Microbiology 205A Ch. 5

Which of the following is the best definition of oxidative phosphorylation? A. A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP. B. Electrons are passed through a series of carriers to O2. C. Electrons are passed through a series of carriers to an organic compound. D. ATP is directly transferred from a substrate to ADP.

A. A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.

Where would you expect to find electron transport chains in a prokaryote? A. Along the plasma membrane B. Along the outer mitochondrial membrane C. Free-floating in the cytoplasm D. Along the inner mitochondrial membrane E. Along the cell wall

A. Along the plasma membrane

What enables competitive inhibitors to bind to a specific enzyme? A. Competitive inhibitors have structures that resemble the enzyme's substrate. B. Competitive inhibitors have unique sugars that are attracted to the enzyme. C. Competitive inhibitors form unique covalent bonds with enzyme structures. D. Competitive inhibitors cover the entire surface of an enzyme.

A. Competitive inhibitors have structures that resemble the enzyme's substrate.

Which of the following molecules is broken down in cellular respiration, providing fuel for the cell? A. Glucose B. ATP C. Water D. Oxygen Molecule

A. Glucose

How is nevirapine used to treat HIV infections? A. It alters the active site of reverse transcriptase, decreasing that enzyme's activity. B. It increases the immune system's ability to detect the virus. C. It binds to the active site of HIV reverse transcriptase, decreasing that enzyme's activity. D. It decreases the virus's ability to find host cells.

A. It alters the active site of reverse transcriptase, decreasing that enzyme's activity.

How does a noncompetitive inhibitor reduce an enzyme's activity? A. The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site. B. The inhibitor degrades the enzyme. C. The inhibitor degrades the enzyme's normal substrate. D. The inhibitor inactivates the enzyme.

A. The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site.

How does a competitive inhibitor slow enzyme catalysis? A. They compete with the substrate for the enzyme's active site. B. They produce products toxic to the enzymes. C. They degrade the substrate. D. They bind to the substrate.

A. They compete with the substrate for the enzyme's active site.

Glycolysis is utilized by cells in both respiration and fermentation. A. True B. False

A. True

In general, ATP is generated in catabolic pathways and expended in anabolic pathways. A. True B. False

A. True

Once an enzyme has converted substrates into products, the active site reverts back to its original form. A. True B. False

A. True

What does oxygen get reduced to at the end of the electron transport chain? A. Water B. ATP C. Protons D. Electrons E. NADH

A. Water

Which of the following uses glucose for carbon and energy? A. chemoheterotroph B. photoautotroph C. chemoautotroph D. photoheterotroph

A. chemoheterotroph

Which energy-rich molecule directly powers cell work? A. Glucose B. ATP C. Water D. Oxygen molecule

B. ATP

Which of the following is true of anabolic reactions? A. Anabolic reactions produce energy, which is used to convert ADP to ATP. B. Anabolic reactions use ATP and small substrates as building blocks to synthesize larger molecules. C. Anabolic and catabolic reactions both build complex organic molecules from simpler ones; however, anabolic reactions use ATP, whereas catabolic reactions transfer energy to create ATP. D. Anabolic reactions break down complex organic compounds into simpler ones.

B. Anabolic reactions use ATP and small substrates as building blocks to synthesize larger molecules.

Which of the following statements regarding competitive inhibitors is true? A. The inhibitor will degrade the substrate. B. Competitive inhibitors decrease the rate of enzyme activity. C. The inhibitor will destroy the enzyme. D. The inhibitor will destroy the substrate.

B. Competitive inhibitors decrease the rate of enzyme activity.

Assume you are working for a chemical company and are responsible for growing a yeast culture that produces ethanol. The yeasts are growing well on the maltose medium but are not producing alcohol. What is the most likely explanation? A. The maltose is toxic. B. O2 is in the medium. C. The temperature is too low. D. Not enough protein is provided. E. The temperature is too high.

B. O2 is in the medium.

What does the electron transport chain do to the concentration of hydrogen ions (protons)? A. The concentration of protons inside the membrane is equal to the concentration outside of the membrane. B. The concentration of protons is higher outside the membrane than inside. C. The concentration of protons is lower outside the membrane than inside.

B. The concentration of protons is higher outside the membrane than inside.

A reaction that involves the transfer of electrons from one molecule to another is referred to as A. an oxidation reaction. B. a redox reaction. C. a reduction reaction.

