ALL E Tutorial QU - multiple choice questions PDF

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Which of these is not a protease that acts in the small intestine? A) Chymotrypsin B) Elastase C) Enteropeptidase D) Secretin E) Trypsin The coenzyme required for all transaminations is derived from: A) niacin. B) pyridoxine (vitamin B6). C) riboflavin. D) thiamin. E) vitamin B12. Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process described as: A) deamination. B) hydrolysis. C) oxidative deamination. D) reductive deamination. E) transamination. In amino acid catabolism, the first reaction for many amino acids is a(n): A) decarboxylation requiring thiamine pyrophosphate (TPP). B) hydroxylation requiring NADPH and O2. C) oxidative deamination requiring NAD+. D) reduction requiring pyridoxal phosphate (PLP). E) transamination requiring pyridoxal phosphate (PLP). The human genetic disease phenylketonuria (PKU) can result from: A) deficiency of protein in the diet. B) inability to catabolize ketone bodies. C) inability to convert phenylalanine to tyrosine. D) inability to synthesize phenylalanine. E) production of enzymes containing no phenylalanine. Nonessential amino acids: A) are amino acids other than those required for protein synthesis. B) are not utilized in mammalian proteins. C) are synthesized by plants and bacteria, but not by humans. D) can be synthesized in humans as well as in bacteria. E) may be substituted with other amino acids in proteins. The hormones epinephrine and norepinephrine are derived biosynthetically from: A) arginine. B) histidine. C) isoleucine. D) tryptophan. E) tyrosine. If a cell were unable to synthesize or obtain tetrahydrofolic acid (H4 folate), it would probably be deficient in the biosynthesis of: A) isoleucine. B) leucine. C) lysine. D) methionine. E) serine.

Urea synthesis in mammals takes place primarily in tissues of the: A) brain. B) kidney. C) liver. D) skeletal muscle. E) small intestine. Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle? A) Adenine B) Aspartate C) Creatine D) Glutamate E) Ornithine If a person's urine contains unusually high concentrations of urea, which one of the following diets has he or she probably been eating recently? A) High carbohydrate, very low protein B) Very high carbohydrate, no protein, no fat C) Very very high fat, high carbohydrate, no protein D) Very high fat, very low protein E) Very low carbohydrate, very high protein Lipoprotein lipase acts in: A) hydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues. B) intestinal uptake of dietary fat. C) intracellular lipid breakdown of lipoproteins. D) lipoprotein breakdown to supply needed amino acids. E) none of the above. Free fatty acids in the bloodstream are: A) bound to hemoglobin. B) carried by the protein serum albumin. C) freely soluble in the aqueous phase of the blood. D) nonexistent; the blood does not contain free fatty acids. E) present at levels that are independent of epinephrine. The role of hormone-sensitive triacylglycerol lipase is to: A) hydrolyze lipids stored in the liver. B) hydrolyze membrane phospholipids in hormone-producing cells. C) hydrolyze triacylglycerols stored in adipose tissue. D) synthesize lipids in adipose tissue. E) synthesize triacylglycerols in the liver.

If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the β-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is: A) 3. B) 10. C) 25. D) 108. E) 1000.

In the disease sprue, vitamin B12 (cobalamin) is poorly absorbed in the intestine, resulting in B12 deficiency. If each of the following fatty acids were in the diet, for which one would the process of fatty acid oxidation be most affected in a patient with sprue? A) CH3(CH2)10COOH B) CH3(CH2)11COOH C) CH3(CH2)12COOH D) CH3(CH2)14COOH E) CH3(CH2)18COOH Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires: A) ATP, carnitine, and coenzyme A. B) ATP, carnitine, and pyruvate dehydrogenase. C) ATP, coenzyme A, and hexokinase. D) ATP, coenzyme A, and pyruvate dehydrogenase. E) carnitine, coenzyme A, and hexokinase. Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because: A) acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not. B) acyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not. C) carnitine is required to oxidize NAD+ to NADH. D) fatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form. E) None of the above is true. Complete oxidation of 1 mole of which fatty acid would yield the most ATP? A) 16-carbon saturated fatty acid B) 18-carbon mono-unsaturated fatty acid C) 16-carbon mono-unsaturated fatty acid D) 16-carbon poly-unsaturated fatty acid E) 14-carbon saturated fatty acid What is the correct order of function of the following enzymes of β oxidation? 1. β-Hydroxyacyl-CoA dehydrogenase 2. Thiolase 3. Enoyl-CoA hydratase 4. Acyl-CoA dehydrogenase A) 1, 2, 3, 4 B) 3, 1, 4, 2 C) 4, 3, 1, 2 D) 1, 4, 3, 2 E) 4, 2, 3, 1 Which enzyme is the major regulatory control point for β-oxidation? A) Pyruvate carboxylase B) Carnitine acyl transferase I C) Acetyl CoA dehydrogenase D) Enoyl CoA isomerase E) Methylmalonyl CoA mutase In comparing fatty acid biosynthesis with β oxidation of fatty acids, which of the following statements is incorrect? A) A thioester derivative of crotonic acid (trans-2-butenoic acid) is an intermediate in the synthetic path, but not in the degradative path. B) A thioester derivative of D-β-hydroxybutyrate is an intermediate in the synthetic path, not in the degradative path. C) Fatty acid biosynthesis uses NADPH exclusively, whereas β oxidation uses NAD+ exclusively. D) Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes. E) The condensation of two moles of acetyl-CoA in the presence of a crude extract is more rapid in bicarbonate buffer than in phosphate buffer at the same pH; the cleavage of acetoacetyl-CoA proceeds equally well in either buffer.

