Biology Chapter 6

Energy that is not converted to useful energy is usually given off as A) radioactivity. B) electricity. C) light. D) heat. E) entropy

D

Entropy is a measure of an increase in A) orderliness. B) high-level energy. C) potential energy. D) randomness. E) kinetic energy.

D

All of the following statements are true of the first law of thermodynamics EXCEPT: A) the amount of useful energy decreases. B) the first law of thermodynamics is often called the law of the conservation of energy. C) the total amount of energy within an isolated system remains the same. D) one form of energy may be converted to a different form of energy.

A

An ________ chemical reaction releases energy, whereas an ________ reaction requires an input of energy. A) exergonic; endergonic B) endergonic; exergonic C) enzymatic; endergonic D) endergonic; enzymatic E) equilibrium; exergonic

A

Competitive and noncompetitive enzyme inhibitors differ with respect to A) the precise location on the enzyme to which they bind. B) their pH. C) their binding affinities. D) their energies of activation.

A

Each of the following requires 12 carbon atoms. Which of the arrangements of carbon atoms has the greatest entropy? A) 12 molecules of carbon dioxide, CO2 B) 1 molecule of the disaccharide maltose, C12H22O11 C) 2 molecules of the monosaccharide glucose, C6H12O6 D) 4 molecules of the monosaccharide pyruvate, C3H4O3

A

For many enzymes, the rate of product formation increases as the concentration of the substrate increases. Eventually the rate of the reaction reaches a maximum at which further increases in the concentration of the substrate have no effect. Why? A) At high concentrations of substrate, all of the enzyme molecules are bound to substrate molecules. B) At high concentrations of substrate, the activation energy of the reaction increases. C) At high concentrations of substrate, the activation energy of the reaction decreases. D) The enzyme is no longer specific for the substrate. E) At high concentrations of substrate, the reaction is endergonic.

A

In exergonic chemical reactions A) the reactants have more energy than the products. B) energy is stored by the reactions. C) the reactants have less energy than the products. D) the reactants and products possess equal amounts of energy.

A

The most common energy carrier molecule in living organisms is A) ATP. B) ADP. C) DNA. D) glucose. E) NADPH

A

The reactant in an enzyme-catalyzed reaction is the A) substrate. B) active site. C) product. D) allosteric inhibitor. E) activation energy

A

Which of the following is NOT a commonly used energy carrier in the cell? A) ADP B) NADH C) Electron carriers D) ATP

A

Which of the following is part of the first law of thermodynamics? A) Energy cannot be created or destroyed. B) Kinetic energy is stored energy. C) Energy cannot be transferred or transformed. D) Exergonic reactions are coupled with endergonic reactions. E) Potential energy equals kinetic energy in a reaction.

A

Which of the following lowers the activation energy of a biochemical reaction? A) Presence of a catalyst B) High temperature C) Low concentration of reactants D) Altering pH to 7 E) High concentration of products

A

Which statement best describes the relationship between an enzyme and a reactant? A) The relationship is temporary. B) Covalent chemical bonds stabilize the relationship. C) The enzyme and the reactant molecule are both permanently changed. D) The resultant product and the enzyme are permanently bonded together. E) The reactant cannot function without the enzyme.

A

Enzymes are important because they A) are structural proteins that make up bodily tissues. B) can enable organisms to evade the laws of thermodynamics. C) bind irreversibly to substrates. D) allow reactions to occur at body temperature. E) increase the body temperature of organisms.

D

The end product of a biosynthetic pathway often acts to block the initial step in that pathway. This phenomenon is called A) allosteric activation. B) denaturation. C) irreversible inhibition. D) feedback inhibition. E) substrate activation

D

To say that an enzyme has been denatured means that A) an inhibitor has bound the enzyme at the active site. B) the enzyme is working at its maximal rate. C) the enzyme is working at an optimal temperature. D) its three-dimensional structure has changed and the enzyme can no longer function properly

D

Which molecule functions in the short-term storage of energy? A) Glycogen B) Steroids C) Phospholipids D) Adenosine triphosphate E) Protein

D

A "high-energy" bond in an ATP molecule is located between A) adenine and ribose. B) two phosphate groups. C) ribose and the first phosphate group. D) adenine and the first phosphate group

B

ATP is an energy carrier. Where is the energy actually located? A) Attached to the phosphate group B) In the bonds between phosphate groups C) Attached to the nucleotide D) Inside the phosphate E) Between the sugar and the phosphate

B

All of the following statements pertaining to catalysts are true EXCEPT: A) biological catalysts are specific enzymes. B) catalysts increase activation energy requirements. C) catalysts increase the reaction rate. D) catalysts are not permanently altered during reaction. E) catalysts can be used over and over again.

