Q&A Hero

Q: All are characteristics of coenzymes EXCEPT: a. carry functional groups. b. maintenance of original structure. c. provide a broader range of catalytic properties. d. can be derived from water-soluble vitamins. e. can serve as an electron carrier.

Q: All of the following are a coenzyme or a precursor of a coenzyme EXCEPT: a. thiamin. b. riboflavin. c. retinol. d. niacin. e. biotin.

Q: The nutritional benefits provided by foods high in fiber result from: a. providing increased digestion speed. b. stimulation of regular functions of the colon and slowing the rate of absorption of certain foods. c. providing for growth of microorganisms that utilize fiber. d. increased vitamin release from complexes with fiber. e. none of the above.

Q: Dietary fiber includes all EXCEPT: a. pectins b. cellulose c. lignins d. gums e. all are dietary fiber

Q: Excess carbohydrate and fat in the human diet is stored as triacylglycerols. The risk of which of the following would be increased in an individual who consistently consumes too much fat and carbohydrate? a. atherosclerosis b. heart disease c. colon cancer d. breast cancer e. all of the above

Q: When carbohydrate intake is low, ____ are formed from acetate units to provide metabolic fuel for the ____ and other tissue. a. fatty acids; liver b. ketone bodies; brain c. ketone bodies; liver d. amino acids; brain e. sterols; heart

Q: When dietary carbohydrate consumption exceeds the energy needs of the individual, excess carbohydrate is converted to ____ and ____ for energy storage. a. amino acids; glucose b. fructose; triacylglycerols c. triacylglycerols; glycogen d. glycogen; protein e. none of the above.

Q: When an individual has a ____ nitrogen balance, excess dietary protein is converted into ____. a. negative; energy b. positive; energy c. negative; nucleic acids d. positive; protein for storage e. both b and d are true

Q: Which of the following statements regarding nutrition is FALSE? a. Dietary protein is a source of essential amino acids b. Organisms can produce all of the essential energy yielding nutrients and micronutrients needed c. Complex carbohydrates can provide simple sugars for the glycolytic pathway d. Essential fatty acids are components of biological membranes e. Fiber is needed to help clear the digestive tract

Q: The enzymes of glycolysis and those of the citric acid cycle are found in which cellular compartments in muscle cells? a. both in the cytoplasm b. glycolysis in cytoplasm and citric acid cycle in mitochondria c. both in mitochondria d. glycolysis in cytoplasm and citric acid cycle in lumen of the endoplasmic reticulum e. both in the lumen of the endoplasmic reticulum

Q: In prokaryotic cells, phospholipid synthesis and oxidative phosphorylation are carried out in: a. plasma membranes. b. cytosol. c. mitochondria. d. ribosomes. e. endoplasmic reticulum.

Q: One advantage of nuclear magnetic resonance (NMR) spectroscopy for the investigation of metabolism is that it utilizes: a. radioisotopes. b. specific metabolic inhibitors. c. autoradiography. d. non-invasive techniques. e. none are true.

Q: In photosynthesis, NADPH is generated as light is used to oxidize ____ to ____. a. water; O2 b. water; CO2 c. NADPH; O2 d. water; NADP+ e. CO2; NADPH

Q: A possible function of NADPH is to: a. provide reducing equivalents to synthesize glucose from CO2. b. carry electrons from anabolic reactions. c. provide a source of hydrogens for oxidative biosynthesis. d. be reduced by hydride ions to form NAD+. e. produce an oxidative product.

Q: From the following types of organic molecules, the order of most reduced to most oxidized is: A. aldehyde B. hydrocarbon C. CO2 D. alcohol E. carboxylic acid a. A, B, C, D, E b. B, E, A, D, C c. C, B, E, A, D d. B, D, A, E, C e. C, D, E, B, A

Q: Dehydrogenases are enzymes that: a. move hydrogens within the molecule. b. add hydrogens across double bonds. c. transfer hydrogens between substrates. d. transfer hydride ions to NAD+ (or NADP+) and release a proton. e. all are true.

