Q&A Hero

Q: How does the body respond to a low-carbohydrate diet?

Q: What is ketosis and how can it be identified? What conditions typically induce a state of ketosis? What are the adverse effects of this condition?

Q: Discuss ways in which the body's metabolism adapts to conditions of fasting/starvation. How do these adaptations affect the rate of weight loss when a person follows a low-kcalorie diet?

Q: Describe interactions among the energy nutrients when each is consumed in excess.

Q: How does the electron transport chain function in the synthesis of ATP?

Q: Explain the roles of protein and fat as nutrients for gluconeogenesis. What are the circumstances that favor low and high rates of gluconeogenesis?

Q: What are the major differences between aerobic and anaerobic metabolism? Give an example of an aerobic reaction and an anaerobic reaction.

Q: List four of the liver's functions in the metabolism of each of these nutrients: carbohydrates, fats, and proteins.

Q: Matching a. Ethyl b. Urea c. MEOS d. Water e. Glucose f. Enzyme g. Glycogen h. Glycerol i. Ammonia j. Coenzyme k. Cori cycle l. Lactate m. Acetoacetate n. Acetyl CoA o. Pyruvate p. Triglyceride q. Gastric alcohol dehydrogenase r. Synthesis of pyruvate from glycogen s. Synthesis of cholesterol from acetate t. Synthesis of acetyl CoA from glucose 1>Example of an anabolic reaction 2>Example of a catabolic reaction 3>A protein that accelerates a chemical reaction 4>A small non-protein organic substance that promotes optimal activity of an enzyme 5>A product of glycolysis 6>A product of pyruvate metabolism when oxygen is limited 7>The oxidation product of pyruvate 8>A recycling process of converting lactate to glucose 9>An irreversible reaction 10>The part of a triglyceride that is convertible to glucose 11>A product of deamination 12>A compound synthesized from acetyl CoA when ATP is plentiful 13>The principal nitrogen-containing waste product 14>Waste product of the electron transport chain 15>A storage form of carbohydrate 16>The major energy fuel for the central nervous system 17>A ketone 18>An enzyme with activity levels related to a person's sex 19>The type of alcohol in distilled spirits, wine, and beer 20>A system for metabolizing drugs and alcohol

Q: In the first step of alcohol metabolism, alcohol dehydrogenase oxidizes alcohol to ____________________.

Q: In the absence of adequate energy intake, ____________________ are formed from combining acetyl CoA fragments derived from fatty acids.

Q: The making of glucose from noncarbohydrate sources is called ____________________.

Q: The final common metabolic pathway for carbohydrates, fats, and amino acids is the ____________________.

Q: Fatty acids are taken apart two carbons at a time in a series of reactions known as ____________________.

Q: When the body needs energy quickly, pyruvate is converted to ____________________; when the energy expenditure is slower, pyruvate is broken down into ____________________.

Q: In the TCA (tricarboxylic acid; Krebs) cycle, ____________________ is broken down into ____________________ and ____________________,

Q: Enzyme helpers are called ____________________.

Q: Some of the energy released during the breakdown of glucose, glycerol, fatty acids, and amino acids is captured in the high-energy compound with three phosphate groups called ____________________.

Q: The process by which green plants use the sun's energy to make carbohydrates from carbon dioxide and water is ____________________.

Q: What proportion of all domestic violence incidents involve alcohol use? a. 25% b. 35% c. 45% d. 55% e. 65%

Q: What is the median weekly number of alcoholic drinks consumed by college students in general? a. 1 ½ b. 3 c. 5 d. 10 e. 14 1/2

Q: Which statement is true regarding alcoholic beverages containing caffeine? a. The FDA has banned their sales. b. The time needed to be intoxicated is slowed by caffeine. c. The presence of caffeine slows down consumption. d. The caffeine slows the development of alcohol-induced impairment. e. The presence of caffeine improves an individual's judgment about his or her level of intoxication.

