15 November 2012

Answers BIO 106 Unit 3 Cell Biology Test Part 3

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question.
For the following questions, match the labeled component of the cell membrane in the figure with its description.

1) Which component is the peripheral protein?
A) A                 B) B                  C) C                  D) D                 E) E

2) Which component is cholesterol?
A) A                 B) B                  C) C                  D) D                 E) E

3) Which component is the fiber of the extracellular matrix?
A) A                 B) B                  C) C                  D) D                 E) E

4) Which component is a microfilament of the cytoskeleton?
A) A                 B) B                  C) C                  D) D                 E) E

5) Which component is a glycolipid?
A) A                 B) B                  C) C                  D) D                 E) E

6) Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
A) by cotransport of glucose and hydrogen
B) by increasing the percentage of cholesterol molecules in the membrane
C) by increasing the percentage of unsaturated phospholipids in the membrane
D) by using active transport
E) by decreasing the number of hydrophobic proteins in the membrane

7) Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
A) glucose        B)K+                 C) an amino acid                       D) starch                      E) CO2

8) An animal cell lacking oligosaccharides (found on either glycolipid or glycoproteins) on the external surface of its plasma membrane would likely be impaired in which function?
A) cell-cell recognition                                                
B) attaching to the cytoskeleton
C) maintaining fluidity of the phospholipid bilayer
D) transporting ions against an electrochemical gradient
E) establishing the diffusion barrier to charged molecules

9) Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?
A) NaCl will passively diffuse into the red blood cells.
B) Water will leave the cells, causing them to shrivel and collapse.
C) The blood cells will take up water, swell, and eventually burst.
D) The blood cells will expend ATP for active transport of NaCl into the cytoplasm.
E) NaCl will be exported from the red blood cells by facilitated diffusion.

10) An organism with a cell wall would most likely be unable to take in materials through
A) phagocytosis.           B) active transport.      C) osmosis.        D) diffusion.     E) facilitated diffusion.

11) Which of the following is an example of potential rather than kinetic energy?
A) water rushing over Niagara Falls                  B) the flight of an insect foraging for food
C) a molecule of glucose                                   D) the muscle contractions of a person mowing grass
E) light flashes emitted by a firefly

12) Which of the following is true for all exergonic reactions?
A) The reactions are rapid.
B) The products have more total energy than the reactants.
C) The reaction proceeds with a net release of free energy.
D) A net input of energy from the surroundings is required for the reactions to proceed.
E) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.

13) Why is ATP an important molecule in metabolism?
A) Its terminal phosphate bond has higher energy than the other two.
B) It provides energy coupling between exergonic and endergonic reactions.
C) It is one of the four building blocks for DNA synthesis.
D) Its hydrolysis provides an input of free energy for exergonic reactions.
E) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.

14) Which of the following statements is true concerning catabolic pathways?
A) They supply energy, primarily in the form of ATP, for the cell's work.
B) They build up complex molecules such as protein from simpler compounds.
C) They are endergonic.
D) They are spontaneous and do not need enzyme catalysis.
E) They combine molecules into more energy-rich molecules.

15) Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
A) activation energy.    B) free-energy content.     C) endothermic level.   D) entropy.        E) equilibrium point.
16) What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?
A) The nitrogen-containing base is different.               B) The number of phosphates is three instead of one.
C) The sugar molecule is different.                              D) There is no difference.
E) The number of phosphates is three instead of two.

17) The active site of an enzyme is the region that
A) binds allosteric regulators of the enzyme.
B) is involved in the catalytic reaction of the enzyme.
C) is inhibited by the presence of a coenzyme or a cofactor.
D) binds noncompetitive inhibitors of the enzyme.

18) According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?  
A) The active site creates a microenvironment ideal for the reaction.
B) The binding of the substrate depends on the shape of the active site.
C) A competitive inhibitor can outcompete the substrate for the active site.
D) The binding of the substrate changes the shape of the enzyme's active site.
E) Some enzymes change their structure when activators bind to the enzyme.

19) When you have a severe fever, what grave consequence may occur if the fever is not controlled?
A) binding of your enzymes to inappropriate substrates   B) change in the tertiary structure of your enzymes
C) destruction of your enzymes' primary structure            D) removal of amine groups from your proteins
E) removal of the amino acids in active sites of your enzymes

20) How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
A) by changing the shape of the enzyme's active site             
B) by binding at the active site of the enzyme
C) by changing the free energy change of the reaction           
D) by decreasing the activation energy of the reaction
E) by acting as a coenzyme for the reaction

21) Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
A) Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
B) The oxidation of organic compounds can be used to make ATP.
C) The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds.
D) The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide.
E) The covalent bond in O2 is unstable and easily broken by electrons from organic molecules.

22) Which of the following statements describes the results of this reaction?
C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy
A) CO2 is reduced and O2 is oxidized.                         B) O2 is reduced and CO2 is oxidized.
C) C6H12O6 is reduced and CO2 is oxidized.                D) O2 is oxidized and H2O is reduced.
E) C6H12O6 is oxidized and O2 is reduced.

23) The oxygen consumed during cellular respiration is involved directly in which process or event?
A) accepting electrons at the end of the electron transport chain       B) the citric acid cycle
C) the phosphorylation of ADP to form ATP                 D) the oxidation of pyruvate to acetyl CoA
E) glycolysis

Activity of various enzymes at various temperatures (a) and at various pH (b).

