Biol 178 Exam 2 Sample Questions Fall 2007

Transcription

1 Biol 178 Exam 2 Sample Questions Fall 2007 FILL IN THE BLANKS 1. The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called. 2. Due to the repellent nature of the polar water molecules, the tails of the phospholipids are sequestered together. 3. While water continually orients phospholipids into a lipid bilayer, it does not fix the lipids permanently into position. Thus they are considered in nature. 4. is the net movement of substances to regions of lower concentration. 5. Because a given channel or carrier will transport only certain kinds of molecules and ions, the plasma membrane is said to be. 6. The net movement of a solute across the plasma membrane toward a region of lower concentration, by means of specific channels or carriers, is called. 7. Glycoproteins and glycolipids are examples of associated with the cell membrane. 8. Both active transport and facilitated transport utilize specific proteins embedded in the cell membrane. 9. Osmosis occurs as water can cross the lipid bilayer through, specialized channels for water movement. 10. Energy is the capacity to do. 11. In bioenergetics, the unit of energy used is the same one as used for heat, the. 12. The process of influencing the chemical bonds in a way that lowers the energy needed to speed up a chemical reaction is called catalysis. 13. Enzymes work most effectively at their temperature and ph conditions. 14. Biochemical are a series of sequential chemical reactions which are maintained in the cell. 15. A chemical reaction which requires energy is called an reaction. 16. A chemical reaction which requires an input of energy is a(n) reaction, while a chemical reaction which releases energy is a(n) reaction. 17. Organisms that can manufacture their own chemical energy sources are called. 18. depend on energy stored in chemical bonds by autotrophs for their food energy. 19. Simple molecules are further broken down in cells in a process called, during which energy stored in their chemical bonds is used to power the production of ATP. 20. Glucose is broken down to carbon dioxide and water in organisms which breathe air in a process called as respiration. 21. In glycolysis, a major portion of the energy remains in the final product, which is called. 22. For further derivation of energy, aerobic cells must convert pyruvate into acetyl coenzyme A by stripping off a C0 2 molecule. This process is known as. 23. All of the reactions of glucose oxidation that follow glycolysis involving the transfer of electrons to their final acceptor, oxygen, take place in eukaryotic cells in the. 24. Because the chemical formation of ATP is driven by a diffusion force similar to osmosis, this process is referred to as. 26. The first stage of cellular respiration,, occurs with or without oxygen present. 27. When oxygen is limiting, during heavy exercise, muscle cells revert to fermentation for energy production. 29. In the reactions of photosynthesis, electron carrier molecules are reduced and ATP is synthesized. 30. Each pigment molecule has a characteristic spectrum, a range of photons that it is capable of absorbing. 31. Molecules that absorb light are called. 32. Plants and algae use a two-stage in the light dependent reactions. 33. The Calvin cycle is driven by ATP and produced in the light reactions. 34. Even though the Calvin cycle reactions require the products of the light reactions, its reactions can occur in the. 35. In eukaryotes, photosynthesis takes place inside the. 36. Carbon fixation occurs during the dark reactions, or the, in photosynthesis. Page 1

2 MULTIPLE CHOICE 37. The specificity of an enzyme is due to its active site. The active site is shaped so that only a certain A) substrate molecule can fit into it B) product molecule can fit into it C) reactant molecule can fit into it D) cofactor molecule can fit into it E) histone molecule can fit into it 38. The chief energy currency of all cells is a molecule called A) cyclic AMP C) FADH D) ATP E) ADP 39. The chemistry of living systems representing all chemical reactions is called A) catabolism B) anabolism C) metabolism D) enzymology E) thermodynamics 40. A calorie is the commonly used unit of chemical energy. It is also the unit of A) light B) magnetism C) sound D) heat E) radioactivity 41. The term oxidation is derived from the name of the element oxygen. This is reasonable, because it A) attracts electrons very strongly B) can be oxidized by accepting electrons C) contains more electrons than are needed D) can react chemically readily in its gas state E) is present everywhere 42. When an atom or molecule gains one or more electrons, it is said to be A) energized B) oxidized C) polarized D) activated E) reduced 43. An electron transferred in a biological system is usually A) boosted to a higher light energy state B) converted into other chemical compounds C) accompanied by a proton D) given off as radiant energy E) lost to the system as heat 44. Life's ultimate source of energy is derived from A) the sun B) plants C) water D) air E) cells Page 2

