bio exam 2

why is energy required for active transport?

because it moves solute against their concentration gradient

which of the following plant cells would exhibit the most turgor pressure?

a cell placed in a hypotonic solution

How does the “fluid mosaic model” describe the structure of the plasma membrane?

Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.

Which of the following is correct regarding integral proteins?

These proteins exhibit both hydrophilic and hydrophobic properties.

Which of the following molecules are most abundant in the plasma membrane?

Phospholipids

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?

Exocytosis and smooth and rough ER

Which of the following statements about diffusion is true?

it is a passive process

what functions do carbohydrates fulfill in the plasma membrane?

cell to cell recognition

Which of the following cell structures exhibits selective permeability between a cell and its external environment?

plasma membrane

Which of the following statements about passive transport is correct?

it permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule

The sodium-potassium pump __________.

transports sodium ions out of the cell and transports potassium ions into the cell

Which of these statements describes some aspect of facilitated diffusion?

Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.

The plasma membrane exhibits selective permeability. This means that __________.

the plasma membrane allows some substances to flow through it more easily than others

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?

a large polar molecule

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?

pinocytosis

What function do carbohydrates fulfill in the plasma membrane?

cell to cell recognition

Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?

the cell will decrease in size as water flows out of the cell

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?

the solution is hypertonic

Which of the following is a correct difference between active transport and facilitated diffusion?

active transport requires energy from ATP, and facilitated diffusion does not

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.

membrane potential, electronegative pumps

Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?

proteins embedded in two layers of phospholipids

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?

membrane carbohydrates function primarily in cell to cell recognition

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.

Which of the following statements about diffusion is true?

it is a passive process

Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________.

b, the diffusion gradient in cell B is steeper

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?

phospholipids form a selectively permeable structure

Which of the following is correct regarding peripheral proteins?

these proteins are found only on the surface of the plasma membrane

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?

a nonpolar molecules, such as hydrocarbon

In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.

channel, carrier

How does cholesterol affect membrane fluidity?

at body temperature, it makes the membrane less fluid

The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

1.0M

What function do carbohydrates fulfill in the plasma membrane?

cell to cell recognition

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

carbon dioxide

Which of the following statements about diffusion is true?

it is a passive process

Which of the following statements about a typical plasma membrane is correct?

The two sides of the plasma membrane have different lipid and protein composition.

The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids.

Carbohydrates on the membrane surface are important in determining the overall bilayer structure.

The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell.

Phospholipids are the primary component that determines which solutes can cross the plasma membrane.

the two sides of the plasma membrane have different lipid and protein composition

Which of the following best describes the structure of a biological membrane?

a fluid structure in which phospholipids and proteins move freely between sides of the membrane

a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot

two layers of phospholipids with proteins embedded between the two layers

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

The permeability of a biological membrane to a specific polar solute depends primarily on which of the following?

the amount of cholesterol in the membrane

the types of transport proteins in the membrane

the phospholipid composition of the membrane

the presence of unsaturated fatty acids in the membrane

the types of polysaccharides present in the membrane

the types of transport proteins in the membrane

Which of the following is least likely to be important in holding the components of a biological membrane together?

covalent interactions between the phospholipid and protein components of the membrane

hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane

hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane

hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane

polar interactions among the phospholipid head groups on the same surface of the membrane

covalent interactions between the phospholipid and protein components of the membrane

A semipermeable membrane is placed between the following solutions.

Which solution will decrease in volume?

Solution A: 1.4% (m/v) starch

Solution B: 7.62% (m/v) starch

solution A

A semipermeable membrane is placed between the following solutions.

Which solution will increase in volume?

Solution C: 9% (m/v) NaCl

Solution D: 12.4% (m/v) NaCl

solution D

A red blood cell placed in a hypertonic solution will shrink in a process called crenation. A red blood cell placed in a hypotonic solution will swell and potentially burst in a process called hemolysis.

To prevent crenation or hemolysis, a cell must be placed in an isotonic solution such as 0.9% (m/v) NaCl or 5.0% (m/v) glucose. This does not mean that a cell has a 5.0% (m/v) glucose concentration; it just means that 5.0% (m/v) glucose will exert the same osmotic pressure as the solution inside the cell, which contains several different solutes.