Q: All of the following are examples of energy transduction EXCEPT: a. dehydrogenase catalyzed reactions b. isomerase reactions c. oxidative phosphorylation d. NAD+- NADH shuttle e. all of the above are correct

Q: Whcih of the following is NOT a characteristic of aerobic catabolic pathways? a. an example of a catabolic pathway is the conversion of hexoses to 3-carbon compounds b. ADP is phosphorylated to ATP as a result of such pathways. c. NADH is a common product of such pathways d. Water is oxidized to O2 e. generally, the energy produced by such pathways is greater than the energy required to activate the substrates for the pathway

Q: Energy is generally extracted from phototrophs and chemotrophs by: a. hydrolysis reactions. b. condensation-cleavage reactions. c. oxidative-reduction reactions. d. acid-base reactions. e. phosphorylation reactions.

Q: In phototrophs, ____ and ____ are the two energy-rich primary products from the transformation of light energy into chemical energy. a. ATP; NAD+ b. NADPH; ATP c. NADH; NADPH d. ATP; NADH e. ATP; NADH

Q: In the case of shared anabolic and catabolic pathways, the ____ serve as the points of regulation. a. largest enzymes b. ATP producing enzymes c. NADH utilizing enzymes d. rate-limiting enzymes e. all are true

Q: Since both glycolysis and gluconeogenesis are spontaneous pathways, which of the following explains how this is true? a. glycolysis uses 10 enzyme catalyzed steps while gluconeogenesis uses 11 b. the three irreversible steps of glycolysis have alternate routes for gluconeogenesis c. glycolysis converts glucose to pyruvate while gluconeogenesis converts pyruvate to glucose d. glycolysis is oxidative while gluconeogenesis is reductive e. glycolysis is catabolic while gluconeogenesis is anabolic

Q: The definition of an amphibolic pathway is: a. a pathway found in animals living in both land and water. b. a pathway that is carried out both in water and organic solvents. c. a pathway found on both sides of the mitochondrial membrane. d. a pathway that is both anabolic and catabolic in nature. e. all of the above.

Q: Many of the catabolic pathways converge to the common two-carbon intermediate: a. alanine. b. acetyl group of acetyl-CoA. c. lactic acid. d. glucose. e. carbon dioxide.

Q: What are the final products of aerobic catabolism? a. pyruvate and H2O. b. acetyl-CoA and CO2. c. CO2 and H2O. d. pyruvate and acetyl-CoA. e. ammonia and O2.

Q: Which of the following is the major advantage of a multi-enzyme complex? a. it's large size enables it to span an entire membrane b. the product of one enzyme is passed directly to the next enzyme without the possibility of diffusion c. multi-enzyme complexes are much less likely to be inhibited d. all of the above e. none of the above

Q: Metabolon characteristics include all EXCEPT: a. "units of metabolism". b. discrete multienzyme complex. c. soluble enzymes associated into stable multienzyme complexes. d. membrane bound multienzyme systems. e. all are characteristics.

Q: All are true about the relationship between catabolism and anabolism EXCEPT: a. They occur simultaneously. b. Products of one process provide substrates for the other. c. They occur in many of the same organelles. d. The generation of ATP by catabolism provides the energy required by anabolism. e. Anabolism is endergonic while catabolism is exergonic.

Q: All are characteristics of anabolism EXCEPT: a. assembly of complex molecules. b. formation of new covalent bonds. c. ATP provides energy. d. NADPH is an electron donor. e. all are true.

Q: Solar energy is converted to the chemical energy of organic molecules by ____, and ____ recover this energy by metabolizing the organic substrates. a. photoautotrophs; heterotrophs b. heterotrophs; chemoautotrophs c. chemoautotrophs; heterotrophs d. photoautotrophs; chemoautotrophs e. none are true.

Q: Some species can adapt to anaerobic conditions by substituting other electron acceptors for oxygen in their energy-producing pathways and are called: a. aerobes. b. obligate aerobes. c. facultative anaerobes. d. obligate anaerobes. e. none of the above.

Q: Which statement is most likely to be true concerning obligate anaerobes? a. These organisms can use oxygen if it is present in their environment. b. These organisms cannot use oxygen as their final electron acceptor. c. These organisms carry out fermentation for at least 50% of their ATP production. d. Most of these organisms are vegetative fungi. e. None of the above.

