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Section 2.2 Questions (Pages 115–116) Understanding Concepts 1. The raw materials required for the cell to produce one molecule of ATP via substrate-level phosphorylation are ADP, Pi (or a phosphate-containing intermediate from glucose), and a substrate enzyme. 2. (a) Glycolysis occurs in the cytoplasm of eukaryotic organisms. (b) Glycolysis refers to the breaking of the glucose molecule into two pyruvate molecules. 3. One molecule of glucose stores more potential energy than one molecule of pyruvate because in glycolysis, some potential energy of the original glucose molecule is shared between 2 NADH and 2 ATP molecules. Some potential energy is also dissipated as heat. 4. (a) The final products of glycolysis are 2 pyruvate, 4 ATP, 2 NADH, 2 H+, and 2 ADP. (b) The two products of glycolysis that enter the mitochondria are pyruvate and NADH. 5. Substrate-level phosphorylation generates ATP directly from an enzyme-catalyzed reaction, whereas oxidative phosphorylation generates ATP indirectly by the chemiosmotic potential created by oxidative phosphorylation. The process is oxidative because it involves several sequential redox reactions, with oxygen being the final electron acceptor. It is more complex than substrate-level phosphorylation, and it produces far more ATP for every glucose molecule processed. 6. Adenosine diphosphate (ADP) has two inorganic phosphate groups attached to an adenosine molecule, whereas adenosine triphosphate (ATP) has three inorganic phosphate groups attached to an adenosine molecule. The ATP molecule has 31 kJ/mol more potential energy than ADP. 7. Heart muscle cells have the most mitochondria, as they require the most energy to contract approximately 70 times per minute. Nerve cells have the second most mitochondria, as they need to maintain the membrane potential necessary to conduct a nerve impulse. Skin cells are next, as their functions require little energy, followed by fat cells, which do nothing but accumulate fat. 8. Mitochondrial membranes perform several vital roles in energy metabolism. The outer membrane of the mitochondria acts as a cell membrane and houses transport proteins that allow substances in and out of the mitochondria. For instance, the outer membrane houses transport proteins, which move the two pyruvate molecules formed during glycolysis from the cytoplasm into the mitochondria, where they undergo pyruvate oxidation before entering the Krebs cycle. The inner membrane of mitochondria serves several functions. It divides the mitochondrion into two compartments: the matrix and the intermembrane space. Both of these areas play important roles in energy metabolism. For instance, the matrix is where most of the Krebs cycle reactions take place and the intermembrane space is where protons are pumped as they are produced by the electron transport chain. These protons are used to create the electrochemical gradient that stores free energy, which is necessary to create ATP. The inner membrane of a mitochondria also houses the numerous proteins and cofactors required ultimately to generate ATP. NADH hydrogenase, cytochrome b- c1 complex, cytochrome oxidase complex, and ATP synthase are all found in the inner mitochondrial membrane. 9. (a) Enzymes are biological catalysts. They speed up reactions without being consumed in the process. Every reaction in cellular respiration is catalyzed by a specific enzyme, as every enzyme has a unique substrate-binding site. The enzymes exhibit specificity to ensure that the correct reaction in the process is being carried out at the correct time. The enzymes ensure that the reactions are occurring in the correct order and that they are occurring at the correct speed. (b) If an organism lacked the first enzyme, in glycolysis, hexokinase, cellular respiration would not occur. 