309
Multiple Biol Choice
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Cellular Energy
(review activation energy1 in Chapter 3) 1. The activation energy of a chemical reaction would be best described as: A. the difference in energy content of the substrate and the product. B. the difference in energy content of the substrate and the transition state. C. the amount of energy that remains in the products after the reaction. D. the amount of energy an enzyme must contribute to the reaction. 2. Which of the following figures correctly shows the effect of an enzyme on the energy curve of a chemical reaction? (solid line without enzyme, dashed line with enzyme)
------------------3. The function of the Krebs cycle would be best described as: A. to produce CO2. C. to fix CO2 into organic molecules. B. to produce ATP and heat. D. to oxidize acetyl groups to yield NADH. 4. Which of the following statements about glycolysis is TRUE? A. This is where most of the energy from glucose is yielded. B. ATP is produced via chemiosmotic phosphorylation. C. Glycolysis is an example of a reductive process. D. CO2 is not a product of these reactions. E. It occurs in the space between the inner and outer membranes of mitochondria. 51. During the process called "substrate level phosphorylation": A. The energy for ATP synthesis comes directly from a substrate molecule. B. ATP synthesis is catalyzed by the enzyme ATP synthase. C. ATP is produced spontaneously, without the aid of enzymes. D. Phosphorylation occurs on the "substrate side" of a membrane. 6. During the reactions called -oxidation: A. fatty acids are oxidized to CO2. B. all of the energy in fatty acids is passed to FADH. C. fatty acids are cleaved into acetyl-CoA units. D. pyruvate is converted to acetyl-CoA. 7. Within a plant, the Calvin cycle occurs: A. only when O2 in abundant B. in the light and in darkness. C. only in the dark. Biol 309 D. only in the absence of carbohydrates. E. only in the presence of light.
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Energy Page 1
8. During oxidative phosphorylation: A. AcCoA is oxidized to yield NADH and FADH. B. 4 ATP are produced per NADH. C. energy is transferred directly from NADH to ATP. D. a H+ gradient powers ATP synthesis. 9. Which one of the following statements correctly describes the relationship between the Krebs cycle and electron transport pathways? A. The Krebs cycle releases H+ used by the e- transport. B. The electron transport pathway obtains electrons from the CO2 produced by the Krebs cycle. C. ATP produced by the Krebs cycle drives e- transport and formation of a H+ gradient. D. NADH produced by the Krebs cycle is used to make ATP by e- transport. 10. The water-splitting reaction of photosynthesis occurs: A. in the final step of electron transport. B. in the stroma of the chloroplasts. C. in the reaction center of photosystem II. D. During both photosystem I and photosystem II. 11. During photosynthesis: A. CO2 is released during the Calvin cycle. B. CO2 is absorbed during the light-independent reactions. C. O2 is released in the light and CO2 is produced during the dark. D. O2 is absorbed during the light-dependent reactions. 12. Which of the following statements is true of both the light-dependent reactions AND electron transport in mitochondria? A. electron transport occurs on the inner membrane of the organelle envelope. B. NADH is the source of electrons for both processes C. both processes create an electrochemical gradient of H+. D. CO2 is released as a by-product of both reactions. 13. The Z-scheme diagram is used to depict: A. the positions of the proteins in the cristae membrane of mitochondria. B. changes in the energy level of electrons during the light-dependent reactions. C. the path of energy flow between the light-dependent reactions and Calvin cycle. D. None of the above answers are correct. 14. Which one of the following statements best describes the function of NADPH? A. It is one of the energy-containing the end products of -oxidation. B. NADPH provides electrons during anabolic reactions. C. NADH is a source of energy for ATP synthesis in electron transport. D. It is used to reduce of pyruvate during fermentation. 15. Which of the following statements correctly describes the process in plants called photorespiration?
Biol 309
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Energy Page 2
A. The process begins when the Rubisco enzyme reacts with O2 instead of CO2. B. This refers to the activity of cellular respiration as it occurs in photosynthetic cells. C. When photorespiration occurs, plants derive extra energy from photosynthesis. D. During photorespiration, CO2 is a product of photosynthesis, instead of O2. 16. Ammonia (NH3) will shuttle H+ across a membrane from the more acidic side to the more basic side. This happens because NH3 is protonated under acidic conditions (NH3 + H+ NH4+), then can freely diffuse across the membrane, and then is deprotonated under the more alkaline side (NH4+ NH3 + H+). If mitochondria are treated with NH3, what would be the expected effect on respiration? A. NADH will accumulate in the mitochondria. B. The rate of ATP synthesis will increase dramatically. C. Chemiosmotic ATP synthesis will cease. D. O2 consumption will decrease. 17.Which one of the following statements correctly explains why energy storage in the form of triglycerides is advantageous over energy storage in glycogen? A. It can be completely oxidized in the Krebs cycle. B. This molecule can be more rapidly metabolized. C. Only this molecule can be oxidized completely to CO2. D. Its molecular structure has a higher energy content. 18. Which one of the above statements correctly explains why energy storage in the form of glycogen is advantageous over energy storage in triglycerides? 19. The function of the light-independent reactions of photosynthesis is to: A. release O2. C. fix CO2 into organic molecules. B. breakdown glucose and release CO2. D. produce ATP and NADPH. 20. Which one of the following equations best summarizes the overall reactions of cellular respiration? A. glucose + 6 O2 ----------> 6 CO2 + 6 H2O B. glucose + 6 CO2 ----------> 6 O2 + 6 H2O C. 6 CO2 + 6 H2O -----------> glucose + 6 O2 D. 6 CO2 + 6 O2 ----------> 6 H2O + 6 glucose Which best summarizes the reactions of photosynthesis? True or false 1. In the absence of oxygen, the energy yield from glycolysis is two ATP. 2. The O2 consumed during cellular respiration is released to the atmosphere as CO2. 3. The conversion of pyruvate to lactate during fermentation produces a NADH molecule. 4. The enzymes of the Krebs cycle are localized in the matrix of the mitochondria. 5. ATP and NADPH are used by Rubisco during the CO2 fixation reaction. Biol 309 Question Bank Energy Page 3
6. An antenna complex is associated with both PSI and PSII. 7. ATP is the terminal electron acceptor of the light-dependent reactions of photosynthesis. 8. The end-product of photosynthesis that is exported from the chloroplast is glyceraldehydephosphate. 9. 1Energy is released during the following reaction: ATP ---------> ADP + Pi 10. The electrons transported during photosynthetic electron transport originate from NADH. 111. ATP is the terminal electron acceptor of the light-dependent reactions of photosynthesis. 121. Thylakoid and cristae membranes serve similar functions. 13. The ATP synthases of mitochondria and chloroplasts are structurally and functionally similar. 14. During photosynthetic electron transport, ATP synthesis is coupled to electron transport between photosystem II and I. 15. Bis-phosphate sugars are unstable intermediates found in both glycolysis and the cycle. CalvinBenson 16. In both mitochondria and chloroplasts, H+ are stored in the space between the inner and outer membranes of the organelle. 17. O2 is a waste product of photosynthesis.