A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur.

• Solution A: 3.21% (m/v) NaCl

• Solution B: 1.65% (m/v) glucose

• Solution C: distilled H₂O

• Solution D: 6.97% (m/v) glucose

• Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl

Drag each solution to the appropriate bin.

A B C D E

crenation: D,A,E

hemolysis: B, C

when molecules move down their concentration, they move from where they are _______ to where they are _______

more concentrated, less concentrated

diffusion across a biological membrane is called _______

passive transport

is osmosis a type of diffusion?

yes

   What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?    

amphipathic nature

Which of the following particles could diffuse easily through a cell membrane?

Oxygen (o2)

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.    

true

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?  

hypotonic

Facilitated diffusion is a type of _______.

passive transport

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

Which of the following statements about osmosis is correct? S

Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment.

If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis.

Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration.

The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.

If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell.

if a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell

In facilitated diffusion, what is the role of the transport protein? See Concept 7.3 (Page)

Transport proteins provide the energy for diffusion of the solute.

Transport proteins organize the phospholipids to allow the solute to cross the membrane.

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

Transport proteins provide a low-resistance channel for water molecules to cross the membrane.

Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane.

transport proteins provide a hydrophilic route for the solute to cross the membrane

Which of the following statements correctly describe(s) the driving forces for diffusion of Na⁺ and K⁺ ions through their respective channels? Select all that apply.  

1- The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.

2- The diffusion of Na+ ions into the cell is impeded by the electrical gradient across the plasma membrane.

3- The diffusion of K+ ions out of the cell is impeded by the K+ concentration gradient across the plasma membrane.

4- The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane.

5- The electrochemical gradient is larger for Na+ than for K+.

1,4,5

Which of the following statements is TRUE with regard to this animation?

Sodium ions are transported down their concentration gradient.

Both sodium and potassium ions are transported against their concentration gradients.

The cell does not expend ATP.

Potassium ions are transported down their concentration gradient.

The cell is not expending energy.

both sodium and potassium ions are transported against their concentration gradient

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?

passive transport

diffusion

active transport

osmosis

facilitated diffusion

active transport

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following?

cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

passive diffusion of the glucose through the lipid bilayer

facilitated diffusion of the glucose using a carrier protein

receptor-mediated endocytosis

movement of glucose into the cell through a glucose channel

cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

Active and passive transport of solutes across a membrane typically differ in which of the following ways?

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.

Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute.

Active transport is used for ions, passive transport is used for uncharged solutes.

Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers.

Active transport is always faster than passive transport.

active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy

Endocytosis moves materials _____ a cell via _____.    

out of ... diffusion

into ... membranous vesicles

out of ... membranous vesicles

into ... facilitated diffusion

into ... a transport protein

into… membranous vesicles

You can recognize the process of pinocytosis when _____.

the cell is engulfing a large particle

a receptor protein is involved

the cell is engulfing extracellular fluid

the cell is engulfing a large particle

A white blood cell engulfing a bacterium is an example of _____.    

pinocytosis

facilitated diffusion

receptor-mediated endocytosis

exocytosis

phagocytosis

phagocytosis

Which of the following correctly describes some aspect of exocytosis or endocytosis?

The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane.

These two processes require the participation of mitochondria.

Exocytosis and endocytosis temporarily change the surface area of the plasma membrane.

Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol.

Endocytosis and exocytosis involve passive transport.

exocytosis and endocytosis temporarily change the surface area of the plasma membrane

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

confined to the hydrophobic interior of the membrane.

free to depart from the fluid membrane and dissolve in the surrounding solution.

spread in a continuous layer over the inner and outer surfaces of the membrane.

randomly oriented in the membrane, with no fixed inside-outside polarity.

embedded in a lipid bilayer.

embedded in a lipid bilayer

Which of the following factors would tend to increase membrane fluidity?

a greater proportion of saturated phospholipids

a lower temperature

a relatively high protein content in the membrane

a greater proportion of unsaturated phospholipids

a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses

a greater proportion of saturated phospholipids

Which of the following processes includes all others?

transport of an ion down its electrochemical gradient

diffusion of a solute across a membrane

passive transport

facilitated diffusion

osmosis

passive transport

Biologists use the fluid mosaic model to describe membrane structure.

Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.

1- The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.

2- The diverse proteins found in and attached to membranes perform many important functions.

3- Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.

4- The kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together.

5- Membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer.

1,2,3

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells.

Which of the following would be a factor that determines whether the molecule selectively enters the target cells?

the phospholipid composition of the target cells’ plasma membrane

the similarity of the drug molecule to other molecules that are transported into the target cells

the concentration of the drug molecule that is transported in the blood

the nonpolar, hydrophobic nature of the drug molecule

the similarity of the drug molecule to other molecules that are transported into the target cells

At low pH, a particular enzyme catalyzes a reaction at a high rate. At neutral pH, the enzyme is completely inactive. What statement best explains the difference in how pH affects the function of this enzyme?

• Low pH causes the enzyme to denature, and neutral pH causes the enzyme to function normally.

• The enzyme functions best at both low and neutral pH.

• Neutral pH provides the optimal environment in which this enzyme functions.

• pH has no effect on enzyme function.

• The enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional

the enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional

How does ATP drive transport work inside a cell?

• By removing a phosphate from a transport protein

• By binding to motor proteins

• By removing free energy from a chemical reaction

• By phosphorylating a transport protein

• By providing free energy to facilitate the formation of polymers from monomers

by phosphorylating a transport protein

At low temperatures, a particular enzyme catalyzes a reaction, but at a slow rate. At high temperatures, the enzyme is completely inactive. What statement best explains the difference in how temperature affects the function of this enzyme?

• Temperature has no effect on enzyme function.

• High temperature provides the optimal environment in which this enzyme functions.

• At low temperatures, there is not enough free energy for the enzyme to function at a high rate, and at high temperatures, the enzyme is denatured, leaving it nonfunctional.

• Low temperatures cause the enzyme to denature, and high temperatures cause the enzyme to move too fast to bind to its substrate.

• The enzyme functions best at both low and high temperatures.

At low temperatures there is not enough free energy for the enzyme to function at a high rate and at high temperatures, the enzyme is denatured leaving it nonfunctional.

The primary manner in which cells manage their energy resources in order to do work is called energy coupling. Which of the following statements accurately defines energy coupling?

• Endergonic and exergonic reactions occur independently of each other.

• Anabolic reactions drive catabolic reactions.

• Endergonic reactions drive exergonic reactions.

• Chemical reactions in cells are always at equilibrium.

• Exergonic reactions drive endergonic reactions.

exergonic reactions drive endergonic reactions

Enzyme activity is affected by pH because __________.

• most substrates don't function well at high or low pH

• low pH will denature all enzymes

• changes in pH can cause loss of cofactors from the enzyme

• high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site

• the binding of hydrogen ions to the enzyme absorbs energy and thus there may not be enough energy to overcome the activation energy barrier

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site

What best characterizes the role of ATP in cellular metabolism?

• The free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate.

• The release of free energy during the hydrolysis of ATP heats the surrounding environment.

• It is catabolized to carbon dioxide and water.

• The ΔG associated with its hydrolysis is positive.

• The charge on the phosphate group of ATP tends to make the molecule very water-soluble.

the free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosaphorylated intermediate

Which of the following statements is correct regarding ATP?

• The energy in an ATP molecule is released from the adenine group.

• ATP molecules do not release free energy when hydrolyzed.

• ATP cannot transfer energy to other molecules.

• The energy in an ATP molecule is released through hydrolysis of one of the phosphate groups.

• The energy in an ATP molecule is released from the ribose group.

the energy in an ATP molecule is released through hydrolysis of one of the phosphate groups

Which of the following statements about the active site of an enzyme is correct?

• The active site has a fixed structure (shape).

• Coenzymes are rarely found in the active site of an enzyme.

• The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.

• The active site allows the reaction to occur under the same environmental conditions as the reaction without the enzyme.

• The structure of the active site is not affected by changes in temperature.

the active site may resemble a groove or pocket in the surface of a protein into which the substrate fots

Which of the following states the relevance of the first law of thermodynamics to biology?energyu

• Energy can be freely transformed among different forms as long as the total energy is conserved.

• Energy is destroyed as glucose is broken down during cellular respiration.

