Biology 1 (Biology 1610) CH.8 - "An introduction to Metabolism."

The cell does 3 main kinds of work. What are they?

1. Chemical work 2. Transport work 3. Mechanical work

What is the structure of ATP (adenosine triphosphate)?

1. The sugar ribose 2. The nitrogenous base adenine 3. A chain of 3 phosphate groups.

Which of the following terms best describes a chemical reaction for which ΔG is positive? A. exergonic B. spontaneous C. endergonic D. enthalpic

C

This is the name given to the process by which the body converts food energy to energy stored in ATP:

Cellular respiration

An explosion or the rusting of an old car over time are examples of: A. Entropy B. Spontaneous process C. Metabolic breakdown D. Both A and B

D

For a system at equilibrium, G (free energy) is at its: A. Highest possible value in that system. B. Equal value in that system. C. Lower value in that system. D. Lowest possible value in that system.

D (Free energy increases when a reaction is somehow pushed away from equilibrium, perhaps by removing some of the products)

A change of a single amino acid at a position distant from the active site of an enzyme can alter the substrate specificity by changing the ________. A. by changing the intracellular location of the enzyme B. by changing the binding site for a competitive inhibitor C. by changing the 3-D shape of the enzyme D. by changing the stability the enzyme

C

Liquid in a thermos bottle, is unable to exchange either energy or matter with its surroundings outside the thermos. This is an example of: A. Systems B. Surroundings C. Isolated system D. Open system

C

Chemical energy is a form of _____ energy. A. motion B. heat C. potential D. kinetic E. entropic

C (Chemical energy is a form of stored energy.)

___________ ___________ is kinetic energy associated with the random movement of atoms or molecules.

Thermal energy

If a chemical process is ______________ (downhill), releasing energy in one direction, then the reverse process must be _________________ (uphill), using energy.

exergonic, endergonic

Chemical equilibrium is reached when: A. the forward and reverse reactions occur at the same rate. B. concentrations of products are higher than the concentrations of reactants. C. there are equal concentrations of reactants and products. D. concentrations of reactants and products remain the same.

A

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. A. exergonic; endergonic B. work; energy C. free energy; entropy D. exergonic; spontaneous

A

Which of the terms below best describes a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway? A. cooperative inhibition B. feedback inhibition C. allosteric inhibition D. metabolic inhibition

B

Zinc is an essential trace element for most organisms. Zinc is required in the active site of the enzyme carboxypeptidase where it most likely functions in which of the following ways? A. as a coenzyme derived from a vitamin B. as a cofactor necessary for enzyme activity C. as a noncompetitive inhibitor of the enzyme D. as an allosteric activator of the enzyme

B

Which of the following statements best describes metabolism in its entirety in all organisms? A. Metabolism uses all of an organism's resources. B. Metabolism manages the increase of entropy in an organism. C. Metabolism depends on a constant supply of energy from food. D. Metabolism consists of all the energy transformation reactions in an organism.

D

Does the breaking of bonds release energy or require energy?

Require energy. (when a bond is formed energy is released.)

What is the name of the barrier that must be overcome before products are formed in a spontaneous reaction? A. activation energy B. the equilibrium point C. entropy D. free energy

A

Which of the following is the strongest evidence that protein structure and function are correlated? A. Denatured (unfolded) proteins do not function normally. B. Proteins can readily form hydrogen bonds with water. C. Enzymes tend to be globular in shape. D. Proteins have four distinct levels of structure and many functions.

A

A specific molecule is altered in a series of defined steps, resulting in a certain product. Each step is catalyzed by a specific enzyme, a macromolecule that speeds up a chemical reaction. This is an example of: A. Energy B. Thermal Energy C. Anabolic pathways D. Metabolic pathways

D

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? A. Additional substrate will be formed. B. The reaction will change from endergonic to exergonic. C. The free energy of the system will change. D. Nothing; the reaction will stay at equilibrium.