10. The function of NAD+ and FAD in cellular respiration is to act as coenzymes that harvest energy from the reactions of glycolysis, pyruvate oxidation, and the Krebs cycle and carry it to power ATP synthesis by oxidative phosphorylation. NAD+ is used to shuttle electrons to the first component of the electron transport chain. During oxidative phosphorylation, NAD+ removes two hydrogen atoms from a part of the original glucose molecule. Two electrons and one proton attach to NAD+, reducing it to NADH (NAD+ is the oxidized form of NADH). This reduction occurs during glycolysis, pyruvate oxidation, and the Krebs cycle. FAD functions in a similar manner to NAD+. FAD is reduced by two hydrogen atoms from the original glucose molecule to FADH2. This is done during the Krebs cycle. These reductions are energy harvesting and will transfer their free energy to ATP molecules. Reduced NAD+ and FAD move free energy from one place to another and from one molecule to another. 11. The final products of cellular respiration are 6 CO2, 6 H2O, and 36 ATP. 12. Glycolysis is not considered a highly effective energyharnessing mechanism, because it only transfers about 2.1% of the free energy available in one mol of glucose into ATP. Most of the energy is still trapped in two pyruvate molecules and two NADH molecules. Aerobic respiration further processes the pyruvate and NADH during pyruvate oxidation, the Krebs cycle, chemiosmosis, and electron transport. During pyruvate oxidation, the pyruvate and NADH are transformed into two molecules each of acetyl-CoA, hydrogen, carbon dioxide, and NADH. Acetyl-CoA enters the Krebs cycle and increases ATP production. By the end of the Krebs cycle, the entire original glucose molecule is consumed. It has been transformed into six CO2 molecules, which are released as waste, and energy, which is stored as four ATP molecules and 12 reduced coenzymes (NADH and FADH2). Most of the free energy stored in NADH and FADH2 will be transformed to ATP in the final stage of aerobic respiration, chemiosmosis, and electron transport. By the end of aerobic respiration, all the energy available in glucose has been harnessed. 13. After glycolysis, pyruvate oxidation, and the Krebs cycle, the rest of the energy not captured in the form of ATP is stored as FADH2 and NADH. Two NADH are produced via glycolysis, two are produced during pyruvate oxidation, and six are produced during the Krebs cycle. Two FADH2 are produced during the Krebs cycle. The free energy stored in these molecules is released during chemiosmosis and electron transport. 14. (a) Hydrogen atoms are the part of the glucose molecule that provides electrons in cellular respiration. (b) Electron transport complexes set up a proton gradient by passing protons from the mitochondrial matrix to the intermembrane space. NADH gives up the two electrons it carries to NADH hydrogenase. Electron carriers, ubiquinone and cytochrome c, shuttle electrons from NADH hydrogenase to cytochrone b- c1 complex to cytochrome oxidase complex. Free energy is lost from the electrons during each step in this process, and this energy is used to pump H+ from the matrix into the intermembrane space. The final step in the electron transport chain sees oxygen accept two electrons from cytochrome oxidase complex, and it consumes protons to form water. (c) The protons that accumulate in the intermembrane space create an electrochemical gradient. The gradient has two components: an electrical one caused by a higher positive charge in the intermembrane space than in the matrix, and a chemical gradient created by the higher concentration of protons in the intermembrane space. The electrochemical gradient stores free energy, which is referred to as protonmotive force (PMF). The mitochondrial membrane is almost impermeable to protons, so the protons are forced to pass through ATP synthase to get back into the mitochondrial matrix. The PMF forces the protons through ATP synthase, reducing the energy of the gradient. The energy is used by the enzyme ATP synthase to create the third phosphate-ester bond between ADP and inorganic phosphate, creating ATP. (d) This process is termed chemiosmosis (oxidative phosphorylation). (e) Chemiosmosis was discovered by Peter Mitchell in 1961. 15. (a) An electron carrier is first oxidized and then reduced by a more electronegative molecule, while a terminal electron acceptor is only reduced—a terminal electron acceptor is at the end of an electron transport chain. (b) The final electron acceptor in aerobic respiration is oxygen. 