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This print-out should have 31 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering.
001 2.0 points When glucose monomers are joined together by glycosidic linkages to form a cellulose poly- mer, the changes in free energy, total energy, and entropy are as follows:?
- −∆G, −∆H, −∆S
- +∆G, +∆H, −∆S correct
- −∆G, +∆H, +∆S
- +∆G, +∆H, +∆S
- +∆G, −∆H, −∆S
Explanation: Energy is required for the addition of an- other bond. Monomers formed into a linkage is more ordered than free monomers.
002 2.0 points Which of the following is NOT true of en- zymes?
- Enzymes always need ATP to speed up chemical reactions. correct
- Enzymes may need a cofactor for cataly- sis.
- Enzymes speed up chemical reactions by lowering activation energy barriers.
- Enzyme activity is influenced by pH and temperature.
- Enzyme activity is reduced if the 3-D conformation is altered.
Explanation: Comprehension and recall.
003 2.0 points An enzyme reaction converts substrate A to
produce B. When a chemical X was added to this reaction, the Km increased and the veloc- ity slowed down. The maximum velocity can be regained by increasing the concentration of A. From this information, we can conclude that the chemical X is
- a non-competitive inhibitor.
- an irreversible inhibitor.
- an activator.
- a competitive inhibitor. correct
- an organic cofactor.
Explanation:
004 2.0 points Phosphofructokinase (PFK) is a complex en- zyme with separate catalytic and regulatory subunits. ATP can bind to its regulatory sub- unit and inhibit this enzyme which phophory- lates Fructose 6 Phophate. This enzyme can alternate between active and inactive forms. We can describe this PFK as a/an enzyme.
- non-competitive
- feed back
- allosteric correct
- simple
- competitive
Explanation:
005 2.0 points Which of the following statements is/are true regarding ATP? I) ATP is a main source of energy cells. II) ATP helps exergonic reactions to be- come endergonic. III) The regeneration of ATP from ADP and Pi is an exergonic reaction.
- I and III only
- III only
- I only correct
- I, II, and III
- II only
Explanation: Comprehension.
006 2.0 points The free energy change of a system is: ∆G = ∆H − T ∆S. Which of the follow- ing is incorrect?
- ∆G can be negative if entropy and tem- perature increases.
- A positive ∆H and negative ∆S can make ∆G negative. correct
- T is absolute temperature and can change the ∆G.
- ∆S is the change in entropy and ∆H is the change in enthalpy.
- ∆G can be negative if enthalpy decre- ses.
Explanation: An increase in enthalpy and decrease in entropy will result in an increase in ∆G or endergonic process.
007 2.0 points A noncompetitive inhibitor inhibits binding of a substrate to an enzyme by
- changing the shape of the active site. correct
- lowering the activation energy.
- increasing the ∆G of the reaction.
- binding to the substrate.
- binding to the active site. Explanation:
008 2.0 points The addition of the competitive inhibitor mevinolin slows the reaction HMG-CoA → mevalonate, which is catalyzed by the en- zyme HMG-CoA reductase. The effects of mevinolin would be overcome and the rate of the reaction increased by
- adding more HMG-CoA. correct
- lowering the temperature of the reac- tion.
- lowering the rate constant of the reac- tion.
- adding a prosthetic group.
- adding more mevalonate. Explanation:
009 2.0 points In glycolysis, the exergonic reaction 1,3- diphosphoglycerate → 3-phosphoglycerate is coupled to the reaction ADP + Pi → ATP. Which of the following is most likely to be true about the reaction ADP + Pi → ATP?
- The reaction never reaches equilibrium.
- The reaction is spontaneous.
- Temperature will not affect the rate con- stant of the reaction.
- There is a large decrease in free energy.
- The reaction is endergonic. correct Explanation:
010 2.0 points Which of the following describes the fate of oxygen utilized directly during cellular respi-
- hydrolysis of ATP.
- reduction of NAD+.
- reduction of FAD.
- hydrolysis of GTP.
- diffusion of protons. correct
Explanation:
016 2.0 points In the first reaction of glycolysis, glucose re- ceives a phosphate group from ATP. This re- action occurs in the:
- endoplasmic reticulum.
- cytosol. correct
- chloroplast.