B

FADH2 is an example of a(n) A) protein. B) electron carrier. C) enzyme. D) enzyme-substrate complex. E) active site.

B

Imagine you are conducting an experiment on a yeast enzyme known as sucrase. This enzyme is used by yeast cells to break down sucrose into glucose and fructose. What type of reaction is this? A) Metergonic B) Exergonic C) Endergonic D) Spontaneous

B

In the liver, the polysaccharide glycogen is broken down into glucose monomers. The glucose molecules are then released into the blood when blood sugar levels need to be raised. This process is an example of a(n) ________ reaction. A) endergonic B) exergonic C) kinetic D) potential

B

Most reactions in the body occur too slowly to sustain life. This is because A) all reactions in the body are endergonic. B) many reactions require large inputs of activation energy. C) no catalysts are present in body cells. D) most biological catalysts are not active at body temperature (37°C). E) there is not enough ATP in body cells.

B

Similar to a car, a human body is about ________ efficient in converting chemical energy to movement. A) 1% B) 25% C) 75% D) 95%

B

Sulfa antibiotics damage bacteria by affecting a certain bacterial enzyme. The sulfa antibiotic looks similar to a substrate normally required by the bacterial cells to live. The sulfa antibiotic occupies the active site of the required enzyme and blocks entry of its normal substrate. This prevents the bacteria from making nucleotides that are required for their reproduction and survival. Based on this information, the action of sulfa antibiotics is an example of A) electron carriers. B) competitive inhibition. C) denaturing of proteins. D) activation energy.

B

The addition of a competitive inhibitor slows down a particular reaction. What could be done to increase the rate of the reaction, even in the presence of the inhibitor? A) Add more inhibitor. B) Add more substrate. C) Lower the temperature of the reaction. D) Add a coenzyme. E) Allow the reaction to reach equilibrium.

B

The optimum reaction rate of a particular enzyme occurs at pH 7.3 at 37°C. This reaction would probably proceed faster by A) decreasing the pH and increasing the temperature. B) increasing the temperature to 38°C and keeping the pH at 7.3. C) increasing the pH and maintaining the temperature at 37°C. D) increasing both temperature and pH.

B

What is the ultimate source of energy for almost all forms of life on Earth? A) Heat energy B) Solar energy C) Thermal energy D) Chemical energy E) Nuclear energy

B

When solid sodium hydroxide is added to water, the solution gets hot. This is an example of a(n) A) endergonic process. B) exergonic process. C) enzyme-catalyzed process. D) release of activation energy. E) conversion of kinetic energy to potential energy

B

Which of the following has the greatest amount of kinetic energy? A) A tank of gasoline B) A moving car C) A hot car engine D) The cool air surrounding the car engine E) An unlit firecracker

B

During photosynthesis, plants convert light energy to chemical energy. This is an example of A) increasing entropy. B) chemical equilibrium. C) the first law of thermodynamics. D) the second law of thermodynamics. E) a spontaneous reaction.

C

How is it possible for living organisms to comply with the second law of thermodynamics? A) Chemical reactions inside cells mostly cause an increase in high-level energy. B) Living organisms are totally isolated systems that are not subject to the laws of physics. C) Sunlight functions as an ultimate source of energy for most forms of life on Earth. D) Living organisms are unique in that they do not require energy for survival. E) Organisms are able to function efficiently on heat energy alone.

C

How is your body able to work against the effects of entropy? A) Regular exercise B) Sunbathing C) Eating a balanced diet D) Regular work

C

In an isolated system, all of the following are true of the second law of thermodynamics EXCEPT: A) the amount of useful energy decreases. B) reactions cause energy to be converted from more useful to less useful forms. C) all chemical reactions release more energy than they consume. D) there is a natural tendency toward greater disorder of the organization of matter.

C

Place these steps of enzyme catalysis in the correct order: 1. The substrate and enzyme change shape. 2. The substrate enters the active site. 3. The enzyme reverts to its original configuration. 4. The product is expelled. A) 1, 2, 3, 4 B) 1, 3, 4, 2 C) 2, 1, 4, 3 D) 2, 1, 3, 4 E) 2, 3, 1, 4

C

Preservatives such as citric acid are added to foods to interfere with bacterial growth. This creates an acidic pH in the food. Why does this affect the bacteria that are present? A) An acidic environment encourages endergonic reactions in the bacterial cells. B) An acidic environment increases the activation energy more quickly in bacteria. C) An acidic environment causes bacterial enzymes to fail or work less efficiently. D) An acidic environment causes the bacteria to grow more rapidly.

C

Triclosan is a broad-spectrum antibacterial agent used in many household products. It is structurally similar to polychlorobiphenyl, a substrate that binds to the active site of the enzyme sulfotransferase. Based on these facts, you can conclude that triclosan most likely: A) lowers the activation energy of chemical reactions. B) functions as an enzyme when sulfotransferase is absent. C) is a competitive inhibitor. D) acts as a noncompetitive inhibitor.