16. The overall equation (C6H12O6 + 6O2 6 6CO2 + 6H2O) for cellular respiration is misleading as it does not include the numerous enzymes, coenzymes, and intermediate chemicals involved in the process. It also shows the conversion of glucose and oxygen to carbon dioxide and water as a simple, one-step process, where it is actually much more involved than that. 17. CO2 cannot serve as a source of free energy because the carbon atoms are fully oxidized; there are no H atoms bonded to any of the C valence electron positions. Thus, its chemical potential energy is 0 kJ/mole. 18. (a) Metabolic rate is the amount of energy consumed by an organism in a period, whereas basal metabolic rate is the minimum amount of energy an organism must consume just to stay alive. (b) A person’s metabolic rate decreases with age because of reduced growth and development. This occurs via a reduction in growth hormone, which causes excess energy to be used to create fat. Applying Inquiry Skills 19. (a) A pH meter could be placed into the mitochondrial matrix and intermembrane space to test Peter Mitchell’s chemiosmotic theory. The pH of the intermembrane space should be significantly lower than the matrix. (b) A voltmeter could be used since an electric gradient is formed between the intermembrane space and the mitochondrial matrix. If the positive probe of a voltmeter is placed in the matrix and the negative probe placed in the intermembrane space, a voltage should be read on the voltmeter if electron transport is occurring. (c) When a detergent is added to the mitochondria, the membranes leak. Since the membranes leak, H+ ions that enter the intermembrane space because of the electron transport chain can diffuse back into the mitochondrial matrix quite easily. The protons do not need to be forced through ATP synthase, so ATP is not produced. 20. (a) The surface area of a teacher who is 180 cm tall and has a mass of 80 kg is 2.02 m2. (b) Total energy content = basal energy req. surface area time = 160 kJ/m2/h 2.02 m2 24 h = 7756.8 kJ (c) Student predictions will vary. (d) Student answers will vary according to solution in (c). Making Connections 21. (a) Mitochondria must be able to reproduce so that there will be enough of them after each successive cell division. (b) All the mitochondria of a grown individual are from the mother’s egg; therefore, the mitochondrial DNA is identical on the mother’s side. (c) Student solutions will vary depending on the diseases chosen. Two examples of mitochondrial diseases are Leigh’s syndrome and Pearson syndrome. Some very common diseases, such as Parkinson’s disease and Alzheimer’s disease, are mitochondrial diseases. Leigh’s syndrome (disease) • Full name: Subacute necrotizing encephalomyelopathy • Symptoms: Seizures, hypotonia (decreased muscle tone), fatigue, nystagmus (an involuntary rhythmic movement of the eyes, usually from side to side), poor reflexes, eating and swallowing difficulties, breathing problems, poor motor function, ataxia • Causes: pyruvate dehydrogenase deficiency, NADH dehydrogenase deficiency, succinate dehydrogenase deficiency, cytochrome c deficiency 22. (a) Vitamin B complex refers to the fact that the vitamin is made up of different B vitamins, not just a single type of vitamin. Vitamin B complex contains vitamin B1, B2, B3, B5, B6, and B12. (b) When a vitamin is water-soluble, it means that excess intake of the vitamin is not stored in the body as fat; it is excreted with urine. These are vitamins that generally need to be replaced in the body often. Other examples of water-soluble vitamins include folic acid, vitamin C, and pantothenic acid. (c) Student solutions will vary. Two possible vitamins are shown below. Vitamin B1 Thiamine enhances circulation and assists in blood formation, carbohydrate metabolism, and the production of hydrochloric acid, which is important for proper digestion. Thiamine also optimizes brain function. It has a positive effect on energy, growth, normal appetite, and learning capacity and is needed for muscle tone of the intestines, stomach, and heart. Good sources include meats, liver, whole grain, nuts, legumes. Deficiency symptoms include beriberi (a degenerative disease of the nerves marked by pain, the inability to move, and swelling), neurological effects, and cardiovascular abnormalities. Vitamin B3 Vitamin B3, also called niacin, niacinamide, or nicotinic acid, is an essential nutrient required by all humans for the proper metabolism of carbohydrates, fats, and proteins, as well as for the production of hydrochloric acid for digestion. Good sources include poultry, meat, fish, peanuts, and fortified grain. Deficiency symptoms include pellagra (which is marked by dermatitis and gastrointestinal and central nervous system symptoms). 