• Living organisms must increase the entropy of their surroundings.

• Photosynthetic organisms produce energy in sugars from sunlight.

• The total energy taken in by an organism must be greater than the total energy stored or released by the organism.

energy can be freely transformed among different forms as long as the total energy is conserved

Which of the following statements is correct regarding competitive and noncompetitive enzyme inhibitors?

• Competitive inhibitors bind to the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away from the active site.

• Only competitive inhibitors affect enzyme function.

• Neither type of inhibitor affects enzyme function.

• Competitive inhibitors do not bind directly to the active site of an enzyme while noncompetitive inhibitors do.

• Inhibitors always bind irreversibly to an enzyme.

competitive inhibitors bind t the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away from the active site

ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called __________.

• competitive inhibition

• feedback inhibition

• positive feedback

• denaturing

• cooperativity

feedback inhibition

Cells use ATP constantly, but ATP is considered a renewable resource. What process makes this possible?

• ATP can be regenerated by the addition of a phosphate group to ADP.

• The hydrolysis of ATP is an irreversible reaction.

• None of the listed responses is correct.

• ADP is generated by the addition of a phosphate group to ATP.

• ADP and ATP are stored in large amounts in a cell.

ATP can be regenerated by the addition of a phosphate group to ADP

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________.

• noncompetitive inhibition

• allosteric regulation

• feedback inhibition

• competitive inhibition

• cooperativity

allosteric regulation

What would the value of ΔS be for a chemical reaction in which a molecule is broken down into smaller components?

• Neutral

• Negative

• Zero

• Positive

positive

Which of these statements about enzyme inhibitors is true?

• A competitive inhibitor binds to the enzyme at a place that is separate from the active site.

• Inhibition of enzyme function by compounds that are not substrates is something that only occurs under controlled conditions in the laboratory.

• A noncompetitive inhibitor does not change the shape of the active site.

• The action of inhibitors may be reversible or irreversible.

• When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback.

the action of inhibitors may be reversible or irreversible

Which of the following reactions would be endergonic?

• C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O

• HCl → H+ + Cl

• ATP → ADP + Pi

• Glucose + fructose → sucrose

• All of the listed responses are correct.

glucose +fructose= sucrose

An exergonic reaction __________ free energy, and an endergonic reaction __________ free energy.

• releases; absorbs

• absorbs; absorbs

• releases; releases

• destroys; creates

• absorbs; releases

releases, absorbs

Which of the following is true regarding metabolic pathways?

• Metabolic pathways are not important to a cell’s ability to function.

• Metabolic pathways consist of a single chemical reaction.

• Metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme.

• Metabolic pathways consist of only anabolic pathways.

• Each reaction in the pathway is catalyzed by the same enzyme.

metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme

How does ATP drive mechanical work inside a cell?

• By removing a phosphate from a transport protein

• By binding to motor proteins

• By phosphorylating a transport protein

• By providing free energy to facilitate the formation of polymers from monomers

• By removing free energy from a chemical reaction

by binding to motor proteins

As ATP begins to build up in a cell, metabolism slows down. How does this happen?

• ATP acts as an allosteric inhibitor to many of the enzymes involved in metabolism, thus slowing their function.

• ATP binds to the active sites of many of the enzymes involved in metabolism, causing them to stop functioning.

• ATP acts as an activator, increasing the rate of its production.

• None of the listed responses is correct.

• Excess ATP causes many of the enzymes involved in metabolism to denature.

ATP acts as an allosteric inhibitor involved in metabolism, thus slowing their functions

Which of the following statements is correct regarding kinetic and potential energy?

• None of the listed responses is correct.

• Chemical energy is a type of kinetic energy, and thermal energy is a type of potential energy.

• Potential energy cannot be converted to kinetic energy.

• Potential energy is related to the relative motion of objects, and kinetic energy is the energy that matter possesses because of its location or structure.

• Kinetic energy is associated with the relative motion of objects, and potential energy is the energy that matter possesses because of its location or structure.

kinetic energy is associated with the relative motion of objects, and potential energy is the energy that matter possess because of its location or structure

Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?

• All of the listed responses are correct.

• All types of cellular respiration produce ATP.

• Cellular respiration releases some energy as heat.