Q: The Wernicke-Korsakoff syndrome in people with chronic alcohol abuse stems primarily from a deficiency of ____. a. folate b. thiamin c. antidiuretic hormone d. alcohol dehydrogenase e. protein

Q: Which functions are first to be affected when a person begins to drink alcohol? a. Speech and vision b. Judgment and reasoning c. Voluntary muscle control d. Respiration and heart function e. Balance and coordination

Q: Excess alcohol intake leads to a reduction in the synthesis rate of ____. a. liver fat b. liver glucose c. ketone bodies d. acetyl CoA molecules e. insulin

Q: In the average healthy person, about how much time is required by the liver to process the alcohol in a typical drink? a. 15 minutes b. 30 minutes c. 1 hour d. 2 hours e. 4 hours

Q: What is acetaldehyde? a. An intermediate in fatty acid synthesis b. An intermediate in alcohol metabolism c. The first product of fatty acid catabolism d. The TCA compound that combines with acetyl CoA e. The final product of alcohol metabolism.

Q: The metabolism of alcohol begins in the ____. a. liver b. brain c. stomach d. intestines e. mouth

Q: What would be the best method of slowing alcohol absorption? a. Not eating b. Eating protein snacks c. Drinking caffeinated drinks d. Eating carbohydrate snacks e. Fasting 6 to 8 hours before drinking

Q: What is the primary organ that oxidizes alcohol? a. Brain b. Liver c. Pancreas d. Stomach e. Small intestine

Q: What is one explanation for the generally lower tolerance for alcohol in women in comparison to men? a. Women fast more often. b. Women do not eat as much food with the alcohol. c. Women consume more of their alcohol in sweetened drinks. d. Women have lower amounts of stomach alcohol dehydrogenase. e. Women are more likely to gulp their drinks.

Q: Approximately how many kcal are contained in 3 ounces of 80-proof rum? a. 50 kcal b. 100 kcal c. 150 kcal d. 200 kcal e. 400 kcal

Q: The amount of ethanol in a typical "drink" is ____. a. 0.5 ounce b. 1 ounce c. 1.5 ounces d. 2 ounces e. 4 ounces

Q: What percentage of U.S. adult men are classified as drinking excessively? What percentage of women are doing the same? a. 2%; 5% b. 5%; 2% c. 8%; 3% d. 10%; 4% e. 11%; 8%

Q: Nationally, what percentage of college students are frequent binge drinkers? a. 5% b. 10% c. 20% d. 30% e. 50%

Q: What organ is the major site for gluconeogenesis? a. Liver b. Brain c. Muscle d. Small intestine e. Pancreas

Q: Which of the following is classified as a ketone body? a. Sorbitol b. Pyruvate c. Acetyl CoA d. Acetoacetate e. Oxaloacetate

Q: Which item is used to supply some of the fuel needed by the brain only after the body has been fasting for a while? a. Ketones b. Glycerol c. Fatty acids d. Amino acids e. Protein

Q: How soon would death occur from starvation if the body was unable to shift to a state of ketosis? a. 3 to 5 days b. 7 to 10 days c. within 3 weeks d. 4 to 6 weeks e. 6 to 12 weeks

Q: Which dietary nutrient would most rapidly reverse a state of ketosis in a starving person? a. Nonessential fatty acids b. Protein c. Amino acids d. Carbohydrate e. Essential fatty acids

Q: During the first few days of a fast, what energy source provides about 90% of the glucose needed to fuel the body? a. Protein b. Ketones c. Glycogen d. Triglycerides e. Glycerol

Q: Of the total amount of glucose energy consumed by the body, approximately what percentage is used by the brain and nerve cells? a. 10% b. 30% c. 50% d. 70% e. 90%

Q: What is a feature of the metabolism of surplus dietary fat? a. Excess fat is almost all stored. b. Excess fat promotes increased fat oxidation. c. Excess fat spares breakdown of body proteins. d. Conversion of excess fat to storage fat is inefficient. e. Excess dietary fat facilitates conversion of other macronutrients to fat.

Q: How does excess carbohydrate intake contribute to obesity? a. It is efficiently converted to storage fat. b. It spares oxidation of body fat and dietary fat. c. It stimulates glucagon release, resulting in inhibition of fatty acid oxidation. d. It stimulates pancreatic lipase secretion, which results in higher dietary fat absorption. e. It results in large amounts of glycogen storage that is increased as carbohydrate consumption increases.

