n) Chapter 7 Brooker - using chapter 9 Campbell, chapter 8 Mader & others**

11. The subunits from which ATP is made are A. ADP and phosphate. B. FAD and NAD+. C. FAD and NADPH. D. ADP and FAD. E. ADP and NAD+.

A

10. During glycolysis _____ carbons will enter the pathway but _____ carbons will leave in the form of pyruvates. A. 6 : 6 B. 6 : 3 C. 3 : 6 D. 12 : 6 E. oxaloacetate

A There are 6 carbons entering glycolysis in the form of glucose and 6 carbons leave in the form of 2 (3 carbon) pyruvates.

149. A(n) __ bond is formed when monosaccharides are polymerized. (A) glycosidic (B) peptide (C) exergonic (D) endergonic (E) hydrogen

A A dehydration reaction, also known as dehydration synthesis, is one that releases a molecule of water in the process of forming a bond between two molecules. Whenever one of these molecules is a saccharide (sugar), then the resulting bond is called a glycosidic bond.

86. The production of two molecules of pyruvate from a molecule of glucose is classified as a(n) (A) catabolic process. (B) synthetic reaction. (C) aerobic respiration. (D) anabolic process. (E) Beta-oxidation reaction.

A Anabolic reactions synthesize larger molecules from smaller ones and store energy within the molecular bonds. Catabolic reactions are the opposite and reduce larger molecules to smaller ones, thereby releasing the energy stored within their bonds. Metabolism is the summation of all catabolic and anabolic processes in a cell.

163. The catabolic intermediate_____is produced by the enzyme_______ (A) fructose 1,6-biphosphate, phosphofructokinase (B) phosphoenolpyruvate, hexokinase (C) 1,3-bisphoglycerate, triosephosphare isomerase (D) glucose 6-phosphate, enolase (E) pyruvate, phosphoglycerate kinase

A The classical process of glycolysis starts with a single molecule of glucose, to which are then added two high-energy phosphate groups before the six-carbon glucose molecule is converted into two three-carbon molecules of pyruvate in a series of nine enzymatic steps. The intermediate fructose 1 ,6-biphosphate is coupled to a second phosphate group to produce fructose 1,6-biphosphate by the enzyme phosphofructokinase just prior to cleavage into two three-carbon intermediates of glycelaldehyde 3-phosphate and dihydroxyacetone phosphate.

37. Compared with other cell components (organelles, cell membrane or nucleus), the mitochondria would be the only one that would A. form an electrochemical gradient across a membrane. B. use significant amounts of oxygen to produce ATP. C. use a chemiosmotic complex to produce ATP. D. produce ATP via glycolysis. E. release protons (H+).

B Compared with other cell components (organelles, cell membrane or nucleus), the mitochondria would be the only one that would use significant amounts of oxygen.

12. One turn of the citric acid cycle produces A. 2 NADH, FADH2, 2 ATP. B. 3 NADH, 1 FADH2, 1 ATP. C. 1 NADH, 3 FADH2, 2 ATP. D. 3 NADH, 2 FADH2, 1 ATP. E. 3 NADH, 1 FADH2, 2 ATP.

B One turn of the citric acid cycle produces 3 NADH, 1 FADH2 and 1 ATP.

93. Aerobic refers to what property of chemotrophs? (A) Chemotrophs remove CO2 from the air. (B) Chemotrophs require oxygen to produce energy. (C) Chemotrophs use but do NOT require oxygen. (D) Fermentation releases great amounts of gas, but only in chemotrophs. (E) Heat losses occur in the presence of oxygen.

B Chemotrophic organisms use the energy contained in chemical compounds for driving their metabolic processes, as opposed to phototrophic organisms that use the energy of light for the same reason. The term aerobic refers to the presence of oxygen molecules that act as terminal electron receptors required by oxidative phosphorylation and is independent of energy sources.

. 132. When NADH is converted to NAD, the process is categorized as (A) dehydration. (B) oxidation. (C) catalysis. (D) reduction. (E) exergonic.

B There are three conditions that define oxidation: (1) when a molecule gains an oxygen atom, (2) when a molecule loses an electron, or (3) when a molecule loses a hydrogen ion (proton). Oxidation is always coupled with reduction, that is, when one molecule is oxidized, another is reduced. Reduction is simply the opposite of oxidation. The conversion of NADH to NAD indicates a loss of a hydrogen ion, and thus oxidation. Two key types of chemical reactions are oxidation and reduction. Oxidation doesn't necessarily have anything to do with oxygen. Here's what it means and how it relates to reduction: Oxidation Definition Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. Oxidation occurs when the oxidation state of a molecule, atom or ion is increased. The opposite process is called reduction, which occurs when there is a gain of electrons or the oxidation state of an atom, molecule, or ion decreases. An example of a reaction is that between hydrogen and fluorine gas to form hydrofluoric acid: H2 + F2 → 2 HF In this reaction, hydrogen is being oxidized and fluorine is being reduced. The reaction may be better understood if it is written in terms of two half-reactions. H2 → 2 H+ + 2 e- F2 + 2 e- → 2 F- Note there is no oxygen anywhere in this reaction! Historical Definition of Oxidation Involving Oxygen: An older meaning of oxidation was when oxygen was added to a compound. This was because oxygen gas (O2) was the first known oxidizing agent. While the addition of oxygen to a compound typically meets the criteria of electron loss and an increase in the oxidation state, the definition of oxidation was expanded to include other types of chemical reactions. A classic example of the old definition of oxidation is when iron combines with oxygen to form iron oxide or rust. The iron is said to have oxidized into rust. The chemical reaction is: 2 Fe + O2 → Fe2O3 The iron metal is oxidized to form the iron oxide known as rust. Electrochemical reactions are great examples of oxidation reactions. When a copper wire is placed into a solution that contains silver ions, electrons are transferred from the copper metal to the silver ions. The copper metal is oxidized. Silver metal whiskers grow onto the copper wire, while copper ions are released into the solution. Cu(s) + 2 Ag+(aq) → Cu2+(aq) + 2 Ag(s) Another example of oxidation where an element combines with oxygen is the reaction between magnesium metal and oxygen to form magnesium oxide. Many metals oxidize, so it's useful to recognize the form of the equation: 2 Mg (s) + O2 (g) → 2 MgO (s) Oxidation and Reduction Occur Together (Redox Reactions) Once the electron was discovered and chemical reactions could be explained, scientists realized oxidation and reduction occur together, with one species losing electrons (oxidized) and another gaining electrons (reduced). A type of chemical reaction in which oxidation and reduction occurs is called a redox reaction, which stands for reduction-oxidation. The oxidation of a metal by oxygen gas could then be explained as the metal atom losing electrons to form the cation (being oxidized) with the oxygen molecule gaining electrons to form oxygen anions. In the case of magnesium, for example, the reaction could be rewritten as: 2 Mg + O2 → 2 [Mg2+][O2-] comprised of the following half-reactions: Mg → Mg2+ + 2 e- O2 + 4 e- → 2 O2- Historical Definition of Oxidation Involving Hydrogen Oxidation in which oxygen is involved is still oxidation according to the modern definition of the term. However, there is another old definition involving hydrogen which may be encountered in organic chemistry texts. This definition is the opposite of the oxygen definition, so it may cause confusion. Still, it's good to be aware. According to this definition, oxidation is the loss of hydrogen, while reduction is the gain of hydrogen. For example, according to this definition, when ethanol is oxidized into ethanal: CH3CH2OH → CH3CHO Ethanol is considered oxidized because it loses hydrogen. Reversing the equation, ethanal can be reduced by adding hydrogen to it to form ethanol. Using OIL RIG to Remember Oxidation and Reduction So, remember the modern definition of oxidation and reduction concern electrons (not oxygen or hydrogen). One way to remember which species is oxidized and which is reduced is to use OIL RIG. OIL RIG stands for Oxidation Is Loss, Reduction Is Gain.

41. Compare the metabolic oxidation of proteins to the metabolic oxidation of carbohydrates in terms of efficiency and specificity.

Both protein and carbohydrates are capable of being oxidized into ATP. When proteins are broken down they can enter the metabolic pool as amino acids. The amino acids can then enter the metabolic pathway at various points: pyruvate conversion, acetyl CoA conversion and the citric acid cycle. When carbohydrates enter the metabolic pathway they will start at the glycolysis stage.

2) Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A) the citric acid cycle B) the electron transport chain C) glycolysis D) reduction of pyruvate to lactate

C

57. Which symptom is characteristic of a patient exposed to monoamine oxidase inhibitors, given that they prevent the breakdown of catecholamines (i.e. epinephrine)? A. decreased blood flow to skeletal muscles B. excessive digestive activity C. dilated pupils D. decreased heart rate

C

58) Even though plants cells carry out photosynthesis, they still use their mitochondria for oxidation of pyruvate. Under what conditions will plant cell mitochondria be active in this process? A) only in photosynthetic cells in the light, while photosynthesis occurs concurrently B) only in cells that store glucose in the form of starch and only in the dark C) in all cells, with or without light D) in photosynthesizing cells in the light, and in other cells in the dark

C

58. The delta G for hydrolysis of ATP to ADP and Pi is: A. Greater than +7.3 kcal/mole B. +7.3 kca/lmole C. -7.3 kcal/mole D. -0.5 kcal/mole

C

59. The active site of an enzyme is where: I. prosthetic group is bound II. proteolysis occurs for zymogens III. non-competitive inhibitors bind A. I only B. II only C. I and II only D. II and III only

C

133. Homeostasis, the steady state that is so vital to life, is possible for cells because (A) the cell cannot convert energy from one form to another. (B) all cells are autotrophic. (C) the cell continually takes up energy from the environment. (D) all cellular reactions are anabolic. (E) all cellular reactions are exergonic.

C The maintenance of homeostasis requires the localized focusing of energy to maintain order. Cells must constantly consume energy to offset the loss of energy and organization as a result of the second law of thermodynamics.

1) In which reactions of cellular respiration and fermentation does substrate-level phosphorylation occur? A) only in glycolysis B) only in the citric acid cycle C) only in the electron transport chain D) in both glycolysis and the citric acid cycle

D

60) Fatty acids usually have an even number of carbons in their structures. Catabolism of fatty acids produces two-carbon fragments that are converted to acetyl CoA molecules. What is the most likely way in which these acetyl CoA molecules would be metabolized in aerobic cellular respiration? A) They would directly enter the electron transport chain. B) They would directly enter the energy-yielding phase of glycolysis. C) They would be converted to pyruvate and then undergo pyruvate oxidation upon transport into mitochondria. D) They would directly enter the citric acid cycle.

D

62. What does the alcoholic fermentation pathway have in common with the oxidation of pyruvate under aerobic conditions? A. no commonality B. triose sugar is a product of each reaction C. ethyl alcohol is a product of each reaction D. C02 is a product of each reaction

D

63. Which one of the following statements is TRUE? A. All disaccharides must contain fructose B. Most polysaccharides contain ribose C. All polysaccharides are energy-generating molecules D. Glucose and fructose have different chemical properties even with the same molecular formula

D

8. Which process produces alcohol or lactate? A. the citric acid cycle B. glycolysis C. the electron transport system D. fermentation E. the preparatory reaction

D Fermentation produces alcohol or lactate.

152. The action of ATP synthase is commonly attributed to the mechanism of (A) symport. (B) ligand-gated channels. (C) mechanical-gated channels. (D) isomeric inversion. (E) chemiosmotic coupling.