23. (a) Function Hummingbird Human Resting heart rate (beats/min) 1260 72 Breathing rate (breaths/min) 450 60 Fastest speed (km/h) 60 37 Average lifespan (years) 5 80 (b) If the average human were to consume as much food as a hummingbird, he or she would have to eat 103 kg of hamburger per day. 2.3 RELATED PATHWAYS Explore an Issue Take a Stand: Fetal Alcohol Syndrome (Page 120) Statement: Women should not drink even small amounts of alcoholic beverages while pregnant. Student answers will vary. Some possible points that students may make include the following: • Because it is not possible to determine a safe amount of alcohol consumption during pregnancy, women should not drink any alcohol at all. It is not fair to the developing fetus to risk any lifelong damage that could occur due to alcohol consumption. • People are overreacting. Women drank and smoked during their pregnancies in the 1970s and 1980s, before all this research was being conducted, and there has not been any study showing that all these children suffer any side effects from their mothers’ habits. • Small amounts of alcohol are probably safe for both mothers and their developing children. In nations such as France where it is natural to have a glass of wine with a meal, normal children are born each day. There is no indication that a glass of wine a day does any harm to a developing fetus. • More studies need to be done to determine what effect small amounts of alcohol have on a fetus. Section 2.3 Questions (Page 124) Understanding Concepts 1. When a cell has sufficient quantities of ATP, the excess acetyl-CoA is used to synthesize fatty acids. 2. Two differences in aerobic respiration and fermentation are that (1) aerobic respiration yields 36 ATP molecules per glucose molecule and produces water and carbon dioxide, and that (2) fermentation yields 2 ATP molecules per glucose molecule and produces ethanol or lactic acid. 3. A student will feel soreness in her chest and legs due to lactic acid buildup in her muscle tissues. This lactic acid buildup is due to a low VO2 max as a result of the longer low-level activity. 4. A nonalcoholic fermentation product is carbon dioxide. 5. The final products of alcohol fermentation are ATP, carbon dioxide, and ethanol. The final products of lactic acid fermentation are ATP and lactate. 6. (a) Two molecules of ethanol are produced for every molecule of glucose in alcoholic fermentation. (b) Two molecules of carbon dioxide are produced during alcoholic fermentation, while lactic acid fermentation produces no carbon dioxide. (c) Fermentation is an anaerobic process and does not require oxygen. 7. Alcoholic fermentation occurs in yeast and plants roots when they are submerged. 8. (a) Lactic acid produced in muscle cells travels in the bloodstream to the liver, where it is oxidized back to pyruvate, which then goes through the Krebs cycle and oxidative phosphorylation. (b) Oxygen debt refers to the extra oxygen required by the liver to oxidize lactic acid to carbon dioxide and water (through the aerobic pathway). Panting “pays” for the oxygen debt. 9. The presence of lactic acid in the muscle tissues leads to stiffness, soreness, and fatigue. 10. Maximum oxygen consumption, VO2 max, is a measure of a body’s capacity to generate the energy required for physical activity. It is the maximum volume of oxygen that the cells of the body can remove from the bloodstream in one minute per kilogram of body mass while the body experiences maximal exertion CHAPTER 2 SUMMARY (Page 132) Chapter 2 Self-Quiz 1. False. During cellular respiration, the oxygen we inhale ends up in the water we exhale or excrete. 