front 1 A pancreatic enzyme deficiency prevents activation of chymotrypsinogen, proelastase, and procarboxypeptidases. Which enzyme is most likely absent? A. Pepsin | back 1 C. Trypsin |
front 2 Trypsin, chymotrypsin, and elastase are all endopeptidases and share which catalytic classification? A. Metalloproteases | back 2 B. Serine proteases |
front 3 A peptide is cleaved at internal peptide bonds rather than sequentially from a terminus. Which class of enzymes performs this function? A. Exopeptidases | back 3 D. Endopeptidases |
front 4 Which one cleaves peptide bonds in which the carboxyl (carbonyl) group is provided by lysine or arginine? A. Elastase | back 4 D. Trypsin |
front 5 A researcher designs a peptide rich in phenylalanine, tyrosine, tryptophan, and leucine. Which enzyme would most strongly favor cleavage of this substrate? A. Chymotrypsin | back 5 A. Chymotrypsin |
front 6 After pancreatic endopeptidases generate oligopeptides, which enzymes remove amino acids one at a time from peptide ends? A. Ligases | back 6 C. Exopeptidases |
front 7 A defect in an enzyme that removes residues sequentially from the carboxyl terminus of peptides would most directly impair which enzyme group? A. Pepsins | back 7 B. Carboxypeptidases |
front 8 preferentially releases hydrophobic AA: A. Carboxypeptidase A | back 8 A. Carboxypeptidase A |
front 9 preferentially releases basic AA: A. Carboxypeptidase A | back 9 B. Carboxypeptidase B |
front 10 Carboxypeptidase B most preferentially releases which amino acids? A. Leucine and valine | back 10 D. Arginine and lysine |
front 11 Which statement best describes pepsinogen physiology? A. Produced in pancreas, activated intestine | back 11 B. Produced in stomach, activated stomach |
front 12 Which enzyme is located on the brush border and removes single amino acids from the amino terminus of peptides? A. Aminopeptidase | back 12 A. Aminopeptidase |
front 13 Proteins can be degraded by lysosomal enzymes called: A. Caspases | back 13 B. Cathepsins |
front 14 An intracellular protein is marked for degradation by covalent attachment of a small peptide to lysine residues. Which molecule provides this targeting signal? A. SUMO | back 14 C. Ubiquitin |
front 15 After polyubiquitination, a damaged cytosolic protein is most directly sent to which structure? A. Proteasome | back 15 A. Proteasome |
front 16 A regulatory protein contains regions rich in proline, glutamate, serine, and threonine. What is the most likely effect of this sequence motif? A. Enhanced secretion | back 16 D. Shorter half-life |
front 17 Amino acids enter intestinal epithelial cells from the lumen primarily through which mechanism? A. Primary active Ca2+ pump | back 17 B. Na+-dependent cotransport |
front 18 Once concentrated within intestinal epithelial cells, amino acids typically leave across the basolateral membrane by: A. Facilitated transport | back 18 A. Facilitated transport |
front 19 In a prolonged fasting state, which statement best
describes amino acid handling by intestinal epithelial
cells? | back 19 D. Take up blood amino acids for fuel |
front 20 Which kinase has an important regulatory role in autophagy? A. AMPK | back 20 D. mTOR |
front 21 In proteasomal degradation, what is used both to unfold the tagged protein and to push the protein into the core of the cylinder? | back 21 ATP hydrolysis |
front 22 Digestive proteases are generally synthesized in inactive precursor forms best termed: A. Isoenzymes | back 22 B. Zymogens |
front 23 What cells secrete hydrochloric acid (HCL)? | back 23 parietal cells |
front 24 What cells secrete pepsinogen? | back 24 Chief cells |
front 25 A child in a famine-stricken region has generalized edema, muscle wasting, and preserved caloric intake from starches. Which diagnosis best fits? A. Kwashiorkor | back 25 A. Kwashiorkor |
front 26 The edema of kwashiorkor is most directly caused by decreased levels of which plasma protein? A. Fibrinogen | back 26 C. Albumin |
front 27 A toddler with protein deficiency appears swollen rather than cachectic. Which finding most specifically explains the apparent “plump” appearance? A. Hepatic glycogen accumulation | back 27 C. Edema with distended abdomen |
front 28 Why must pancreatic zymogens be activated within a short span after trypsin appears? A. Active enzymes digest one another | back 28 A. Active enzymes digest one another |