3 45. As energy is being reconverted through the many forms, it is continuously lost as A) electricity B) light C) sound D) heat E) chemical energy 46. Reactions that do not proceed spontaneously because they require energy from an outside source are called A) exergonic B) xerogonic C) metabolic D) endergonic E) endocytic 47. Molecules that act as catalysts in biological systems are A) ATP B) cofactors C) coenzymes D) enzymes E) genes 48. Enzymes catalyze chemical reactions by lowering the A) entropy B) free energy C) activation energy D) enthalpy E) calories 49. When the substrate is bound to the enzyme, the shape of the enzyme may change slightly, leading to A) a better induced fit B) a great range of possible catalytic activities C) a greater supply of activation energy D) more permanent binding through intimate total contact E) more possible products of the reaction 50. Enzymes are very specific in their choices of substrates because each different enzyme has an active site that A) depends on unusual amino acids not common in proteins B) has a certain unique amino acid to fit each substrate C) is shaped to fit a certain substrate molecule D) is lined with glycolipids and glycoproteins E) passes electrons from one part of the substrate to another 51. The ability of an enzyme to catalyze a reaction can be affected by chemical and physical factors such as A) temperature B) ph C) salt concentration D) binding of specific regulatory molecules E) all of the above 52. One of the most important coenzymes that accepts electrons/hydrogens is A) NAD+ C) ATP D) NADPH E) ribozyme Page 3

4 53. ATP gives up energy when it is converted to A) DNA B) NADP C) NADH D) ADP and phosphate E) RNA 54. The First Law of Thermodynamics simply states that A) Energy is constantly being created in the universe. B) Energy is being lost as heat in the universe. C) Energy can be created but not destroyed. D) Energy cannot be created or destroyed, just changed from one form to another. E) Energy can be recycled through the universe. 55. The Second Law of Thermodynamics simply states that A) Energy can be recycled through the universe. B) Energy cannot be created or destroyed, just changed from one form to another. C) Energy is constantly being lost as heat in the universe. D) Energy is constantly being created in the universe. E) Energy can be created but not destroyed. 56. The temperature is raised slightly above the optimum for a specific enzyme. What would you expect to observe as a result of the change in temperature? A) increased enzyme activity B) decreased enzyme activity C) no change in enzyme activity D) enzyme denaturation E) all of the above 57. A molecule that stores energy by linking charged phosphate groups near each other is called A) ATP C) FADH D) cyclic AMP E) pyruvate 58. An electron carrier that is used in harvesting energy from glucose molecules in a series of gradual steps in the cytoplasm is A) pyruvate B) cyclic AMP C) ATP D) NAD+ E) NADH 59. In eukaryotes, the glycolytic reactions take place in the A) mitochondria of the cell B) cytoplasm of the cell C) ribosomes of the cell D) endoplasmic reticulium of each cell E) Golgi bodies of the cell 60. The first stage of cellular respiration, and the oldest in terms of evolution is A) decarboxylation B) deamination C) fermentation D) chemiosmosis E) glycolysis Page 4

5 61. In the absence of oxygen, hydrogen atoms generated by glycolysis are donated to organic molecules in a process called A) fermentation B) decarboxylation C) chemiosmosis D) electron transport chain reactions E) acetyl-coa formation 62. At least 90% of organisms on the earth are heterotrophs. Examples include all of the following except A) plants B) fungi C) most eubacteria D) animals E) most protists 63. Fermentation can be described as a process A) that takes place only in the absence of oxygen B) in which the recipient of hydrogen atoms is an organic molecule C) in which water is not one of the by-products D) in which the Krebs cycle and electron transfer through ETS do not occur E) all of the above are true 64. Chemiosmotic generation of ATP is driven by A) phosphate transfer through the plasma membrane B) sodium, potassium pump C) a difference in H+ concentration on the two sides of the mitochondrial membrane D) osmosis of macromolecules E) large quantities of ADP 65. The reaction, C 6 H 6 O 6 + 6O 2 = 6 CO H 2 O, when it occurs in living cells is known as A) aerobic fermentation B) anaerobic fermentation C) aerobic respiration D) glycolysis E) oxidative phosphorylation 66. In which of the following steps of glycolysis, 2 ATP molecules are required? A) cleavage and rearrangement B) glucose priming C) oxidation D) pyruvate formation E) acetyl-coa formation 67. A process common to all living organisms, aerobic and anaerobic, is A) glycolysis B) fermentation C) the Krebs cycle D) electron transport chain reactions E) pyruvate oxidation 68. All of the following are the end products of glycolysis except A) pyruvate B) ATP C) NADH D) NAD+ Page 5