Q: Which of the following is a characteristic of the metabolism of specific macronutrients? a. The rate of fat oxidation does not change when fat is eaten in excess. b. The rate of protein oxidation does not change when protein is eaten in excess. c. The rate of glucose oxidation does not change when carbohydrate is eaten in excess. d. The conversion of dietary glucose to fat is the major pathway of carbohydrate utilization. e. The conversion of protein to muscle is hastened when protein intake exceeds protein requirements.

Q: If a person consumes 100 kcalories in excess of energy needs from olive oil, approximately what percentage of the kcalories are stored in the body? a. 55% b. 65% c. 75% d. 85% e. 95%

Q: Storing excess energy from dietary carbohydrate as body fat requires ____ percent of the ingested energy intake. a. 5 b. 15 c. 25 d. 35 e. 45

Q: What is the most likely explanation for the body's higher metabolic efficiency of converting a molecule of corn oil into stored fat compared with a molecule of sucrose? a. The enzymes specific for metabolizing absorbed fat have been found to have higher activities than those metabolizing sucrose. b. The absorbed corn oil is transported to fat cells at a faster rate than the absorbed sucrose, thereby favoring the uptake of corn oil fat. c. There are fewer metabolic reactions for disassembling the corn oil and re-assembling the parts into a triglyceride for uptake by the fat cells. d. Because corn oil has a greater energy content than sucrose, conversion of these nutrients into stored fat requires a smaller percentage of the energy from the corn oil. e. The metabolic reactions for disassembling the corn oil and re-assembling the parts into a triglyceride for uptake by the fat cells require less energy themselves.

Q: Which of the following can be synthesized from all three energy-yielding nutrients? a. Lactate b. Glycogen c. Acetyl CoA d. Oxaloacetate e. Glucose

Q: The number of ATP molecules that can be produced from a molecule of protein, fat, or carbohydrate is generally related to the number of atoms of ____. a. carbon b. oxygen c. nitrogen d. hydrogen e. potassium

Q: What accounts for the higher energy density of a fatty acid compared with the other energy-yielding nutrients? a. Fatty acids have a lower percentage of hydrogen-oxygen bonds. b. Fatty acids have a greater percentage of hydrogen-carbon bonds. c. Other energy-yielding nutrients have a lower percentage of oxygen-carbon bonds. d. Other energy-yielding nutrients undergo fewer metabolic reactions, thereby lowering the energy yield. e. Other energy-yielding nutrients have a lower percentage of oxygen-hydrogen bonds.

Q: Which of the following is a feature of the electron transport chain? a. It captures energy in the high-energy bonds of ATP. b. It pumps carbon dioxide across the mitochondrial membrane. c. It is composed of a series of coenzymes that transfer electrons up a concentration gradient. d. It combines oxygen from carbon dioxide with hydrogen generated from the splitting of water. e. It facilitates the transport of sodium and calcium.

Q: In addition to energy, what are the principal end products of cellular oxidation of carbohydrates? a. Water and carbon dioxide b. Carbon, hydrogen, and urea c. Indigestible fiber and nitrogen d. Monosaccharides and amino acids e. Oxygen and carbolic acid

Q: What are the products of the complete oxidation of fatty acids? a. Urea and acetone b. Fatty acids and glycerol c. Carbon, hydrogen, and oxygen d. Water, carbon dioxide, and energy e. Pyruvate and acetyl CoA

Q: When protein consumption is in excess of body needs and energy needs are met, the excess amino acids are metabolized and the energy in the molecules is ____. a. stored as fat only b. excreted in the feces c. stored as amino acids only d. stored as glycogen and fat e. excreted in the urine

Q: If the carbohydrate content of the diet is insufficient to meet the body's needs for glucose, what can be converted to glucose? a. Fatty acids b. Acetyl CoA c. Amino acids d. Carbon dioxide e. Urea

Q: When energy-yielding nutrients are consumed in excess, which one(s) can lead to storage of fat? a. Fat only b. Carbohydrate only c. Fat and carbohydrate only d. Fat, carbohydrate, and protein e. Protein and fat only

Q: Which process leads to the production of urea? a. Oxidation of glucose b. Oxidation of amino acids c. Incomplete oxidation of fatty acids d. Synthesis of protein from amino acids e. Incomplete oxidation of glycerol

Q: After digestion and absorption, an amino acid not used to build protein will first be subjected to ____. a. removal of its amino group b. removal of its carboxyl group c. hydrolysis of its peptide bond d. condensation of its peptide bond e. removal of its acetyl group