- mitochondrion.
- nucleus.
Explanation: Glycolysis takes place in the cytosol of the cell.
017 2.0 points The chemiosmotic generation of ATP is driven by
- osmotic movement of water into an area of high solute concentration.
- the addition of protons to ADP and phos- phate via enzymes.
- None of these
- oxidative phosphorylation.
- a difference in H+^ concentration on both sides of a membrane. correct
Explanation:
018 2.0 points
Conversion of corn sugar to ethanol is an in- efficient process of energy conversion. Louis Pasteur proved that yeast grown under anaer- obic conditions to make ethanol consumed 100 times more sugar than those under aerobic conditions did , because
- Krebs cycle happens in fermentation but no ATP is produced.
- glycolysis does not happen under anaero- bic condition.
- no Krebs cycle nor oxidative phospho- rylation would occur in such fermentation. correct
- corn sugar is not a good source for making ethanol or ATP.
- lactate fermentation is more efficient than ethanol fermentation.
Explanation:
019 2.0 points What happens to most people if they eat so many carbohydrates that they exceed the glycogen storage capacity of their liver and muscle cells?
- Their metabolism slows.
- Their metabolism increases.
- They excrete glucose in their urine.
- The glucose is converted to fat. correct
- Their muscle cells switch to lactate fer- mentation.
Explanation: Excess glucose is converted to fat.
020 2.0 points Why do plants use visible (light) part of the electromagnetic spectrum to do photosynthe- sis and not the areas of spectrum with shorter (UV and below) or longer wavelength (IR and
above)?
- Visible spectrum is weaker than IR and safer than UV spectrum.
- Visible spectrum is prefered by the pro- teins in Calvin cycle.
- UV light and IR spectrum are more dam- aging than visible light.
- Visible light has the optimum level of energy and safety to perform photosynthesis. correct
Explanation: Visible light spectrum is safer than UV and shorter wavelnegths and at the same time has more energy than IR and longer wavelength of the electromagnetic spectrum.
021 2.0 points Which of the following parts of the plant are responsible to allow air and nutrients to enter the leaf cells respectively?
- stoma, stroma
- inner membrane, matrix
- stoma, xylem correct
- thylakoid, stomata
- chloroplast, phloem
Explanation:
022 2.0 points In which of the following structures does the Calvin cycle of photosynthesis take place?
- chlorophyll molecule
- outer membrane of the chloroplast
- stroma of the chloroplast correct
- thylakoid membrane
- cytoplasm surrounding the chloroplast Explanation: The Calvin Cycle of photosynthesis takes place inside the stroma of the chloroplast. It is in the Calvin Cycle that CO 2 is converted into a glucose molecule.
023 2.0 points In mitochondrial chemiosmosis, translocation of protons takes place from the matrix into the intermembrane space. Which of the following statements describes the direction of translocation of protons in chloroplasts?
- from the stroma to the chlorophyll
- from the light reactions to the Calvin cycle
- from the stroma into the thylakoid com- partment correct
- from the matrix to the stroma
- from the intermembrane space to the ma- trix Explanation: In mitochondrial chemiosmosis, transloca- tion of protons takes place from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis occurs from the stroma into the thylakoid compartment.
024 2.0 points During the light reaction, the pH of the stroma of choloroplast will
- depend on the Calvin cycle.
- remain the same.
- depend on oxidative phosphorylation.
- decrease.
- increase. correct Explanation:
- bacterial cells going through conjugation (mating)
Explanation:
029 2.0 points The exchange of genetic material between chromatids on homologous chromosomes oc- curs during
- interphase.
- anaphase II.
- anaphase I.
- mitosis and meiosis.
- prophase I. correct
Explanation:
030 2.0 points The phases of meiosis that cause the most variation in the four daughter cells are
- anaphase I and prophase II.
- metaphase I and telophase II.
- prophase I and telophase II.
- prophase II and anaphase II.
- prophase I and metaphase I. correct
Explanation: Explanation
031 2.0 points The initiation of the S phase and the M phase of the cell cycle depends on and combining to make.
- ligand; enzyme; complex
- insulin; receptor; G-protein
- actin; myosin; fibers
- Cdk; cyclin; MPF correct
- ADP; Pi; ATP Explanation:
