Deck 5: The Working Cell

Question 1

When a cell uses chemical energy to perform work,it uses the energy released from a(n)reaction to drive a(n)reaction.

A)endergonic ...exergonic
B)exergonic ...spontaneous
C)exergonic ...endergonic
D)spontaneous ...exergonic

Answer 1

C

Question 2

Which of the following statements regarding membrane function is false?

A)The plasma membrane is the control center of the cell.
B)The plasma membrane has receptors for chemical messages.
C)The plasma membrane forms a selective barrier around the cell.
D)The plasma membrane plays a role in signal transduction.

Answer 2

A

Question 3

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell.The presence of these organelles tells you that the environment

A)contains a higher concentration of solutes than the protozoan.
B)is isotonic to the protozoan.
C)is hypotonic to the protozoan.
D)is hypertonic to the protozoan.

Answer 3

C

Question 4

The fluid mosaic model describes the plasma membrane as consisting of

A)carbohydrates and phospholipids that can drift in the membrane.
B)two layers of phospholipids with cholesterol sandwiched between them.
C)diverse proteins embedded in a phospholipid bilayer.
D)a phospholipid bilayer with embedded carbohydrates.

Question 5

Which of the following statements regarding enzyme function is false?

A)An enzyme's function depends on its three- dimensional shape.
B)Enzymes emerge unchanged from the reactions they catalyze.
C)Enzymes are very specific for certain substrates.
D)Enzymes are used up when they catalyze a chemical reaction,so must be synthesized for each new chemical reaction.

Question 6

A cell that neither gains nor loses water when it is immersed in a solution must be

A)metabolically inactive.
B)hypotonic to its environment.
C)hypertonic to its environment.
D)isotonic to its environment.

Question 7

You are adrift in the Atlantic Ocean,and,being thirsty,drink the surrounding seawater.As a result,

A)your cells become turgid.
B)you quench your thirst.
C)your cells lyse from excessive water intake.
D)you dehydrate yourself.

Question 8

Which of the following statements regarding membrane protein function is false?

A)Membrane proteins form junctions between cells.
B)Membrane proteins serve as enzymes.
C)Membrane proteins act as receptors to molecules like hormones.
D)Membrane proteins transfer genetic information to the cytoplasm.

Question 9

Facilitated diffusion across a biological membrane requires and moves a substance its concentration gradient.

A)transport proteins ...against
B)transport proteins ...down
C)energy and transport proteins ...against
D)energy and transport proteins ...down

Question 10

In the reaction A -B + C + heat,

A)there is a net input of energy.
B)the potential energy of the products is less than that of the reactant.
C)the potential energy of the products is greater than that of the reactant.
D)entropy has decreased.

Question 11

Which of the following is a typical feature of an ATP- driven active transport mechanism?

A)The solute moves against the concentration gradient.
B)The transport protein must cross to the correct side of the membrane before the solute can bind to it.
C)The transport protein is irreversibly phosphorylated as transport takes place.
D)The transport protein catalyzes the conversion of ADP to ATP.

Question 12

Which of the following statements regarding thermodynamics is false?

A)An automobile engine is a closed system because it does not exchange energy and matter with its surroundings.
B)A single cell or the planet Earth could be a thermodynamic system.
C)Thermodynamics is the study of energy transformations that occur in a collection of matter.
D)An open system exchanges both energy and matter with its surroundings.

Question 13

Which of the following statements regarding diffusion is false?

A)Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.
B)Diffusion requires no input of energy into the system.
C)Diffusion occurs even after equilibrium is reached and no net change is apparent.
D)Diffusion is a result of the thermal energy of atoms and molecules.

Question 14

In the lab,you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water.The solution in the balloon is relative to the solution in the beaker.

A)hydrophilic
B)hypotonic
C)hypertonic
D)isotonic

Question 15

Most of a cell's enzymes are

A)carbohydrates.
B)amino acids.
C)proteins.
D)lipids.

Question 16

An energy barrier

A)is the amount of energy that must be produced by the reactants to end a chemical reaction.
B)prevents the spontaneous breakdown of molecules in the cell.
C)is higher than the activation energy of a reaction.
D)can only be overcome with the use of enzymes.

Question 17

Which of the following processes is endergonic?

