

Answer 23

Transfer of a phosphate group from one molecule to another.

Question 24

Energy

Answer 24

The capacity to do work.

Question 25

Electron Transfer Chain

Answer 25

Array of enzymes and other molecules that accept and give up electrons in sequence, thus releasing the energy of the electrons in usable increments.

Question 26

Recognition Protein

Answer 26

Plasma membrane protein that identifies a cell as belonging to self (one’s own body).

Question 27

Transport Protein

Answer 27

Protein that passively or actively assists specific ions or molecules across a membrane.

Question 28

ATP/ADP Cycle

Answer 28

Process by which cells regenerate ATP. ADP forms when ATP loses a phosphate group, then ATP forms again as ADP gains a phosphate group.

Question 29

Hypertonic

Answer 29

Describes a fluid that has a high overall solute concentration relative to another fluid.

Question 30

Hypotonic

Answer 30

Describes a fluid that has a low overall solute concentration relative to another fluid.

Question 31

Coenzyme

Answer 31

An organic molecule that is a cofactor.

Question 32

Fluid Mosaic

Answer 32

Model of a cell membrane as a two-dimensional fluid of mixed composition.

Question 33

Feedback Inhibition

Answer 33

Mechanism in which a change that results from some activity decreases or stops the activity.

Question 34

Concentration Gradient

Answer 34

Difference in concentration between adjoining regions of fluid.

Question 35

Entropy

Answer 35

Measure of how much the energy of a system is dispersed.

Question 37

Isotonic

Answer 37

Describes two fluids with identical solute concentrations.

Question 38

Endocytosis

Answer 38

Process by which a cell takes in a small amount of extracellular fluid by the ballooning inward of its plasma membrane.

Question 40

Calcium Pump

Answer 40

Active transport protein; pumps calcium ions across a cell membrane against their concentration gradient.

Question 41

Pinocytosis

Answer 41

Endocytosis of bulk materials.

Question 42

Diffusion

Answer 42

Spontaneous spreading of molecules or ions in a liquid or gas.

Question 43

Osmosis

Answer 43

The diffusion of water across a selectively permeable membrane in response to a concentration gradient.

Question 44

Exocytosis

Answer 44

Process by which a cell expels a vesicle’s contents to extracellular fluid.

Question 45

Phagocytosis

Answer 45

“Cell eating”; an endocytic pathway by which a cell engulfs particles such as a microbes or cellular debris.

Question 46

Concentration

Answer 46

Number of molecules or ions per unit volume.

Question 47

Osmotic Pressure

Answer 47

Amount of turgor that prevents osmosis into cytoplams or other hypertonic fluid.

Question 48

Receptor Protein

Answer 48

Plasma membrane protein that binds to a particular substance outside of the cell.

Question 50

Active Transport

Answer 50

Energy-requiring mechanism in which a transport protein pumps a solute across a cell membrane against its concentration gradient.

Question 51

Passive Transport

Answer 51

Mechanism by which a concentration gradient drives the movement of a solute across a cell membrane through a transport protein. Requires no energy input.

Question 53

Turgor

Answer 53

Pressure that fluid exerts against a wall, membrane, or other structure that contains it.

Question 54

Adhesion Protein

Answer 54

Membrane protein that helps cells stick together in animal tissues.

Question 58

Redox Reaction

Answer 58

Oxidation-reduction reaction, in which one molecule accepts electrons (it becomes reduced) from another molecule (which becomes oxidized).