BIO 201 TEST 2 PRACTICE QUESTIONS

2. Factors that increase membrane fluidity have the effect of making the membrane: A. More permeable B. Less permeable C. Thicker D. Denser

A

16.1 What is ∆G°' for the hydrolysis of ATP? A. +7.3 kcal/mol B. -7.3 kcal/mol C. 0 D.+1

B

4. In what way(s) are the functions of tight junctions and extracellular matrix similar? A. They both mediate cell migration B. They are both involved in anchoring cells C. They are both involved in creating tight junctions D. All of the above

B

13. Which of the following is a mechanism by which cells ensure a strong response to a small amount of ligand? A. receptor-mediated endocytosis B. GTP hydrolysis by G-proteins C. Enzyme cascades D. Zymogen activation

C

21. Which is true of ALL enzymes? A. They provide energy for endergonic reactions B. They alter delta G of the reaction they catalyze C. They alter the transition state D. They harness energy from ATP

C

39.1 The Calvin Cycle: A. Takes place in mitochondria. B. Produces ATP and NADPH C. Is anabolic. D. Requires O2. E. All of the above.

C

28. Which of the following is NOT required for glycolysis? A. Glucode B. ADP C. ATP D. NADH

D

7.1 Inhibition of which of the following would prevent indirect active transport of glucose into cells? A. GluT1 B. Ca++ ATPase C. Ligand-gated ion channels D. Na+/K+ ATPase

D

1. Which of the following could be considered both an advantage and a disadvantage of multicellularity? A. Large size B. Increased ability to absorb compounds from outside the organism C. Increased stability D. All of the above

A

10.1 Dr. Hutson really likes coffee. Caffeine is a chemical called a xanthine, which is a class of purine. One of the mechanisms by which caffeine acts is to inhibit cAMP phosphodiesterase. How does caffeine alter how Dr. Hutson's liver cells respond to epinephrine? A. It would increase glucose production. B. It would decrease glucose production. C. Neither answer 1 nor 2

A

14. Dr. Hutson really likes coffee. Caffeine acts in part by inhibiting the enzyme cAMP phosphodiesterase. How would caffeine affect liver cell responses to epinephrine? A. Liver cells would produce more glucose. B. Liver cells would produce less glucose C. Liver cells would secrete more digestive enzymes D. Liver cells would secrete fewer digestive enzymes

A

14.1 What happens to GTP in response to epinephrine binding to its receptor on liver cells? A. It binds to G-alpha B. It falls off of G-alpha C. It is hydrolyzed D. It gets phosphorylated

A

18. You place both X and Y in solution, each at 1 M. After they reach equilibrium, you determine that the temperature is 25 C, the pH is 7.0, and the concentrations are: [X] = 0.9 M, [Y] = 1.1 M. >1 Keq, <0 delta G. Is the reaction exergonic or endergonic? A. Exergonic B. Endergonic C. Neither D. Not enough information

A

20. Which of the following is NEVER TRUE of a catalyst? A. It increases of decreases delta G for a reaction B. It lowers the activation energy for a reaction C. It interacts chemically with the reactants D. It makes reactions happen more quickly

A

22.1 The enzyme phenylalanine hydroxylase (PAH) catalyzes the conversion of the amino acid phenylalanine to tyrosine (the first step of the breakdown pathway for phenylalanine, as well as the pathway for synthesis of tyrosine!). For this reaction, ∆G = -1.7 kcal/mol. This reaction is: A. Exergonic B. Endergonic C. Neither exergonic nor endergonic

A

26. What is always made along with release of CO2 during glucose catabolism? A. NADH B. ATP C. Acetyl CoA D. Pyruvate

A

26.1 The reaction below, phosphorylation of glucose, is exergonic because it is coupled to ATP hydrolysis. The enzyme hexokinase catalyzes this reaction. Which of the following best describes how an enzyme for this reaction works? glucose + ATP <---> glucose-6-P + ADP A. The enzyme alters the mechanism of the reaction by altering the transition state. B. The enzyme makes the reaction exergonic. C. The enzyme activated by phosphorylation, thereby providing the energy for the reaction. D. The enzyme is not even needed as long as ATP is available to provide energy for the reaction.