E During electron transport in the mitochondrial membrane, pairs of hydrogen ions (H+) are moved from the matrix to the intermembrane space side of the membrane. This produces an electrochemical gradient and lowers the pH within the intermembrane space. The return of the ions to their original location is used to/convert the energy stored in the gradient to phosphorylate ADP to ATP. This coupled reaction is known as chemiosmotic coupling.

94. Which of the following is a four-carbon molecule? (A) alpha-ketoglutarate (B) oxaloacetate (C) citrate (D) succinyl CoA (E) both A and B

E All four of the options are components of the citric acid cycle, also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle. In this process, citrate, containing six carbon atoms, is converted to the five-carbon-containing a-ketoglutarate, releasing a molecule of CO2 in the process. Similarly, the a-ketoglutarate is converted to the four-carbon-containing succinyl CoA. After that there are several molecular rearrangements until oxaloacetate is produced, which then combines with a molecule of acetyl CoA to restore a molecule of citrate for the continuation of the process.

137. Which of the following would NOT be used as a final electron acceptor in anaerobic respiration? (A) Sulfur (B) Protons (C) Iron (D) Nitrogen (E) Oxygen

E Anaerobic respiration is defined as "an ATP generating process in which mol- ecules are oxidized and the final electron acceptor is an inorganic molecule other than oxygen." Oxygen can act as a final electron acceptor like the other choices, but when it is used for that purpose, the result is known as aerobic, not anaerobic, respiration.

102. The respiration process that results in the buildup of organic compounds in cells is known as (A) dehydration. (B) oxidation. (C) reduction. (D) anaerobiosis. (E) fermentation.

E Cellular respiration operates under rwo different conditions: aerobic (in the pres- ence of oxygen) or anaerobic (when oxygel})s not present). Aerobic respiration is much more efficient, allowing the cell to convert a molecule of glucose into CO2, water, and 36 ATP molecules. Anaerobic respiration, which does not permit the use of the electron transport system, has a much lower energy yield (2 ATP per glucose molecule) because much of the energy remains in organic molecules. This process is also known as fermentation.

18. Glycolysis produces 1 pyruvate and 3 NADH coenzymes.

F It is not true that glycolysis produces 1 pyruvate and 3 NADH coenzymes. It produces 2 pyruvates and 1 NADH.

48. The final electron acceptor in glycolysis is oxygen and this step will occur within the matrix of the mitochondria.

FALSE This is not a true statement. Oxygen is the final electron acceptor from the electron transport chain which is located in the cristae of the mitochondria. Glycolysis is an anaerobic process.

43. Under what circumstances would your body synthesize fat? Considering that scientific studies report that metabolic processes slow down while you sleep and don't 'kick on' again until you eat, suggest healthy eating habits that would minimize the amount of energy stored as fat.

Our bodies are designed to store food for the future. If you consume more food (calories) than you need to meet your energy needs, then your body stores that extra food energy as fat. It is a survival instinct!! The body stores energy to be used at a later time, in case food is not available. Healthy eating habits would include: eating earlier (ie. breakfast) to 'quick start' your metabolism, eating frequent, smaller meals to rev up your metabolism several times a day and avoiding eating late in the day as your metabolism slows down and food is more likely to be stored as fat.

46. Relate the overall processes of photosynthesis and aerobic respiration in terms of substrates, end products, byproducts and locations.

Photosynthesis and aerobic respiration are linked in several ways. Glucose, which is a product of photosynthesis, is the substrate for glycolysis (aerobic respiration). Oxygen, which is produced during the light reactions of photosynthesis, may be used as the final electron acceptor from the electron transport chain. The oxygen is then reduced to form water. Water is used in photosynthesis and in the citric acid cycle of cellular respiration. The carbon dioxide produced in the citric acid cycle of aerobic cellular respiration may be fixed in the Calvin cycle, and then reduced to form carbohydrates, such as glucose.

15. Glycolysis occurs before fermentation.

T

16. Glycolysis occurs before the preparatory reaction and the citric acid cycle.

T

49. Fermentation follows glycolysis in some cells when oxygen is not available.

TRUE It is true that fermentation follows glycolysis in some cells when oxygen is not available.

42. Alcohol fermentation is used to produce beer, wine and other alcoholic beverages. Archaeological evidence suggests that the fermentation of fruit to produce wine may have occurred as early as 6000 to 5000 BC in the ancient cultures that lived in modern-day Georgia and Iran. How might the first wine have been 'discovered'? Why would wine have been a more convenient drink than the grape juice from which wine is made?

Wine was probably discovered quite by mistake. Fruit juice being stored in a nonsterile container was somehow contaminated with yeast. The yeast fermented the juice to wine. Ancient man was thirsty and drank his first sips of fine wine. In ancient cultures, with no refrigeration and/or sterilization methods, grape juice would have constantly fermented and/or soured.

1. When electrons move closer to a more electronegative atom, a. energy is released. b. chemical energy is stored. c. a proton gradient is established. d. water is produced.

a

10. In the electron transport system, H+ ions are pumped to a. the intermembrane space. b. the matrix of the mitochondrion. c. the citric acid cycle. d. the cytoplasm.

a

11. When glucose is oxidized to CO2 and water, approximately 66% of its energy is transformed to a. heat. b. ATP. c. a proton-motive force. d. potential energy.

a

12. The energy required for the chemiosmotic synthesis of A TP is provided by a. a gradient of hydrogen ions. b. a gradient of sodium ions. c. ADP. d. water.

a

16. If muscle cells do not receive enough oxygen from the blood, they use lactic acid fermentation to produce ATP. What do these cells gain from the reduction of pyruvate? a. ATP b. ATP and NAD+ c. CO2 and NAD+ d. ATP and CO2

b

2. In the reaction C6H1206 + 6 O2 ---> 6 CO2 + 6 H20, a. glucose becomes reduced. b. oxygen becomes reduced. c. water is a reducing agent. d. oxygen is a reducing agent.

b

20. Fats and proteins can be used as fuel in the cell because they a. can be converted to glucose by enzymes. b. can be converted to intermediates of glycolysis or the citric acid cycle. c. can pass through the mitochondrial membrane to enter the citric acid cycle. d. contain more energy than glucose.

b

21. Which of the following statements is false con- cerning the enzyme phosphofructokinase? a. It is an allosteric enzyme. b. It is inhibited by citrate. c. It is inhibited by AMP. d. It is an early enzyme in the glycolytic pathway.

c

22. Brown fat, which is found in newborn infants and hibernating mammals, has uncoupler proteins that, when activated, make the inner mitochon- drial membrane leaky to H+. What is the function of brown fat? a. It produces more ATP than does regular fat and is also found in the flight muscles of ducks and geese, providing more energy for long- distance migrations. b. It lowers the pH of the intermembrane space, which results in the production of more ATP per gram than is produced by the oxidation of glucose or regular fat tissue. c. Because it dissipates the proton gradient, it generates heat through cellular respiration without producing ATP, thereby raising the body temperature of hibernating mammals or newborn infants. d. Its main function is insulation in the endother- mic animals in which is it common.

c

3. In which of the following conversions is the first molecule becoming reduced to the second molecule? a. pyruvate ~ acetyl CoA b. glucose ~ pyruvate c. NADH + H+ ~ NAD+ + 2 H d. pyruvate ~ lactate

d

11. For the following reaction, which statement is TRUE? A TP + Glucose ---t Glucose-6-phosphate + ADP A. reaction results in the formation of a phosphoester bond B. reaction is endergonic C. reaction is part of the Krebs cycle D. free energy change for the reaction is approx. -4 kcal

A

13. Acetyl-CoA is produced from A. pyruvate and a coenzyme. B. citric acid and a coenzyme. C. ATP and pyruvate. D. CO2 and pyruvate. E. citric acid and CO2.

A

13. Which statement is NOT true about the Krebs cycle? A. Krebs cycle is the single greatest direct source of ATP in the cell B. Citrate is an intermediate in the Krebs cycle C. Krebs cycle produces nucleotides such as NADH and F ADH2 D. Krebs cycle is linked to glycolysis by pyruvate

A

2. The ATP molecule contains three phosphate groups, two of which are: A. bound as phosphoanhydrides B. bound to adenosine C. never hydrolyzed from the molecule D. cleaved off during most biochemical reactions

A

21. The site of the TCA cycle in eukaryotic cells, as opposed to prokaryotes, is: A. mitochondria B. endoplasmic reticulum C. cytosol D. nucleolus

A

23. When measuring the reaction velocity as a function of substrate concentration, what is likely to occur if the enzyme concentration changes? A. V max changes, while Km remains constant B. V max remains constant, while V changes c. V max remains constant, while Km changes D. V max remains constant, while V and Km change

A

28. An apoenzyme is: A. inactive enzyme without its cofactor B. inactive enzyme without its inorganic cofactor C. active enzyme with its cofactor D. active enzyme with its coenzyme

A

3 Which of the following statements about glycolysis is correct? A It is anaerobic, occurs in the cytoplasm and includes at least one phosphorylation reaction. B It is aerobic and includes a lysis reaction. C In the final stages, two molecules of ATP are used in the formation of pyruvate. D It is aerobic and does not include a lysis reaction.

A

3) The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A) oxygen. B) water. C) NAD+. D) pyruvate.

A

3) What happens when electrons are passed from one atom to a more electronegative atom? A) The more electronegative atom is reduced, and energy is released. B) The more electronegative atom is reduced, and energy is consumed. C) The more electronegative atom is oxidized, and energy is consumed. D) The more electronegative atom is oxidized, and energy is released.

A

30) Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration? A) glucose → NADH → electron transport chain → oxygen B) glucose → pyruvate → ATP → oxygen C) glucose → pyruvate → electron transport chain → NADH → ATP D) food → glycolysis → citric acid cycle → NADH → ATP

A

37. Vitamins are: A. necessary components in the human diet B. present in plants but not in animals C. absent in bacteria within the gastrointestinal tract D. all water soluble

A

38. Some bacteria are strict aerobes and others are strict anaerobes. Some bacteria, however, are facultative anaerobes and can live with or without oxygen. If given the choice of using oxygen or not, which pathway should a facultative anaerobe perform? A. Use oxygen since aerobic metabolism provides more ATP per molecule of carbohydrate broken down than anaerobic metabolism. B. Not use oxygen since it is a facultative anaerobe, it doesn't tolerate oxygen well. C. Use oxygen because aerobic metabolism is easier. D. It doesn't matter; both processes will produce the same results.

A

39. The correct sequence for aerobic metabolic breakdown of glucose is A. glycolysis—preparatory reaction--cirtric acid cycle--electron transport system B. preparatory reaction--glycolysis---electron transport--citric acid cycle C. electron transport system--citric acid cycle---preparatory reaction--glycolysis D. None of the choices are correct.

A

39. Which of these amino acids is nonoptically active because it does not contain four different groups bonded to the alpha carbon? A. glycine B. aspartic acid C. glutamate D. cysteine

A

4 Which of the following statements about the link reaction and Krebs cycle is correct? A Pyruvate in the mitochondrion matrix is oxidised to acetyl CoA. B At the end of the link reaction, coenzyme A is recycled back into the cytoplasm to combine with another pyruvate molecule. C During one rotation of the Krebs cycle there are three decarboxylation reactions. D The link reaction occurs in the mitochondrial matrix and Krebs cycle occurs on the mitochondrial cristae.

A

4) Which of the summary statements below describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) O2 is reduced and CO2 is oxidized.