B. a redox reaction.

The process of generating ATP using a proton gradient is referred to as A. the electron transport chain. B. chemiosmosis. C. water damming.

B. chemiosmosis.

Which of the following statements regarding redox reactions is true? A. Redox reactions must either be oxidizing reactions or reducing reactions. B. No metabolic reactions are redox reactions. C. Redox reactions involve an oxidation reaction coupled with a reduction reaction. D. Redox reactions are only seen in the electron transport chain.

C. Redox reactions involve an oxidation reaction coupled with a reduction reaction.

If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? A. The substrate will destroy the inhibitor. B. Sulfanilamide products will be in higher concentration. C. The enzyme will stop functioning. D. PABA products will increase in concentration.

C. The enzyme will stop functioning.

A strictly fermentative bacterium produces energy A. by aerobic respiration only. B. only in the absence of oxygen. C. by glycolysis only. D. by fermentation or aerobic respiration. E. only in the presence of oxygen.

C. by glycolysis only.

Which organism is NOT correctly matched to its energy source? A. chemoautotroph - Fe2+ B. chemoautotroph-NH3 C. photoautotroph - CO2 D. photoheterotroph - light E. chemoheterotroph - glucose

C. photoautotroph - CO2

Which of the following statements regarding metabolism is false? A. ADP is formed in anabolic reactions. B. Heat may be released in both anabolic and catabolic reactions. C. Anabolic reactions are degradative. D. ATP is formed in catabolic reactions.

C.Anabolic reactions are degradative.

Which statements are true? 1-Electron carriers are located at ribosomes. 2-ATP is a common intermediate between catabolic and anabolic pathways. 3-ATP is used for the long-term storage of energy and so is often found in storage granules. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels. A. 2, 3, 5 B. 1, 2, 3 C. 1, 3, 4 D. 2, 4, 5 E. All of the answers are correct.

D. 2, 4, 5

Why do all enzymatic reactions need activation energy? A. Energy is needed for the enzyme to find its substrate. B. Energy is required by an enzyme so that it can be reused. C. Energy allows only the substrate to bind. D. Energy is required to disrupt a substrate's stable electron configuration.

D. Energy is required to disrupt a substrate's stable electron configuration.

Why are enzymes important to biological systems? A. Enzymes increase the energy barrier required of chemical reactions. B. Enzymes are reuseable. C. Enzymes prevent unwanted chemical by-products from forming. D. Enzymes decrease the amount of activation energy required for chemical reactions to occur.

D. Enzymes decrease the amount of activation energy required for chemical reactions to occur.

What is meant by the statement "Enzymes are biological catalysts"? A. Enzymes produce biological organisms. B. Enzymes produce products useful for biology. C. Enzymes are products of biological systems. D. Enzymes speed up the chemical reactions in living cells.

D. Enzymes speed up the chemical reactions in living cells.

What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor? A. A decrease in the concentration of enzyme would be observed. B. A decrease in the amount of inhibitor would be observed. C. You would begin to see an increase in the enzyme's rate of activity. D. No change in enzyme activity would be observed.

D. No change in enzyme activity would be observed.

Why is reduction the term used to describe the gain of an electron? A. The amount of energy in the molecule decreases. B. The number of molecules in the reaction decreases. C. The electron acceptor gets smaller. D. The electron acceptor's net charge decreases.

D. The electron acceptor's net charge decreases.

Which of the following conditions would increase enzymatic activity in a bacterial cell that normally thrives in the human body? A. placing the bacteria in the refrigerator B. adding another substrate that can act as a competitive inhibitor C. increasing the substrate level in the environment beyond saturation D. slightly increasing the temperature within the optimum range

D. slightly increasing the temperature within the optimum range

During an oxidation reaction, A. the acceptor molecule gains an electron and becomes oxidized. B. the acceptor molecule loses an electron and becomes oxidized. C. the donor molecule gains an electron and becomes oxidized. D. the donor molecule loses an electron and becomes oxidized.

D. the donor molecule loses an electron and becomes oxidized.

Which compounds provide electrons to the system? A. NADH B. FADH2 C. Water D. Oxygen E. NADH and FADH2

E. NADH and FADH2

Which of the following compounds is NOT an enzyme? A. cellulase B. β-galactosidase C. sucrase D. dehydrogenase E. coenzyme A

E. coenzyme A

What are the inputs and outputs of cellular respiration?

Inputs: Glucose and O2 Outputs: CO2, H2O, and ATP