Fill-in, etc. 1. The chlorophyll molecule is embedded in the _______________ membranes of the chloroplast by its hydrophobic tail. The light-absorbing part of the molecule is called the __________________ ring. 2. During photosynthetic electron transport, light energy is absorbed into a cluster of pigment molecules called a ___________________ and resonantly focused into the _________________________ of Photosystem ___. 3. The electrons used in photosynthesis originate from ______, and then pass through an electron transport complex called ________________________ to Photosystem- ___.
Biol 309
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Energy Page 4
4. What three components needed to make ATP via oxidative phosphorylation are missing from this list: membrane, electron-transporting H+ pumps, ATP synthase, ADP, H+ _________ __________ _________ 5. In the transition reaction, _________________ is decarboxylated and coupled to CoA to yield ____________________, which then is covalently attached to the Krebs cycle intermediate _________________ to produce ___________________. 6. Choosing from the following list, identify the cellular compartment(s) in which each of the following is located cytosol, stroma, thylakoid membranes, thylakoid lumen, chloroplast intermembrane space matrix, cristae, mitochondrial intermembrane space, mitochondrial outer membrane Krebs cycle enzymes _______________ b-oxidation enzymes _______________ glycolytic enzymes _______________ Calvin-Bensen cycle enzymes ______________ Rubisco _______________ Cytochrome oxidase ATP synthase P680 reaction center high [H+] _______________ _______________ _______________ _________________
7. Complete the following tables to show the ATP yield from the cellular respiration of 2 glucose molecules and 12 carbon fatty acid (using 2.5 ATP/NADH, or 1.5 ATP/glycolytic NADH or FADH) From 1 glucose: Glycolysis ____ NADH x ____ ATP = ____ ATP = Transition Rx ____ NADH x ____ ATP x 2 pyr = Krebs cycle ____ NADH x ____ ATP x 2 pyr = ____ FADH x ____ ATP x 2 pyr = ____ GTP x ____ ATP x 2 pyr = Total = ATP yield _______ _______ _______ _______ _______ _______ _______ x 2 = _________
From a 12 carbon fatty acid: B-oxidation ATP yield ____ FADH x ____ ATP x 6 acCoA = _______ ____ NADH x ____ ATP x 6 acCoA = _______ Krebs cycle ____ NADH x ____ ATP x 6 acCoA = _______ ____ FADH x ____ ATP x 6 acCoA = _______ ____ GTP x ____ ATP x 6 acCoA = _______ Total = _______
Biol 309
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Energy Page 5
8. What is wrong with this statement: In plants, O2 is produced during photosynthesis so that it is available for use during cellular respiration.?
9. Draw a line connecting the compartments and membranes that serve analogous functions in chloroplasts and mitochondria. (not all will be connected) Chloroplasts outer chloroplast membrane inner chloroplast membrane intermembrane space stroma thylakoid membrane thylakoid lumen Mitochondria outer mitochondrial membrane cristae membrane intermembrane space matrix
10. In the Hill reaction experiment that we perform in the lab, spinach leaves are fractionated to yield thylakoid membranes free of the surrounding stroma and metabolites. These can be stimulated to carry on electron transport in the light if the electron acceptor DCPIP is provided. DCPIP absorbs electrons from the b6/f cytochrome complex, and changes in color from blue to clear as it becomes reduced a change that can be measured to follow the rate of electron transport. A capstone student studied the effect of 3 sunstances on the rate of photosynthetic electron transport (PET) as measured by the Hill reaction: Hydroxylamine -- an electron donor to the P680 reaction center Simazine -- a PET inhibitor at P680 DSPD -- a PET inhibitor after P700 For each experiment, PET was allowed to proceed for a while only in the presence of DCIP. [Note that because DCPIP becomes clear as it accepts electrons, the absorbance of the thylakoid suspension decreases as PET occurs.] After initially establishing that PET was occurring normally, a test substance was then added to the mixture (at the time points indicated by the arrows in the Figure). Unfortunately, the student forgot to label the test tubes, and thus was unsure which molecule was used in each experiment. Based upon the results shown below, which substance appears to have been added in experiments 1, 2, and 3? Explain each.
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