A

4. Which form of energy is NOT correctly associated with the related example? A. kinetic energy: fat molecules B. kinetic energy: movement of muscles C. chemical energy: glucose D. potential energy: water held behind a dam E. potential energy: ATP

A

40. Which of the following statements is TRUE for glycolytic pathway? A. glucose produces a net of two molecules of ATP and two molecules ofNADH B. glucose produces one molecule of pyruvate C. 02 is a reactant for glycolysis D. glucose is partially reduced

A

42) A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. What is the most likely way that the lost fat left the body? A) It was released as CO2 and H2O. B) It was converted to heat and then released. C) It was converted to ATP, which weighs much less than fat. D) It was eliminated from the body as feces.

A

43. Clostridium butyricum is an obligate anaerobe that grows on glucose and converts it to butyric acid. If the delta G for this reaction is -50 kcal, the synthesis of ATP occurs through: A. substrate-level phosphorylation B. oxidative phosphorylation C. neither substrate-level nor oxidative phosphorylation D. both substrate-level and oxidative phosphorylation

A

44) Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements about these inside-out membrane vesicles is true? A) The inside of the vesicles will become acidic when NADH is added. B) The inside of the vesicles will become alkaline when NADH is added. C) ATP will be produced from ADP and i in the interior of the vesicle. D) The vesicles will pump protons out of the interior of the vesicle to the exterior using energy from ATP hydrolysis.

A

45. All of the following statements apply to oxidative phosphorylation, EXCEPT: A. it can occur under anaerobic conditions B. it produces two ATPs for each FADH2 C. it involves 02 as the final electron acceptor D. it takes place on the inner membrane of the mitochondrion

A

47) Which of the following metabolic processes take place in the cytosol of a eukaryotic cell? A) glycolysis and fermentation B) fermentation and chemiosmosis C) oxidation of pyruvate to acetyl CoA D) citric acid cycle

A

48) In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules? A) ATP, CO2, and ethanol (ethyl alcohol) B) ATP, CO2, and lactate C) ATP, NADH, and ethanol D) ATP, CO2, and acetyl CoA

A

52) Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A) glucose B) cholesterol C) fatty acids D) amino acids

A

54. Which of the following coenzymes will accept two electrons and two hydrogens during oxidation? A. FAD B. NAD+ C. FADH D. NADH

A

55. During the preparatory reaction of aerobic respiration what happens to the carbon molecules? A. The carbon molecules are broken down from a 3-carbon to a 2-carbon acetyl group and a 1-carbon CO2 is released. B. The carbon molecules are broken down from a 4-carbon to a 3-carbon acetyl group and a 2-carbon CO2 is released. C. The carbon molecules are converted from a 2-carbon to a 3-carbon acetyl group and a 1-carbon CO2 is consumed. D. The carbon molecules are broken down from a 3-carbon to a 1-carbon acetyl group and two 1-carbon CO2 are released.

A

56. Which statement is correct about the input and output of carbon during glycolysis? A. There is an input of 6 carbons (glucose) and an output of 6 carbons (2 pyruvates). B. There is an input of 6 carbons (2 pyruvates) and an output of 6 carbons (1 glucose). C. There is an input of 6 carbons (glucose) and an output of 6 carbons (6 CO2). D. There is an input of 3 carbons (glucose) and an output of 3 carbons (pyruvate).

A

57) A young dog has never had much energy. He is brought to a veterinarian for help, and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells cannot move NADH from glycolysis into the mitochondria. C) His cells lack the enzyme in glycolysis that forms pyruvate. D) His cells have a defective electron transport chain, so glucose is metabolized to lactate instead of to acetyl CoA.

A

57. What is the correct summary for the energy investment vs. energy harvesting steps of glycolysis? A. 2 ATP are invested and 4 ATP are harvested to produce a net gain of 2 ATP. B. 4 ATP are invested and 6 ATP are harvested to produce a net gain of 2 ATP. C. No ATP are invested and 2 ATP are harvested to produce a net gain of 2 ATP. D. 2 ATP are invested and no ATP are harvested to produce a net loss of 2 ATP.

A

6) When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A) The pH of the matrix increases. B) ATP synthase pumps protons by active transport. C) The electrons gain free energy. D) NAD+ is oxidized.

A

61. Which of the following statements is TRUE? A. Protein function can be altered by modification after synthesis B. Covalent bonds stabilize the secondary structure of proteins C. A protein with a single polypeptide subunit has quaternary structure D. Integral proteins contain high amounts of acidic amino acids

A

7) Which of the following statements about NAD+ is true? A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD+ has more chemical energy than NADH. C) NAD+ can donate electrons for use in oxidative phosphorylation. D) In the absence of NAD+, glycolysis can still function.

A

7. Which process produces both NADH and FADH2? A. the citric acid cycle B. glycolysis C. the electron transport system D. fermentation E. the preparatory reaction

A

8. When determining a protein's amino acid sequence, acid hydrolysis causes a partial destruction of tryptophan, conversion of asparagine into aspartic acid and conversion of glutamine into glutamic acid. Which of the following statements is NOT correct? A. Glutamine concentration is related to the level of aspartic acid B. Glutamic acid levels are an indirect indicator of glutamine concentration C. Tryptophan levels cannot be estimated accurately D. Asparagine levels cannot be estimated accurately

A

141. Bacteria are capable of producing 38 net molecules of ATP from every molecule of glucose that is fully metabolized by oxidative phosphorylation. Which of the following is NOT true about this datum? (A) The majority of the ATP molecules are produced within the mitochondria. (B) This number is greater than that produced from a molecule of glucose within a human cell. (C) This total yield of ATP includes the molecules produced by substrate-level phosphorylation. (D) The presence of oxygen is required to produce this total yield of ATP. (E) This yield includes ATP expenses required to drive glycolysis forward.

A In eukaryotes, the electron transport system resides in the mitochondria. There, the high-energy electrons harvested from glucose are bled of their energy to drive the proton pumps. Bacteria are capable of oxidative phosphorylation, but they are prokaryotic in structure, and their electron transport system resides within their cell membrane, not within an organelle.

151. In what way is the enzyme catalase related to the food industry? (A) It is used in a cold pasteurization process for milk. (B) It is used to prevent crystal formation in ice cream. (C) It produces a desirable flavor in cheeses. (D) It enhances the color of white bread. (E) It is used to preferentially isomerize glucose in candy.

A Milk is commonly pasteurized to eliminate pathogenic bacteria such as Myco- bacterium tuberculosis or Listeria sp. that might sicken those who drink it. The classical process involves heating the milk to 63°C for 30 min, but this changes the flavor a bit, as do the faster methods of high-temperature, short-time (HTST) and ultra-high-temperature (UHT) processes. A cold process that retains most of the original flavor involves the addition of bacteriocidal hydrogen peroxide, which greatly reduces microbial content. This H2O2 is then converted back to water with the enzyme catalase.

100. Chemoautotrophs may capture energy from all of the following EXCEPT (A) CO2, (B) H2S. (C) NH4+' (D) N02-. (E) All of the above might be used.

A Organisms that are chemoautotrophs use chemical compounds as an energy source as opposed to using energy extracted from photons. These organisms, as autotrophs, use inorganic carbon molecules as their carbon source as opposed to the preformed organic compounds required by hererotrophs. Carbon dioxide is a molecule generated as a waste product in respiration because it no longer contains enough energy to be useful to organisms and is thus not used as an energy source.

87. Which of the following classes of compounds contain the most energy per gram? (A) fats (B) proteins (C) carbohydrates (D) monosaccharides (E) B, C, and D

A Oxidizing organic compounds release energy. The unit of measure of this energy is the calorie (c), which is the amount of heat it takes to raise 1 gram of water 1 degree centigrade. Because this is rather small, we more commonly use the unit kilocalorie (kcal or C). Both carbohydrates and proteins contain approximately 4 C per gram. Lipids, on the other hand, contain more than twice that at 9 C per gram.

105. The net CO2 production from a single turn of the TCA cycle is (A) 2. (B) 3. (C) 11. (D) 12. (E) none of the above

A The TCA cycle starts when a molecule of acetyl CoA, containing two carbon atoms, combines with a molecule of oxaloacetate, containing four carbon atoms, to produce a single six-carbon-containing molecule of citrate. The remainder of the cycle drains the energy contained within the bonds of those two new carbon atoms from the acetyl moiety, which are then discarded as waste CO2 molecules. Thus each cycle brings in two carbon atoms and discards two carbon atoms.

156. What is the relationship between an equilibrium constant for any reaction and the free energy of the reaction? (A) The natural logarithm of Keq is equal to a negative delta G divided by RT. (B) The Keq is equal to a delta G divided by RT. (C) The Keq is equal to a negative delta G multiplied by RT. (D) The natural logarithm of Keq is equal to a delta G multiplied by RT. (E) There is no real relationship, as the two are independent of each other.

A The natural logarithm of the equilibrium constant (Keq) is equal to the change in free energy (delta G) divided by the molar heat capacity (R, in Joule * mol to -1 * Kelvin to -1) times T (degrees Kelvin).

136. Of the following components of the mitochondrial electron transport system, which transfers protons in addition to electrons? (A) Coenzyme Q (B) Cytochrome a (C) Cytochrome c (D) ATP synthase (E) Cytochrome c1 (c one)

A When a high-energy electron is delivered to the electron transport system from NADH, it starts traveling down the chain at the flavoprotein FMN. Some energy from this electron is then used to pump a pair of hydrogen ions (H+) from the matrix to the inner membrane space. The electron is then transferred to the second component, coenzyme Q, which repeats the same function. Thus, this latter component transfers both electrons and protons.

161. Which of the following processes is especially associated with fasting? (A) Gluconeogenesis (B) Anaerobic respiration (C) Fermentation (D) Translation (E) Chemiosmosis

A When a vertebrate fasts, the blood sugar level begins to drop as the animal becomes hypoglycemic. In order to correct for this event, and to maintain homeostasis, the liver becomes involved in both the breakdown of the energy storage product glycogen, which releases glucose into the bloodstream; and the synthesis of new glucose from a variety of molecular sources, including pyruvate, glycerol, and some amino acids.

146. Which of the following lipids, as a whole, has the highest burning (smoking) point? (A) Saturated fats (B) Polyunsaturated fats (C) Vegetable oils (D) Trans fats (E) Partially saturated fats

A Generally, the less saturated a lipid is, the greater the volume required by each molecule. Conversely, the greater the saturation, the more densely the molecules can pack together, thus requiring more heat to break them apart.

47. Compare the efficiency of aerobic respiration and fermentation in ATP energy production. If aerobic respiration converts 40% of the available energy of glucose into ATP, then what percentage does fermentation convert to ATP?

Aerobic respiration produces 36 (to 38) ATPs from one glucose molecule, whereas fermentation only produces 2 ATPs from one glucose molecule. Therefore, fermentation produces only 1/18 (to 1/19th) the amount of energy. If 36 ATP's is 40% of the available energy in the six-carbon glucose molecule, then 2 ATPs would be equal to 1/18 of 40%, which is 2.2%. While aerobic respiration converts approximately 40% of the available energy of glucose to ATPs, fermentation converts approximately 2.2% of the available energy to a usable form, ATP.