D

Enzymes work by _____. A. increasing the potential energy difference between reactant and product B. decreasing the potential energy difference between reactant and product C. adding energy to a reaction D. adding a phosphate group to a reactant E. reducing EA

E (Enzymes do not affect this potential energy difference. Enzymes work by reducing the energy of activation.)

Which of these is exhibiting kinetic energy? A. an archer with a flexed bow B. a rock on a mountain ledge C. a person sitting on a couch while watching TV D. the high-energy phosphate bonds of a molecule of ATP E. a space station orbiting Earth

E (Kinetic energy is energy of motion.)

The bonds between the phosphate groups of ATP can be broken by _____________. When the terminal phosphate bond is broken by addition of a water molecule, a molecule of inorganic phosphate leaves the ATP, which becomes adenosine diphosphate, or ADP.

hydrolysis

A pool player uses the motion of the cue stick to push the cue ball, which in turn moves the other balls; water gushing through a dam turns turbines; and the contraction of leg muscles pushes bicycle pedals. These are examples of: A. Kinetic energy B. Thermal energy C. Potential energy D. Chemical energy

A

Enzymes are described as catalysts, which means that they __________. A. increase the rate of a reaction without being consumed by the reaction B. are proteins increase the free energy of the reactants to make the reaction go faster C. can alter the free energy change (ΔG) for a chemical reaction D. provide activation energy for the reactions they facilitate

A

Select the correct statement about chemical energy, a term used by biologists to refer to potential energy available for release in a chemical reaction. A. Light energy is converted to chemical energy during photosynthesis. B. A photosynthetic cell within a plant leaf produces chemical energy, stored within glucose molecules. C. When a glucose molecule is catabolized to CO2 and H2O, chemical energy is lost.

A

Which of the following statements best describes a primary mechanism by which the energy released in ATP hydrolysis is used directly to drive endergonic chemical reactions in a cell? A. The released phosphate is used to form phosphorylated intermediates that are more reactive than the original unphosphorylated substrate. B. Binding of ATP to an enzyme active site converts an endergonic reaction to an exergonic reaction. C. The phosphate is combined with ADP to regenerate ATP. D. Free energy is released as heat, which speeds up the rate of endergonic reactions.

A

______________ is a macromolecule that acts as a catalyst, a chemical agent that speeds up a reaction without being consumed by the reaction. A. Enzyme B. Protein C. Lipid D. Cholesterol

A

Consumes energy to build complicated molecules from simpler ones. This is known as: A. Thermal energy B. Catabolic pathways C. Anabolic pathways D. Bioenergeitcs

C

Most cells cannot harness heat to perform work because: A. heat does not involve a transfer of energy. B. cells do not have much thermal energy; they are relatively cool. C. temperature is usually uniform throughout a cell. D. heat can never be used to do work.

C

What occurs if a cell reaches metabolic equilibrium?

The cell dies. (The fact that metabolism as a whole is never at equilibrium is one of the defining features of life.)

A process that, on its own, leads to a decrease in entropy is said to be ____________________.

non-spontaneous

Which of the following is a chemical reaction? A. The formation of a covalent bond between two amino acids. B. Making a hydrogen bond between a water molecule and a sugar molecule. C. Changing a carbon atom to a nitrogen atom by radioactive decay. D. The melting of ice.

A (Chemical reactions involve the making and breaking of chemical bonds, leading to changes in the composition of matter.)

When ATP is hydrolyzed to activate a target protein, what is often the fate of the inorganic phosphate that is released? A. It enters the nucleus to be incorporated in a nucleotide. B. It may be used to form a phosphorylated intermediate. C. It is secreted as waste. D. It is always used to regenerate more ATP.

