Ch. 8

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.

According to the animation, what does oxygen get reduced to at the end of the electron transport chain? a. NADH b. Water c. Protons d. ATP e. Electrons

b. Water

The immediate result of electron movement through the electron transport chain is the pumping of protons across the bacterial cell membrane, creating a _____ outside the cell than inside the cell. a. lower concentration of protons b. higher concentration of protons c. lower concentration of electrons d. higher concentration of electrons

b. higher concentration of protons

Which phosphorylation mechanism for recharging ADP to ATP is incorrectly matched with its description? a. Oxidative Phosphorylation: Passes electrons stripped from nutrients through an electron transport chain b. Photophosphorylation: Passes electrons energized by solar energy through an electron transport chain c. Substrate-level phosphorylation: A phosphate is transferred to ADP from a high-energy substrate after passing through an electron transport chain. d. The descriptions for oxidative phosphorylation and photophosphorylation are incorrectly matched. e. The descriptions for oxidative phosphorylation, photophosphorylation, and substrate-level phosphorylation are incorrectly matched.

c. Substrate-level phosphorylation: A phosphate is transferred to ADP from a high-energy substrate after passing through an electron transport chain.

How does a competitive inhibitor slow enzyme catalysis? a. They produce products toxic to the enzymes. b. They bind to the substrate. c. They compete with the substrate for the enzyme's active site. d. They degrade the substrate.

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

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

c. a redox reaction.

Oxidation of nutrients by cells results in a. a requirement for energy which can be used to recharge ADP to ATP. b. a release of energy, which is released by converting ATP to ADP. c. a release of energy, which can be used to recharge ADP to ATP. d. a requirement of energy which can be obtained by converting ATP to ADP. e. either a release or a requirement for energy depending on what type of nutrient is available.

c. a release of energy, which can be used to recharge ADP to ATP.

Catabolic reactions a. are hydrolytic. b. involve breaking down larger molecules into smaller molecules. c. are hydrolytic and involve breaking down larger molecules into smaller molecules. d. are endergonic. e. are endergonic and are hydrolytic.

c. are hydrolytic and involve breaking down larger molecules into smaller molecules.

Enzymes are necessary for cells because a. enzymes allow chemical reactions to occur under physiological conditions. b. enzymes allow chemical reactions to occur quickly enough to facilitate life. c. enzymes allow chemical reactions to occur under physiological conditions and within a time frame conducive to life. d. enzymes allow chemical reactions to take place that would otherwise be impossible. e. enzymes slow down chemical reactions that would otherwise occur too quickly to facilitate life.

c. enzymes allow chemical reactions to occur under physiological conditions and within a time frame conducive to life.

The main function of the Krebs cycle during cellular respiration is to ______. a. produce a large amount of ATP b. break glucose in half c. make NADH and FADH2 through redox reactions d. create acetyl-CoA

c. make NADH and FADH2 through redox reactions

Which of the following factors may influence an enzyme's activity by altering its three-dimensional structure? a. competitive inhibitor b. pH, temperature, and competitive inhibitor c. pH and temperature only d. pH e. temperature

c. pH and temperature only

During an oxidation reaction, a. the acceptor molecule gains an electron and becomes oxidized. b. the donor molecule gains an electron and becomes oxidized. c. the donor molecule loses an electron and becomes oxidized. d. the acceptor molecule loses an electron and becomes oxidized.

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

Why is ATP required for glycolysis? a. ATP is used to convert DHAP into G3P. b. ATP is used to convert PEP into pyruvic acid. c. ATP is used to reduce NAD+ to NADH. d. ATP makes it easier to break apart glucose into two three-carbon molecules.

d. ATP makes it easier to break apart glucose into two three-carbon molecules.

Which of the following statements regarding competitive inhibitors is true? a. The inhibitor will destroy the substrate. b. The inhibitor will destroy the enzyme. c. The inhibitor will degrade the substrate. d. Competitive inhibitors decrease the rate of enzyme activity.

d. Competitive inhibitors decrease the rate of enzyme activity.