Q: What is the relationship between photoautotrophs and heterotrophic cells? a. Photoautotrophs use light energy for synthesis of organic molecules while heterotrophs metabolize organic substances for fuel and building blocks. b. photoautotrophs use organic compounds as a source of carbon while heterotrophs use CO2 as a source of carbon. c. Photoautotrophs synthesize CO2 while heterotrophs synthesize O2. d. Heterotrophs convert solar energy into chemical energy while photoautotrophs break down organic molecules. e. There is no relationship between the two.

Q: All of the following are chemoheterotrophs EXCEPT: a. Staphylococci aureus. b. fungi. c. algae. d. animals. e. non-photosynthetic roots.

Q: Photoheterotrophs require: a. organic carbon sources and light. b. carbon dioxide and light. c. organic carbon sources and oxidation-reduction reactions. d. carbon dioxide and inorganic compounds. e. carbon dioxide and oxidation-reduction reactions.

Q: Likely the most ancient of the metabolic pathways in which energy is released from glucose and captured in the form of ATP under anaerobic conditions is called: a. photooxidation. b. oxidative phosphorylation. c. citric acid cycle. d. glycolysis. e. none of the above.

Q: Which of the following statements is true regarding metabolic pathways? a. catabolic pathways are generally reductive while anabolic pathways are generally oxidative b. catabolic pathways use a wide variety of substrates to produce a small number of waste products. c. an amphibolic pathway is extremely wasteful because it simultaneously operates as both an anabolic pathway and a catabolic pathway. d. NAD+ is used as a reducing agent in catabolic pathways while NADPH is used as an oxidizing agent in anabolic pathways e. none of the above

Q: Most organisms show ____ in their major pathways of metabolism. a. marked similarity b. some similarity c. minimal similarity d. considerable diversity e. major diversity

Q: All are characteristics of metabolism EXCEPT: a. a process which synthesizes either energy or complex cellular substances. b. a process of intermediates. c. the conversion of food energy into energy of motion. d. a free-flow unregulated process. e. a process responding to the momentary energy requirements of a cell.

Q: What coenzyme would be required in the following reaction? a. NAD+ b. thiamine pyrophosphate c. biotin d. lipoic acid e. coenzyme A

Q: What coenzyme would be required in the following reaction? a. ADP b. thiamine pyrophosphate c. biotin d. lipoic acid e. coenzyme A

Q: For the following reaction, what coenzyme is missing from the reactants? a. FADH2 b. NAD+ c. acetyl CoA d. NADH e. NADPH

Q: The conversion of glucose-6-phosphate to glucose-1-phosphate has a of + 8.4 kJ/mol. How can a reaction such as this proceed in a cell?a. it must be coupled to ATP hydrolysisb. the product must be rapidly used in a subsequent step of the pathwayc. it can only occur with the help of an enzymed. this reaction can not proceed and must go in the reverse mannere. both B and C are correct

Q: The cofactors NAD+, NADPH and FAD all have what common chemical feature? a. they all contain a guanine nucleotide b. they all contain a sulfhydryl group that acts as a nucleophile c. they all pick up or release two electrons during an oxidation/reduction reaction d. they all can be used for phosphorylation of enzyme substrates e. none of the above

Q: What coenzyme is found in pyruvate decarboxylase that aids in the decarboxylation of acids?a. Thiamine pyrophosphateb. Folic acidc. Biotind. Lipoic acide. none of the above

Q: The statements are correct about the diseases caused by vitamin deficiencies EXCEPT: a. niacin deficiency leads to gout. b. vitamin A deficiency leads to night blindness that can be reversed by adding -carotene to the diet. c. vitamin B12 prevents pernicious anemia. d. vitamin D deficiency leads to demineralization of bones and rickets. e. vitamin C prevents scurvy.

Q: What vitamin is needed for coagulation of blood and what must happen for it to be functional? a. vitamin D, a co-translational modification of serine. b. vitamin K, a posttranslational carboxylation of glutamate. c. vitamin K, a co-translational carboxylation of aspartate. d. vitamin D, a posttranslational glycosylation of serine. e. vitamin E, a posttranslational glycosylation of tyrosine.