B

Which of the following statements best describes an example of a reaction that may be at chemical equilibrium in a cell? A. an exergonic reaction in which the entropy change in the cell is precisely balanced by an opposite entropy change in the cell's surroundings B. an exergonic reaction in which the free energy at equilibrium is higher than the energy content of the reaction at any point away from equilibrium C. a chemical reaction in which there is no change in the net concentrations of reactants or products at that time in the cell D. an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment

C

Which of the following statements best describes the central role that ATP plays in cellular metabolism? A. Hydrolysis of the terminal phosphate group from ATP stores free energy that is used for cellular work. B. The terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules. C. ATP provides energy coupling between exergonic and endergonic reactions. D. Hydrolysis of ATP provides an input of free energy for exergonic reactions.

C

Which of these are by-products of cellular respiration? A. ATP and carbon dioxide B. glucose, carbon dioxide, and water C. heat, carbon dioxide, and water D. carbon dioxide and water E. ATP, carbon dioxide, and water

C (While ATP is produced by cellular respiration, it is not considered a by-product of the process.)

Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes? A. the enzyme binds a cofactor that interacts with the substrate to facilitate the reaction B. binding of the substrate to the active site can stretch bonds in the substrate that need to be broken C. the active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction D. the active site can provide heat from the environment that raises the energy content of the substrate E. the binding of two substrates in the active site provides the correct orientation for them to react to form a product

D

Which of the following statements best describes catabolic pathways? A. They require energy from ATP hydrolysis to break down polymers into monomers. B. They are endergonic and release energy that can be used for cellular work. C. They combine small molecules into larger, more energy-rich molecules. D. They are exergonic and provide energy that can be used to produce ATP from ADP and Pi.

D

Which of the following statements is consistent with the second law of thermodynamics? A. Without an input of energy, the entropy of an organism would tend to decrease over time. B. Every energy transformation performed by an organism decreases the entropy of the universe. C. A gain of free energy in a system is never associated with conversion of energy from one form to another. D. A constant input of energy is required to maintain the high level of organization associated with living cells.

D

Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones? A. dehydration B. anabolism (anabolic pathways) C. metabolism D. catabolism (catabolic pathways)

D

Which of the following types of reactions would decrease the entropy within a cell? A. catabolic reactions B. digestion C. hydrolysis D. anabolic reactions

D

An _____________ ______________ proceeds with a net release of free energy.

exergonic reaction

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________________ is to _________________. A. exergonic; spontaneous B. exergonic; endergonic C. free energy; entropy D. work; energy

B

Some metabolic pathways release energy by breaking down complex molecules to simpler compounds. This is known as: A. Thermal energy B. Catabolic pathways C. Anabolic pathways D. Bioenergetics

B

Transport and mechanical work in the cell are also nearly always powered by: A. Diffusion B. Hydrolysis of ATP C. Kinetic energy D. Selective permeability

B

Which statement about the binding of enzymes and substrates is correct? A. Substrate molecules bind to the active site of the enzyme only by weak bonds, such as hydrogen bonds or hydrophobic attraction. B. When substrate molecules bind to the active site of the enzyme, the enzyme undergoes a slight change in shape. C. Substrate molecules fit into the active site of an enzyme like a key fits into a lock.

B (As the substrate enters the active site, the enzyme changes shape slightly due to interactions between the substrate's chemical groups and chemical groups on the side chains of the amino acids that form the active site. This shape change makes the active site fit even more snugly around the substrate. This induced fit is like a clasping handshake.)

Which of the following statements about ATP (adenosine triphosphate) is correct? A. The hydrolysis of ATP can supply energy needed for catabolic pathways. B. The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. C. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. D. Almost all of the free energy released in the hydrolysis of ATP is released as heat. E. The hydrolysis of ATP is an endergonic process.

B (Catabolic pathways provide the energy needed to make ATP from ADP and Pi. The hydrolysis of ATP to ADP + Pi releases the same amount of energy, which can be used to drive anabolic pathways.)