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

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

Enzymes can lower the activation energy of a chemical reaction by a. properly positioning reactants. b. stabilizing the transition state. c. raising the temperature so that reactants collide more forcefully. d. properly positioning reactants and stabilizing the transition state. e. properly positioning reactants and raising the temperature so that reactants collide more forcefully.

d. properly positioning reactants and stabilizing the transition state.

Anabolic reactions a. are endergonic and involve breaking down larger molecules into smaller molecules. b. involve dehydration synthesis. c. are endergonic. d. involve breaking down larger molecules into smaller molecules. e. are endergonic and involve dehydration synthesis.

e. are endergonic and involve dehydration synthesis.

What are the products made during glycolysis? a. 4 ATP (net gain of 2) b. 4 ATP (net gain of 2) and 2 NADH and 2 pyruvic acid c. 2 NADH d. 2 pyruvic acid e. 4 ATP (net gain of 2) and 2 NADH

b. 4 ATP (net gain of 2) and 2 NADH and 2 pyruvic acid

According to the animation, which compounds provide electrons to the system? a. NADH and FADH2 b. Oxygen c. FADH2 d. Water e. NADH

a. NADH and FADH2

What is the final electron acceptor in aerobic cellular respiration? a. Oxygen b. Nitrate c. Water d. Sulfate

a. Oxygen

According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)? a. The concentration of protons is higher outside the membrane than inside. b. The concentration of protons is lower outside the membrane than inside. c. The concentration of protons inside the membrane is equal to the concentration outside of the membrane.

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

Which of the following statements correctly describes what happens during chemiosmosis? a. The energy of protons flowing through the ATP synthase enzyme powers the recharge of ADP to ATP. b. Protons are added directly to ADP to recharge it to ATP. c. Only electrons from the reduced carrier NADH are deliver to the electron transport chain; the reduce carrier FADH2 takes its electrons elsewhere. d. Protons flow through the ATP synthase enzyme from the side of the membrane where they are lower in concentration to the side where they are higher in concentration. e. The purpose is to generate water from oxygen.

a. The energy of protons flowing through the ATP synthase enzyme powers the recharge of ADP to ATP.

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

a. chemiosmosis.

Glycolysis makes ATP using ______. a. substrate-level phosphorylation b. oxidative phosphorylation c. photophosphorylation d. chemiosmosis

a. substrate-level phosphorylation

Glycolysis literally means a. sugar splitting. b. Embden-Meyerhof. c. sugar producing. d. energy producing.

a. sugar splitting.

In the typical ATP-ADP cycle, which part of the ATP molecule is removed when energy is released and added back when energy is stored? a. the terminal phosphate group b. ribose c. adenine d. the terminal two phosphate groups e. all three phosphate groups

a. the terminal phosphate group

Which is the key difference between aerobic and anaerobic respiratory chains? a. Aerobic respiratory chains are found in prokaryotic cells only while anaerobic chains are found in eukaryotic cells only. b. Aerobic respiratory chains always use oxygen as the final electron acceptor while anaerobic respiratory chains may use a variety of inorganic substances other than oxygen as the final electron acceptor. c. Aerobic respiratory chains accept electrons from both NADH and FADH2 while anaerobic chains only accept electrons from FADH2. d. Aerobic respiratory chains that accept electrons depend on membrane-associated electron carrier molecules that carry out redox reactions while anaerobic chains use cytoplasm-associated molecules that carry out redox reactions. e. Aerobic respiratory chains are organized so that electrons are passing from a higher to lower energy state while anaerobic chains are organized so that electrons are passing from a lower to a higher energy state.

b. Aerobic respiratory chains always use oxygen as the final electron acceptor while anaerobic respiratory chains may use a variety of inorganic substances other than oxygen as the final electron acceptor.

Where would you expect to find electron transport chains in a prokaryote? a. Free-floating in the cytoplasm b. Along the plasma membrane c. Along the cell wall d. Along the outer mitochondrial membrane e. Along the inner mitochondrial membrane

b. Along the plasma membrane

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

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

Why are enzymes important to biological systems? a. Enzymes increase the energy barrier required of chemical reactions. b. Enzymes decrease the amount of activation energy required for chemical reactions to occur. c. Enzymes are reuseable. d. Enzymes prevent unwanted chemical by-products from forming.

b. 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 speed up the chemical reactions in living cells. c. Enzymes are products of biological systems. d. Enzymes produce products useful for biology.