1. Which of the following statements is correct about enzymes? A Most enzymes use the lock-and-key model of substrate interaction as it is the most stable. B In allosteric control of metabolic pathways, a product within the pathway can act as a non- competitive inhibitor of an enzyme earlier in the pathway. C Increasing the concentration of substrate has no effect on the rate of a reaction being inhibited by a competitive inhibitor. D Competitive inhibitors bind to an allosteric site and alter the shape of the active site.

B

10) A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply? A) He or she has to sit down and rest. B) Catabolic processes are activated that generate more ATP. C) ATP is transported into the cell from the circulatory system. D) Other cells take over, and the muscle cells that have used up their ATP cease to function.

B

10. Coupling occurs when the energy released by an exergonic reaction is A. used to drive another exergonic reaction. B. used to drive an endergonic reaction. C. lost as nonusable heat to the environment. D. used to decrease the entropy of the universe. E. All of the choices are correct.

B

13) Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products? A) 2 NAD+, 2 pyruvate, and 2 ATP B) 2 NADH, 2 pyruvate, and 2 ATP C) 4 NADH, 2 pyruvate, and 4 ATP D) 6 CO2, 2 pyruvate, and 2 ATP

B

14) In glycolysis, for each molecule of glucose oxidized to pyruvate, ________. A) two molecules of ATP are used, and two molecules of ATP are produced B) two molecules of ATP are used, and four molecules of ATP are produced C) four molecules of ATP are used, and two molecules of ATP are produced D) two molecules of ATP are used, and six molecules of ATP are produced

B

15. A reaction in which the substrate glucose binds to the enzyme hexokinase, and the conformation of both molecules changes, is an example of: A. lock-and-key mechanism B. induced fit mechanism C. competitive inhibition D. allosteric inhibition

B

18) Which electron carrier(s) function in the citric acid cycle? A) NAD+ only B) NADH and FADH2 C) the electron transport chain D) ADP and ATP

B

18. alpha-helices and beta-pleated sheets are characteristic of which level of protein folding? A. primary B. secondary C. tertiary D. quaternary

B

2 Which of the following statements is correct? A Oxidation can involve the removal of oxygen from a compound. B The solution inside a mitochondrion is called the matrix and the solution inside a chloroplast is called the stroma. C The folds of the inner membrane of a mitochondrion are called grana. D The photosynthetic pigments in a chloroplast are found on the cristae.

B

2) Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction? A) It gains electrons and gains potential energy. B) It loses electrons and loses potential energy. C) It gains electrons and loses potential energy. D) It loses electrons and gains potential energy.

B

2. Which organelles contain functioning ATP synthetase complexes in their membranes? A. golgi complexes and lysosomes B. mitochondria and chloroplasts C. endoplasmic reticulum and vesicles D. vacuoles and vesicles E. mitochondria and endoplasmic reticulum

B

20) Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A) glycolysis and the oxidation of pyruvate to acetyl CoA B) oxidation of pyruvate to acetyl CoA and the citric acid cycle C) oxidative phosphorylation and fermentation D) fermentation and glycolysis

B

20. Degradative reactions A. cause death. B. can drive anabolism. C. tend to be endergonic. D. include the buildup of products such as complex proteins and nucleic acids. E. All of the choices are true.

B

20. Hemoglobin is an example of a protein that: A. is initially inactive in the cell B. has a quaternary structure B. carries out a catalytic reaction D. has only tertiary structure

B

21) If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA? A) 1/6 B) 1/3 C) 2/3 D) all of it

B

22. All of the following are metabolic waste products, EXCEPT: A. lactate B. pyruvate C. CO2 D. H2O

B

24. The membrane protein (enzyme) _________ will transform ADP + P ATP as H+ flow down a gradient from the intermembrane space into the matrix. A. the sodium-potassiuim pump B. ATP synthase C. cholesterol D. NADH-Q reductase

B

26) Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? A) ATP B) acetyl CoA C) citrate D) water

B

29) Which of the following processes is driven by chemiosmosis? A) substrate-level phosphorylation B) oxidative phosphorylation C) ATP hydrolysis D) reduction of NAD+ to NADH

B

29. Several different forces are involved in the stabilization of the tertiary structure of a protein. Which of the following is most likely involved in this stabilization? A. glycosidic bonds B. disulfide bonds C. peptide bonds D. anhydride bonds

B

30. In the non-oxidative branch of the pentose phosphate pathway, transketolase is a reaction catalyst enzyme and its activity depends on a prosthetic group. Which bond is used by a prosthetic group to attach to its target? A. van der Waals interactions B. covalent bond C. ionic bond D. hydrogen bond

B

31) Where are the proteins of the electron transport chain located? A) mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix

B

34. All proteins: A. are post-translationally modified B. have a primary structure C. have catalytic activity D. contain prosthetic groups

B

36. All of the following statements about glycolysis are true, EXCEPT: A. end-product can be lactate, ethanol, C02, and pyruvate B. FADH2 is produced during glycolysis C. one molecule of glucose is converted into two molecules of pyruvate D. net total of two ATPs is produced

B

4) In mitochondria, exergonic redox reactions A) are the source of energy driving prokaryotic ATP synthesis. B) provide the energy that establishes the proton gradient. C) reduce carbon atoms to carbon dioxide. D) are coupled via phosphorylated intermediates to endergonic processes.

B

4. Fermentation yields less energy than aerobic respiration because: A. it requires a greater expenditure of cellular energy B. glucose molecules are not completely oxidized C. it requires more time for ATP production D. oxaloacetic acid serves as the final H+ acceptor

B

40) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 8 B) 12.5 C) 16 D) 25

B

41. Which of these metabolic processes take(s) place in the mitochondria? I. Krebs cycle II. glycolysis III. electron transport chain A. II only B. I and III only C. II and III only D. 1, II and 111

B

46) Which of the following metabolic processes normally occurs regardless of whether or not oxygen (O2) is present? A) citric acid cycle B) glycolysis C) lactate fermentation D) oxidative phosphorylation

B

48. Which interactions stabilize parallel and non-parallel beta-pleated sheets? A. hydrophobic interactions B. hydrogen bonds C. van der Waals interactions D. covalent bonds

B

5. How would the reaction kinetics of an enzyme and its substrate change if an anti-substrate antibody is added? A. The antibody binds to the substrate, which increases the V max B. The antibody binds to the substrate, which increases K m C. No change because K m and V max are independent of antibody concentration D. The antibody binds the substrate, which decreases V max

B

5. Which best describes the first law of thermodynamics? A. Energy is changed from one form to another with a loss of usable energy. B. Energy is not created nor destroyed, but it can change from one energy form to another. C. Energy can be created from matter or used to produce matter. D. Some useful energy is lost as heat whenever an energy transfer occurs. E. Energy transfers are always 100% efficient in changing energy from one useful form to another.

B

51) Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A) It produces much less ATP than does oxidative phosphorylation. B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. C) It is present in prokaryotic cells but not in eukaryotic cells. D) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.

B

52. All biological reactions: A. are exergonic B. have an activation energy C. are endergonic D. occur without a catalyst

B

54) High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of ________. A) competitive inhibition B) allosteric regulation C) the specificity of enzymes for their substrates D) positive feedback regulation

B

6. The first phase of aerobic cellular respiration is A. the citric acid cycle. B. glycolysis. C. the electron transport system. D. fermentation. E. the preparatory reaction.

B

60. The hydrolysis of ATP --> ADP + phosphate allows glucose-6-phosphate to be synthesized from glucose and phosphate because: A. heat produced from ATP hydrolysis drives glucose-6-phosphate synthesis B. enzymatic coupling of these two reactions allows the energy of ATP hydrolysis to drive the synthesis of glucose-6-phosphate C. energy of glucose phosphorylation drives ATP splitting D. all of the above

B

61) New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels? A) During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions, and muscles begin to cramp, thus athletic performance suffers. B) During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration. C) During aerobic respiration, muscles cells produce too much lactate, which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. D) During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue.

B

7) Most CO2 from catabolism is released during A) glycolysis. B) the citric acid cycle. C) lactate fermentation. D) electron transport.

B

8) The oxygen consumed during cellular respiration is directly involved in which of the following processes or events? A) glycolysis B) accepting electrons at the end of the electron transport chain C) the citric acid cycle D) the oxidation of pyruvate to acetyl CoA

B

9. What is the correct sequence of energy sources used by the body? A. fats ~ glucose ~ other carbohydrates ~ proteins B. glucose ---t other carbohydrates ---t fats ---t proteins C. glucose ---t other carbohydrates ---t proteins ---t fats D. glucose ---t fats ---t proteins ---t other carbohydrates

B

9. Which of these statements is NOT a consequence of the second law of thermodynamics? A. While the total amount of energy is unchanged, the energy lost as heat is no longer useful to the cell in doing work. B. Reactions that occur spontaneously are those that increase the amount of useful energy in a system. C. The amount of disorder in the universe is always increasing. D. To maintain organization of a cell, a continual input of energy is required.

B

1. Which of these processes occurs in the cytosol? A. the citric acid cycle B. glycolysis C. the electron transport system D. the preparatory reaction

B Glycolysis occurs in the cytosol. The citiric acid cycle, preparatory reaction and the electron transport system are in the mitochondria.

11. The electron transport chain and chemiosmosis produces ______ ATP from each NADH and/or _________ ATP from each FADH2 entering the system. A. 4; 2 B. 3; 2 C. 2; 4 D. 2; 3

B The electron transport chain and chemiosmosis produces 3 ATPs from each NADH and/or 2 ATPs from each FADH2 entering the system.

165. An organic compound that is a carboxylic acid with a long aliphatic tail describes a (A) nucleic acid. (B) fatty acid. (C) polysaccharide. (D) peptide. (E) lipopolysaccharide.

B Any organic compound with a -COOH carboxyl group is a carboxylic acid. Any organic compound that lacks a cyclic feature such as a benzene ring is classified as aliphatic. A fatty acid may be either saturated (where each carbon atom in the chain is bonded to as many hydrogen atoms as possible) or unsaturated (where carbon-to-carbon double bonds exist).

157. Which of the following are pentoses? (A) Glucose and lactose (B) Ribose and deoxyribose (C) DNA and RNA (D) Lactase and lactose (E) Deoxyribose and deoxyfructose

B Biologic monosaccharidesare most commonly hexoses (with six carbon atoms) or pentoses (with five carbon atoms). Also common are disaccharides composed of two monosaccharides, whether they be pentoses or hexoses. Perhaps the most common disaccharides are sucrose (a combination of glucose and fructose) and lactose (a combination of galactose and glucose). By far the most common pentoses that are of biological importance are ribose and deoxyribose, both of which are major constituents in RNA and DNA, respectively.

167. Which of the following is NOT a characteristic associated with apoptosis? (A) Blebbing (B) Inflammation (C) DNA fragmentation (D) Chromatic condensation (E) Cellular condensation

B Cells of multicellular organisms can cease to function and die through one of two major mechanisms: by program or by trauma. The mechanism of programmed cell death, also known as apoptosis, consists of a series of metabolic and enzymatic processes that result in the orderly breakdown and containment of cellular materials, which are then removed by phagocytosis. In contrast, cells that die as a result of external trauma produce the uncontrolled release of active cellular materials that damage adjacent cells and tissues, resulting in damaging inflammatory processes.

145. For each electron released by an NADH molecule sent through the mitochondrial electron transport chain, _______ATP is/are produced. (A) one (B) three (C) two (0) eleven (E) four

B Each of the first three components of the electron transport chain captures enough energy from the donated electron to permit it to pump a pair of hydrogen ions from one side of the mitochondrial membrane to the other. Each pair then returns to its original place by passing through a molecule of ATP synthase, which, in turn, converts one molecule of ADP to ATP. Three pairs per electron thus produce three molecules of ATP by oxidative phosphorylation.