A)the synthesis of glucose from carbon dioxide and water
B)cellular respiration
C)the burning of wood
D)the breakdown of glucose

Question 18

Which figure depicts an animal cell placed in a solution hypotonic to the cell?

A)cell A
B)cell B
C)cell C
D)cell D

Question 19

Plasma membranes are selectively permeable.This means that

A)the plasma membrane allows some substances to enter or leave a cell more easily than others.
B)anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy.
C)glucose cannot enter the cell.
D)plasma membranes must be very thick.

Question 20

White blood cells (WBCs)are more resistant to lysis than red blood cells (RBCs).When looking at a sample of blood for WBCs,what could you do to reduce interference from RBCs?

A)Mix the blood in a hypotonic solution,which will cause the RBCs to lyse.
B)Mix the blood in a hypertonic solution,which will cause the RBCs to lyse.
C)Mix the blood in an isotonic solution and allow the WBCs to float to the top.
D)Mix the blood in a salty solution to cause the RBCs to lyse.

Question 21

In the lab,you use a special balloon that is permeable to water,but not sucrose,to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water.Which of the following will occur?

A)Sucrose will enter the balloon.
B)Water will enter the balloon.
C)Water will leave the balloon.
D)Sucrose will leave the balloon.

Question 22

Bacterial production of the enzymes needed for the synthesis of the amino acid tryptophan declines with increasing levels of tryptophan and increases as tryptophan levels decline.This is an example of

A)irreversible inhibition.
B)competitive inhibition.
C)noncompetitive inhibition.
D)feedback inhibition.

Question 23

The active site of an enzyme is

A)the highly changeable portion of an enzyme that adapts to fit the substrates of various reactions.
B)the region of an enzyme that attaches to a substrate.
C)the region of a substrate that is changed by an enzyme.
D)the region of a product that detaches from the enzyme.

Question 24

Heating inactivates enzymes by

A)causing enzyme molecules to stick together.
B)breaking the covalent bonds that hold the molecule together.
C)removing phosphate groups from the enzyme.
D)changing the enzyme's three- dimensional shape.

Question 25

Kinetic energy differs from chemical energy in that

A)kinetic energy can be converted into various forms of energy,whereas chemical energy can only be converted into heat.
B)kinetic energy is the energy of a moving object,whereas chemical energy is the potential energy of molecules.
C)chemical energy is a particular form of kinetic energy.
D)kinetic energy is stored energy that has the potential to do work,and chemical energy is the energy of movement.

Question 26

Which characteristic promoted the utilization of lipids as the first cell membrane?

A)self- assembly into a simple membrane
B)ability to form an impermeable membrane
C)formation of a semi- solid membrane
D)spontaneous degradation of the intracellular environment

Question 27

How does inhibition of an enzyme- catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?

A)Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site.
B)Competitive inhibitors bind to the enzyme reversibly; noncompetitive inhibitors bind to it irreversibly.
C)Competitive inhibitors change the enzyme's tertiary structure; noncompetitive inhibitors cause polypeptide subunits to dissociate.
D)Competitive inhibitors interfere with the enzyme; noncompetitive inhibitors interfere with the reactants.

Question 28

A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue.This illustrates

A)that energy transformations are typically 100% efficient.
B)the second law of thermodynamics.
C)the first law of thermodynamics.
D)that some energy is destroyed in every energy conversion.

Question 29

When an enzyme catalyzes a reaction,

A)it raises the activation energy of the reaction.
B)it acts as a reactant.
C)it lowers the activation energy of the reaction.
D)it is used once and discarded.

Question 30

The energy required to initiate an exergonic reaction is called

A)input energy.
B)the activation energy.
C)exergonic energy.
D)endergonic energy.

Question 31

Diffusion does not require the cell to expend ATP.Therefore,diffusion is considered a type of

A)passive transport.
B)endocytosis.
C)exocytosis.
D)active transport.

Question 32

Inhibition of an enzyme is irreversible when

A)covalent bonds form between inhibitor and enzyme.
B)a competitive inhibitor is involved.
C)a noncompetitive inhibitor is involved.
D)the shape of the enzyme is changed.

