Ch. 5 Mastering Biology

Question 1

What is the function of cholesterol in the cell membrane?

Answer 1

Stabilization of phospholipids.

Question 2

What enhances the fluidity of an animal cell plasma membrane?

Answer 2

Cholesterol molecules.

Question 3

How are the lipids arranged in a cell membrane?

Answer 3

The nonpolar parts of two lipids point toward each other.

Question 4

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by what?

Answer 4

Proteins.

Question 5

Most cellular work is powered by the transfer of a phosphate group from one molecule to another in what process?

Answer 5

Phosphorylation.

Question 6

What is another word for exergonic?

Answer 6

Energy-releasing.

Question 7

What is another word for endergonic?

Answer 7

Energy-requiring.

Question 8

What is the energy shuttle between exergonic and endergonic reactions?

Answer 8

ATP.

Question 9

What speeds up chemical reactions of the cell?

Answer 9

Enzymes.

Question 10

What mechanism enables precise control over the cell’s chemical reactions?

Answer 10

Feedback inhibition.

Question 11

What is metabolism?

Answer 11

The collective chemical reactions in a cell.

Question 12

What is kinetic energy?

Answer 12

The energy of a moving object.

Question 13

What is chemical energy?

Answer 13

The potential energy of molecules.

Question 14

What can easily pass through a membrane’s lipid bilayer?

Answer 14

Small, nonpolar, hydrophobic molecules such as fatty acids.

Question 15

What is a type of passive transport that does not require the cell to expend ATP?

Answer 15

Diffusion.

Question 16

What is an ideal osmotic environment for an animal cell?

Answer 16

Isotonic.

Question 17

How will a plant cell be if it is surrounded by an isotonic solution?

Answer 17

Flaccid (limp).

Question 18

What happens to an animal cell in a hypotonic solution?

Answer 18

The cell gains water, swells, and possibly bursts.

Question 19

What happens to an animal cell in a hypertonic solution?

Answer 19

The cell loses water and plasmolyzes.

Question 20

What kind of solution has a net diffusion of water outside the animal cell?

Answer 20

Hypertonic.

Question 21

What kind of solution is the ideal osmotic environment for a plant cell?

Answer 21

Hypotonic.

Question 22

What allows diffusion to occur?

Answer 22

Presence of transport protein.

Question 23

What does a transport protein facilitate?

Answer 23

The movement of solute across the plasma membrane.

Question 24

What allows water to cross the plasma membrane via facilitated diffusion?

Answer 24

Aquaporins.

Question 25

What moves solutes against their concentration gradient?

Answer 25

Active transport.

Question 26

What does diffusion move?

Answer 26

Substances down their concentration gradient.

Question 27

What does active transport require?

Answer 27

The expenditure of cellular energy.

Question 28

What happens in exocytosis?

Answer 28

A vesicle inside the cell fuses with the plasma membrane and release its contents outside the cell.

Question 29

What happens in endocytosis?

Answer 29

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

Question 30

What happens in facilitated diffusion?

Answer 30

Molecules move across the plasma membrane using a transport protein.

Question 31

What happens in diffusion?

Answer 31

Molecules move across the plasma membrane by crossing the lipid bilayer.

Question 32

What happens in active transport?

Answer 32

Molecules move against their concentration gradient.

Question 33

What is the process of a white blood cell engulfing a bacterium?

Answer 33

Phagocytosis.

Question 34

Phagocytosis is to eating as pinocytosis is to what?

Answer 34

Drinking.

Question 35

Where do cells store energy that they use for work?

Answer 35

In the arrangement of atoms within molecules.

Question 36

What is energy?

Answer 36

The capacity to cause change (do work).

Question 37

What are two forms of energy?

Answer 37

Kinetic and potential.

Question 38

What are examples of kinetic energy?

Answer 38

Light and heat.

Question 39

What is the energy of motion?

Answer 39

Kinetic energy.

Question 40

What is the energy of location or structure?

Answer 40

Potential energy.

Question 41

What is an example of potential energy?

Answer 41

Chemical energy.

Question 42

What is the first law of thermodynamics?

Answer 42

Energy cannot be created or destroyed.

Question 43

What is the second law of thermodynamics?

Answer 43

Energy can be transferred or transformed and always increases disorder or randomness.

Question 44

What is entropy?

Answer 44

Disorder or randomness.

Question 45

What can some energy be converted into?

Answer 45

Heat.

Question 46

What happens to chemical energy that is extracted from molecules by cellular activities but is not used for cellular work?

Answer 46

The energy contributes to the entropy of the system.

Question 47

What is an example of an endergonic process?

Answer 47

The synthesis of glucose from carbon dioxide and water.

Question 48

What reaction releases energy?

Answer 48

Exergonic.

Question 49

What reaction absorbs energy?

Answer 49

Endergonic.

Question 50

What is the transfer of a phosphate group to a molecule or compound?

Answer 50

Phosphorylation.

Question 51

Most cellular work is accomplished by ___, which energizes molecules by ___ them.

Answer 51

ATP ... phosphorylating.

Question 52

Because enzymes are catalysts, what do they change?

Answer 52

The rate of a reaction without being consumed by a reaction.

Question 53

What happens when an enzyme catalyzes a reaction?

Answer 53

It lowers the activation energy of the reaction.

Question 54

Why is an enzyme considered a catalyst?

Answer 54

It speeds up a chemical reaction without being used up.

Question 55

What is the reactant called in a catalyzed reaction?

Answer 55

Substrate.

Question 56

The shape of an enzyme's ___ matches only particular reactants.

Answer 56

Active site.

Question 57

What strains bonds and helps the reaction proceed between an active site and its substrate?

Answer 57

The induced fit.

Question 58

What is often a vitamin that binds to an enzyme and plays a role in catalysis?

Answer 58

Coenzyme.

Question 59

What denatures an enzyme?

Answer 59

High temperatures or changes in pH.