A

29. Fermentation occurs under ________ conditions, and most likely evolved for the primary purpose of making ________. A. Anaerobic, NAD+ B. Anaerobic, ethanol or lactic acid C. Aerobic, NAD+ D. Aerobic, ethanol or lactic acid

A

32.2 Which of the following is NOT a product of the Citric Acid Cycle? A. Citric acid B. CO2 C. NADH D. FADH2 E. All of the above are products

A

34. How are the light dependent reactions of photosynthesis similar to the electron transport system in aerobic metabolism? A. They both involved generation of a proton gradient that is harnessed to produce ATP B. Reduced coenzymes donate their electrons to the electron transport system, which harnesses the energy to produce a proton gradient C. They both use O2 as the final electron receptor. D. All of the above

A

34.1 In prokaryotes, where does the Citric Acid Cycle occur? A. Cytoplasm B. Rough ER C. Mitochondria D. Plasma membrane

A

35.1 The reaction shown below is a/an ______________ reaction. FADH2 → FAD + 2H+ + 2e- A. Oxidation B. Reduction

A

36.1 The reduction potential of FADH2 is _________ than/as that of NADH. A. Higher B. Lower C. The same

A

38.1 What is the primary purpose of fermentation? A. Re-oxidation of NADH B. Formation of ATP C. Production of ethanol or lactic acid D. Reduction of NAD+ E. Both re-oxidation of NADH and formation of ATP

A

40.1 In eukaryotes, where does glycolysis occur? A. Cytoplasm B. Rough ER C. Mitochondria D. Plasma membrane

A

44.1 Conversion of a 6-carbon compound to two 3-carbon compounds characterizes which of the following pathways? A. Glycolysis B. Fermentation C. Pyruvate decarboxylation D. The Citric Acid Cycle

A

45.1 True or false: in anaerobic organisms, all of the ATP that can be produced through glucose catabolism comes from glycolysis. A. True B. False

A

46.1 In order for any endergonic reaction to proceed, energy must be provided by a coupled exergonic reaction. There is virtually always more energy released by the exergonic reaction than is consumed by the endergonic reaction. The energy left over is ________. A. Released as heat B. Converted to potential energy C. Coupled to reduction of a coenzyme D. Nothing - it disappears

A

47.1 True or false: in aerobic organisms, all of the ATP that can be produced through glucose catabolism in the absence of O2 comes from glycolysis. A. True B. False

A

48.1 Imagine that you could engineer a cell that has all of the enzymes and other machinery for only glycolysis and the electron transport system. Would this cell be able to produce ATP to stay alive as long as glucose and O2 were available? A. Yes B. No

A

5. If you had a patient who had defective connective tissues, specifically brittle cartilage that lacked structural support, you might suspect a defect in: A. Collagen B. Laminin C. A proteoglycan D. The cytoskeleton

A

5.1 Which of the following never uses simple diffusion to pass through the cell membrane? A. Ions B. Small polar uncharged molecules C. Small hydrophobic molecules D. Large hydrophobic molecules.

A

1.1 Which of the following is a disadvantage of being a multicellular organism? A. Need for increased mobility to escape predators B. More difficult to absorb nutrients C. Larger size requires cytoskeleton for stability D. All of the above

B

11. Which of the following is a DISADVANTAGE of ENDOCRINE signaling? A. It is fast B. By the time it reaches the target cell, the ligand concentration is likely to be very low. C. It usually involved regulated secretion D. It may involve G protein coupled receptors

B

11.1 Pertussis toxin is produced by Bordetella pertussis, the bacterium that causes whooping cough. Pertussis toxin catalyzes the addition of ADP-ribose (structure below) to Gα, which prevents Gα from binding to GPCRs thus "locking" it in the GDP-bound state. How would this affect liver cell responses to epinephrine? A. It would decrease contraction. B. It would decrease glucose production C. It would decrease glycogen production. D. It would decrease endocytosis.