Q: Unsaturated fatty acids in membranes are particularly susceptible to ____ and vitamin E may provide protection because it is a potent ____. a. oxidation; antioxidant b. reduction; reducing agent c. reduction; reducing agent d. substitution; reactant e. substitution; reactant

Q: What are the principal minerals in the human body? a. iron and chloride b. sodium and potassium c. calcium and sodium d. calcium and phosphorus e. sulfur and phosphorus

Q: Cholecalciferol is hydroxylated twice to form ____ that acts like a ____ to regulate ____ and ____ metabolism. a. 24,25-hydroxyvitamin D; vitamin D-binding protein; calcium; chloride b. ergosterol; vitamin D-binding protein; sodium; calcium c. 7-dehydrocholesterol; hormone; calcium; phosphate d. 1,25-dihydroxycolecarciferol; prehormone; sodium; phosphate e. 1,25-dihydroxycolecarciferol; hormone; calcium; phosphate

Q: Retinol and the carotenoids follow the pathways of ____ digestion and absorption. a. complex carbohydrates b. proteins c. simple sugars d. nucleic acids e. lipids

Q: Which vitamin is essential to vision? a. A b. C c. D2 d. B12 e. B1

Q: Pyruvate + CoA + NAD+->___ + CO2 + ____a. oxaloacetate; ATPb. malonyl CoA; NADH + H+c. methylmalonyl CoA; biotind. acetyl CoA; NADH + H+e. succinyl CoA; NAD+

Q: In a biotin-dependent carboxylation, _____ provides the energy for activation of ____. a. acetyl CoA; carbon dioxide b. ATP; lysine amine group c. NADH; bicarbonate d. ATP; bicarbonate e. acetyl CoA; carboxyl group

Q: ____ functions to couple acyl-group transfer and electron transfer during oxidation and decarboxylations of ____.a. biotin; propionateb. lipoate; propionatec. lipoate; d. TPP; e. TPP; acetyl-CoA

Q: ______ is often used in carboxylation reactions while ____ is often used in decarboxylation reactions. a. thiamine pyrophosphate; lipoate b. lipoate; biotin c. biotin; thiamine pyrophosphate d. pyridoxal-5-phosphate; biotin e. lipoate; pyridoxal-5-phosphate

Q: All of the coenzymes listed participate in electron transfer EXCEPT: a. FAD. b. biotin. c. NAD+. d. vitamin C. e. lipoic acid.

Q: What causes pyridoxal-5-phosphate (PLP) to be so versatile? a. It reacts very quickly with simple sugars. b. Its ability to be a one or two electron carrier. c. The formation of a thioester bond. d. Its ability to transfer methyl groups. e. Its ability to form a Schiff base and act as an electron sink.

Q: Thioesters have higher ____ than that of oxygen esters.a. mobilityb. electronegativityc. resonanced. positive Ge. group transfer potential

Q: Pyridoxal-5-phosphate (PLP) is involved in all EXCEPT:a. aminotransferases (transaminases).d. racemizations.e. all of the above.

Q: Which of the following is the first event following ATP binding in the movement of actin and myosin? a. binding of actin and myosin b. the power stroke c. dissociation of actin and myosin d. the up-lever state e. the down-lever state

Q: Which of the following best describes the conditions of switch 1, switch 2 and the actin-cleft during myosin rigor? a. switch 1 open, switch 2 open, actin-cleft open b. switch 1 open, switch 2 open, actin-cleft closed c. switch 1 closed, switch 2 open, actin-cleft open d. switch 1 open, switch 2 closed, actin-cleft closed e. switch 1 open, switch 2 closed, actin-cleft open

Q: Which of the following loops are present in the myosin head to give rise to the ATP-binding site? a. switch 1 b. switch 2 c. relay helix d. converter domain e. both A and B are correct

Q: In E. coli, rotation of the flagella is powered by: a. phosphorylation of the motB protein by phosphoenolpyruvate. b. a proton gradient across the plasma membrane of the bacterium. c. the hydrolysis of ATP by the motB protein. d. the hydrolysis of GTP by the flagella. e. none of the above.

Q: Troponin C (TnC) exhibits all of the following characteristics EXCEPT: a. TnC has two binding sites that are always complexed to Ca2+. b. the Ca2+ binding increases the interaction of TnC and TnI. c. TnC has four equivalent Ca2+ binding sites. d. Ca2+ binding to TnC decreases interaction between TnI and actin. e. a conformational change in TnC occurs on Ca2+ binding.