6 E) energy 69. The fate of the end-product of glycolysis depends on the type of organism. The name of the end-product is A) ATP B) NAD+ C) alcohol D) ADP E) pyruvate 70. The decarboxylation of pyruvate produces A) NADH B) acetylcoa C) CO 2 D) ATP E) only a, b, and c are correct 71. In the cyclic reaction sequence called the Krebs cycle, the following chemical events take place except A) the acetyl group is joined with a four carbon molecule, oxaloacetate B) the resulting six carbon molecule is oxidized C) electrons generated are used to produce NADH D) two carbons per cycle are made into CO 2 molecules E) pyruvate molecules are restored to the cycle 72. A single glucose molecule can drive the Krebs cycle A) one turn B) two turns C) three turns D) four turns E) six turns 73. The coenzyme electron carriers produced in the Krebs cycle are A) ATP and ADP B) pyruvate and acetyl-coa C) FADH 2 and NADH D) NAD and NADH E) NADH and ATP 74. The oxygen utilized in cellular respiration finally shows up as A) CO 2 B) ATP C) new O 2 D) H 2 O E) part of a sugar 75. The electron transport chain, a series of membrane-associated electron carriers, loses most of the energy by driving several transmembrane A) proton pumps B) electron pumps C) sodium, potassium pumps D) active transport pumps E) water pumps 76. The enzymes of the Krebs cycle are located in the A) cytoplasm B) inter-membrane space of mitochondria C) vesicles of the ER Page 6

7 D) outer membrane of the mitochondria E) matrix of the mitochondria 77. Since membranes are relatively impermeable to ions, most of the protons re-enter the matrix by passing through special channels in the inner mitochondrial membrane. Because of the inward flow of protons these channels allow the synthesis of A) ADP from ATP and Pi B) ATP from ADP and Pi C) glucose from pyruvate D) acetyl-coa from pyruvate E) citrate from oxaloacetate and acetyl-coa 78. Regardless of the electron or hydrogen acceptor used, one of the products of fermentation is always A) ADP B) ATP C) NAD + D) pyruvate E) alcohol 79. Yeast cells under anaerobic conditions A) die B) produce ethyl alcohol (ethanol) C) produce oxygen D) switch to oxidative respiration E) push the glycolytic pathway backward 80. In muscle cells, fermentation produces not alcohol but A) ATP C) pyruvate D) kinetic energy E) lactate 81. What type of cell respiration occurs when an organic molecule accepts hydrogen atoms? A) aerobic respiration B) anaerobic respiration C) fermentation D) catabolism E) digestion 82. A biochemist wants to control the initial substrate-level phosphorylation that occurs in the tracheal cells of grasshoppers once glucose has crossed the plasma membrane. This means that he will A) have to prevent camp from entering the tracheal cells B) have to prevent pyruvate reduction from occurring C) have to prevent glycolysis from occurring in the mitochondria D) have to prevent glycolysis from occurring in the cytoplasm E) have to prevent aerobic respiration in the cytoplasm 83. Select the correct sequence concerning glucose catabolism. A) glycolysis Pyruvate Acetyl CoA Electron Transport Chain Kreb Cycle B) glycolysis Pyruvate Acetyl CoA Kreb Cycle Electron Transport Chain C) glycolysis Acetyl CoA Pyruvate Electron Transport Chain Kreb Cycle D) glycolysis Acetyl CoA Pyruvate Kreb Cycle Electron Transport Chain 84. Which of the following statements accurately reflects what happens to a glucose molecule during the initial five phases of glycolysis? Page 7

8 A) Glucose, a six-carbon sugar, enters the cell by passive transport and is primed and converted into glucose threephosphate, which requires two ATP molecules. The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules. B) Glucose, a six-carbon sugar, enters the cell by active transport and is primed and converted into glucose threephosphate, which requires two ATP molecules. The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules. C) Glucose, a six-carbon sugar, enters the cell by simple diffusion and is primed and converted into glucose threephosphate, which requires two ATP molecules. The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules. D) Glucose, a six-carbon sugar, enters the cell by G protein mediation and is primed and converted into glucose three-phosphate, which requires two ATP molecules. The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules. 85. When substrate-level phosphorylation occurs, it means that A) NAD is converted into NADH B) ATP is converted into ADP + a phosphate group C) ADP is converted into ATP by addition of a phosphate group D) camp is converted into ADP by adding a phosphate group E) NADH is converted into NAD + H 86. Cells release energy from molecules such as glucose in a process very similar to inhalation of air and exhalation of carbon dioxide by humans. This process is known as cellular A) oxidation B) reduction C) photosynthesis D) radiation E) respiration 87. Carbon atoms of CO 2 are incorporated into organic molecules in a series of dark reactions called A) carbon reduction B) carbon synthesis C) carbon fixation D) carbon activation E) carbon oxidation 88. Most plants incorporate carbon dioxide into sugars by means of a cycle of reactions called the A) CAM cycle B) carbon cycle C) Calvin cycle D) Krebs cycle E) Electron transport cycle 89. Flattened sacs of internal membranes which have proteins embedded and are associated with photosynthesis are called A) chloroplasts B) photosystems C) the stroma D) thylakoids E) cristae 90. In green plant photosynthesis, the electron donor for the light dependent reaction is A) carbon dioxide B) oxygen C) RuBP D) chlorophyll II E) water Page 8