B

17. Imagine that your T.A. asks you to determine the energetics of the equilibrium of X and Y shown below. So you place both X and Y in solution, each at 1 M. After they reach equilibrium, you determine that the temperature is 25 C, the pH is 7.0, and the concentrations are: [X] = 0.9 M, [Y] = 1.1 M. What are Keq and delta G for this reaction? X-->Y A. >1 Keq, >0 delta G B. >1 Keq, <0 delta G C. <1 Keq, >0 delta G D. <1 Keq, <0 delta G

B

19. Which is not an enzyme? A. Ras B. Glycogen C. Na+/K+ ATPase D. Trypsin

B

19.1 Consider the reaction: A + B à C. At equiliubrium; the concentrations of the compounds are [A] = 0.1 M, [B] = 0.1 M, [C] = 1.9 M; and the pH is 10.0. What is ∆G for the reaction? (You should not need a calculator for this.) A. > 0 B. < 0 C. = 0 D. not enough information to tell

B

24.1 Which of the following is never true of enzymes? A. They change the transition state of a reaction. B. They lower ΔG of a reaction. C. They interact chemically with the reactants. D. They are restored to their original form at the end of the reaction

B

25. Phosphofructokinase-1 (PFK-1) is an important enzyme in glycolysis. If you wanted to (unwisely) design a drug that causes your cells to produce an infinite supply of ATP regardless of the circumstances, you might engineer this pill to contain a compound that: A. Prevents binding of ATP to the active site. B. Decreases the affinity of the allosteric site for ATP C. Increases the affinity of the allosteric site for citric acid D. Makes PFK-1 less active at low pH

B

30.1 Why is O2 required for aerobic metabolism, but not for production of ATP? (read answer choices carefully!) A. Because O2 is the last electron acceptor in the electron transport system, O2 is necessary for electron transport, and thus oxidative phosphorylation. However, both glycolysis and the Citric Acid Cycle can continue without O2, enabling the cell to continue producing small amounts of ATP through substrate-level phosphorylation. B. Because O2 is the last electron acceptor in the electron transport system, O2 is necessary for electron transport, and thus oxidative phosphorylation. However, glycolysis can continue in its absence, enabling the cell to continue producing small amounts of ATP through substrate-level phosphorylation. C. Because O2 is the last electron acceptor in the electron transport system, it is required for electron transport, and thus substrate-level phosphorylation. However, glycolysis and the Citric Acid Cycle can continue it its absence, enabling the cell to continue producing small amounts of ATP through oxidative phosphorylation. D. Because O2 is the last electron acceptor in the electron transport system, it is required for electron transport, and thus substrate-level phosphorylation. However, glycolysis can continue in its absence, enabling the cell to continue producing small amounts of ATP through oxidative phosphorylation.

B

32. Which of the following involves reduction of FAD to FADH2? A. Fermentation B. Citric Acid Cycle C. Light-dependent reactions D. Calvin Cylce

B

35. Which of the following pathways uses NADH and pyruvate as reactants? A. Glycolysis B. Fermentation C. The Citric Acid Cycle D. The Calvin Cycle

B

37.1 In the 1930's 2,4-dinitrophenol (DNP; shown below) was introduced to the market as a diet drug. DNP is a chemiosmotic "uncoupler" just like uncoupling protein (UCP) in brown fat. Uncouplers make the inner mitochondrial membrane permeable to protons (H+), causing them to flow down their concentration gradient without going through F0 and thereby bypassing the F1 ATP Synthase. As a result, the mitochondria fails to produce ATP when it breaks down glucose. DNP causes protons (H+) to flow: A. From the intermembrane space to the cytoplasm. B. From the intermembrane space into the mitochondrial matrix. C. From the cytoplasm to the intermembrane space. D. From the mitochondrial matrix to the intermembrane space.

B

7. Soon after you eat, what type of transport is used to move glucose into your cells? A. Simple diffusion B. Facilitated diffusion C. Direct active transport D. Indirect active transport

B

8.1 Which of the following is an advantage of endocrine signaling? A. It is fast. B. It affects large numbers of cells. C. It can be bidirectional. D. All of the above

B

36. Complete the following statement: "Glycolysis, come on sugar, come on sugar for the _______"

Breakdown

12. Liver cells respond to epinephrine by: A. Producing ATP B. Increasing the rate of glycosis C. Breaking down glycogen D. Producing NADH

C

12.1 Which of the following most closely approximates a second messenger? A. An odorant receptor on the surface of a mouse olfactory epithelium cell that undergoes a conformational change upon binding of metabolites (breakdown products) of thyroid hormones, activating an intracellular G-protein. B. The enzyme cyclic GMP phosphodiesterase, which is activated when photons the light "receptor" rhodopsin in rod photoreceptors (as in rods and cones of the retina). C. Na+ ions, which flow into a muscle cell in response to binding of acetylcholine to its receptor, which leads to Ca++ release from internal stores. D. The neurotransmitter secreted by a neuron in response to an electrical impulse traveling down its axon when it is stimulated by another neuron.

