07 January 2013

ANSWERS BIO 106 Unit 3 Cell Biology Part 6

1.       Which of the following statements about osmosis is correct
A. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis
B. Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration
C. Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment
D. IF a cell is placed in an istonic solution, more water will enter the cell than leaves the cell.
E. If a solution outside the cell is hypotonic compared to the cytoplasm, water will move into the cell by osmosis

2.       Which of the following statements about a typical plasma membrane is correct?
A. Carbohydrates on the membrane surface are important in determining the overall bilayer structure.
B. The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids
C. The two sides of the plasma membrane have different lipid protein composition
D. The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell
E. Phospholipids are the primary content that determines which solutes can cross the plasma membrane

3.       Which of the following correctly describes some aspect of exocytosis and endocytosis?
A. The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane
B. Endocytosis and exocytosis involve passive transport
C. These two processes require the participation of mitochondria
D. Exocytosis and endocytosis change the surface area of the plasma membrane
E. Both processes provide a mechanism for exchanging membrane impermeable molecules between the organelles and the cytosol

4.       If the concentration of phosphate in the cytosol is 3.0 mM and the concentration of phosphate in the surrounding fluid is 0.2 mM, how could the cell increase the concentration of phosphate in the cytosol?
A. Passive transport
B. Diffusion
C. Active transport
D. Osmosis
E. Facilitated diffusion

5.       Which of the following is least likely to be important in holding components of a biological membrane together?
A. Hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane
B. Polar interactions among the phospholipid head groups on the same surface of the membrane
C. Hydrophobic interactions among the fatty acid tails of phospholipids on the opposite sides of the membrane
D. Covalent interactions between the phospholipid and protein components of the membrane
E. Hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane

6.       The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following?
A. Movement of glucose into the cell through a glucose cahnnel
B. Passive diffusion of the glucose through the lipid bilayer
C. Facilitated diffusion of the glucose using a carrier protein
D. Cotransport of the glucose with sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
E. Receptor-mediated endocytosis

7.       The permeability of a biological membrane to a specific charged solute may depend on which of the following?
A. The total amount of cholesterol in the membrane
B. The types of transport proteins in the membrane
C. The phospholipid composition of the membrane
D. The presence of unsaturated fatty acids in the membrane
E. The types of polysaccharides present in the membrane

8.       Active and passive transport of solutes across the membrane typically differ in which of the following ways?
A. Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute
B. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy
C. Active transport is always faster than passive transport
D. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers.
E. Active transport is used for ions, passive transport is used for uncharged solutes

9.       Which of the following factors does not affect membrane fluidity and/or permeability
A. The amount of cholesterol in the membrane
B. Temperature
C. Saturation of hydrocarbon tails in membrane phospholipids
D. The polarity of membrane phospholipids

10.   What distinguishes facilitated diffusion from simple diffusion?
A Water never moves through membranes by facilitated diffusion
B. No energy is used to move molecules ocross the membrane
C. Molecules move from a region of higher concentration to a region of lower concentration
D. Membrane proteins help move molecules across the membrane

11.   Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide is correct?
A. The free energy lost in this combustion is less than the energy that appears as heat.
B. The reverse reaction, making glucose from water and carbon dioxide, must be an exergonic reaction
C. The entropy of the products is greater than the entropy of the reactants.
D. The entropy of the universe decreases as the result of this reaction
E. This is the process of cellular respiration, on anabolic pathway that releases free energy

12.   Which of these is exhibiting kinetic energy?
A. an archer with a flexed bow
B. a person sitting on a couch while watching TV
C. A space station orbiting Earth
D. a rock on o mountain ledge
E. The high-energy phosphate bonds of o molecule of ATP

13.   Which of the following statements about equilibrium of chemical reactions is correct?
A. Reactions con only go in the direction toward equilibrium
B. The equilibrium point is where the system hos the highest free energy
C. The equilibrium point of a reaction represents the least stable configuration for that reaction
D. Most reactions in a living cell are close to equilibrium
 E. A reaction that is at equilibrium is not capable of doing any work

14.   Which of the following would be unlikely to contribute to the specificity of an enzyme?
A. A positive charge on the substrate to a negative charge in the active site of the enzyme
B. The enzyme has the ability to change its configuration in response to the substrate binding
C. A hydrophobic Group on the substrate interacts with several hydrophobic amino acids on the enzyme
D. The enzyme has an allosteric regulatory site
E. A similar shape exists between a pocket on the surface of the enzyme and a functional group on the substrate

15.   The binding of a compound to on enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation
A. The compound causes a cofactor to be last from the enzyme
B. The compound reduces disulfide bonds, causing the enzyme molecules to partially unfold
C. The compound forms a covalent bond with one of the amino acid residues needed f or enzyme activity.
D. The compound is a negative allosteric regulator
E. The compound is a competitive inhibitor

16.   Which of the following statements about ATP (adenosine triphosphate) is correct?
A. Almost all of the free energy released on the hydrolysis of ATP is released as heat
B. the cycling between ATP on ADP +Pi provides an energy coupling between catabolic on anabolic pathways
C. The hydrolysis of ATP is an endergonic process
D. The hydrolysis of ATP con supply energy needed for catabolic pathways
E. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond

17.   Which statement about the binding of enzymes on substrates is correct?
A. substrate molecules fit into the active site of an enzyme like a key fits into a lock
B. substrate molecules bind to the active site of the enzyme, The enzyme undergoes a slight change in shape.
C. Substrate molecules bind to the active site of the enzyme only by weak bonds, such as hydrogen bonds or hydrophobic attraction

18.   In general, most known enzymes are what kinds of molecules?
A. lipids
B. Proteins
C. carbohydrates
D. nucleic acids
E. minerals