9 91. In the dark reactions of photosynthesis, CO 2 is added to a five-carbon sugar-phosphate known as A) cyclic AMP C) NAD + D) RuBP E) CAM 92. Which of the following scientists is not associated with studies on photosynthesis? A) Blackman B) Jan Ingenhousz C) Krebs D) Calvin E) Van Niel 93. Light consists of units of energy called A) electrons B) photons C) protons D) neutrons E) pigments 94. Visible light has a wavelength range of A) nanometers B) nanometers C) nanometers D) nanometers E) ,000 nanometers 95. Molecules that absorb light are called A) enzymes B) electron carriers C) pigments D) photosynthesizers E) absorbers 96. Which of the following two types of pigments are used in photosynthesis? A) chloroplasts B) carotenoids C) chlorophylls D) a and b E) b and c 97. Chlorophyll b absorbs in green wavelengths of light that chlorophyll a cannot absorb. In this respect, chlorophyll b acts as A) an accessory pigment B) an energizer for photosynthetic bacteria C) a light absorber in the green light D) a more efficient pigment E) all of the above are true 98. The photosystem channels the excitation energy gathered by absorption of light by any one of the pigment molecules to a specific reaction center chlorophyll, which in turn passes the energy to A) photosystem I B) photosystem II C) the primary electron acceptor D) the secondary electron center Page 9

10 E) cytochrome 99. Which of the following is common to both cellular respiration and the light reactions of photosynthesis? A) the transfer of electrons to glucose B) the chemiosmotic formation of ATP C) oxygen is one of the byproducts D) mitochondria are essential organelles E) must have light 100. Photosystem II differs from photosystem I in that the following molecule is not made directly from the process A) ATP C) NADPH D) carbohydrates E) water 101. The dark reactions of photosynthesis are those that A) convert chlorophylls into enzymes B) convert enzymes into chlorophylls C) convert water into hydrogen and oxygen D) convert CO 2 into reduced molecules (sugars) E) only occur in the dark 102. The cyclic carbon fixation reactions are also known as the A) Krebs cycle B) Calvin cycle C) citric acid cycle D) tri carboxylic acid cycle E) Blackman cycle 103. Which part of the chloroplasts contain the Calvin-cycle enzymes? A) stroma B) thylakoids C) grana D) envelope E) cristae 104. The photosynthetic electron transport causes the accumulation of protons in which part of the chloroplast? A) matrix B) stroma C) envelope D) outer membrane E) internal thylakoid space 105. What products of light reactions of photosynthesis are used in the Calvin cycle? A) oxygen and protons B) carbon dioxide and water C) ATP and NADPH D) ADP and NADP E) glucose and oxygen 106. A method devised by succulent desert plants to reduce the problem of photorespiration is A) the C 3 pathway B) the CAM metabolism C) the Calvin cycle D) light reactions Page 10

11 E) nitrogen fixation 107. Most of the atmospheric oxygen occurs as a result of photosynthesis. From which of the following molecules is the oxygen derived? A) water B) carbon dioxide C) glucose D) chlorophyll 108. Carotenoids are important to many plants because these pigments are able to A) remove carbon dioxide from the air B) absorb wavelengths of light that neither chlorophyll a nor b can absorb C) absorb water so that hydrolysis can be carried out in the chloroplasts D) capture UV radiation that is harmful to the DNA in the nucleus of plant cells E) store electrons for use during the dark reaction of photosynthesis 109. Fall leaf color on deciduous trees is a result of A) the production of more accessory pigments because of the cooler temperatures B) the reduction in the production of accessory pigments because of the cooler temperatures C) cessation of chlorophyll production, which allows the accessory pigments to be revealed D) the increased angle of the sun during the fall, which reflects more of the accessory pigments causing the human eye to see the red, yellow, and orange colors that were masked by the green chlorophyll 110. In the plants that utilize the CAM pathway, what happens to the stomata? A) The stomata open in the afternoon but close as soon as the sun sets. B) The stomata open in the morning but close in the afternoon. C) The stomata open in the evening but close in the morning. D) The stomata open only when the sun is shining and close at night Which of the following is not part of the light-dependent reactions? A) primary photoevent B) charge separation C) calvin Cycle D) electron transport E) chemiosmosis 112. The Calvin Cycle requires all of the following except A) carbon dioxide B) oxygen C) ATP D) NADPH E) water Page 11