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Biology II Chapters 6-8 Review Match the following events or conditions with the location in which they occur. Answers may be used more than once. 1. __A_ glycolysis 2. __B_ citric acid cycle 3. C & D electron transport chain 4. __C_ light reactions 5. __E_ light-independent reactions 6. __E_ Calvin cycle 7. __B_ Krebs cycle 8. F & G high concentration of protons (H+) 9. __D_ photosystems 10. A. cytosol B. matrix C. inner membrane of mitochondria D. membrane of thylakoids E. stroma F. lumen (of thylakoids) G. intermembrane space/outer compartment (of mitochondria ) Fill in the missing terms in this description of photosynthesis. During the first phase of photosynthesis, known as the ______light-dependent_reactions______ , light energy is captured by chlorophyll/protein complexes known as __photosystem___I and ___photosystem ___II. This causes the splitting of __water__ molecules into 2H+, 2e- and ½ O2. _O2_ is considered the waste product of photosynthesis and is released through openings in the leaves called __stomata__. The energized electrons are passed along a series of proteins known as the _____electron_transport_chain_______. As they are passed along, _H+_ are pumped from the __stroma___ across the thylakoid membrane into the __lumen____ of the thylakoid. This creates a concentration gradient between the stroma and the lumen. The protons are allowed to flow back across the membrane through a protein complex known as ATP __synthase____. This flow of H+, called __chemiosmosis____, drives the production of ATP by the fusion of _ADP__ with inorganic phosphate (_Pi_). Also produced at the end of the electron transport chain are molecules of __NADPH____ as the electrons are passed to NADP+. NADPH, along with the ATP formed, then power the second phase of photosynthesis, the __light-independent_reactions_, also known as the ____Calvin_cycle ____. During this second phase, the energy from NADH and ATP is used to assemble 3 molecules of __CO2_ into 3-carbon sugar molecules which will eventually be joined into 6-carbon molecules of __glucose____. 11. W hat process is this diagram illustrating? 12. Label the following on the diagram below: ATP lumen stroma ATP synthase NADP+ thylakoid membrane the light-dependent reactions of photosynthesis Calvin cycle photosystem I electron transport chain photosystem II Calvin Cycle ATP NADP + stroma thylakoid membrane electron transport photosystem I photosystem II chain ATP synthase lumen 13. Fill in the missing terms in this description of cellular respiration. ___Cellular_ respiration___ is the process by which cells extract the chemical energy of ___glucose_____ and convert it into energy stored in the form of ATP. The waste products of this process are __CO2__ and water. Cellular respiration has 3 distinct phases. The first phase, _____glycolysis______, occurs in the _____cytosol_____ outside the _______mitochondrion__________. In this phase the 6-carbon molecule, ______glucose_______ is broken down into two 3-carbon molecules of ___pyruvate______. The net result of this reaction is the production of 2 molecules of water, 2 molecules of _NADH_ and 2 molecules of _ATP_ . After glycolysis, the pyruvates enter the inner compartment of the mitochondrion, known as the ___matrix____. Upon entering the mitochondrion, pyruvate is joined to CoA, forming ___acetyl_coenzyme_ A______ . This reaction also produces 2 waste molecules of __CO2__ and 2 energy carrying molecules of __ATP___. Acetyl-CoA now proceeds to the second phase of cellular respiration, the _____citric_acid_cycle___________, also known as the _____Krebs_cycle_______ __. During this complex series of reactions the two molecules of acetyl-CoA are broken down into 4 more molecules of _CO2_. This also produces 2 molecules of _FADH2_ and 4 more molecules of _NADH_. The NADH and the FADH2 are then oxidized, transferring electrons to the __electron_transport_chain___ (ETC), the __third__ phase in cellular respiration. The ETC is a series of proteins embedded in the folds of the inner membrane known as the __cristae___. As electrons are passed along the ETC, ___protons___ (H+) from the matrix are pumped across the inner membrane into the outer compartment or ____inner_membrane______ space. The protons are now concentrated on one side of the membrane. They diffuse down their concentration ___gradient____ through a protein complex called ____ATP_synthase_____. This generates the production of 34 more _ATP_ by a process called __oxidative_phosphorylation__. The maximum total number of ATP produced from one glucose is _38_. At the end of cellular respiration the electrons and protons from the ETC are removed by joining with __O2__ to produce __H2O__, the other waste product of cellular respiration. 