C

15.1 Pertussis toxin is produced by Bordetella pertussis, the bacterium that causes whooping cough. Pertussis toxin catalyzes the addition of ADP-ribose (structure below) to Gα, which prevents Gα from binding to GPCRs thus "locking" it in the GDP-bound state. Which of the following would you expect to see in liver cells treated with pertussis toxin? A. A decrease in Ca++ released in response to epinephrine B. Inhibition of ACh-mediated sodium channel opening C. A decrease in Adenylate Cyclase activity D. An increase in Protein Kinase A activity

C

22. Protein kinases regulate the activity of other enzymes using: A. Competitive inhibition B. Allosteric inhibiton C. Covalent modification D. Zymogen activation

C

27. Which of the following processes produces ATP using substrate level phosphorylation? A. Fermentation B. Pyruvate decarboxylation C. The citric acid cycle D. The calvin cycle

C

27.1 The enzyme phosphofructokinase-1 (PFK-1) catalyzes the 3rd reaction in glycolysis. ATP is a substrate for this reaction and therefore must bind in the active site in order for the enzyme to catalyze the reaction. However, when ATP concentrations get very high, ATP also binds to a separate site on PFK-1, inhibiting its activity, even if some ATP is bound to the active site. Inhibition of PFK-1 by ATP is an example of: A. Competitive inhibition B. Allosteric activation C. Allosteric inhibition D. Covalent modification E. Two of the above

C

3.1 The most fundamental function of the epithelium in animals is to prevent entry of pathogens and toxins from the environment. Which of the following is common to all epithelial cells? A. They are columnar. B. They are ciliated. C. They are held together by tight junctions. D. They have very high levels of cholesterol in their membranes

C

30. Similar to the way DNP works, Thermogenin in newborn mammals is produced in brown fat to uncouple proton diffusion from ATP synthesis. This results in: A. Increased ATP production and thereby increased levels of energy B. Decreased glucose consumption and thereby conservation of energy C. Increased heat production from photons diffusing down the concentration gradient D. Decreased rate of oxidation of NADH and FADH2 and thereby decreased rates of Glycolysis, Pyruvate decarboxylation, and the Citric Acid Cycle

C

31. Which of the following statements is FALSE regarding our relationship to photosynthesis? A. Aerobic respiration requires O2, which is produced during photosynthesis B. Most photosynthetic organisms fix CO2 reducing it to make the sugars that we use for both carbon and energy C. We use ATP and NADPH that are produced by photosynthetic organisms to make sugars from CO2. D. Plants use aerobic respiration

C

33.3 DNP was a very effective diet aid introduced in the 1930's, but it was nearly immediately taken off the market after several users died of acute hyperthermia (overheating). Why would DNP cause hyperthermia? A. Individuals taking it would have the sensation of increased energy and would therefore become extremely physically active, increasing their body temperature. B. The energy resulting from the increased metabolic rate would be released as heat. C. Protons flowing down their concentration gradient is an exergonic process, the energy from which, when not captured by ATP Synthase, is released as heat. D. Rapid oxidation of NADH and FADH2 would be uncoupled from proton transport and the energy from these reactions would be released as heat.

C

6. Cells shrink when you place them in a solution with a high concentration of the compound dithiothreitol, or DTT. This indicates that the cell membrane: A. IS permeable to both DTT and water B. IS permeable to DTT but NOT water C. Is NOT permeable to DTT but IS permeable to water D. Is NOT permeable to DTT or water

C

6.1 The H+ ATPase (a.k.a. "proton pump") creates electrochemical gradients across the membranes of plants, fungi, and protists. This is an example of: A. Simple diffusion. B. Facilitated diffusion. C. Direct active transport. D. Indirect active transport

C

8. Inhibiting the Na+/K+ ATPase would prevent which of the following? A. Facilitated diffusion of Ca++ into the cytoplasm from the smooth ER. B. Trasport of glucose into cells soon after eating C. Transport of glucose up its concentration gradient D. All of the above