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

Which of the following statements about glycolysis is true? a. All cells perform glycolysis. b. Glycolysis is also called the Embden-Meyerhof pathway. c. Glycolysis produces glucose. d. Glycolysis is the main source of NADH in the cell.

b. Glycolysis is also called the Embden-Meyerhof pathway.

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

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

What carbon molecules remain at the end of glycolysis? a. Dihydroxyacetone phosphate (DHAP) b. Pyruvic acid c. Glucose d. Glyceraldehyde 3-phosphate (G3P)

b. Pyruvic acid

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

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

Why is reduction the term used to describe the gain of an electron? a. The amount of energy in the molecule decreases. b. The electron acceptor's net charge decreases. c. The number of molecules in the reaction decreases. d. The electron acceptor gets smaller.

b. The electron acceptor's net charge decreases.

When we say that catabolic and anabolic reactions are coupled, what does that really mean? a. Catabolic reactions provide the activation energy required for anabolic reactions to proceed. b. Anabolic reactions provide the reducing equivalents that catabolic reactions require to reduce intermediates. c. Catabolic reactions provide energy and smaller molecules required by anabolic reactions. d. Catabolic reactions regenerate the ADP that anabolic reactions require to power reactions.

c. Catabolic reactions provide energy and smaller molecules required by anabolic reactions.

Catabolic and anabolic reactions depend upon each other, as evidenced by which of the following statements? a. Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules. b. Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules. c. Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions. d. Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions. e. Catabolic reactions release energy which is used by anabolic reactions

c. Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions.

Select the best definition of metabolism. a. Metabolism refers to the cellular reactions that combine energy and molecules to build new substances. b. Metabolism refers to the collection of amphibolic pathways in a cell. c. Metabolism refers to all of the chemical reactions in a cell that impact energy use and release. d. Metabolism refers to the collection of cellular reactions that break down substances to release energy.

c. Metabolism refers to all of the chemical reactions in a cell that impact energy use and release.

What is the relationship between the ATP-ADP cycle and catabolic and anabolic reactions? a. Energy released from catabolic reactions is used to break ATP down to ADP. Then the energy needed for anabolic reactions is released by to recharging ADP back to ATP. b. Catabolic reactions require energy, which is provided by anabolic reactions. ADP is recharged to ATP by energy from anabolic reactions. c. Energy released from anabolic reactions is used to recharge ADP back to ATP. Then the energy needed for catabolic reactions is released by breaking ATP down to ADP. d. Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP. e. There is no relationship between the ATP-ADP cycle and catabolic and anabolic reactions.

d. Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP.

How do electrons get from glycolysis, the intermediate step, and the Krebs cycle to the electron transport chain? a. Oxygen recruits electrons to the electron transport chain. b. Acetyl-CoA carries electrons to the electron transport chain using redox reactions. c. Pyruvic acid transports the electrons using decarboxylation reactions. d. NADH and FADH2 transport electrons to the electron transport chain.

d. NADH and FADH2 transport electrons to the electron transport chain.

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 amount of inhibitor would be observed. b. You would begin to see an increase in the enzyme's rate of activity. c. A decrease in the concentration of enzyme would be observed. d. No change in enzyme activity would be observed.

d. No change in enzyme activity would be observed.

If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? a. Sulfanilamide products will be in higher concentration. b. PABA products will increase in concentration. c. The substrate will destroy the inhibitor. d. PABA will not be catalyzed.

d. PABA will not be catalyzed.

How many net ATPs can be made from one molecule of glucose in glycolysis? a. Four b. One c. Six d. Two

d. Two

Which structural and functional feature(s) listed are key to an enzyme's activity? a. consumed each time a reaction takes place and contains an active site where the enzyme can interact with a specific substrate b. consists of a three-dimensional protein structure that interacts with a substrate in a fixed "lock-and-key" model c. consumed each time a reaction takes place d. contains an active site where the enzyme can interact with a specific substrate e. consumed each time a reaction takes place and consists of a three-dimensional protein structure that interacts with a substrate in a fixed "lock-and-key" model

d. contains an active site where the enzyme can interact with a specific substrate