• The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water.

the aerobic respiration of one molecule of glucose produces 6 molecules each of carbon dioxide and water

Which of the following is changed by the presence of an enzyme in a reaction?

• The G value for the reactants

• The magnitude of ΔG

• The activation energy

• The G value for the products

• The sign of ΔG

activation energy

Which of the following statements correctly describes cofactors and coenzymes?

• Both are nonprotein enzyme helpers; but most coenzymes are metal ions, and most cofactors are organic molecules.

• Neither cofactors nor coenzymes assist enzyme function.

• Cofactors that are metal ions activate enzymes, but coenzymes deactivate them.

• Both cofactors and coenzymes act as allosteric inhibitors to various enzymes.

• Both are nonprotein enzyme helpers; but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor.

both are nonprofit enzyme helpers, but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor

Which of the following statements about enzymes is true?

• All of the listed responses are correct.

• Enzymes react with their substrate (form chemical bonds), forming an enzyme-substrate complex, which irreversibly alters the enzyme.

• Enzymes increase the rate of a reaction by raising the activation energy for reactions.

• The more heat that is added to a reaction, the faster the enzymes will function.

• Enzymes speed up the rate of the reaction without changing the ΔG for the reaction.

enzymes speed up the rate of the reaction without changing the change G for the reaction

Which of the following correctly states the relationship between anabolic and catabolic pathways?

• Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.

• Energy derived from catabolic pathways is used to drive the breakdown of organic molecules in anabolic pathways.

• The flow of energy between catabolic and anabolic pathways is reversible.

• Degradation of organic molecules by anabolic pathways provides the energy to drive catabolic pathways.

• Catabolic pathways produce usable cellular energy by synthesizing more complex organic molecules.

anabolic pathways synthesize more complex molecules using the energy derived from catabolic pathways

An exergonic (spontaneous) reaction is a chemical reaction that __________.

• is common in anabolic pathways

• releases energy when proceeding in the forward direction

• occurs only when an enzyme or other catalyst is present

• leads to a decrease in the entropy of the universe

• cannot occur outside of a living cell

release energy when proceeding in the forward direction

In general, the hydrolysis of ATP drives cellular work by __________.

• releasing free energy that can be coupled to other reactions

• acting as a catalyst

• lowering the free energy of the reaction

• changing to ADP and phosphate

• releasing heat

releasing free energy that can be coupled to the other reactions

Which of the following statements about enzyme function is correct?

• None of the listed responses is correct.

• Enzymes can change the equilibrium point of reactions, but they cannot speed up reactions because they cannot change the net energy output.

• Enzymes can greatly speed up reactions, but they cannot change the activation energy because they cannot change the net energy output.

• Enzymes can greatly speed up reactions, but they cannot change the net energy output because they cannot change the activation energy.

• Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.

Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

• Heat is being used by the organism as a source of energy.

• Energy input into the organism must be occurring to drive the decrease in entropy.

• In this situation, the second law of thermodynamics must not apply.

• The entropy of the organism's environment must also be decreasing.

• The first law of thermodynamics is being violated.

energy input into the organism must be occurring to drive the decrease in entropy

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely.

What can you do to regain the activity of the enzyme?

Removing the irreversible inhibitor should get the reaction working again.

The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.

Adding more substrate will increase the rate of reaction.

Adding more inhibitor should get the reaction up to speed again.

the enzyme is inactive at this point. new enzyme must be added to regain enzyme activity

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down.

What can you do to speed the reaction up again?

Add more inhibitor to speed up the reaction.

Add more substrate; it will outcompete the inhibitor and increase the reaction rate.

Increase the temperature.

Increase the pH.

add more substrate; it will outcompete the inhibitor and increase the reaction rate.

Consider a situation in which the enzyme is operating at optimum temperature and pHpH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

Increase the pHpH.

Increase the temperature.

Increase the enzyme concentration.

Increase the substrate concentration.

increase the enzyme concentration

The Haber process is typically carried out at a temperature of approximately 500∘C∘C. What would happen to the rate of the forward reaction if the temperature were lowered to 100∘C∘C?

The reaction rate would increase.

The reaction rate would not change.

The reaction rate would decrease.

the reaction rate would decrease