Which of the following statements about equilibrium of chemical reactions is correct? A. The equilibrium point of a reaction represents the least stable configuration for that reaction. B. A reaction that is at equilibrium is not capable of doing any work. C. The equilibrium point is where the system has the highest free energy D. Most reactions in a living cell are close to equilibrium. E. Reactions can only go in the direction toward equilibrium.

B (The ΔG for a reaction at equilibrium is zero, which means that there is no free energy available to do any work.)

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction? A. by binding to the active site of the enzyme, thus preventing binding of the normal substrate B. by increasing the activation energy of the reaction C. by binding to an allosteric site, thus changing the shape of the active site of the enzyme D. by decreasing the free-energy change of the reaction catalyzed by the enzyme

C

An ________________ _______________ is one that absorbs free energy from its surroundings.

endergonic reaction

The totality of an organism's chemical reactions is called: A. Metabolic pathways B. Emergent property C. Metabolism D. Anabolic pathways

C

"Every energy transfer or transformation increases the entropy of the universe." This is the first or second law of thermodynamics?

The second law of thermodynamics

Scientists use a quantity called ___________ as a measure of molecular disorder, or randomness. The more randomly arranged a collection of matter is, the greater its ___________.

entropy

Without regulation by ______________, chemical traffic through the pathways of metabolism would become terribly congested because many chemical reactions would take such a long time.

enzymes

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to: A. add more of the enzyme. B. heat the solution to 90°C. C. add more substrate. D. add a noncompetitive inhibitor.

A

Which of the following statements best describes an exergonic reaction? A. The reaction proceeds with a net release of free energy. B. The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. C. A net input of energy from the surroundings is required for the reaction to proceed. D. The products have more total energy than the reactants.

A

Water behind a dam is an example of what type of energy? A. Thermal energy B. Metabolic energy C. Anabolic energy D. Potential energy

D

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions? A. The enzyme contains both α-helix and β-pleated sheet regions. B. The enzyme has two distinct active sites. C. The enzyme is subject to both competitive inhibition and allosteric regulation. D. The enzyme is composed of at least two identical subunits.

B

Which of the following is a characteristic feature of anabolic pathways? A. They decrease the entropy of the organism and its environment. B. They consume energy to build up polymers from monomers. C. They release energy by degrading polymers to monomers. D. They are usually spontaneous chemical reactions.

B

Which of the following statements best describes a system at chemical equilibrium? A. The system consumes energy at a steady rate. B. The system can do no work. C. The kinetic energy of the system is zero. D. The system releases energy at a steady rate.

B

Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do? A. Hydrolysis reactions increase G, or Gibbs free energy of the system. B. Hydrolysis reactions are exergonic and increase entropy of the system. C. Hydrolysis reactions are endergonic and increase entropy of the system. D. Hydrolysis reactions are exergonic and decrease entropy of the system.

B

Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is correct? A. This is the process of cellular respiration, an anabolic pathway that releases free energy. B. The entropy of the products is greater than the entropy of the reactants. C. The entropy of the universe decreases as the result of this reaction. D. The free energy lost in this combustion is less than the energy that appears as heat. E. The reverse reaction, making glucose from water and carbon dioxide, must be an exergonic reaction.

B (A large molecule (glucose) has been converted into several smaller molecules (water and carbon dioxide); thus, the products have more disorder (greater entropy) than the reactants.)

Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy? A. potential energy with the heat released from a living organism B. potential energy with the covalent bonds of a sugar molecule C. kinetic energy with the energy associated with a gradient of ions across a membrane D. potential energy with the motion of individual molecules E. kinetic energy with the energy related to the height of a bird above the ground

B (Bonds are a form of potential energy because the energy arises from the relative positions of the atoms that form the bond.)

In the citric acid cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. This reaction is inhibited by malonate, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate molecules to those of malonate in the reaction reduces the inhibitory effect of malonate. What role does malonate play with respect to succinate dehydrogenase? A. Malonate is a noncompetitive inhibitor. B. Malonate is an allosteric regulator. C. Malonate is a competitive inhibitor. D. Malonate blocks the binding of fumarate.