14. What process is illustrated in this diagram? 15. Label the following on the diagram: 2 ATP cytosol NADH cellular respiration 2 ATP electron transport chain NADH and FADH2 NADH 34 ATP intermembrane space pyruvate intermembrane space citric acid cycle pyruvate citric acid cycle matrix NADH FADH2 electron transport chain matrix cytosol 2 ATP 2 ATP 34 ATP 16. Under what condition does fermentation occur? How is muscle fermentation different from yeast fermentation? Fermentation occurs when eukaryotic cells have exhausted their O2 supply. When O2 is not available, pyruvate cannot continue into the citric acid cycle and is therefore catabolized (broken down) by another chemical pathway. The pathway differs in muscle and yeasts. Muscle cells convert pyruvate into lactic acid, while yeasts convert it into ethyl alcohol and carbon dioxide. 17. How are cellular respiration and photosynthesis linked in biological systems? Cellular respiration and photosynthesis are essentially opposites of each other, the products of one reaction being the reactants in the other. This creates a cyclic situation in which one reaction cannot occur without the other. In this way living systems are linked to one another. For instance, plants rely on the carbon dioxide produced through cellular respiration by animals, while animals rely on the glucose and oxygen produced by plants. 18. How does the first law of thermodynamics relate to photosynthesis and cellular respiration? The first law of thermodynamics states that energy cannot be created nor destroyed, but can be converted from one form to another. Photosynthesis and cellular respiration are two methods of converting energy from one form to another. In photosynthesis, light energy (electromagnetic energy) is converted into chemical energy stored in molecules of glucose. In cellular respiration, the chemical energy from glucose is released and used to produce ATP which will then be used to cause motion (mechanical energy) of molecules or cell parts. Some of the energy from glucose is also released as heat, another form of energy. 19. What do enzymes do to facilitate chemical reactions? Enzymes facilitate (speed up) reactions by lowering the activation energy required for a reaction to proceed. In other words they lower the energy barrier that must be reached to produce the intermediate products of a reaction. 20. Why is the shape of an enzyme so important? The shape of an enzyme is critical to its function, because the enzyme must physically attach to the substrate on which it acts. An enzyme has a special location called the active site which allows a substrate to fit, much like a key fits a lock. If the enzyme’s shape is changed (This is called denaturing.) , the substrate cannot attach. 21. What does it mean that photosynthesis is an endergonic process? In an endergonic reaction, the change in free energy of the system is positive. This means that the chemical energy (stored in the bonds) of the products is greater than that of the reactants. In photosynthesis, glucose is formed from carbon dioxide and water which contain less chemical energy. 22. What reactions do the following equations represent? ____cellular_respiration____ C6H12O6 + 6O2 6CO2 + 6H2O + energy _light-dependent_reactions__ H2O + ADP + Pi + NADP+ _____photosynthesis_______ 6CO2 + 6H2O + energy C6H12O6 + 6O2 ______glycolysis_______ C6H12O6 + 2ATP + 2NAD+ _light-independent_reactions_ ATP + NADPH + H+ + ½O2 2Pyruvate + 4ATP + 2NADH + 2H2O 6CO2 + 12NADPH + 12H+ + 18ATP C6H12O6 + 12NADP+ + 18ADP + 18Pi + 6H2O ___alcoholic_fermentation___ C6H12O6 2CH3CH2OH + 2CO2 + energy ethyl alcohol