C

10. A warthog is chased by a cheetah and is almost certainly experiencing a surge in epinephrine secreted by cells of its adrenal medulla into its bloodstream where it circulates to target cells throughout the body. This is an example of _____________ signaling. A. Autocrine B. Paracrine C. Juxtacrine D. Endocrine

D

13.1 Which of the following is NOT TRUE of a second messenger in signal transduction? A. It is diffusible B. It is produced when the "first messenger" binds to its receptor C. It can activate a cellular response, even in the absence of the "first messenger" D. All of the above are TRUE

D

15. Receptor Tyrosine Kinase signaling differs from G-protein coupled receptor signaling in that it: A. Does not require GTP B. Involves enzyme cascades C. Is the mechanism used by hormones D. Has very long term effects

D

16. Hydrolysis of ATP is considered to be: A. slightly endergonic B. slightly exergonic C. very endergonic D. very exergonic

D

2.1 Collagen is constitutively secreted by fibroblast cells, which are a type of connective tissue cell. If you had a patient in which collagen is synthesized normally, but fails to be secreted into the ECM, which of the following would you examine as the likely cause of this problem? A. A Ca++ deficiency B. A failure of the Na+/K+ ATPase C. A H+ pump disorder D. None of the above

D

23.1 A mutation that causes a decrease in the GTPase activity of G-alpha in liver cells would have the effect of: A. Increasing the activity of Protein Kinase A B. Increasing the activity of Glycogen phosphorylase C. Increasing the production of glucose D. All of the above E. None of the above

D

24. For the reaction pathway shown, what is the best way to ensure that compound B is made available for other processes, but only after compound D has reached an ideal threshold concentration? A <--E1--> B <--E2--> C <--E3--> D A. Allosteric inhibition of E1 by B B. Allosteric activation of E1 by A C. Allosteric inhibition of E3 by A D. Allosteric inhibition of E2 by D

D

31.1 Fermentation is active in _____ organisms. A. Anaerobic B. Aerobic organisms in the presence of O2 C. Aerobic organisms in the absence of O2 D. Both anaerobic organisms and aerobic organisms in the absence of O2

D

33. What metabolic pathway is summarized by the reaction shown here? CO2 + H2O ---> sugars + O2 A. Glycolysis B. Aerobic Metabolism C. The Calvin Cycle D. All of Photosynthesis

D

4.1 Which of the following would you expect to be found in lipid rafts at a HIGHER concentration that in the surrounding membrane? A. More unsaturated lipids B. Phospholipids with shorter fatty acid chains C. Phospholipids D. Cholesterol E. All of the above

D

41.1 Which of the following is true of the ATP Synthase in the mitochondria? A. It is an enzyme. B. It can catalyze either phosphorylation of ADP or dephosphorylation of ATP. C. It is a proton transporter. D. All of the above

D

42.1 What do glycolysis and the Citric Acid Cycle have in common? A. They both involve oxidation of glucose. B. They both occur in the cytoplasm. C. They both produce CO2 D. They both produce ATP and NADH

D

43.1 The reactions converting glucose into CO2 taken together are _____ and ______: A. Anabolic; require energy B. Anabolic; release energy C. Catabolic; require energy D. Catabolic; release energy

D

49.1 What are the major products of the Light-dependent reactions? A. G3P, O2 B. H2O, ATP, NADPH C. Glucose, H2O D. ATP, NADPH, O2

D

50.1 Rubisco is one of the most important (and abundant) proteins on Earth. What makes it so special? A. It catalyzes the formation of ATP from ADP using only the energy of the proton gradient. B. It converts the energy stored in reduced intermediates to formation of a proton gradient. C. It can catalyze the oxidation of water to O2. D. It catalyzes the incorporation of CO2 into organic molecules, making it possible to synthesize sugars and other biological molecules that sustain most of life on Earth.

D

9. Which of the following does not ever cross the plasma membrane using simple diffusion? A. Water B. Small polar uncharged molecules C. Large hydrophobic molecules D. Ions

D

9.1 "He was awakened in the middle of the night by a low growling that sounded as if it was coming from just outside his tent. In response, the cells of his adrenal medulla began to secrete epinephrine, causing his palms to sweat, his heart to race, and his hair to stand on end." Epinephrine is involved in what type of signaling as described in this passage? A. Paracrine B. Juxtacrine C. Autocrine D. Endocrine

D