150. What Le Chatelier's principle is to chemistry, is to biology. (A) the Gram stain (B) homeostasis (C) muscle contraction (D) vision (E) natural selection

B Le Chatelier's principle briefly states that substances in equilibrium will be main- tained in equilibrium unless standing conditions such as concentration, pressure, or temperature change, in which case the system will shift until a new equilibrium is achieved. The biological equivalent is homeostasis, where a biological system maintains internal cellular parameters under certain conditions. However, when those conditions change, the internal system will make adjustments until a new internal balance is attained.

90. An organism that uses a compound such as a protein for both its energy and carbon source would be classified as a(n) (A) photoautotroph. (B) chemoheterotroph. (C) phoroheterotroph. (D) chemoautotroph. (E) autotroph.

B Organisms can be classified based on their nutritional requirements for energy, car- bon, or electron sources. An organism can get its energy from either the sun (phototroph) or chemicals (chemotroph). An organism can get its carbon in inorganic form from the air or water (autotroph) or in prepackaged organic form (heterotroph). And an organism can get its electrons from either inorganic (lithotroph) or organic (organotroph) sources. Thus an organism that gets both its energy and carbon from the same molecule would be identified as a chemoheterotroph.

97. Photoheterotrophs are best described as organisms that obtain energy to make ATP (A) from organic compounds but use sunlight to produce carbon sources. (B) from sunlight but cannot make organic compounds from CO2, (C) and organic compounds from sunlight. (0) from some forms of chemicals. (E) from organic compounds.

B Terms used to describe the nutritional profiles of various organisms include prefixes that identify their source of electrons (litho- vs. organo-), their source of carbon (auto- vs. hetero-), and their source of energy (photo- vs. chemo-). Thus a photoheterotroph identifies an organism that feeds (-troph) on the energy of light (photo-) and on carbon from other (hetero-) organisms.

140. The origin of CO2 in the blood is (A) the natural equilibrium conversion process from 02 (B) glycolysis and the Krebs cycle in tissue cells. (C) the product from acting as the final electron acceptor in oxidative phosphorylation. (D) passive diffusion from the atmosphere. (E) conversion from bicarbonate in the blood.

B The CO2 generated in the tissues come from the metabolism of glucose, in which each of the six carbon atoms is used to produce this low-energy-containing waste gas.

138. The respiration process that results in the buildup of organic waste compounds in a cell is known as (A) dehydration. (B) fermentation. (C) reduction. (D) anaerobiasis. (E) oxidation.

B The basis for identifying the form of respiration is always based on the substance that acts as the final electron acceptor in the process. If the final electron acceptor is oxygen or an inorganic ion, the process is considered aerobic or anaerobic respiration, respectively. The last possibility, the final electron acceptor being an organic molecule, defines fermentation.

99. When NADH is converted to NAD, the process is categorized as (A) dehydration. (B) oxidation. (C) catalysis. (D) reduction. (E) exergonic.

B Whenever oxygen is added to a molecule, or when an electron (e-) or hydrogen ion (H+) is removed, the process is called oxidation. The opposite processes of removing an oxygen atom or adding an e- or H+ is called reduction. Oxidation and reduction processes are always coupled and are known as redox reactions. The conversion of NADH to NAD involves the removal of a hydrogen ion and is thus an oxidation reaction.

1) The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the A) oxidation of glucose and other organic compounds. B) flow of electrons down the electron transport chain. C) H+ concentration gradient across the membrane holding ATP synthase. D) transfer of phosphate to ADP.

C

12) The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol, and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO2 or water produced as products of glycolysis.

C

12. ATP is considered to be A. an enzyme used widely in all kinds of cells. B. a coenzyme used to inhibit or activate different enzymes. C. a molecule that carries a great deal of chemical energy in a chemical bond. D. the precursor of a high-energy membrane-bounded protein.

C

15) Which kind of metabolic poison would most directly interfere with glycolysis? A) an agent that reacts with oxygen and depletes its concentration in the cell B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that reacts with NADH and oxidizes it to NAD+

C

17. A coenzyme is A. an ionic cofactor that interacts with an enzyme to allow it to work. B. a protein cofactor that interacts with an enzyme to allow it to work. C. a nonprotein organic cofactor that interacts with an enzyme to allow it to work. D. an ionic cofactor that interacts with an enzyme to inhibit it. E. a protein cofactor that interacts with an enzyme to inhibit it.

C

17. Glucokinase and hexokinase catalyze the first glycolysis reaction; glucokinase has a higher K m. Which of the following is a correct statement, if K m is equal to [Substrate] = one half V max? A. hexokinase is always functional and is not regulated by negative feedback B. hexokinase and glucokinase are not isozymes c. glucokinase is not a zymogen D. glucokinase becomes active from high levels of fructose

C

19. Coenzymes are: A. minerals such as Ca2+ and Mg2+ B. small inorganic molecules that work with an enzyme to enhance reaction rate C. small organic molecules that work with an enzyme to enhance reaction rate D. small molecules that do not regulate enzymes

C

22. Adult humans cannot synthesize _____ out of the _____ common amino acids. A. eleven; twenty B. nine; eleven C. nine; twenty D. any; twenty E. half; all

C

24. A holoenzyme is: A. inactive enzyme without its cofactor B. inactive enzyme without its coenzyme C. active enzyme with its cofactor D. active enzyme with its coenzyme

C

25) In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Which of the following sets of products result from these reactions? A) acetyl CoA, O2, and ATP B) acetyl CoA, FADH2, and CO2 C) acetyl CoA, NADH, and CO2 D) acetyl CoA, NAD+, ATP, and CO2

C

27) Which of the following events takes place in the electron transport chain? A) the breakdown of glucose into six carbon dioxide molecules B) the breakdown of an acetyl group to carbon dioxide C) the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle D) substrate-level phosphorylation

C

27. Which of the following choices represents a correct pairing of aspects for cellular respiration? A. Krebs cycle - cytoplasm B. fatty acid degradation - Iysosomes C. electron transport chain - inner mitochondrial membrane D. glycolysis - inner mitochondrial membrane

C

28) Which of the following statements about the electron transport chain is true? A) It is driven by ATP hydrolysis. B) It includes a series of hydrolysis reactions associated with mitochondrial membranes. C) It consists of a series of redox reactions D) It occurs in the cytoplasm of both prokaryotic and eukaryotic cells.

C

3. Which attractive force is used by the side chains of nonpolar amino acids to interact with other nonpolar amino acids? A. ionic bonds B. hydrogen bonds C. hydrophobic interaction D. disulfide bonds

C

31. The process of C6H12O6 + O2 ----->> CO2 + H2O is completed in the A. plasma membrane B. cytoplasm C. mitochondria D. nucleus

C

32. In a hyperthyroidism patient, the oxidative metabolism rate measured through the basal metabolic rate (BMR) will be: A. indeterminable B. below normal C. above normal D. normal

C

34) Water is one of the end products of aerobic respiration. What is the source of the oxygen atom used in formation of the water? A) carbon dioxide (CO2) B) glucose (C6H12O6) C) molecular oxygen (O2) D) pyruvate (C3H3O3-)

C

35) In chemiosmosis, what is the most direct source of energy that is used to convert ADP + P to ATP? A) energy released as electrons flow through the electron transport chain B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, down their electrochemical gradient D) energy released as electrons are transported across the inner mitochondrial membrane

C

36) Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? A) cytoplasm adjacent to the mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix

C

41) In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation.

C

42. Which statement below best describes the usual relationship of the inhibitor molecule to the allosteric enzyme in feedback inhibition of enzyme activity? A. The inhibitor is the substrate of the enzyme B. The inhibitor is the product of the enzyme-cat alyzed reaction C. The inhibitor is the final product of the metabolic pathway D. The inhibitor is a metabolically unrelated signal molecule

C

46. Like other catalysts, enzymes: I. increase the rate of reactions without affecting delta G II. shift the chemical equilibrium from more reactants to more products III. do not alter the chemical equilibrium between reactants and products A. I only B. I and II only C. I and III only D. III only

C

47. Enzyme activity can be regulated by: 1. zymogen proteolysis II. changes in substrate concentration III post-translational modifications A. I only B. II and III only C. I, II and III D. I and II only

C

49) Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation? A) reduction of NAD+ to NADH B) reduction of FAD to FADH2 C) oxidation of NADH to NAD+ D) hydrolysis of ATP to ADP + P

C

49. Glycogen is: A. degraded by glycogenesis B. synthesized by glycogenolysis C. the storage polymer of glucose D. found in both plants and animals

C

5) What happens to a glucose molecule when it loses a hydrogen atom as the result of an oxidation-reduction reaction? A) The glucose molecule is hydrolyzed. B) The glucose molecule is an oxidizing agent. C) The glucose molecule is oxidized. D) The glucose molecule is reduced.

C

50. If [S] = 2 Km, what portion of active sites of the enzyme is filled by substrate? A. 3/4 B. 2/3 C. 1/2 D 1/3

C

51. In allosteric regulation, how is enzyme activity affected by the binding of a small regulatory molecule to an enzyme? A. It is inhibited B. It is stimulated C. Can be either stimulated or inhibited D. Is neither stimulated nor inhibited

C

53. In eukaryotes, the energy is trapped in a high-energy phosphate group during oxidative phosphorylation that occurs in the: A. nucleus B. mitochondrial matrix C. inner mitochondrial membrane D. outer mitochondrial membrane

C

55) The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. PFK is inhibited by high levels of which of the following molecules? A) glucose and NAD+ B) AMP and ATP C) ATP and citrate D) citrate and CO2

C

56) The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Given its critical role in glycolysis, which of the following conditions would be a likely consequence for dogs afflicted with this disorder? A) They would die as embryos. B) They would have elevated blood-glucose levels, which may result in a high incidence of diabetes. C) They would be lethargic and readily tire from exercise. D) They would carry out elevated levels of oxidative phosphorylation.

C

6) When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes ________. A) dehydrogenated B) oxidized C) reduced D) redoxed

C

6. Metabolism is: A. consumption of energy B. release of energy C. all conversions of matter and energy taking place in an organism D. production of heat by chemical reactions

C

8. Endergonic reactions A. release energy. B. have a negative G and occur spontaneously. C. can only occur if there is an input of energy. D. have products with less free energy than the reactants. E. All of the choices are correct.

C

9) Why are carbohydrates and fats frequently considered high-energy foods? A) They contain many oxygen atoms. B) They contain no nitrogen atoms. C) They contain many electrons associated with hydrogen atoms. D) They are strong oxidizing molecules.

C

9. Which process reduces molecular oxygen to water? A. the citric acid cycle B. glycolysis C. the electron transport system D. fermentation E. the preparatory

C

18. Which of the following is NOT a form of potential energy? A. food B. water in a dam C. a muscle contracting D. All of the choices are not potential energy.

C A muscle contracting is a form of kinetic energy, not potential energy.

40. Some desert beetles can live out their life without ever drinking liquid water. They survive on "metabolic water," which A. was produced as water in the organisms they eat and is retained, never to pass out of the cell membrane. B. is absorbed from the air along with respiratory oxygen. C. is formed as a result of the reduction of oxygen as the final electron acceptor from the electron transport chain. D. is a breakdown product from glycolysis in the cytoplasm. E. is an original storehouse of water that is never allowed to pass out the cell membrane.