19.   How does on enzyme increase the rate of the chemical reaction it catalyzes?
A. An enzyme's active site binds only the reactants, on not the products of a reaction, pushing the equilibrium f or the reaction for to the right.
B. An enzyme reduces the free-energy change (delta G) of the reaction it catalyzes
C. An enzyme reduces the Activation Energy (Ea) of the reaction it catalyzes

20.   the electrons stripped from glucose in aerobic cellular respiration end up forming which molecule?
A. Water
B. Oxygen
C. Carbon dioxide

21.   In this reaction ___________________________ 

A. CD is a product
B. products have less potential energy that the reactants
C. AC is a reactant
D. entropy has decreased
E. the products have been rearranged to form reactants

22.   Which statement about the citric acid cycle is correct?
A. The oxidation of compounds by the citric acid cycle directly requires molecular oxygen
B. The citric acid cycle oxidizes glucose to carbon dioxide
C. The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis
D. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
E. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain

23.   Which one of the following statements about the redox reactions of the electron transport chain is correct?
A. NADH gains electrons in the initial reaction of the electron transport chain.
B. The redox reactions of the electron transport chain ore directly coupled to the movement of protons across a membrane
C. The electron transport chain takes electrons from water and gives them to oxygen
D. The redox reactions of the electron transport chain ore directly coupled with the synthesis of ATP
E. The oxidation of NADH is directly coupled to the reduction of oxygen to water

24.   Which of the following describes the process of glycolysis?
A. Glycolysis produces 30 ATP from each molecule of glucose
B. It requires ATP and NADH
C. Glycolysis occurs in the mitochondria
D. It represents the first stage in the chemical oxidation of glucose
E. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide

25.   A glucose molecule is completely broken down to carbon dioxide on water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?
A. It was lost as heat
B. It is stored in NADH and FADH2
C. It is stored in pyruvate
D. It is stored in carbon dioxide and water molecules released by these processes
E. It is stored in the ATP that was formed by glycolysis and the citric acid cycle

26.   In the combined process of glycolysis and cellular respiration, What is consumed and what is produced?
A. ATP is consumed, and oxygen is produced
B. Oxygen is consumed, and glucose is produced
C. Glucose is consumed, and carbon dioxide is produced
D. Water is consumed, and ATP is produced
E. Carbon dioxide is consumed, and water is produced

27.   Identify the correct statement about the basic function of fermentation
A. The basic function of fermentation is the production of ethyl alcohol or lactic acid
B. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis
C. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis

28.   Select the correct statement about cellular respiration
A. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level
B. Animals carry out cellular respiration whereas plants carry out photosynthesis
C. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis

29.   In muscle cells, fermentation produces:
A. lactate, NAD+, and ATP
B. carbon dioxide, ethanol, NADH, and ATP
C. Pyruvate and NAD+
D. Carbon dioxide, ethanol, and NAD+
E. Pyruvate only

30.   In cellular respiration, a series of molecules forming an electron transport chain alternatively accepts and then donates electrons. What is the advantage of such an electron transport chain?
A. The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates
B. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor
C. The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates.

For each of the following phrases, pick the best term (A through J) that best matches it. Each term is used only once
A) Activation energy   B) Active site  C) Energy Coupling  D) Entropy  E) Enzyme
F) Enzyme inhibitor    G) Induced fit  H) Metabolism   I) Plasmolysis  J) Substrate

31) the transfer of energy from processes that yield energy to those that consume it
32) a specific substance (reactant) on which an enzyme acts
33) a phenomenon that occurs in plant cells in a hypertonic environment
34) a measure of disorder, or randomness
35) the many chemical reactions that occur in organisms
36) chemicals that interfere with on enzyme's activities
37) the type of energy that reactants must absorb before a chemical reaction will start
38) a protein that serves as biological catalysts
39) the interaction between substrate molecules on the active site of an enzyme
40) the part of an enzyme molecule where a substrate molecule attaches

For each of the following phrases, pick the best term (A through J) that best matches it. Each term is used only once

A) aerobic  B) anaerobic  C) autotroph  D) facultative anaerobe  E) fermentation
F) hetertroph  G) obligate aerobe  H) obligate anaerobe  I) oxidation  J) reduction

41) on organism that cannot survive without oxygen
42) type of chemical reaction that does not use oxygen
43) organism that makes its organic matter from inorganic nutrients
44) acceptance of electrons during a redox reaction
45) on organism that cannot survive in the Presence of oxygen
46) loss of electrons during a redox reaction
47) anaerobic harvest of food energy
48) a type of anaerobe that con make ATP using aerobic or anaerobic respiration
49) chemical reaction using oxygen
50) organism that cannot make its own organic food molecules

51. Draw a figure representing the lipid bilayer of the fluid mosaic model of cell membranes. Include and labele each of the following components: peripheral protein, transmembrane protein, cholesterol, fiber of extracellular matrix, filament of the cytoskeleton, glycolipid, and integral glycoprotein

52. Write the overall balanced chemical equation for cellular respiration
C6H12O6 + 6O2 ----> 6CO2 + 6H2O

53. Which graph below (A or B) best represents each of the following terms. Place A or B in front of each of the following terms.

            _A_ anabolic reaction      _B_ catabolic reaction
            _B_ exergonic reaction    _A_endergonic reaction

54. USE THE WORD BANK BELOW: Correctly name each stage of cellular respiration (A – D)
State the main reactants and products for each stages
List the net number of ATPs, NADHs, and FADH2s produced during each stage. Zero is an appropriate answer. Words may be used more than once

Acetyl CoA,         Carbon Dioxide                 Glucose                                Glycolysis
Citric Acid cycle                 Oxidative phosphorylation          Oxygen
Pyruvate              Shuttle Step                       Water


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