2. False. Overall, glycolysis is an exergonic reaction. 3. True 4. False. T he following reactions take place in both plant and animal cells: C6H12O6 + 6O2 6 6CO2 + 6H2O 5. True 6. False. NADH is oxidized by the first protein complex of the electron transport chain. 7. False. If a poison blocks the flow of protons through ATP synthase, the Krebs cycle stops, but glycolysis will continue 8. False. The amino group is first removed from the amino acid as waste and the rest of the amino acid is modified before entering glycolysis or the Krebs cycle. 9. True 10. True 11. False. Maximum oxygen consumption, VO2 max, decreases as people grow older. 12. (b) 13. (c) 14. (e) 15. (b) 16. (b) 17. (a) 18. (d) 19. (b) Chapter 2 Review (Pages 134–135) Understanding Concepts 1. 2. (a) Glycolysis occurs in the cytoplasm. (b) Pyruvate oxidation and the Krebs cycle occur in the mitochondrial matrix. (c) The electron transport chain and ATP synthesis occur in the inner mitochondrial membrane. 3. (a) Ubiquinone (Q) is an electron carrier. As part of the electron transport chain, it carries electrons from NADH dehydrogenase to cytochrome b-c1 complex within the membrane. (b) FADH2 is an electron carrier from the Krebs cycle that transfers its two electrons to Q. (c) Pyruvic acid is a product of glycolysis that enters the mitochondrial matrix to undergo pyruvate oxidation and then enters the Krebs cycle. (d) ATP synthase is an enzyme complex located in the inner mitochondrial membrane that uses the proton motive force to generate ATP. 4. (a) Theoretically, NADH and FADH2 should generate three and two ATP molecules, respectively. (b) NADH passes its electrons to the first protein complex in the electron transport chain, NADH hydrogenase. FADH2 transfers its electrons to the second protein in the chain, ubiquinone (Q). The free energy released by the oxidation of FADH2 is used to pump two protons into the intermembrane space, while NADH oxidation pumps out three electrons. The result is that two ATP are formed per FADH2, and three ATP molecules are formed per mitochondrial NADH. 5. (a) The net gain in ATP after one molecule of glucose undergoes cellular respiration is 36 ATP. (b) The net gain in ATP after one molecule of glucose undergoes alcoholic fermentation is 2 ATP. 6. 7. i. Glycolysis occurs in the cytoplasm. ii. Pyruvate oxidation occurs in the mitochondrial matrix. iii. The Krebs cycle occurs in the mitochondrial matrix. iv. The electron transport chain and chemiosmosis occur in the inner membrane of the mitochondria. 8. NAD+ accepts two electrons and one proton during glycolysis and the Krebs cycle. 9. FADH2 is used as an electron acceptor in step 6 of the Krebs cycle, because the reaction is not exergonic enough to reduce NAD+ to NADH. 10. (a) An electrochemical gradient is created by pumping ions into a space surrounded by a membrane that is impermeable to ions. The gradient has two components: an electrical component caused by a difference in charge across the membrane and a chemical component caused by a difference in ion concentration. (b) An electrochemical gradient is created during electron transport as the enzyme complexes move protons from NADH and FADH2 into the intermembrane space. The intermembrane space becomes an H+ reservoir because the membrane is almost impermeable to protons. There is, therefore, a much higher concentration of protons in the intermembrane space than in the matrix. Also, protons are consumed in the mitochondrial matrix as oxygen accepts electrons and form water. (c) The electrochemical gradient is used to power ATP synthesis by the enzyme complex ATP synthase. The electrochemical gradient stores free energy and this energy is referred to as proton-motive force (PMF). Protons move through ATP synthase in response to the PMF, reducing the energy of the gradient. This energy drives the synthesis of ATP from ADP and inorganic phosphate in the mitochondrial matrix. 11. Yeast cells produce ATP from glucose by alcoholic fermentation. NADH passes its hydrogen atoms to acetylaldehyde, which is formed when a carbon dioxide molecule is removed from pyruvate using pyruvate decarboxylase. This produces ATP, ethanol, and carbon dioxide. 