Question 33

Membrane phospholipids

A)have hydrophilic tails that face outward and are exposed to water.
B)have hydrophobic heads that face the center of the membrane and are shielded from water.
C)remain fluid because they are tightly packed against one another.
D)are able to drift about in the plasma membrane

Question 34

Anything that prevents ATP formation will most likely

A)force the cell to rely on ADP for energy.
B)have no effect on the cell.
C)result in cell death.
D)force the cell to rely on lipids for energy.

Question 35

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place,the water will

A)exhibit a net movement to the side with lower free water concentration.
B)exhibit an equal movement in both directions across the membrane.
C)exhibit a net movement to the side with lower solute concentration.
D)exhibit a net movement to the side with higher free water concentration.

Question 36

In a hypotonic solution,an animal cell will

A)shrivel.
B)neither gain nor lose water.
C)experience turgor.
D)lyse.

Question 37

Which of the following statements regarding active transport is false?

A)Active transport requires the cell to expend energy.
B)Active transport uses ATP as an energy source.
C)Active transport can move a solute against its concentration gradient.
D)Active transport is driven by the concentration gradient.

Question 38

According to ,energy cannot be created or destroyed.

A)the second law of thermodynamics
B)Aristotle's first principle
C)the third law of thermodynamics
D)the first law of thermodynamics

Question 39

Oxygen crosses a plasma membrane by

A)passive transport.
B)active transport.
C)pinocytosis.
D)osmosis.

Question 40

All cells are enclosed by a plasma membrane that is similar in and .

A)lucidity ...texture
B)permeability ...content
C)structure ...function
D)thickness ...composition

Question 41

A child is brought to the hospital with a fever of 107°F.Doctors immediately order an ice bath to lower the child's temperature.Which of the following statements offers the most logical explanation for this action?

A)Elevated body temperatures will increase the energy of activation needed to start various chemical reactions in the body.This will interfere with the ability of enzymes to catalyze vital chemical reactions.
B)Elevated body temperatures cause molecules to vibrate more quickly and prevent enzymes from easily attaching to reactants.This would slow vital body reactions.
C)Elevated body temperature will increase reaction rates in the child's cells and overload the limited number of enzymes found in the cell.
D)Elevated body temperatures may denature enzymes.This would interfere with the cell's abilities to catalyze various reactions.

Question 42

The transfer of a phosphate group to a molecule or compound is called

A)carboxylation.
B)hydrogenation.
C)ionization.
D)phosphorylation.

Question 43

Which of the following energy transfers is impossible in living systems?

A)chemical energy to kinetic energy
B)heat to light energy
C)light energy to potential energy
D)light energy to chemical energy

Question 44

Osmosis can be defined as

A)the diffusion of water.
B)active transport.
C)the diffusion of a solute.
D)the diffusion of nonpolar molecules.

Question 45

ATP can be used as the cell's energy exchange mechanism because

A)ATP is a disposable form of chemical energy,used once and then discarded by the cell.
B)endergonic reactions can be fueled by coupling them with the formation of ATP from ADP.
C)ATP is the most energy- rich small molecule in the cell.
D)endergonic reactions can be fueled by coupling them with the hydrolysis of high- energy phosphate bonds in ATP.

Question 46

Which of the following statements is true among all types of passive transport?

A)Only small polar molecules are able to cross the plasma membrane.
B)Ions never cross the plasma membrane by passive transport.
C)The concentration gradient is the driving force.
D)Proteins are needed to transport molecules across the membrane.

Question 47

Which of the following statements about the ATP molecule is true?

A)It contains five phosphate groups.
B)It releases energy when one phosphate group leaves ATP.
C)Extremely stable bonds link the second and third phosphate groups.
D)It contains the sugar glucose.

Question 48

If placed in tap water,an animal cell will undergo lysis,whereas a plant cell will not.What accounts for this difference?

A)the relative impermeability of the plant cell wall to water
B)the expulsion of water by the plant cell's central vacuole
C)the fact that plant cells are isotonic to tap water
D)the relative inelasticity and strength of the plant cell wall

Question 49

The molecules responsible for membrane transport are

A)proteins.
B)steroids.
C)carbohydrates.
D)phospholipids.

Question 50

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach.This enzyme is a protein.Which of the following processes could be responsible for its secretion?