C Some desert beetles can live out their life without ever drinking liquid water. They survive on "metabolic water," which is formed as a result of the reduction of oxygen as the final electron acceptor from the electron transport chain.

3. The preparatory reaction breaks A. glucose into pyruvates. B. pyruvates into glucose. C. pyruvates into acetyl-CoA and carbon dioxide. D. pyruvates into acetyl-CoA and water. E. acetyl CoA into pyruvates and carbon dioxide.

C The preparatory reaction breaks pyruvates into acetyl-CoA and carbon dioxide.

95. The breakdown of glucose to pyruvate by a cell is an example of a(n) ______ reaction. (A) anabolic (B) aerobic (C) catabolic (0) synthesis (E) none of the above

C A molecule of glucose contains six carbon atoms and the covalent bonds between each of them contains stored energy. A molecule of pyruvate contains three carbon atoms. The production of two molecules of pyruvate from a single molecule of glucose is called glycolysis, which is a catabolic process identified by the reduction in size of organic molecules and the resulting release of free energy.

159. What is the relationship of acetyl-CoA to the TCA cycle? (A) The former is composed of the latter. (B) The former is a product of the latter. (C) The former feeds into the latter. (D) The latter is a product of the former. (E) The two are unrelated.

C Acetyl-coenzyme A (or acetyl-CoA) is the end product of glycolysis and pyruvate conversion and contains two carbon atoms. These molecules are fed into the TCA cycle; this drives the cycle one complete turn, which results in the release of the these two carbon atoms as CO2 waste gas.

88. Which of the following molecules contains the most available energy? (A) ATP (B) cAMP (C) glucose (D) ADP (E) NADH

C Adenosine triphosphate (ATP) contains three phosphate groups in sequence. Each of those phosphate groups contains a high-energy electron that can be transferred to other molecules for use in bond destabilization. Thus ATP contains more energy than ADP, which contains more than AMP or cAMP. NADH similarly contains a single high-energy electron. However, when a molecule of glucose is fully oxidized through aerobic respiration, it results in the production of 36 ATP (eukaryotes) or 38 ATP (prokaryotes).

154. The relationship between glucose and galactose is (A) that they are pentoses. (B) that galactose is a disaccharide containing glucose and fructose. (C) that they are epimers. (D) that glucose is a disaccharide containing galactose and ribose. (E) that galactose is a disaccharide containing two glucose monomers.

C Epimers are carbon-based polymers that can be differentiated not by chemical formula, meaning that they have identical atomic content, but by structure. Epimers are stereo isomers that are identical except for a single -OH reorientation, such as that seen with glucose and galactose at the C-4 position.

148. How many molecules of CO2 are released from a fully oxidized molecule of glucose? (A) 2 (B) 4 (C) 6 (D) 12 (E) 1

C Glucose is a hexose, as it is a carbohydrate containing six carbon atoms. Thus, any cell that extracts all the energy from a single molecule will produce, as a waste gas, six molecules of carbon dioxide containing single carbon atoms.

25. Clostridium butyricum is a heterotrophic anaerobe that grows on glucose and converts it to butyric acid as a product. If the free energy for this reaction is -50 kcal, the maximum number of ATP that this organism can synthesize from one molecule of glucose is approximately: A. 5 ATP B. 36 ATP C. 7 ATP D. 38 ATP

C Hydrolysis of 1 mole of ATP into ADP releases 30.5 kilo joules or about 7 kilo calories of energy. This energy is liberated because of the cleavage of high energy phosphate bond in ATP converting it into ADP

139. If 6.5 g of a protein was fully oxidized, what would be the net energy released for use by a body? (A) 36 Calories (B) 114 Calories (C) 26 Calories (D) 58.5 Calories (E) 6.5 Calories

C Lipids (oils or fats) contain 9 C per gram, while proteins and carbohydrates both contain 4 C each gram. Thus, if 6.5 g of protein is consumed, there are 6.5 g X 4 C/g, which equals 26 C available for use by the body. Thus, all options other than C are incorrect.

160. Which of the following is NOT related to a cyclic process? (A) TCA (B) Citric acid (e) Pyruvate (D) Krebs (E) Tricarboxylic acid

C The central metabolic process most commonly known as the Krebs cycle (from its discoverer, Hans Krebs, in 1937) has also more recently been identified as the citric acid cycle (a compound containing four carbon atoms that regenerates the cycle) or the tricarboxylic acid (or TCA) cycle (because the citric acid contains three carboxyl groups).

96. In eukaryotes, aerobic respiration generates ____ ATP molecules from a molecule of glucose. (A) 2 (B) 3 (C) 36 (0) 38 (E) 11

C The energy contained within a molecule of glucose is most efficiently produced when harvested through several mechanisms. These mechanisms include glycolysis, pyruvate conversion to acetyl CoA, and the electron transport system (ETS) housed within the mitochondria. Although some initial ATP investment is required to initiate the process, the net production is 36 ATP in eukaryotes when in the presence of oxygen. The lack of oxygen prevents the functioning of the ETS, which reduces the ATP yield to 2. Prokaryotes are slightly more efficient and can produce 38 ATP from a single molecule of glucose.

144. A(n) __ bond holds the two strands of DNA within its double helix form and must be overcome for gene expression, protein production, and replication. (A) polar (B) nonpolar (C) hydrogen (D) ionic (E) covalent

C The two strongest forms of chemical bonds are ionic and covalent, and the latter can be of either a polar or a nonpolar variety. The form of bond that holds together two complementary strands of DNA, which can be overcome with the simple heating of water, is the hydrogen bond.

1. The atom responsible for generating a hydrogen bond that helps to stabilize the alpha-helical configuration of a polypeptide is: A. peptide bond atom B. atom found in the R-groups C. hydrogen of the carbonyl oxygen D. hydrogen of the amino nitrogen

D

10. Enzymes act by: A. lowering the overall free energy change ofthe reaction B. decreasing the distance reactants must diffuse to find each other C. increasing the activation energy D. decreasing the activation energy

D

11) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A) 0% B) 2% C) 38% D) 100%

D

12. Which of the following is a correct classification of cAMP, considering the fact that cAMP-dependent protein phosphorylation activates hormone-sensitive lipase? A. DNA polymerase B. lipoproteins C. glycosphingolipids D. second messenger

D

13. ATP is considered a high-energy compound because under cellular conditions, 7.3 kcal per mole of energy is released when a bond is broken between A. the base adenine and the sugar ribose. B. the adenosine and the phosphate groups. C. the base adenine and the phosphate groups. D. the adenosine diphosphate and the third phosphate. E. All of the bonds release energy as ATP is completely broken down.

D

14. The majority of the carbon dioxide we exhale is produced in A. glycolysis. B. the electron transport system. C. lactate fermentation. D. the citric acid cycle.

D

14. The rate of V max is directly related to: 1. Enzyme concentration II. Substrate concentration 111. Concentration of a competitive inhibitor A. I, II, and III B. I and III only c. I and n only D. I only

D

16) During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released? A) glycolysis B) electron transport C) oxidation of pyruvate to acetyl-CoA D) the citric acid cycle

D

16. You are studying an enzyme that catalyzes a reaction that has a free energy change of +5 kcal. If you double the amount of your enzyme in a reaction mixture, what would be the free energy change for the reaction? A. -10 kcal B. -5 kcal C. 0 kcal D. +5 kcal

D

17) Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is stored in the form of which of the following molecules? A) acetyl-CoA B) NAD+ C) pyruvate D) NADH

D

19. Energy coupling of endergonic and exergonic reactions within cells A. permits biological reactions to proceed at temperatures consistent with life. B. uses heat released by one reaction to fuel the other reaction. C. utilizes ATP to carry energy between the exergonic and endergonic reactions. D. All of the choices are correct.

D

2. Complete oxidative breakdown of glucose results in ______ ATP molecules. A. 2 B. 4 C. 32 D. 36 E. 39

D

23. The amino acids we cannot synthesize are called _____ because we _____. A. unnecessary; therefore do not need them B. limiting; must include them in our diet C. anabolic; must use alternative amino acids D. essential; must include them in our diet E. superfluous; must survive without them

D

26. Which amino acid is directly affected by dithiothreitol (DTT) known to reduce and break disulfide bonds? A. methionine B. leucine C. glutamine D. cysteine

D

3. The activity of an enzyme might be increased by all of the following except ________. A. increase in substrate concentration B. a vitamin C. a 2-4 degree increase in temperature D. the presence of lead

D

32) During aerobic respiration, which of the following molecules directly donates electrons to the electron transport chain at the lowest energy level? A) NADH B) ATP C) water D) FADH2

D

33) Which of the following statements best describes the primary role played by oxygen in cellular respiration? A) It yields energy in the form of ATP as it is passed down the electron transport chain. B) It oxidizes glucose to form two molecules of pyruvate. C) It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. D) It serves as the final acceptor for electrons from the electron transport chain. Answer: D

D

33. Cofactors are: I. small inorganic molecules that work with an enzyme to enhance reaction rate II. small organic molecules that work with an enzyme to enhance reaction rate Ill. small molecules that regulate enzyme activity A. I only B. I and II only C. II and III only D. I, II and III

D

36. The most important contribution of the citric acid cycle to cellular respiration is A. production of large quantities of ATP. B. creation of proton gradients. C. reduction of glucose and corresponding oxidation of carbon dioxide. D. oxidation of metabolite molecules and the corresponding reduction of coenzymes. E. release of CO2.

D

37) Which of the following processes generates a proton-motive force in mitochondria? A) the flow of protons through ATP synthase down their concentration gradient B) the reduction of NAD+ by the first electron carrier in the electron transport chain C) lowering of pH in the mitochondrial matrix D) pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space

D

38) Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? A) 2 B) 4 C) 18-24 D) 30-32

D

38. Hemoglobin is a protein that contains a: B. site where proteolysis occurs C. phosphate group at its active site C. bound zinc atom D. prosthetic group

D

39) The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of which of the following processes? A) active transport B) allosteric regulation C) a reaction with a positive ΔG D) coupling of an endergonic reaction to an exergonic reaction

D

4. The first reaction in the citric acid cycle is binding A. carbon dioxide to a four-carbon (C4) molecule. B. carbon dioxide to a five-carbon (C5) molecule. C. acetyl-CoA to a C5 molecule. D. acetyl-CoA to a C4 molecule.

D

43) Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, which components involved in oxidative phosphorylation must be present for electron transfer and ATP synthesis to still occur? A) only the electron transport system B) only the ATP synthase system C) all of the electron transport system and the proteins that add CoA to acetyl groups D) all of the electron transport system and ATP synthase

D

44. While covalent bonds are the strongest bonds that form protein structure, which of the following are connected by a peptide bond? A. ammonium group and ester group B. two amino groups C. the alpha carbons D. amino group and carboxylate group

D

45) What kinds of cells carry out ATP synthesis by chemiosmosis? A) all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor B) only animal cells in mitochondria, exclusively using oxygen as the electron acceptor C) only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

D

5 Which of the following statements about the electron transport chain is correct? A As electrons flow along the chain, protons are pumped into the mitochondrial matrix. B ATP is formed as electrons flow through the enzyme ATP synthase. C The flow of electrons along the chain causes the pH of the inter-membrane space to increase. D When protons diffuse through ATP synthase into the matrix, ATP is formed.