front 29 A congenital defect prevents conversion of trypsinogen to trypsin at the intestinal surface. Which enzyme is deficient? A. Aminopeptidase | back 29 D. Enteropeptidase |
front 30 _____ first activates a small amount of trypsinogen into trypsin, which then triggers a rapid cascade by cleaving all other pancreatic zymogens into their _____ forms. This immediate activation ensures that these potent proteases begin digesting dietary proteins simultaneously before they can undergo autolysis or autodigestion. | back 30 Enteropeptidase active |
front 31 Enteropeptidase is secreted by which cells? A. Pancreatic acinar cells | back 31 B. Small-intestinal brush-border cells |
front 32 Failure of trypsin generation would most directly impair activation of all except which enzyme? A. Chymotrypsin | back 32 D. Pepsin |
front 33 A child with cystic fibrosis develops protein, fat, and carbohydrate maldigestion from pancreatic insufficiency. The primary defect initially causes inspissation of which secretions? A. Endocrine pancreatic secretions | back 33 C. Pancreatic exocrine secretions |
front 34 In cystic fibrosis, failure of pancreatic enzymes to reach the intestinal lumen is caused primarily by: A. Zymogen overactivation | back 34 B. Ductal obstruction |
front 35 The pancreas synthesizes a secretory trypsin inhibitor primarily to prevent: A. Intrapancreatic zymogen activation | back 35 A. Intrapancreatic zymogen activation |
front 36 Loss of pancreatic trypsin inhibitor would most likely predispose to which condition? A. Cystinuria | back 36 D. Pancreatitis |
front 37 Hartnup disease is caused by defective transport of which class of amino acids? A. Basic amino acids | back 37 B. Neutral amino acids |
front 38 Hartnup disease affects transport across which epithelial sites? A. Hepatic and alveolar | back 38 C. Intestinal and renal |
front 39 In both Hartnup disease and cystinuria, impaired tubular handling causes what urinary change? A. Increased urinary amino acids | back 39 A. Increased urinary amino acids |
front 40 Excess amino acid carbon skeletons are primarily converted into: A. Cholesterol and ketones | back 40 D. Glycogen and triacylglycerols |
front 41 A young adult with recurrent nephrolithiasis has stones composed of a poorly soluble amino acid. Which substance is the culprit in cystinuria? A. Tyrosine | back 41 C. Cystine |
front 42 A patient with cystinuria presents with severe flank pain radiating to the groin and gross hematuria. Which complication most likely explains this presentation? A. Papillary necrosis | back 42 D. Ureteral stone obstruction |
front 43 A misfolded cytosolic protein is targeted for proteasomal degradation after a small peptide is covalently attached to the ε-amino group of which residue? A. Serine | back 43 B. Lysine |
front 44 Proteins rich in proline, glutamate, serine, and threonine are typically degraded by which pathway? A. Lysosomal cathepsin pathway | back 44 C. Ubiquitin–proteasome system |
front 45 The γ-glutamyl cycle is required for synthesis of which antioxidant compound? A. Taurine | back 45 C. Glutathione |
front 46 Glutathione is protection against: A. Thermal injury | back 46 B. Oxidative damage |
front 47 Which protease is active within the stomach lumen? A. Trypsin | back 47 C. Pepsin |
front 48 Which set contains only pancreatic proteases? A. Pepsin, trypsin, aminopeptidase | back 48 B. Trypsin, chymotrypsin, elastase |
front 49 Which enzyme is located on the intestinal brush border? A. Chymotrypsin | back 49 D. Aminopeptidase |
front 50 Cystinuria results from defective renal reabsorption of which amino acids? A. Cysteine, arginine, lysine | back 50 A. Cysteine, arginine, lysine |
front 51 The most serious complication of cystinuria results from the poor solubility of: A. Cysteine | back 51 D. Cystine |
front 52 Neutrophil-derived elastase is normally inhibited by which molecule? A. α-1-antitrypsin | back 52 A. α-1-antitrypsin |
front 53 Alpha-1 antitrypsin deficiency (AATD) is a genetic condition causing low levels of the protective protein AAT, leading to: A. Pulmonary fibrosis | back 53 B. Emphysema |
front 54 The lung injury in α-1-antitrypsin deficiency is primarily due to: A. Autoimmune alveolitis | back 54 C. Proteolytic tissue destruction |