Q: Which of the following troponin subunits is responsible for inhibiting actin-myosin binding? a. troponin G b. troponin I c. troponin C d. troponin M e. troponin Y

Q: Muscle contraction is stimulated by: a. an increase in [Ca2+] in the vicinity of the muscle fibers. b. a decrease in the [Ca2+] in the mitochondria. c. an increase in [Ca2+] in the sarcolemma. d. a decrease in the [Ca2+] in the Golgi. e. an increase in [Ca2+] in the sarcoplasmic reticulum.

Q: The power stroke in muscle contraction is associated with: a. the binding of ATP to ATPase. b. the dissociation of ADP and Pi from the ATPase. c. binding of myosin to actin. d. addition of water for ATP hydrolysis. e. the hydrolysis of ATP.

Q: Order the reaction sequence for the involvement of free actin, free myosin and ATPase activity on each other. A. Actin binds and activates ATPase activity by stimulating release of Pi and ADP. B. In the absence of actin, the addition of ATP to myosin produces a rapid release of H+. C. The binding of new ATP to the actomyosin complex. D. Actomyosin dissociates into actin and myosin. E. Low energy conformation change in myosin head. a. B, A, E, C, D b. A, B, C, D, E c. B, E, C, A, D d. E, B, A, D, C e. C, A, D, E, B

Q: Which of the following muscle protein components is responsible for ATP hydrolysis? a. tropomyosin b. myosin c. troponin C d. actin e. troponin M

Q: All of the following occur during muscle contraction EXCEPT: a. the length of the sarcomere is reduced. b. the length of the thick filament is reduced. c. the contraction produces an increased overlap of the actin and myosin filaments of the A band. d. ATP hydrolysis occurs. e. the length of the thin filaments is constant.

Q: If the non-hydrolyzable ATP analog were given to muscle cells, where would inhibition occur?a. during formation of the cross bridge between actin and myosin when Pi is releasedb. during the conformational change in the myosin head that moves actin and myosin relative to each otherc. during the ATP binding step where actin and myosin dissociated. during the conformational change in the myosin head when ATP hydrolysis occurse. at steps c and d above

Q: In the of the segment of myosin, the ____ sequence likely binds ATP and is found in other nucleotide-binding proteins. The general sequence is:a. cys-X-X-cys-X-hisb. arg-X-X-his-X-glyc. gly-X-X-gly-X-glyd. ser-X-arg-X-lys-X-glye. lys-X-gly-X-X-ser

Q: Of the six polypeptides that make up the thick filament, the ATPase activity is in the: a. LC1 b. LC2 c. Myosin heavy chains d. Essential light chains e. Regulatory light chains

Q: The protein in the troponin complex that shows 70% homology to calmodulin and involved in Ca2+binding is: a. TnT. b. TnC. c. TnI. d. TnA. e. TnB.

Q: All of the statements about the bands observed by electron microscopy of myofibrils are true EXCEPT: a. I bands show a hexagonal array of thick filaments. b. thin filaments are composed mainly of actin, troponin, and tropomyosin. c. H zones contain an array of thick filaments that are composed mainly of myosin. d. thick filaments are joined by cross-bridges. e. Z lines lie in the middle of the I bands, marking the ends of the sarcomere.

Q: The component that houses a high concentration of Ca2+and releases it to trigger muscle contraction is: a. sarcoplasmic reticulum. b. sarcomere. c. t-tubules. d. sarcolemma. e. troponin.

Q: Myofibrils are linear arrays of cylindrical ____, the basic structural unit in the contraction of striated muscle. a. foot structures b. sarcomeres c. sarcolemmas d. sarcoplasmic reticulum (SR) e. t-tubules

Q: Negative cooperativity of Rep helicase from E. colimeans that: a. when one subunit binds DNA, the other releases from the DNA. b. when both subunits are bound to DNA, ATP hydrolysis promotes release of both subunits. c. ATP hydrolysis promotes DNA binding of both subunits simultaneously. d. once it binds ssDNA, binding dsDNA is prohibited. e. none of the above.

Q: Rep helicase of E. coliand kinesin are alike in that they both have: a. binding sites for the DNA lattice. b. ring-like structures that encircle the substrate. c. two subunits, one of which is always bound to the polymer at any moment. d. tubulin binding heads that hydrolyze ATP. e. the capacity to move organelles.