15 November 2012

Answers BIO 106 Unit 3 Cell Biology Test Part1

BIO 106                                 Print Name:   (Last name first)                                                                  
EXAM III, 2011                   
MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question.
1) Which of the following types of molecules are the major structural components of the cell membrane?
A) phospholipids and cellulose   B) phospholipids and proteins     C) glycoproteins and cholesterol
D) nucleic acids and proteins     E) proteins and cellulose

2) Of the following functions, which is most important for the sugars on glycoproteins and glycolipids of animal cell membranes?  
A) facilitated diffusion of molecules down their concentration gradients
B) active transport of molecules against their concentration gradients
C) maintaining the integrity of a fluid mosaic membrane
D) a cell's ability to distinguish one type of neighboring cell from another
E) maintaining membrane fluidity at low temperatures

3) Which of these are not embedded in the lipid bilayer at all?
A) peripheral proteins                     B) glycoproteins                    C) transmembrane proteins
D) integrins                                       E) integral proteins

4) Which of the following statements is correct about diffusion?
A) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
B) It is very rapid over long distances.
C) It requires integral proteins in the cell membrane.
D) It requires an expenditure of energy by the cell.
E) It is an active process in which molecules move from a region of lower concentration to one of higher concentration.

The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half filled with a solution of 2 M sucrose and 1 M glucose. Side B is half filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.

5) Initially, in terms of tonicity, the solution in side A with respect to that in side B is
A) hypotonic.                        B) hypertonic.           C) isotonic.    D) plasmolyzed.        E) saturated.

6) A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water (very hypotonic), equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?
A) The patient's red blood cells will shrivel up because the blood fluid is hypotonic compared to the cells.
B) The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
C) It will have no unfavorable effect as long as the water is free of viruses and bacteria. 
D) The patient's red blood cells will burst because the blood fluid is hypertonic compared to the cells.
E) The patient's red blood cells will shrivel up because the blood fluid is hypertonic compared to the cells.

7) When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
A) the cell will become turgid        B) the cell membrane will lyse       C) the cell will burst
D) plasmolysis will shrink the interior       E) the cell will become flaccid

8) Ions diffuse across membranes down their
A) electrochemical gradients.        B) chemical gradients.         C) electrical gradients.
D) concentration gradients.                       E) none are correct.

9) The difference between pinocytosis and receptor-mediated endocytosis is that
A) pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot.
B) pinocytosis brings only water into the cell, but receptor-mediated endocytosis brings in other molecules as well.
C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
D) pinocytosis increases the surface area of the plasma membrane whereas receptor-mediated endocytosis decreases the plasma membrane surface area.
E) pinocytosis requires cellular energy, but receptor-mediated endocytosis does not.

10) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? 
A) metabolism          B) anabolism                          C) dehydration         D) catabolism           E) catalysis 

11) Which of the following is a statement of the first law of thermodynamics?
A) Energy cannot be created or destroyed. 
B) Energy cannot be transferred or transformed. 
C) The entropy of the universe is decreasing. 
D) Kinetic energy is stored energy that results from the specific arrangement of matter.  
E) The entropy of the universe is constant. 

12) Which of the following is an example of potential rather than kinetic energy?
A) a firefly using light flashes to attract a mate
B) a food molecule made up of energy-rich macromolecules
C) an insect foraging for food
D) water rushing over Niagara Falls
E) a boy mowing grass

13) A chemical reaction that has a positive G is correctly described as
A) endothermic.       B) exothermic.          C) unfavorable.         D) endergonic.          E) enthalpic. 

14) Which of the following is most similar in structure to ATP?
A) an amino acid with three phosphate groups attached         B) an RNA nucleotide 
C) a DNA helix         D) an anabolic steroid                     E) a phospholipid 

15) A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because 
A) starch cannot be hydrolyzed in the presence of so much water.
B) the starch solution has less free energy than the sugar solution. 
C) the hydrolysis of starch to sugar is endergonic. 
D) the activation energy barrier for this reaction cannot be surmounted. 
E) starch hydrolysis is nonspontaneous. 

16) Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
A) an increase in a cell's catabolic activity         B) an increase in a cell's anabolic activity
C) an increased amino acid concentration                        D) an increased influx of cofactor molecules
E) the cell's increased transport of materials to the environment

17) The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as 
A) feedback inhibition.                   B) noncooperative inhibition.          C) metabolic inhibition. 
D) reversible inhibition.                  E) allosteric inhibition. 

18) Which of the following statements describes NAD+?
A) NAD+ is reduced by the action of hydrogenases.
B) NAD+ can donate electrons for use in oxidative phosphorylation.
C) NAD+ has more chemical energy than NADH.
D) NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.
E) In the absence of NAD+, glycolysis can still function.

19) The ATP made during glycolysis is generated by
A) chemiosmosis.       B) substrate-level phosphorylation.       C) oxidation of NADH to NAD+.
D) electron transport.         E) photophosphorylation.

20) During aerobic respiration, electrons travel downhill in which sequence?
A) food  NADH  electron transport chain  oxygen
B) food  glycolysis  citric acid cycle  NADH  ATP
C) glucose  AT electron transport chain  NADH
D) glucose  pyruvate  ATP  oxygen
E) food  citric acid cycle  ATP  NAD+

21) In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
A) energy released from substrate-level phosphorylation
B) energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix
C) energy released as electrons flow through the electron transport system
D) energy released from movement of protons through ATP synthase
E) No external source of energy is required because the reaction is exergonic.

22) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
A) ATP, pyruvate, and oxygen.                  B) ATP, CO2, and ethanol (ethyl alcohol).  
C) ATP, CO2, and lactate.                           D) ATP, NADH, and pyruvate.   
E) ATP, pyruvate, and acetyl CoA.

23) One function of both alcohol fermentation and lactic acid fermentation is to
A) reduce FAD+ to FADH2.                       B) oxidize NADH to NAD+.                        C) reduce FADH2 to FAD+.
D) reduce NAD+ to NADH.                        E) none of the above

24) What are the products of the light reactions that are subsequently used by the Calvin cycle?  
A) ATP and NADPH                                     B) water and carbon                        C) electrons and photons
D) carbon dioxide and RuBP                       E) oxygen and carbon dioxide

25) Where does the Calvin cycle take place?
A) cytoplasm surrounding the chloroplast                       B) outer membrane of the chloroplast
C) thylakoid membrane                                           D) stroma of the chloroplast
E) chlorophyll molecule

26) In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane       B) plasma membrane                        C) inner mitochondrial membrane
D) A and C                             E) A, B, and C

27) In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
A) the matrix to the stroma.                                 B) the stroma to the photosystem II.
C) the stroma to the thylakoid space.                  D) the intermembrane space to the matrix.
E) ATP synthase to NADP+ reductase.

28) What wavelength of light in the figure is most effective in driving photosynthesis?
A) 625 nm                 B) 730 nm                  C) 420 nm                  D) 475 nm                 E) 575 nm

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

30) Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
A) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions.
B) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP.
C) There is no relationship between the light reactions and the Calvin cycle.
D) The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split.
E) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.

 31 - 32 removed due to redundancies

33. List the four stages of cellular respiration discussed in lecture and give the location of each and the net number of ATP, NADH, FADH2 produced per glucose molecule during each stage.
                                                                        Location                       # ATP              NADH          FADH2
1.        Glycolysis                                                  Cytoplasm                         2                 2                       0      

2.             Shuttle/Acetyl CoA                              Mitochondria                  0                   2                      0       

3.         Kreb's/Citric Acid cycle                             Matrix                       2                      6                      2      

4.     Oxidative Phosphorylation                    [H+] intermembrane         34                      -10                 -2      

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