front 55 Pepsinogen becomes pepsin when gastric acidity increases because: A. HCl directly hydrolyzes proteins | back 55 B. Low pH activates pepsinogen |
front 56 Cystinuria is most directly caused by which underlying abnormality? A. Defective glomerular filtration barrier | back 56 B. Mutated tubular amino acid transporter |
front 57 Which statement best describes pepsin’s enzymatic action? A. Carboxyl-terminal exopeptidase | back 57 C. Endopeptidase in stomach |
front 58 Which group contains only endopeptidases? A. Pepsin, trypsin, elastase | back 58 A. Pepsin, trypsin, elastase |
front 59 Which pair contains only exopeptidases? A. Pepsin and trypsin | back 59 D. Carboxypeptidase and aminopeptidase |
front 60 Which event is the key initiating step that leads to activation of the major pancreatic zymogens? A. Pepsinogen cleavage by HCl | back 60 B. Enteropeptidase activates trypsinogen |
front 61 During acute inflammation, elastase released from which cell type can contribute to tissue injury if not properly inhibited? A. Eosinophil | back 61 B. Neutrophil |
front 62 Exopeptidases are best defined as enzymes that: A. Cleave internal peptide bonds | back 62 B. Remove one terminal residue |
front 63 Which kinase directly integrates nutrient and growth factor signals
to inhibit autophagy when active? | back 63 B. mTOR |
front 64 During energy deprivation, which kinase is activated to
initiate autophagy via mTOR inhibition? | back 64 C. AMPK |
front 65 In the low-energy autophagy pathway, what is the direct effect of
AMPK on the TSC1/TSC2 complex? | back 65 B. Dephosphorylates and inactivates TSC1/TSC2 |
front 66 Under low-energy conditions, with inactive Rheb and inhibited mTOR,
what happens to autophagy? | back 66 D. mTOR inhibited, autophagy proceeds |
front 67 In the presence of insulin or growth factors, which kinase is
activated upstream of mTOR to oppose autophagy? | back 67 D. Akt |
front 68 Under insulin signaling with active Rheb-GTP, what
is the net effect of mTOR on cell processes? | back 68 C. Inhibits autophagy and stimulates protein synthesis |
front 69 A patient presents with diarrhea, dermatitis, and dementia.
Pellagra is suspected. This syndrome most commonly
results from deficiency of: | back 69 A. Niacin or dietary tryptophan |
front 70 In cystinuria, the abnormal transport protein normally reabsorbs amino acids from which location? A. Blood into glomerulus | back 70 B. Kidney lumen into tubular cells |
front 71 Which enzyme is both a pancreatic protease and an exopeptidase? A. Chymotrypsin | back 71 C. Carboxypeptidase |
front 72 Which metabolic condition most directly activates AMPK in the autophagy pathway described? A. High ATP state | back 72 B. High AMP state |
front 73 In the fed state, activation of mTOR has which additional major effect besides inhibiting autophagy? A. Blocks peptide absorption | back 73 B. Stimulates protein synthesis |
front 74 Which of the following proteases is primarily responsible for the execution of programmed cell death (apoptosis)? A. Matrix metalloproteinases B. Caspases C. Calpains D. Serine proteases | back 74 B. Caspases |
front 75 Which group of proteases plays a major role in physiological processes such as digestion and blood clotting? A. Caspases B. Calpains C. Serine proteases D. Matrix metalloproteinases | back 75 C. Serine proteases |
front 76 The remodeling of extracellular matrix components is a function primarily attributed to which of the following? A. Proteasomes B. Matrix metalloproteinases C. Serine proteases D. Caspases | back 76 B. Matrix metalloproteinases |
front 77 Which of these cysteine proteases is described as having "many different cellular roles" that are strictly dependent on calcium levels? A. Serine proteases B. Caspases C. Calpains D. Proteasomes | back 77 C. Calpains |
front 78 A segment of dietary protein consists mainly of alanine, glycine, and
serine. Which enzyme preferentially cleaves peptide bonds whose
carboxyl group is contributed by these small side chains? | back 78 D. Elastase |
front 79 Which statement best describes the cap complexes regulating the
ubiquitin–proteasome system? | back 79 D. Four ATP-dependent caps recognize ubiquitin |
front 80 In both Hartnup disease and cystinuria, how are the affected amino
acids handled? | back 80 C. Tubular reabsorption decreased, urinary levels increased |