12. The oxidized form of NAD has a positive charge, whereas the reduced form is neutral. NADH contains two electrons and one proton (H+), which come from a glucose molecule. NADH is the reduced form of nicotinamide adenine dinucleotide, while NAD+ is the oxidized form. 13. Muscle cells produce lactate from pyruvate when there is no oxygen available to accept electrons from the cytochrome oxidase complex. 14. Ethanol is made of two carbon atoms, while pyruvate is made of three carbon atoms. Ethanol has one fewer carbon atom that is lost as carbon dioxide. 15. Lactic acid is produced in the cytoplasm. 16. Two acetyl-CoA molecules are produced from one glucose molecule during aerobic respiration. 17. (a) The Krebs cycle occurs in the mitochondrial matrix. (b) The enzymes for the electron transport chain are located in the inner mitochondrial membrane. 18. A cell that cannot undergo respiration or fermentation will die. 19. Thirty-two percent of the energy stored in glucose is captured and stored in ATP during aerobic respiration. 20. A: inner mitochondrial membrane B: cristae C: mitochondrial matrix D: outer mitochondrial space 2 1 . D in it r o p h e n o l r e d u c e s t h e a b ilit y o f a c e l l t o p r o d u c e A T P b y m a k i n g t h e in n e r m it o c h o n d r ia l m e m b r a n e le a k y . D N P t h u s p r e v e n t s t h e c r e a t io n o f a c h e m io s m o t ic g r a d ie n t t h a t is u s e d t o g e n e r a t e A T P . T h e r e f o r e , c e lls w o u ld n o lo n g e r f u n c t io n p r o p e r ly a n d a p e r s o n w o u ld d ie . 2 2 . M e t a b o lis m in a h e a r t u n d e r g o in g a h e a r t a t t a c k w o u ld s w i t c h f r o m c e llu la r r e s p ir a t io n t o la c t i c a c id f e r m e n t a t io n b e c a u s e o f t h e la c k o f o x y g e n , w h ic h w o u ld b e c a u s e d b y a b l o c k e d c o r o n a r y a r t e r y . H o w e v e r , la c t i c a c id f e r m e n t a t io n d o e s n o t p r o v id e e n o u g h e n e r g y t o k e e p t h e h e a r t b e a t in g a t a lif e -s u s t a in in g r a t e . 2 3 . I t is e s s e n t ia l t h a t m u s c le c e lls c o n t in u e t o c o n v e r t p y r u v a t e t o la c t a t e o r e ls e t h e m u s c le c e lls w o u ld c e a s e t o c o n t r a c t a n d t h e c e lls w o u ld d ie . 2 4 . B a s a l m e t a b o lic r a t e r e f e r s t o t h e m in im u m e n e r g y r e q u ir e d t o r e m a in a liv e , w h e r e a s m a x im u m o x y g e n c o n s u m p t io n r e f e r s t o t h e b o d y ’s m a x im u m c a p a c it y t o g e n e r a t e t h e e n e r g y r e q u i r e d f o r p h y s ic a l a c t iv it y . 2 5 . A p e r s o n w it h a h i g h e r V O 2 m a x w ill f e e l le s s t ir e d t h a n a p e r s o n w it h a lo w e r V O 2 m a x b e c a u s e t h e y a r e m o r e e f f i c ie n t in s u p p ly in g o x y g e n t o t h e ir c e lls , a n d t h e r e f o r e , a c c u m u la t e le s s la c t a t e . A p p ly in g I n q u ir y S k ills 2 6 . S t u d e n t s s h o u ld d e s ig n a n e x p e r im e n t t h a t h a s a t le a s t t h r e e r e p e a t s a n d t w o le v e l s o f o x y g e n c o n c e n t r a t io n s ( n o n e a n d a t m o s p h e r ic le v e l s ) . S t u d e n t s s h o u ld s t a t e t h a t t h e y e a s t t h a t g r o w s b e s t in t h e p r e s e n c e o f o x y g e n is t h e a e r o b ic y e a s t a n d t h e y e a s t t h a t g r o w s b e s t in t h e a b s e n c e o f o x y g e n in t h e a n a e r o b ic y e a s t . 2 7 . A h ig h c o n c e n t r a t io n o f á -k e t o g lu t a r a t e in t h e u r in e w o u ld b e d u e t o in e f f e c t iv e p r o t e in c a t a b o lis m . P r o lin e is c o n v e r t e d in t o á -k e t o g lu t a r a t e , w h ic h t h e n e n t e r s c e llu la r r e s p ir a t io n a s a n in t e r m e d ia t e . H i g h le v e ls o f á -k e t o g lu t a r a t e m a y in d ic a t e g e n e t ic p r o b le m s w it h t h e in f a n t . M a k i n g C o n n e c t io n s 2 8 . (a ) S o y s a u c e , t o f u , s o y m ilk , m is o (a f e r m e n t e d s o y b e a n p a s t e ), s o y b u t t e r ( b ) S o y s a u c e a n d m is o ( c ) P e d io c o c c u s h a lo p h iu s , S a c c h a r o m y c e s r o u x ii, a n d T o r u lo p s is v e r s a t ilis ( d ) S o y s a u c e is p r o d u c e d a s f o llo w s : 1 . S o y b e a n s a n d w h e a t a r e b le n d e d u n d e r c o n t r o lle d c o n d it io n s . N e x t , t h e m ix t u r e is in o c u la t e d w it h m ic r o o r g a n is m s a n d a llo w e d t o m a t u r e f o r s e v e r a l d a y s in la r g e , v a t s t h r o u g h w h ic h a ir is c ir c u la t e d . 