D

5. Aerobic cellular respiration yields about ____ of the energy of glucose in ATP molecules. A. 2% B. 15% C. 28% D. 39%

D

50) An organism is discovered that thrives in both the presence and absence of oxygen. Interestingly, as oxygen is removed from the organism's environment, the rate of sugar consumption increases while the growth rate decreases. What do these observations suggest about the likely identity of this organism? A) It is an unremarkable eukaryotic organism. B) It is a photosynthetic organism. C) It is an obligate anaerobic organism. D) It is a facultative anaerobic organism.

D

53) What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ A) NADH B) NAD+ C) lactate D) pyruvate

D

54. All of the following statements about enzymes are true, EXCEPT: A. They function optimally at a particular temperature B. They function optimally at a particular pH C. They may interact with non-protein molecules to achieve biological activity D. Their activity is not affected by a genetic mutation

D

55. The Gibbs free-energy change (delta G) of a reaction is determined by: I. intrinsic properties of the reactants and products II. concentrations of the reactants and products III. the temperature of the reactants and products A. I only B. I and III only C. II and III only D. I, II and III

D

56. Allosteric enzymes: I. are regulated by metabolites that bind at sites other than the active site II. have quaternary structure III. show cooperative binding of substrate A. I only B. I and II only C. II and III only D. I, II and III

D

59) Beta oxidation generates substrates for cellular respiration through which of the following processes? A) catabolism of glucose B) catabolism of glycogen C) catabolism of proteins D) catabolism of fatty acids

D

6. Which best describes the second law of thermodynamics? A. Energy is not created nor destroyed, but it can change into matter. B. Energy is not created nor destroyed, but it can change from one energy form to another. C. Energy can be created from matter or used to produce matter. D. Some useful energy is lost as heat whenever an energy transfer occurs. E. Energy transfers are always 100% efficient in changing energy from one useful form to another.

D

7. A living organism represents stored energy in the form of chemical compounds. When an organism dies, what happens to this stored energy? A. All chemicals immediately lose their high-energy bonds. B. All molecules immediately degrade into basic elements. C. All energy immediately leaves, and that is one manifestation that the organism is dead. D. The chemical compounds in cells lose their organization over time because there is no longer an input of energy to maintain the organized state. E. The chemical compounds remain exactly intact and ready to start up again unless digested by a consumer or decay organism.

D

7. During alcoholic fermentation, all of the following occurs, EXCEPT: A. release of C02 B. oxidation of glyceraldehyde-3-phosphate C. oxygen is not consumed in the reaction D. ATP synthesis as a result of oxidative phosphorylation

D

21. For fatty acids to enter the citric acid cycle of aerobic respiration, the fatty acids must be A. deaminated. B. combined with glycerol. C. combined with ATP. D. converted to acetyl groups. E. converted into five-carbon sugars.

D For fatty acids to enter the citric acid cycle of aerobic respiration, the fatty acids must be converted to acetyl groups.

15. Which statement is NOT true about how various conditions will effect the activity of an enzyme? A. Higher temperatures generally increase the activity of an enzyme up to a point. B. Above a certain range of temperatures, the protein of an enzyme is denatured. C. A change in pH can cause an enzyme to be inactivated. D. An enzyme's activity is generally reduced by an increase in substrate concentration. E. When sufficient substrate is available, the active site will nearly always be occupied.

D It is not true that an enzyme's activity is generally reduced by an increase in substrate concentration. Enzyme activity will increase as substrate concentration increases, until the maximum rate is reached.

14. Which statement describes the currently accepted theory of how an enzyme and its substrate fit together? A. As the product is released, the enzyme breaks down. B. The enzyme is like a key that fits into the substrate, which is like a lock. C. The active site is permanently changed by its interaction with the substrate. D. As the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction.

D The currently accepted theory of how an enzyme and its substrate fit together is the induced fit model: as the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction.

166. An organic compound closely associated with photosynthesis, bioluminescence, and apoptosis would most likely be classified as a (A) fluorochrome. (B) cytochrome (C) pigment. (D) flavoprotein. (E) peptidoglycan.

D A flavoprotein is a protein that is conjugated to a compound derived from vitamin B2, or riboflavin. Beside those characteristics already identified, flavoproteins are also associated with mutation repair, control of superoxide radicals, and the electron transport chain.

162. What are the end products of the hydrolysis of ATP? (A) Water and ADP (B) Glucose, ADP, and inorganic phosphate (C) ADP, inorganic phosphate, energy, and ketone bodies (D) The production of ADP and inorganic phosphate, and the release of energy (E) The release of energy and water

D ATP is a high-energy-containing molecule that commonly acts as a coenzyme and consists of the nitrogenous base adenine coupled to the pentose ribose (forming the nucleoside adenosine). Attached to this core can commonly be found a single inorganic phosphate group (low-energy adenosine monophosphate, or AMP), two sequential phosphate groups (mid-energy-containing adenosine diphosphate, or ADP), or, ultimately, three inorganic phosphate groups in sequence (high-energy-containing adenosine triphosphate, or ATP). When energy is released from this molecule by removing the terminal electron-carrying phosphate group, the end products are ADP + Pi.

92. What is the final electron acceptor in the mitochondrial electron transport chain? (A) ADP (B) ATP (C) CoQ (D) O2 (E) NAD

D After NADH is oxidized back into NAD, the first component of the electron transport chain, FMN, is reduced with the donated high-energy electron. After passing down through the ETC omponents, the energy of this electron is drained off to power the proton pumps that move hydrogen ions across the mitochondrial membrane. In order for another electron to pass down through the system, the previous drained electron must be discarded onto a final electron acceptor sink. This sink component is oxygen gas, which is reduced to a molecule of water.

31. Why would an organism utilize alcohol fermentation if it is wasteful of the energy in food molecules and poses a threat of death due to high levels of toxic alcohol? A. The organism can survive short spells of anaerobic conditions and maintain growth and reproduction. B. If glucose levels are not high, there may be time to disperse the alcohol "waste." C. Fermentation can provide a rapid burst of ATP since it does not have to go through the full breakdown cycle. D. All of the choices are advantages. E. None of the choices is an advantage; anaerobes only survive where aerobes cannot.

D All of the choices are advantages of fermentation.

155. What is the purpose of an equilibrium constant? (A) To calculate the initial concentration of the reactants (B) To determine the specific preequilibrium components (C) To calculate the rate of a reaction (D) To determine the composition of any system at equilibrium (E) To identify the component of free energy

D An equilibrium constant is not dependent on the concentration of either the initial chemical product or the reactant, but is dependent on the reaction temperature. This constant can be derived as a reaction quotient only after the reaction reaches equilibrium, where the rate forward is the same as the reverse rate.

134. Energy is important to all forms of life because (A) all forms of life require a continuous supply of it. (B) it is required in order to do work. (C) it is required in order to make specific alterations in the cell. (D) all of the above. (E) both A and B only.

D Energy is constantly required by any living organism because it must be used to constantly counter the degenerative effects of increased randomness; thus, option A is true. Energy is also required to "do work," which means to allow all cellular functions to continue, so options B and C are equally true .

153. Glucose and ___ are the most closely related. (A) starch (B) glycogen (C) fructose (D) dextrose (E) cellulose

D Glucose is the primary product of photosynthesis and is used in the manu- facture of cellulose and starch in plants and glycogen in animals. It is one of the three primary monosaccharides, along with fructose and galactose, that are most quickly absorbed during digestion. Glucose is also known historically as dextrose because of its ability to rotate light to the right (dextro-) when the light is passed through a solution containing it.

135. How many enzymatic steps are involved in converting glucose to pyruvate through the process of glycolysis? (A) 3 (B) 5 (C) 8 (D) 10 (E) 12

D Glycolysis refers to the catalysis of glucose to pyruvate through this one primary cellular route. It takes five enzymatic steps to reduce glucose to two molecules of phosphoglyceraldehyde and five additional steps to rearrange the PGAL molecules to the structure called pyruvate. Thus, glycolysis involves 10 steps, making option D the true answer.

89. Pyruvate can be regarded as the end product of a) photolysis b) acetyl CoA conversion c) electron transport. d) glycolysis. e) the Krebs cycle.

D In order to harvest energy from a molecule of glucose, the molecule is subjected to a sequential series of enzymatic steps that splits the six-carbon-atom-containing glucose into two identical three-carbon molecules. It takes five steps to convert glucose into two molecules of phosphoglyceraldehyde (PGAL) and then an additional five steps to convert the two PGAL molecules into the end product of glycolysis, pyruvate.

131. Which of the following is NOT a product of the TCA cycle? (A) CO2 (B) ATP (C) NADH (D) Acetyl-Co.A (E) FADH2

D The TCA cycle defines a process whereby a molecule of acetyl-CoA is fed into a looping series of reactions that consumes the molecule and restores the cycle for the input of the next one. For every two carbon atoms contained within the acetyl-CoA input, two molecules of CO2, two molecules of ATP produced by substrate-level phosphorylation, three molecules ofNADH, and one molecule of FADH2 are kicked out.

5) What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ ---> Lactate + NAD+ Pyruvate + NADH + H+ < --- Lactate + NAD+ A) oxygen B) NADH C) lactate D) pyruvate

D The conversion of lactate to pyruvate is enzymatically catalyzed by lactate dehydrogenase. In this reaction lactate loses two electrons (becomes oxidized) and is converted to pyruvate. NAD+ gains two electrons (is reduced) and is converted to NADH. Both lactate and NAD+ bind to the active site of the enzyme lactate dehydrogenase and both lactate and NAD+ participate in the catalysis reaction. In fact, catalysis could not occur unless the coenzyme NAD+ is bound to the active site.

104. The process of converting pyruvate to acetyl CoA (A) produces one molecule of CO2. (B) produces three ATP by substrate-level phosphorylation. (C) produces three ATP by oxidative phosphorylation. (D) both A and C (E) both A and D

D The process of oxidizing a single molecule of pyruvate, containing three carbon atoms, into a single molecule of acetyl CoA, containing only two carbon atoms, generates a single molecule of the waste gas CO2 and the reduction of a molecule of NAD to NADH. The high-energy electron contained within the NADH is then transferred to the electron transport system, where the energy of the electron is used to pump six pairs of hydrogen ions across the mitochondrial membrane. Each of these pairs, in turn, flood through a molecule of ATP synthase, and this energy drives the conversion of ADP to ATP. Three pairs of H+ thus produce three ATP molecules.

147. Any organism that requires organic compounds such as glucose as its energy source would be categorized as a(n) (A) heterotroph. (B) lithotroph. (C) phototroph. (D) chemotroph. (E) autotroph.

D The terms autotroph and heterotroph refer to sources of carbon. Lithotroph and organotroph refer to sources of electrons. A phototroph gets its energy from light, while a chemotroph gets its energy from organic molecules.

142. Frequently the final compound produced by a metabolic pathway will serve as a down regulator for that pathway. This mechanism is known as (A) first-product inhibition. (B) coenzyme suppression. (C) noncompetitive inhibition. (D) feedback inhibition. (E) steric hindrance.

D This self-regulating mechanism is known as both end-product inhibition and feedback inhibition. The activation of this mechanism is produced by any buildup of pathway product.