C

When a muscle cell demands energy to perform its work of contraction, ATP A) manufactures more ATP. B) enters a metabolic pathway. C) is broken down. D) is phosphorylated. E) catalyzes the reaction.

C

When, if ever, do molecules stop moving? A) at the freezing point (0°C) B) at the boiling point (100°C) C) at absolute zero (-273.15°C) D) never

C

Which of the following functions as a biological catalyst? A) Energy carrier molecule B) Amino acid C) Enzyme D) Substrate E) Steroid

C

Animals have enzymes that break apart starch molecules but not cellulose, despite the fact that both are made up of glucose subunits. Which enzyme characteristic best explains this? A) Enzyme activity is regulated. B) Enzymes usually speed up chemical reactions. C) Enzymes are not permanently changed by the reactions they promote. D) Enzymes are highly specific. E) All enzymes are proteins.

D

Which of these statements regarding enzymes is FALSE? A) Enzymes are proteins that function as biological catalysts. B) Enzymes are highly specific for the molecules to which they attach. C) Enzymes provide energy for the reactions they catalyze. D) The activity of enzymes can be regulated by factors in their environment. E) An enzyme may be used many times for the same specific reaction.

C

Activation energy is necessary for all ________ reactions. A) exergonic B) endergonic C) coupled D) chemical

D

All of the following are examples of competitive inhibitors EXCEPT: A) insecticides. B) lead. C) penicillin. D) ibuprofen

D

All of the following are ways in which enzymes are regulated by the cell EXCEPT: A) a gene coding for the enzyme may be turned off. B) by first synthesizing the enzyme in an inactive form. C) by feedback inhibition. D) a heavy metal may block the enzymes active site.

D

Why is photosynthesis a coupled reaction? A) The exergonic reaction occurs in the plant, and the endergonic reaction occurs in the soil. B) The exergonic reaction occurs in the plant, and the endergonic reaction occurs in the sun. C) Photosynthesis requires a couple of reactants: carbon dioxide and water. D) An exergonic reaction occurs in the sun, and an endergonic reaction occurs in the plant. E) Sunlight energy enters a plant and is ultimately lost as heat.

D

The hydrolysis of sucrose to glucose and fructose is a spontaneous reaction. However, if you dissolve sucrose in water and keep the solution overnight at room temperature, there is no detectable conversion to glucose and fructose. Why not? A) The reaction is at equilibrium. B) The energy of the products is higher than the energy of the reactants. C) The activation energy of the reaction decreases. D) The reaction is endergonic. E) The reaction requires a catalyst.

E

When a high-energy bond of ATP is broken, what primarily happens to the released energy? A) It is lost as light energy. B) It functions as a second messenger. C) It polarizes the cell. D) It converts inorganic phosphates to energy carrier molecules. E) It drives endergonic reactions in the cell.

E

Which of the following does NOT have much potential energy? A) A water droplet at the top of a waterfall B) A glucose molecule C) A diver on a springboard D) A 9-V battery E) A ball that has rolled downhill and stopped

E

Which of the following is the best description of a coupled reaction? A) Two reactions that occur simultaneously B) A reaction that occurs right after another reaction C) Two reactions that occur in the same organelle D) Reactions that occur during sexual reproduction E) Two reactions that involve one providing energy for the other

E

Which of the following will bind to the active site of an enzyme? A) Substrate only B) Competitive inhibitor only C) Allosteric inhibitor only D) Noncompetitive inhibitor only E) Both substrate and competitive inhibitor

E

Why is photosynthesis considered an endergonic reaction? A) Activation energy is not required. B) Photosynthesis does not comply with the physical laws of the universe. C) Sugar has less energy than the sun. D) Protein catalysts are not needed. E) Low-energy reactants are converted to high-energy products.

E

ADP stores energy in its chemical bonds and is able to use that energy for work in the cell. True or False?

FALSE

In cells, endergonic reactions are often coupled with enzymatic reactions that store energy. True or False?

FALSE

Kinetic energy is like sitting at the top of a hill, and potential energy is like coasting down that hill on your bike. True or False?

FALSE

The burning of sugar is an example of an endergonic reaction, and photosynthesis is an example of an exergonic reaction. True or False?

FALSE

The law of conservation of energy states that although the form of energy used remains the same, the total amount of energy changes. True or False?

FALSE

Activation energy can be provided by the kinetic energy of moving molecules. True or False?

TRUE

Energy is defined as the capacity to do work. True or False?

TRUE

The metabolism of a cell is the sum of all its chemical reactions. True or False?

TRUE

The photosynthetic reaction is considered to be an endergonic reaction. True or False?

TRUE