2 . T h e r e s u lt in g c u lt u r e , o r k o j i, is t h e n t r a n s f e r r e d t o f e r m e n t a t io n t a n k s a n d m ix e d w it h s a lt w a t e r t o p r o d u c e a m a s h c a lle d m o r o m i. T h e m o r o m i is a llo w e d t o f e r m e n t f o r s e v e r a l m o n t h s w it h v a r io u s la c t ic a c id b a c t e r ia a n d y e a s t s . T h e f e r m e n t a t io n p r o c e s s c r e a t e s t h e d is t in c t f la v o u r a n d f r a g r a n c e o f s o y s a u c e . 3 . A f t e r m o r o m i f e r m e n t a t io n , t h e r a w s o y s a u c e is s e p a r a t e d f r o m t h e s o lid s b y p r e s s in g it t h r o u g h m a n y la y e r s o f c lo t h . T h e r e s u lt in g liq u id is f in a lly p a s t e u r iz e d a n d p a c k a g e d . 2 9 . ( a ) L a c t o b a c illu s b a c t e r ia u n d e r g o la c t i c a c id f e r m e n t a t io n . ( b ) T h is f o r m o f m e t a b o lis m in c r e a s e s t h e s h e lf lif e o f f o o d b y in c r e a s in g t h e a c id it y t o le v e l s t h a t in h ib it t h e g r o w t h o f b a c t e r ia . E x t e n s io n 3 0 . (a ) N o m in im u m d r in k in g a g e in J a m a ic a , P o la n d , P o r t u g a l , a n d S w e d e n ; 1 4 y e a r s in S w it z e r la n d ; 1 6 y e a r s in I t a ly , F r a n c e , a n d G e r m a n y ; 1 8 y e a r s in C h ile , B r i t a in ; 1 9 y e a r s in C a n a d a ; 2 0 y e a r s in J a p a n ; 2 1 y e a r s in U n it e d S t a t e s . ( b ) I n m o s t c a s e s t h e r e a s o n s f o r t h e r e s t r ic t io n s a r e t o r e d u c e a l c o h o l d e p e n d e n c e a n d a b u s e , a llo w f o r m a t u r it y a n d r e s p o n s ib ilit y b e f o r e d r i n k in g , e n f o r c e p a r e n t a l r ig h t s , a n d r e s p o n d t o c u lt u r a l , r e lig i o u s , a n d p o lit ic a l c o n c e r n s . ( c ) E t h a n o l a f f e c t s t h e c e n t r a l n e r v o u s s y s t e m . I t is a d e p r e s s a n t t h a t in h ig h e n o u g h c o n c e n t r a t io n s , m a y a c t a s a g e n e r a l a n a e s t h e t ic . I t s u p p r e s s e s c e r t a in b r a in f u n c t io n s . A t v e r y lo w d o s e s , it a c t s a s a s t im u la n t , s u p p r e s s in g c e r t a in in h ib it o r y b r a in f u n c t io n s . A s e t h a n o l’s c o n c e n t r a t io n in c r e a s e s , f u r t h e r s u p p r e s s io n o f b r a in f u n c t io n s p r o d u c e t h e c la s s ic s y m p t o m s o f in t o x ic a t io n : s lu r r e d s p e e c h , u n s t e a d y w a lk , d is t u r b e d s e n s o r y p e r c e p t io n s , a n d s lo w r e a c t io n t o s t im u li. A t v e r y h ig h c o n c e n t r a t io n s , a n in t o x ic a t e d p e r s o n w ill f a ll a s le e p a n d b e v e r y d if f ic u lt t o w a k e . I f t h e p e r s o n is a w a k e n e d , h e o r s h e m a y b e u n a b le t o m o v e v o lu n t a r ily . W h e n b l o o d le v e l s r e a c h 0 . 4 p e r c e n t , u n c o n s c io u s n e s s r e s u lt s . A b o v e 0 .5 p e r c e n t , t h e b r e a t h in g c e n t r e o f t h e b r a in a n d t h e b e a t i n g a c t i o n o f t h e h e a r t c a n b e a n a e s t h e t i z e d , r e s u lt in g in d e a t h . ( d ) S t u d e n t o p in io n s w ill v a r y . T h e r e is n o c o r r e c t a n s w e r , b u t p a p e r s m u s t b e w e ll r e a s o n e d a n d t h o u g h t o u t . 3 1 . (a ) p a lm it a t e + 7 C o A + 7 F A D + 7 N A D + + 7 H 2 O 6 8 a c e t y l-C o A + 7 F A D H 2 + 7 N A D H + 5 H + 1. F rom 7 N A D H a nd 7 FA D H 2 : 2 .5 A T P p e r N A D H = 2 .5 7 = 1 7 .5 A T P 1 .5 A T P p e r F A D H 2 = 1 .5 7 = 1 0 .5 A T P 7 A T P m o le c u le s a r e u s e d T o t a l A T P p r o d u c e d f r o m 7 N A D H a n d 7 F A D H 2 = 1 7 .5 + 1 0 .5 – 7 = 2 1 A T P