24)Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?
A) curves 2 and 4         B) curves 1 and 5          C) curves 2 and 5          D) curves 3 and 5      E) curves 3 and 4

25) Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
A) curves 2 and 4         B) curves 1 and 4          C) curves 3 and 4          D) curves 1 and 5      E) curves 2 and 5

26) Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
A) chemiosmosis                       B) electron transport                C) the citric acid cycle            
D) oxidative phosphorylation    E) glycolysis

27) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
A) 100%           B) 10%              C) 38%             D) 2%               E) 0%

28) During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is
A) transferred to ADP, forming ATP.   B) stored in the NADH produced.         C) transferred directly to ATP.
D) used to phosphorylate fructose to form fructose 6-phosphate.        E) retained in the two pyruvates.

29) Starting with one molecule of glucose, the energy-containing products of glycolysis are
A) 6 CO2, 30 ATP, and 2 pyruvate.    B) 2 NAD+, 2 pyruvate, and 2 ATP.   C) 2 NADH, 2 pyruvate, and 2 ATP.
D) 2 FADH2, 2 pyruvate, and 4 ATP.                E) 6 CO2, 2 ATP, and 2 pyruvate.

30) During cellular respiration, acetyl CoA accumulates in which location?
A) mitochondrial intermembrane space             B) mitochondrial inner membrane        
C) mitochondrial outer membrane                     D) mitochondrial matrix                      
E) cytosol

The following questions are based on the reaction A + B  C + D shown below

31) Which of the following terms best describes the forward reaction in Figure 8.1?
A) exergonic, ∆G < 0                            B) endergonic, ∆G < 0               C) chemical equilibrium, ∆G = 0
D) endergonic, ∆G > 0                           E) exergonic, ∆G > 0

32) Which of the following represents the ΔG of the reaction in Figure 8.1?
A) a                  B) b                  C) c                  D) d                              E) e

33) Which of the following in Figure 8.1 would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
A) a                  B) b                  C) c                  D) d                              E) e

34) Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products in Figure 8.1?
A) a                  B) b                  C) c                  D) d                              E) e

35) Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?
A) a                  B) b                  C) c                  D) d                              E) e

36) Which of the following represents the activation energy required for a noncatalyzed reaction in Figure 8.1?
A) a                  B) b                  C) c                  D) d                              E) e

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

38) Where are the proteins of the electron transport chain located in most animal cells?
A) mitochondrial matrix        B) mitochondrial outer membrane    C) mitochondrial intermembrane space
D) cytosol                              E) mitochondrial inner membrane

39) The primary role of oxygen in cellular respiration is to
A) act as an acceptor for electrons and hydrogen, forming water.
B) combine with carbon, forming CO2.
C) combine with lactate, forming pyruvate.
D) yield energy in the form of ATP as it is passed down the respiratory chain.
E) catalyze the reactions of glycolysis.

40) Energy released by the electron transport chain is used to pump H+ into which of the following locations in eukaryotic cells?  
A) cytosol                                B) mitochondrial inner membrane         C) mitochondrial outer membrane
D) mitochondrial matrix           E) mitochondrial intermembrane space

41) Why are carbohydrates and fats considered high energy foods?
A) They can have very long carbon skeletons.   B) They have lots of electrons associated with hydrogen.
C) They have no nitrogen in their makeup.        D) They are easily reduced.
E) They have lots of oxygen atoms.

42) An organism is discovered that thrives both in the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism
A) must use a molecule other than oxygen to accept electrons from the electron transport chain.
B) is a normal eukaryotic organism.       C) is photosynthetic.    D) is a facultative anaerobe.
E) is an anaerobic organism.

43) Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
A) H2O and O2                        B) ADP, i, and NADP+            C) electrons and H+
D) ATP and NADPH                  E) CO2 and glucose

44) Where does the Calvin cycle take place?
A) interior of the thylakoid (thylakoid space)              B) outer membrane of the chloroplast
C) thylakoid membrane                                                 D) cytoplasm surrounding the chloroplast
E) stroma of the chloroplast

45) In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane and plasma membrane                          B) plasma membrane only
C) thylakoid membrane and inner mitochondrial membrane       D)inner mitochondrial membrane only
E) thylakoid membrane only
46) Which of the following statements best describes the relationship between photosynthesis and respiration?
A) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
B) Respiration is anabolic and photosynthesis is catabolic.
C) Respiration runs the biochemical pathways of photosynthesis in reverse.
D) ATP molecules are produced in photosynthesis and used up in respiration.
E) Photosynthesis occurs only in plants and respiration occurs only in animals.

47) In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during
A) photorespiration only.                                  B) photosynthesis only.             C) respiration only.
D) both photosynthesis and respiration.           E) neither photosynthesis nor respiration.

48) Reduction of NADP+ occurs during
A) respiration.                          B) both photosynthesis and respiration.            C) photosynthesis.
D) photorespiration.                 E) neither photosynthesis nor respiration.

49) The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
A) neither photosynthesis nor respiration.        B) photosynthesis.        C) photorespiration.
D) respiration.                          E) both photosynthesis and respiration.

50) What is the primary function of the Calvin cycle?
A) use NADPH to release carbon dioxide                      B) split water and release oxygen
C) use ATP to release carbon dioxide                           D) transport RuBP out of the chloroplast
E) synthesize simple sugars from carbon dioxide

51) (5 pts.) An artificial cell consisting of an aqueous solution enclosed in a selectively permeable membrane is immersed in a beaker containing a different solution. The membrane is permeable to water and the simple sugars glucose and fructose but impermeable to the disaccharide sucrose.
A) Initially, the solution outside the cell is [isotonic, hypotonic, or hypertonic] (circle one.)

B) List the solutes that will initially have a net movement into the cell.

C) List the solutes that will initially have a net movement out of the cell.

D) Initially, the net movement of water will be [into/out of] (circle one) the cell.

E) At equilibrium the cell will become more flaccid, more turgid, or stay the same volume?

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