101. Of the following electron carriers of the electron transport system, which transfers protons in addition to electrons? (A) cytochrome a (B) cytochrome c (C) ATP synthase (D) coenzyme Q (E) cytochrome cl

D When an electron is delivered by NADH or FADH2 to the early components of the electron transport system, whether found in eukaryotic mitochondrial or prokaryotic plasma membranes, it contains enough energy to power two or three proton pumps in sequence. However, once this energy has been significantly depleted from the electron, it is then passed through the later cytochrome components. Their job is simply to bleed off the remaining energy until it can be discarded onto a molecule of oxygen, converting it to a molecule of water. One of the proton pumps is coenzyme Q.

164. Besides the phosphate group, how can NADH and NADPH be differentiated? (A) By the different structure of the hydrogen added to each. (B) The former is formed by enzymes, the latter by abiotic mechanisms. (e) The formation of the former is exergonic, while the formation of the latter is endergonic. (D) The former is used in catalytic reactions, the latter in anabolic reactions. (E) Other than the phosphate group, there is no difference.

D While the difference in the phosphate group may seem minor, the biochemi- cal difference is massive. Only NADH is used in catabolic reactions in all cells, whereas NADPH is used only in anabolic reactions associated with photosynthesis in plants. The key is in the respective enzymes' ability to discriminate between the two.

35. Normally our body will run aerobic respiration in order to produce the required amount of ATP to sustain life. When we run out of oxygen we will shift over to anaerobic respiration. What is the value of anaerobic respiration to our system?

During aerobic respiration we will be producing 36 ATP with the availability of oxygen. When the oxygen levels decrease it can cause our system to shift over to anaerobic respiration. This will cause us to build up lactic acid which leads to muscle cramping and fatigue. It is the cramping, fatigue and lack of ATP that causes us to decrease our activity level. This decreased activity level allows the system time to recover and shift itself back to a state of aerobic respiration. The lactic acid produced will eventually be converted into ATP for the cell.

1. The sum of the chemical reaction in a cell constitute A. coupling reactions. B. free energy. C. endergonic reactions only. D. exergonic reactions only. E. metabolism.

E

16. Which statement is NOT true about enzyme inhibition? A. In competitive inhibition, the inhibitor binds to the active site of the enzyme. B. In noncompetitive inhibition, the inhibitor binds to the allosteric site of the substrate. C. In irreversible inhibition, a poison binds to the enzyme so that it can never work again. D. Most inhibitors act in a reversible fashion. E. All of the statements are true.

E

143. A chemical reaction that results in negative free energy (-delta G) is considered to be (A) catabolic. (B) anabolic. (C) exergonic. (D) endergonic. (E) both A and C.

E Energy is contained within all chemical bonds that hold a molecule together. Reactions that increase the molecule's size tend to increase that energy content, known as delta G. Reactions that reduce molecular size tend to release energy; this is -delta G. These energy-releasing reactions are always exergonic and are also generally catabolic.

98. The sequential process of fatty acid catabolism to acetyl CoA is called (A) hydrogenation. (B) oxidative phosphorylation. (C) the glyoxylate cycle. (0) reduction. (E) Beta-oxidation.

E Fatty acids are composed of long chains of carbon atoms and are used in the construction of mono-, di-, and triglycerides. Most of the fatty acid chains found in cells contain an even number of these carbons. Fatty acids are usually tapped as an energy source only when other forms of chemical energy storage such as ATP, carbohydrates, and proteins have been used. Pairs of carbon atoms are removed, converted to acetyl CoA, and then fed into the Krebs cycle in a process known as Beta-oxidation.

158. What glycogen is to starch, __ is to __ . (A) DNA, RNA (B) peptidoglycan, chitin (C) a polysaccharide, a monosaccharide (D) ADP, ATP (E) a glycoprotein , a polypeptide

E Glycogen and starch are both forms of polysaccharides. The former is highly branched and is formed in the livers of animals, while the latter is mostly unbranched and is formed in plants. While polypeptides are long, unbranched chains of amino acids, in biologic systems, they are commonly found as glycoproteins, which are polypeptides onto which sometimes numerous carbohydrate side chains have been attached.

85. Which is a five-carbon compound that is a portion of the TCA cycle? (A) succinyl CoA (B) acetyl CoA (C) oxaloacetate (D) pyruvate (E) a-ketoglutarate

E One two-carbon atom molecule (acetyl CoA) from glycolysis will enter the TCA cycle by attaching to a recycling molecule with four carbon atoms (oxaloacetate) to produce a molecule with six carbon atoms (citrate). The cycle continues with a molecule of CO2 being released, producing a molecule containing five carbon atoms (a-ketoglutarate), which in turn releases another molecule of CO2 to produce a four-carbon-atom-containing compound (succinyl CoA).

103. The conversion of glucose to pyruvate takes place (A) in the mitochondrial matrix. (B) in the mitochondrial cristae. (C) only in heterotrophic cells. (D) in the nucleus of eukaryotes. (E) none of the above

E The energy of glucose is released in three major steps: glycolysis, pyruvate conver- sion, and the electron transport system. The latter rwo occur within the mitochondria of eukaryotic cells. Glycolysis, the 10-enzymatic-step process of breaking down glucose into pyruvate, takes place within the cytosol of both prokaryotic and eukaryotic cells.

91. ________ is a component of the mitochondrial electron transport.chain. (A) Flavoprotein (B) Pyruvate (C) Cytochrome (D) both A and B (E) both A and C

E The mitochondrial electron transport chain consists of both protein and nonpro- tein electron carriers physically arranged in sequence within the mitochondrial membrane. These include the flavoprotein FMN, derived from vitamin B2; ubiquinone, a nonprotein component that is also known as coenzyme Q; and the iron-containing cyrochromes. Pyruvate is the end product of glycolysis and is not an ETC component.

50. Each molecule of NADH produced in the mitochondria provides the energy for two ATP molecules.

FALSE Each molecule of NADH produced in the mitochondria provides the energy for three ATP molecules.

45. Compare and contrast how ATP is formed in photosynthesis and aerobic respiration.

In both photosynthesis and aerobic respiration, ATP is formed by the ETC and chemiosmosis. In both the noncyclic pathway of photosynthesis and in aerobic respiration, a hydrogen ion (H+) gradient is established as electrons passing through the ETC. As the H+ flow down their electrochemical gradient through ATP sythase, ATP is produced. In photosynthesis, the splitting of water also contributes to the H+ gradient, which ultimately drives ATP synthesis. In aerobic respiration, ATP is also formed through substrate-level phosphorylation when an enzyme passes a high energy phosphate to ADP.

44. Why does your body store more energy as fat than as a carbohydrate? Compare the amount of ATP produced from carbohydrates to that produced from fats to support your answer. Use the data provided. (The following information will help with your comparisons. Both fats and carbohydrates undergo catabolism to produce ATP energy. Fat (triglyceride) is hydrolyzed to form glycerol and three fatty acids. An 18-carbon fatty acid produces approximately 108 ATP molecules when broken down. Calculate the number of ATPs produced by a fat made of 3 fatty acids, each of 18 carbon. Compare to ATPs formed from one glucose.)

Our bodies store energy as fat because it is a more efficient form of energy storage. Fat has a greater caloric density per gram (9 kilocalories) than carbohydrates (4 kilocalories). One triglyceride containing three fatty acids, each with 18 carbons, would produce approximately 324 ATPs compared to the 36 produced by one glucose molecule. The human body would have to carry more weight if it were to store its energy in carbohydrates rather than fat.

17. Glycolysis will yield a net of 2 ATP only during aerobic respiration.

T

19. Glycolysis is a catabolic process.

T

51. The breakdown of glucose in cellular respiration is a catabolic reaction.

TRUE

52. Fermentation is the process that produces bubbles of carbon dioxide that makes bread dough rise.

TRUE

53. Chloroplast are capable of running photosynthesis which is the most abundant form of anabolic metabolism in life.

TRUE

6. In which organelle of a plant cell does the citric acid cycle occur? a. chloroplast b. mitochondrion c. endoplasmic reticulum d. nucleus

b

8. Aerobic eukaryotes produce CO2 as a by-product during cellular respiration. Which of the following is a correct statement of the origin of CO2 produced by the complete oxidation of 1 molecule of glucose? a. 1 CO2 from glycolysis; 1 CO2 from the oxida- tion of pyruvate to acetyl CoA; 4 CO2 from the citric acid cycle b. 2 CO2 from the oxidation of pyruvate to acetyl CoA; 4 CO2 from the citric acid cycle c. 1 CO2 from the oxidation of pyruvate to acetyl CoA; 2 CO2 from the citric acid cycle d. 3 CO2 from the citric acid cycle

b

17. Glucose made from six radioactively labeled carbon atoms is fed to yeast cells in the absence of oxygen. How many molecules of radioactive alcohol (C2HsOH) are formed from each molecule of glucose? a. O c. 2 b. 1 d.3

c

19. Which of the following substances produces the most ATP per gram? a. glucose, because it is the starting place for glycolysis b. glycogen or starch, because they are polymers of glucose c. fats, because they are highly reduced compounds d. proteins, because of the energy stored in their tertiary structure

c

4. Some prokaryotes use anaerobic respiration, a process that a. does not involve an electron transport chain. b. produces ATP solely by substrate-level phosphorylation. c. uses a substance other than oxygen as the final electron acceptor. d. Both a and b are correct.

c

9. Which of the following statements correctly describes the role of oxygen in cellular respiration? a. It is reduced in glycolysis as glucose is oxidized. b. It combines with H+ diffusing through ATP synthase to produce H20. c. It is the final electron acceptor for the electron transport chain. d. It combines with the carbon removed during the citric acid cycle to form CO2.

c

13. Which of the following statements correctly de scribes a metabolic effect of cyanide, a poison that blocks the passage of electrons along the electron transport chain? a. The pH of the intermembrane space becomes much lower than normal. b. Alcohol would build up in the mitochondria. c. NADH supplies would be exhausted, and ATP synthesis would cease. d. No proton gradient would be produced, and ATP synthesis would cease.

d

14. The citric acid cycle is best described as a. the principle site for ATP synthesis within the cell. b. the process by which C02 is fixed into stable organic molecules in plants. c. the process in which oxygen is required during respiration. d. a process that stores chemical energy primarily in the form of intermediates such as FADH2 and NADH.

d

15. Fermentation produces less ATP than cellular respiration because a. NAD+ is regenerated by alcohol or lactate production, without the electrons of NADH passing through the electron transport chain. b. pyruvate still contains most of the "hilltop" electrons that were present in glucose. c. its starting reactant is pyruvate and not glucose. d. Both a and b are correct.

d

18. Glycolysis is considered one of the first metabolic pathways to have evolved because it a. relies on fermentation, which is characteristic of archaea and bacteria. b. is found only in prokaryotes, whereas eukary- otes use mitochondria to produce ATP. c. produces ATP only by substrate-level phos- phorylation and does not involve redox reactions. d. is nearly universal, is located in the cytosol, and does not involve O2.

d

35. After being gently denatured with the denaturant removed, proteins can recover significant activity because recovery of structure depends on? A. 4° structure of the polypeptide B. 3° structure of the polypeptide C. 2° structure of the polypeptide D. 1 ° structure of the polypeptide

d

5. Which of the following reactions is incorrectly paired with its location? a. ATP synthesis-inner membrane of the mitochondrion, mitochondrial matrix, and cytosol b. fermentation-cell cytosol c. glycolysis-cell cytosol d. citric acid cycle-cristae of mitochondrion

d

7. Which of the following compounds produces the most ATP when completely oxidized to CO2? a. acetyl CoA c. pyruvate b. glucose d. fructose-l,6-bisphosphate

d