C

In the citric acid cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. This reaction is inhibited by malonate, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Which of the following statements best describes the role played by molecules described in the reaction? A. Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction. B. Succinate dehydrogenase is the enzyme, and malonate is the substrate in the reaction. C. Succinate is the substrate, and fumarate is the product in the reaction. D. Fumarate is the product, and malonate is a noncompetitive inhibitor in the reaction.

C

Penicillin is an antibiotic that kills bacteria by binding to the active site of an enzyme involved in synthesis of the bacterial cell wall. Which of the following phenomena best describes the mechanism of action of penicillin? A. allosteric regulation B. feedback inhibition C. competitive inhibition D. noncompetitive inhibition

C

Some bacteria are metabolically active in hot springs because: A. they are able to maintain a lower internal temperature. B. high temperatures make catalysis unnecessary. C. their enzymes have high optimal temperatures. D. their enzymes are completely insensitive to temperature.

C

The first law of Thermodynamics states: A. Energy can be created or destroyed, but it cannot be transferred or transformed. B. Energy can be transformed or destroyed, but cannot be created or transferred. C. Energy can be transferred or transformed but cannot be created or destroyed. D. None of the above

C

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements best describes a term in this equation? A. ΔH is the change in entropy, the energy available to do work. B. ΔS is the change in enthalpy, a measure of randomness. C. ΔG is the change in free energy. D. T is the temperature in degrees Celsius.

C

The ΔG of ATP hydrolysis in a test tube under standard conditions is -7.3 kcal/mol. The ΔG for the reaction A+B C under the same conditions is +4.0 kcal/mol. How would the addition of an enzyme that catalyzes A+B C most likely alter the coupled reactions? A. It would increase the rate of production of C and decrease the overall ΔG for the coupled reactions. B. It would increase the rate of production of C and increase the overall ΔG for the coupled reactions. C. It would result in no change in the overall ΔG for the coupled reactions. D. It would result in no change in the rate of production of C and decrease the overall ΔG for the coupled reactions.

C

This transformation also occurs in the engine of a car when the hydrocarbons of gasoline react explosively with oxygen, releasing the energy that pushes the pistons and producing exhaust. This is an example of: A. Thermal energy B. Catabolic energy C. Chemical energy D. Anabolic energy

C

Which of the following statements best summarizes a consequence of the second law of thermodynamics? A. If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe. B. Each chemical reaction in an organism must decrease the total entropy of the universe. C. If entropy of a system decreases, there must be a corresponding increase in the entropy of the universe. D. If the entropy of a system decreases, there must be a corresponding decrease in the entropy of the universe.

C

Which of the following statements best summarizes an important consequence of the first law of thermodynamics for living organisms? A. An organism grows by converting energy into organic matter. B. The entropy of an organism decreases with time as the organism grows in complexity. C. Each organism ultimately must obtain all of the necessary energy for life from its environment. D. The energy content of a single organism is constant.

C

Which of the following statements about the role of ATP in cell metabolism is true? A. The free energy released by ATP hydrolysis has a much more negative ΔGΔG value than the hydrolysis of phosphate groups from other phosphorylated molecules. B. The phosphate bonds of ATP are unusually strong bonds. C. The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule.

C (A key feature in the way cells manage their energy resources to do this work is energy coupling, the use of an exergonic process to drive an endergonic one. ATP is responsible for mediating most energy coupling in cells, and in most cases it acts as the immediate source of energy that powers cellular work. Read about energy coupling.)

"Conservation of energy" refers to the fact that _____. A. the entropy of the universe is always increasing B. the net amount of disorder is always increasing C. no chemical reaction is 100 percent efficient D. energy cannot be created or destroyed but can be converted from one form to another E. if you conserve energy you will not be as tired

D

___________ is the capacity to cause change or the ability to rearrange a collection of matter.

Energy