Which of the following is not required in the synthesis of fatty acids? A) Acetyl-CoA B) Biotin C) HCO3– (CO2) D) Malonyl-CoA E) NADH Which of these can be synthesized by plants but not by humans? A) Linoleate [18:2(Δ9,12)] B) Palmitate (16:0) C) Phosphatidylcholine D) Pyruvate E) Stearate (18:0) Which of the following statements is not true concerning glycolysis in anaerobic muscle? A) Fructose 1,6-bisphosphatase is one of the enzymes of the pathway. B) It is an endergonic process. C) It results in net synthesis of ATP. D) It results in synthesis of NADH. E) Its rate is slowed by a high [ATP]/[ADP] ratio. Which of the following reactions in glycolysis requires ATP as a substrate? A) Hexokinase B) Glyceraldehyde-3-phosphate dehydrogenase C) Pyruvate kinase D) Aldolase E) Phosphoglycerate kinase Inorganic fluoride inhibits enolase. In an anaerobic system that is metabolizing glucose as a substrate, which of the following compounds would you expect to increase in concentration following the addition of fluoride? A) 2-phosphoglycerate B) Glucose C) Glyoxylate D) Phosphoenolpyruvate E) Pyruvate Glycogen is converted to monosaccharide units by: A) glucokinase. B) glucose-6-phosphatase C) glycogen phosphorylase. D) glycogen synthase. E) glycogenase. Which of the following reactions in glycolysis produces ATP as a product? A) Hexokinase B) Glyceraldehyde-3-phosphate dehydrogenase C) Pyruvate kinase D) Aldolase E) Phosphofructokinase-1 Which of the following is a cofactor in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase? A) ATP B) Cu2+ C) heme D) NAD+ E) NADP+

Anaplerotic reactions . A) produce oxaloacetate and malate to maintain constant levels of citric acid cycle intermediates B) produce biotin needed by pyruvate carboxylase C) recycle pantothenate used to make CoA D) produce pyruvate and citrate to maintain constant levels of citric acid cycle intermediates E) all of the above In comparison with the resting state, actively contracting human muscle tissue has a: A) higher concentration of ATP. B) higher rate of lactate formation. C) lower consumption of glucose. D) lower rate of consumption of oxygen E) lower ratio of NADH to NAD+. In humans, gluconeogenesis: A) can result in the conversion of protein into blood glucose. B) helps to reduce blood glucose after a carbohydrate-rich meal. C) is activated by the hormone insulin D) is essential in the conversion of fatty acids to glucose. E) requires the enzyme hexokinase. The metabolic function of the pentose phosphate pathway is to: A) act as a source of ADP biosynthesis. B) generate NADPH and pentoses for the biosynthesis of fatty acids and nucleic acids. C) participate in oxidation-reduction reactions during the formation of H2O. D) provide intermediates for the citric acid cycle. E) synthesize phosphorus pentoxide. Gluconeogenesis must use “bypass reactions” to circumvent three reactions in the glycolytic pathway that are highly exergonic and essentially irreversible. Reactions carried out by which three of the enzymes listed must be bypassed in the gluconeogenic pathway? 1) Hexokinase 2) Phosphoglycerate kinase 3) Phosphofructokinase-1 4) Pyruvate kinase 5) Triosephosphate isomerase A) 1, 2, 3 B) 1, 2, 4 C) 1, 4, 5 D) 1, 3, 4 E) 2, 3, 4 Which of the following statements about gluconeogenesis in animal cells is true? A) A rise in the cellular level of fructose-2,6-bisphosphate stimulates the rate of gluconeogenesis. B) An animal fed a large excess of fat in the diet will convert any fat not needed for energy production into glycogen to be stored for later use. C) The conversion of fructose 1,6-bisphosphate to fructose 6-phosphate is not catalyzed by phosphofructokinase-1, the enzyme involved in glycolysis. D) The conversion of glucose 6-phosphate to glucose is catalyzed by hexokinase, the same enzyme involved in glycolysis. E) The conversion of phosphoenol pyruvate to 2-phosphoglycerate occurs in two steps, including a carboxylation.

