MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 Name Advanced Biology Enzyme and Cellular Respiration Test Part I Multiple Choice (75 points) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The active site of an enzyme is the region that 1) A) is inhibited by the presence of a coenzyme or a cofactor. B) binds allosteric regulators of the enzyme. C) is involved in the catalytic reaction of the enzyme. D) binds the products of the catalytic reaction. 2) According to the induced fit hypothesis of enzyme catalysis, which of the following is correct? 2) A) A competitive inhibitor can outcompete the substrate for the active site. B) The binding of the substrate changes the shape of the enzyme's active site. C) The active site creates a microenvironment ideal for the reaction. D) The binding of the substrate depends on the shape of the active site. E) Some enzymes change their structure when activators bind to the enzyme. 3) Which of the following is true of enzymes? 3) A) Enzymes may require a nonprotein cofactor or ion for catalysis to take speed up more appreciably than if the enzymes act alone. B) Enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered. C) Enzymes increase the rate of chemical reaction by lowering activation energy barriers. D) Enzyme function is independent of physical and chemical environmental factors such as ph and temperature. 1

2 The following questions are based on the reaction A + B C + D shown in Figure 8.2. Figure 8.2 4) Which of the following terms best describes the reaction? 4) A) allosteric B) nonspontaneous C) endergonic D) exergonic E) anabolic 5) Which of the following represents the activation energy required for the enzyme-catalyzed reaction? A) a B) b C) c D) d E) e 5) 6) When you have a severe fever, what may be a grave consequence if this is not controlled? 6) A) destruction of your enzymes' primary structure B) removal of the amino acids in active sites C) change in the folding of enzymes D) binding of enzymes to inappropriate substrates E) removal of amine groups from your proteins 7) The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as A) feedback inhibition. B) allosteric inhibition. C) reversible inhibition. D) noncooperative inhibition. E) metabolic inhibition. 7) 8) How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? 8) A) by changing the free energy change of the reaction B) by acting as a coenzyme for the reaction C) by changing the shape of a enzyme D) by binding at the active site of the enzyme E) by decreasing the activation energy of the reaction 2

3 9) Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy A) O2 is oxidized and H2O is reduced. B) O2 is reduced and CO2 is oxidized. C) C6H12O6 is oxidized and O2 is reduced. D) CO2 is reduced and O2 is oxidized. E) C6H12O6 is reduced and CO2 is oxidized. 9) 10) The ATP made during glycolysis is generated by 10) A) electron transport. B) photophosphorylation. C) oxidation of NADH to NAD+. D) chemiosmosis. E) substrate-level phosphorylation. 11) Where does glycolysis takes place? 11) A) mitochondrial matrix B) mitochondrial intermembrane space C) mitochondrial inner membrane D) mitochondrial outer membrane E) cytosol 12) Which of the following statements describes NAD+? 12) A) NAD+ has more chemical energy than NADH. B) In the absence of NAD+, glycolysis can still function. C) NAD+ can donate electrons for use in oxidative phosphorylation. D) NAD+ is reduced by the action of hydrogenases. E) NAD+ is reduced to NADH during both glycolysis and the citric acid cycle. 13) Why are carbohydrates and fats considered high energy foods? 13) A) They have a lot of electrons associated with hydrogen. B) They are easily reduced. C) They have no nitrogen in their makeup. D) They have a lot of oxygen atoms. E) They can have very long carbon skeletons. 14) During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is 14) A) transferred to ADP, forming ATP. B) used to phosphorylate fructose to form fructose-6-phosphate. C) stored in the NADH produced. D) transferred directly to ATP. E) retained in the pyruvate. 3

4 15) In addition to ATP, what are the end products of glycolysis? 15) A) CO2 and pyruvate B) H2O, FADH2, and citrate C) CO2 and NADH D) NADH and pyruvate E) CO2 and H2O 16) Why is glycolysis described as having an investment phase and a payoff phase? 16) A) It both splits molecules and assembles molecules. B) It uses stored ATP and then forms a net increase in ATP. C) It uses glucose and generates pyruvate. D) It shifts molecules from cytosol to mitochondrion. E) It attaches and detaches phosphate groups. 17) Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? 17) A) fermentation and glycolysis B) the citric acid cycle and oxidative phosphorylation C) oxidation of pyruvate to acetyl CoA and the citric acid cycle D) oxidative phosphorylation and fermentation E) glycolysis and the oxidation of pyruvate to acetyl CoA 18) Cellular respiration harvests the most chemical energy from which of the following? 18) A) oxidative phosphorylation B) substrate-level phosphorylation C) converting oxygen to ATP D) generating carbon dioxide and oxygen in the electron transport chain E) transferring electrons from organic molecules to pyruvate 19) Where are the proteins of the electron transport chain located? 19) A) mitochondrial intermembrane space B) mitochondrial matrix C) cytosol D) mitochondrial inner membrane E) mitochondrial outer membrane 20) The primary role of oxygen in cellular respiration is to 20) A) combine with carbon, forming CO2. B) combine with lactate, forming pyruvate. C) catalyze the reactions of glycolysis. D) act as an acceptor for electrons and hydrogen, forming water. E) yield energy in the form of ATP as it is passed down the respiratory chain. 4

5 21) The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation is 21) A) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers. B) the final transfer of electrons to oxygen. C) the difference in H+ concentrations on opposite sides of the inner mitochondrial membrane. D) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP. E) oxidation of glucose to CO2 and water. 22) When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the A) formation of ATP. B) lowering of ph in the mitochondrial matrix. C) creation of a proton gradient. D) reduction of NAD+. E) restoration of the Na+/K+ balance across the membrane. 23) Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration? A) 15 B) 2 C) 76 D) 4 E) 38 22) 23) 24) One function of both alcohol fermentation and lactic acid fermentation is to 24) A) reduce FADH2 to FAD+. B) reduce FAD+ to FADH2. C) reduce NAD+ to NADH. D) oxidize NADH to NAD+. E) none of the above 25) Why is glycolysis considered to be one of the first metabolic pathways to have evolved? 25) A) It is found in prokaryotic cells but not in eukaryotic cells. B) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells. C) It is found in the cytosol, does not involve oxygen, and is present in most organisms. D) It produces much less ATP than does oxidative phosphorylation. E) It relies on chemiosmosis which is a metabolic mechanism present only in the first cells-prokaryotic cells. 5