Q: Where do the TCA cycle reactions take place? a. Golgi bodies b. Endoplasmic reticulum c. Nucleus of the mitochondria d. Inner compartment of the mitochondria e. Outer membrane of the Golgi bodies

Q: An immediate consequence of a cellular deficiency of oxaloacetate is a slowing of ____. a. glycolysis b. the TCA cycle c. lactate synthesis d. ketone formation e. protein excretion

Q: How many acetyl CoA molecules may be obtained from oxidation of a 16-carbon fatty acid? a. 2 b. 4 c. 6 d. 8 e. 16

Q: What percentage (by weight) of a triglyceride molecule can be converted to glucose? a. 0% b. 5% c. 25% d. 50% e. 75%

Q: Production of excessive amounts of acetyl CoA molecules leads to the synthesis of ____. a. fatty acids only b. fatty acids and glucose only c. fatty acids and fructose only d. fatty acids, glucose, and amino acids e. amino acids only

Q: Fatty acid oxidation results in the direct production of ____. a. ketones b. fructose c. pyruvate d. acetyl CoA e. lactate

Q: What is a possible fate of acetyl CoA? a. Degradation to urea b. Synthesis to glycerol c. Synthesis to fatty acids d. Degradation to ammonia e. Storage in lipids

Q: Which nutrient can be made from compounds composed of 2-carbon skeletons? a. Glucose b. Fructose c. Glycogen d. Fatty acids e. Pyruvate

Q: What is a possible metabolic reaction in the cell? a. Pyruvate to urea b. Lactate to pyruvate c. Acetyl CoA to pyruvate d. Carbon dioxide to glycerol e. Fatty acids to glucose

Q: When a person is performing intense physical exercise and begins to feel fatigue and a burning pain in the muscles, the response of the muscles is to synthesize more ____. a. lactate b. glucose c. citric acid d. fatty acids e. galactate

Q: The Cori cycle involves the interconversion of ____. a. lactate and glucose b. glucose and amino acids c. pyruvate and citric acids d. fatty acids and acetyl CoA e. glycerol and glucose

Q: An aerobic reaction is one that requires ____. a. alcohol b. oxygen c. nitrogen d. ammonia e. glucose

Q: Which statement describes lactate production by muscle cells? a. It occurs only during intense exercise. b. When rapid, it causes muscle fatigue. c. It produces lactate that may eventually be used by the liver for glucose production. d. It lowers the pH of the muscle cell, thereby lowering muscle performance. e. It is an aerobic process.

Q: Which of the following is a feature of aerobic metabolism? a. Little or no oxygen is consumed. b. Lactic acid is a major byproduct. c. Energy is produced more slowly than in anaerobic metabolism. d. Pyruvate is converted to glucose by reverse glycolysis to yield a net of 2 ATPs. e. The process can only be sustained for relatively brief periods of time.

Q: The series of reactions involving the conversion of glucose to pyruvate is known as ____. a. pyrolysis b. glycolysis c. beta-oxidation d. coupled reaction e. gluconeogenesis

Q: Glycolysis is the conversion of ____. a. glycogen to fat b. glycogen to protein c. glucose to pyruvate d. glucose to glycogen e. glycogen to glucose

Q: Which statement describes a correct energy-yielding endpoint? a. Carbohydrates yield glucose only when proteins are not available. b. Proteins cannot yield fat stores. c. Fatty acids yield amino acids. d. Glycerol yields nonessential amino acids when nitrogen is present. e. Fatty acids yield glucose.

Q: In photosynthesis, the plant uses energy from the sun, plus water and carbon dioxide, to synthesize ____. a. carbohydrates only b. fats and carbohydrates only c. protein and carbohydrates only d. fats, proteins, and carbohydrates e. protein only

Q: A typical cell contains "powerhouses," which is another name for ____. a. DNA b. ribosomes c. mitochondria d. electron transport chains e. RNA

Q: A feature of catabolic reactions is that they ____. a. involve the release of energy b. occur only in mitochondria c. involve consumption of energy d. occur only during loss of body weight e. require carbon dioxide

Q: What term is specific to reactions in which simple compounds are combined into more complex molecules? a. Anabolic b. Catabolic c. Ergogenic d. Gluconeogenic e. Anaerobic