Which combination of cofactors is involved in the conversion of pyruvate to acetyl-CoA? A) Biotin, FAD, and TPP B) Biotin, NAD+, and FAD C) NAD+, biotin, and TPP D) Pyridoxal phosphate, FAD, and lipoic acid E) TPP, lipoic acid, and NAD+ Which of the following is not an intermediate of the citric acid cycle? A) Acetyl-coA B) Citrate C) Oxaloacetate D) Succinyl-coA E) α-Ketoglutarate The reaction of the citric acid cycle that is most similar to the pyruvate dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA is the conversion of: A) citrate to isocitrate. B) fumarate to malate. C) malate to oxaloacetate. D) succinyl-CoA to succinate. E) α-ketoglutarate to succinyl-CoA. Which of the following is not true of the reaction catalyzed by the pyruvate dehydrogenase complex? A) Biotin participates in the decarboxylation. B) Both NAD+ and a flavin nucleotide act as electron carriers. C) The reaction occurs in the mitochondrial matrix. D) The substrate is held by the lipoyl-lysine “swinging arm.” E) Two different cofactors containing —SH groups participate. Which of the following is not true of the citric acid cycle? A) All enzymes of the cycle are located in the cytoplasm, except succinate dehydrogenase, which is bound to the inner mitochondrial membrane. B) In the presence of malonate, one would expect succinate to accumulate. C) Oxaloacetate is used as a substrate but is not consumed in the cycle. D) Succinate dehydrogenase channels electrons directly into the electron transfer chain. The two moles of CO2 produced in the first turn of the citric acid cycle have their origin in the: A) carboxyl and methylene carbons of oxaloacetate B) carboxyl group of acetate and a carboxyl group of oxaloacetate. C) carboxyl group of acetate and the keto group of oxaloacetate. D) two carbon atoms of acetate. E) two carboxyl groups derived from oxaloacetate. All the oxidative steps of the citric acid cycle are linked to the reduction of NAD+ except the reaction catalyzed by: A) isocitrate dehydrogenase. B) malate dehydrogenase. C) pyruvate dehydrogenase D) succinate dehydrogenase. E) the -ketoglutarate dehydrogenase complex.

Citrate synthase and the NAD+-specific isocitrate dehydrogenase are two key regulatory enzymes of the citric acid cycle. These enzymes are inhibited by: A) acetyl-CoA and fructose 6-phosphate. B) AMP and/or NAD+. C) AMP and/or NADH. D) ATP and/or NAD+. E) ATP and/or NADH. Which of the following is not a feature of complex IV? A) Cytochrome c is a one-electron donor. B) Oxygen is a substrate. C) Copper is an essential metal for the reaction. D) For every electron passed to complex IV, two protons are consumed from the matrix (N) side. E) In order to generate two water molecules, complex IV must go through the catalytic cycle two times. Almost all of the oxygen (O2) one consumes in breathing is converted to: A) acetyl-CoA. B) carbon dioxide (CO2). C) carbon monoxide and then to carbon dioxide. D) none of the above. E) water. Cyanide, oligomycin, and 2,4-dinitrophenol (DNP) are inhibitors of mitochondrial aerobic phosphorylation. Which of the following statements correctly describes the mode of action of the three inhibitors? A) Cyanide and 2,4-dinitrophenol inhibit the respiratory chain, and oligomycin inhibits the synthesis of ATP. B) Cyanide inhibits the respiratory chain, whereas oligomycin and 2,4-dinitrophenol inhibit the synthesis of ATP. C) Cyanide, oligomycin, and 2,4-dinitrophenol compete with O2 for cytochrome oxidase (complex IV). D) Oligomycin and cyanide inhibit synthesis of ATP; 2,4-dinitrophenol inhibits the respiratory chain. E) Oligomycin inhibits the respiratory chain, whereas cyanide and 2,4-dinitrophenol prevent the synthesis of ATP. Which of the following electron carriers is not able to transfer one electron at a time? A) NADH B) FMN C) FAD D) Ubiquinone E) Heme Which of the following statements about the chemiosmotic theory is correct? A) Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane. B) It predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrance. C) The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes. D) The membrane ATP synthase has no significant role in the chemiosmotic theory. E) All of the above are correct. Which of the following is correct concerning the mitochondrial ATP synthase? A) It can synthesize ATP after it is extracted from broken mitochondria. B) It catalyzes the formation of ATP even though the reaction has a large positive ΔG'°. C) It consists of F0 and F1 subunits, which are transmembrane (integral) polypeptides. D) It is actually an ATPase and only catalyzes the hydrolysis of ATP. E) When it catalyzes the ATP synthesis reaction, the ΔG'° is actually close to zero.