A)pinocytosis
B)diffusion
C)endocytosis
D)exocytosis

Question 51

Cells acquire LDLs by

A)receptor- mediated endocytosis.
B)pinocytosis.
C)diffusion.
D)phagocytosis.

Question 52

Which of the following examples is classified as a metabolic pathway?

A)osmosis
B)passive diffusion
C)protein synthesis
D)cell lysis

Question 53

Phagocytosis is to eating as pinocytosis is to

A)drinking.
B)osmosis.
C)chewing.
D)lysis.

Question 54

Many of the enzymes that control a deep- sea firefly squid's ability to produce light energy from chemical energy are located

A)within mitochondria.
B)within chloroplasts.
C)outside of cells.
D)in membranes.

Question 55

A plant cell in a hypotonic solution

A)becomes turgid because of an inflow of water.
B)bursts because of an inflow of water.
C)wilts because of an outflow of water.
D)shrivels because of an outflow of water.

Question 56

Small,nonpolar,hydrophobic molecules such as fatty acids

A)require transport proteins to pass through a membrane's lipid bilayer.
B)easily pass through a membrane's lipid bilayer.
C)very slowly diffuse through a membrane's lipid bilayer.
D)are actively transported across cell membranes.

Question 57

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

A)a small,nonpolar molecule such as butane (C4H10)
B)CO2
C)Na+
D)O2

Question 58

What is the basic difference between exergonic and endergonic reactions?

A)Exergonic reactions involve ionic bonds; endergonic reactions involve covalent bonds.
B)Exergonic reactions release energy; endergonic reactions absorb it.
C)Exergonic reactions involve the breaking of bonds; endergonic reactions involve the formation of bonds.
D)In exergonic reactions,the reactants have less chemical energy than the products; in endergonic reactions,the opposite is true.

Question 59

Which of the following is a coenzyme?

A)iodine
B)vitamin B6
C)iron
D)zinc

Question 60

The process of a white blood cell engulfing a bacterium is

A)pinocytosis.
B)osmosis.
C)receptor- mediated endocytosis.
D)phagocytosis.

Question 61

Which of the following substances could be a cofactor?

A)a protein
B)a ribosome
C)a polypeptide
D)a zinc atom

Question 62

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

A)proteins.
B)phospholipids.
C)cholesterol.
D)glycolipids.

Question 63

Which of the following processes can move a solute against its concentration gradient?

A)passive transport
B)active transport
C)osmosis
D)facilitated diffusion

Question 64

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell is called

A)signal transduction.
B)selective permeability.
C)competition.
D)inhibition.

Question 65

Which part of the ATP molecule breaks free of the rest when an ATP molecule is used for energy?

A)part A
B)part B
C)part C
D)part D

Question 66

Glucose molecules provide energy to power the swimming motion of sperm.In this example,the sperm are changing

A)kinetic energy into thermal energy.
B)chemical energy into potential energy.
C)chemical energy into kinetic energy.
D)kinetic energy into potential energy.

Question 67

The cholesterol associated with animal cell membranes

A)is attached to membrane proteins and extends into the watery environment surrounding the cell.
B)is an abnormality resulting from a diet high in cholesterol.
C)helps solidify the membranes when the room temperature is below freezing.
D)helps to stabilize the cell membrane at body temperature.

Question 68

Which of the following statements regarding enzymes is true?

A)Enzymes are inorganic.
B)All enzymes depend on protein cofactors to function.
C)An enzyme's function is unaffected by changes in pH.
D)Enzymes catalyze specific reactions.

Question 69

Substrates bind to an enzyme's site.

A)active
B)inhibitory
C)phosphate
D)allosteric

Question 70

When physicians perform an organ transplant,they choose a donor whose tissues match those of the recipient as closely as possible.Which of the following cell components are being matched?

A)plasma membrane cholesterols
B)plasma membrane proteins
C)plasma membrane phospholipids
D)cell- surface carbohydrates

Question 71

A major function of glycoproteins and glycolipids in the cell membrane is to

A)glue cells together to form tissues.
B)help the cell retain its shape.
C)allow the cells of an embryo to sort themselves into tissues and organs.
D)attach the cell membrane to the cytoskeleton.