Mammals produce heat by using the endogenous uncoupling agent: A) the small molecule 2-4-Dinitrophenol synthesized by the cell. B) the protein thermogenin. C) the protein thioredoxin. D) the protein cytochrome c. E) a modified form of the FoF1 ATPase. Which of the following statements about metabolism in the mammalian liver is false? A) Most plasma lipoproteins are synthesized in the liver. B) The enzymatic complement of liver tissue changes in response to changes in the diet. C) The liver synthesizes most of the urea produced in the body. D) The presence of glucose 6-phosphatase makes liver uniquely able to release glucose into the bloodstream. E) Under certain conditions, most of the functions of the liver can be performed by other organs. Which one of the following statements is true? A) The brain prefers glucose as an energy source, but can use ketone bodies. B) Muscle cannot use fatty acids as an energy source. C) In a well-fed human, about equal amounts of energy are stored as glycogen and as triacylglycerol. D) Fatty acids cannot be used as an energy source in humans because humans lack the enzymes of the glyoxylate cycle. E) Amino acids are a preferable energy source over fatty acids. An elevated insulin level in the blood: A) inhibits glucose uptake by the liver. B) inhibits glycogen synthesis in the liver and muscle. C) results from a below-normal blood glucose level. D) stimulates glycogen breakdown in liver. E) stimulates synthesis of fatty acids and triacylglycerols in the liver. The largest energy store in a well-nourished human is: A) ATP in all tissues. B) blood glucose. C) liver glycogen. D) muscle glycogen. E) triacylglycerols in adipose tissue. The One distinction between peptide and steroid hormones is that peptide hormones: A) act through nonspecific receptors, whereas steroid hormones act through specific receptors. B) are generally water-insoluble, whereas steroid hormones are water soluble. C) are more stable than steroid hormones. D) bind to cell surface receptors, whereas steroid hormones bind to nuclear receptors. E) bind to their receptors with high affinity, whereas steroid hormones bind with low affinity. Some hormones are derived from amino acids; for example, catecholamines are derived from ( _____)while Eicosanoids are derived from( ). A) tyrosine; arachidonate B) tryptophan; lysine C) tyrosine; cholesterol D) tryptophan; arginine E) histidine; lysine The major ketone body during extended fasting is: A) Acetone. B) Acetoacetate. C) β-Hydroxybuterate. D) Creatine.

The maturation of insulin from its precursor (preproinsulin) involves: A) acetylation. B) oxidation. C) phosphorylation. D) proteolysis. E) reduction. Some hormones are derived from amino acids; for example, catecholamines are derived from while NO is derived from . A) tyrosine; arginine B) tryptophan; lysine C) tyrosine; histidine D) tryptophan; arginine E) histidine; lysine The tropic hormones (such as thyrotropin, somatotropin, and luteinizing hormone) are produced and released by the: A) anterior pituitary. B) hypothalamus. C) ovaries. D) pancreas. E) posterior pituitary. The normal sequence of action of these components of the hormonal hierarchy is: A) adrenal cortex → hypothalamus → anterior pituitary. B) anterior pituitary → adrenal cortex → hypothalamus. C) anterior pituitary → hypothalamus → adrenal cortex. D) hypothalamus → adrenal cortex → anterior pituitary. E) hypothalamus → anterior pituitary → adrenal cortex. Epinephrine triggers an increased rate of glycolysis in muscle by: A) activation of hexokinase. B) activation of phosphofructokinase-1. C) conversion of glycogen phosphorylase a to glycogen phosphorylase b. D) inhibition of the Cori Cycle E) the Pasteur effect. The peptide hormone adiponectin, produced in adipose tissue, circulates in the blood and: A) enhances fatty acid synthesis in liver cells. B) increases the rate of β-oxidation of fatty acids in muscle cells. C) inhibits glucose uptake and catabolism in muscle and liver cells. D) reduces the transport of fatty acids into muscle cells. E) stimulates gluconeogenesis in liver cells. In its role in the hormonal hierarchy, the hypothalamus produces and releases: A) epinephrine. B) insulin. C) progesterone. D) releasing factors. E) thyroxine. Which of the following is not a mechanism for treating diabetes? A) Increasing TAG by weight loss B) Activating AMPK through exercise C) Activating AMPK by taking metformins D) Activating PPARγ through rosiglitazone E) Stimulating insulin secretion by taking sulfonylureas

Which of the following hormones stimulates appetite? A) Grehlin B) Insulin C) Adiponectin D) Both A and B E) Both A and C Long-term maintenance of body weight is regulated by the hormone: A) adiposin. B) hypothalmin. C) leptin. D) obesin. E) testosterone....