WorksheetsPage 1
Total questions: 140
Worksheet time: 2hrs 53mins
Which statement best describes enzymes in biological systems?
Carbohydrates that form structural fibers
Proteins that act as biological catalysts
Lipids that store metabolic energy
Nucleic acids that encode genetic traits
Fill in the blank: The study of enzymes and their roles in metabolic pathways is called (a) .
Which option correctly pairs the molecule type with its role: substrate and product?
Product binds enzymes; substrate leaves reactions unchanged
Substrate is a byproduct of enzyme action; product is waste
Product is what enzymes act upon; substrate is formed
Substrate is what enzymes act upon; product is formed
List two reasons why measuring plasma enzyme levels can indicate tissue damage, and explain the underlying mechanism.
Which statement about enzyme concentrations is accurate?
Higher in cells than in plasma
Equal in cells and plasma
Higher in plasma than in cells
Absent in plasma under normal conditions
Which best explains why enzymes are crucial for metabolic pathways?
They replace the need for regulatory proteins entirely
They permanently alter substrates into inactive molecules
They catalyze individual steps at life-sustaining rates
They supply energy directly to cellular respiration
Explain how clinical enzymology is applied in diagnosing and treating diseases, giving one example of application.
Which statement about isoenzymes is most accurate?
Isoenzymes catalyze the same reaction but differ by tissue
Isoenzymes are identical proteins across all tissues
Isoenzymes are carbohydrates used for metabolism
Isoenzymes perform unrelated reactions in plasma
Tight regulation of enzyme activity is essential for homeostasis. What term describes genetic diseases arising from enzyme dysfunction?
Hemostatic dyscrasias
Autoimmune enzymopathies
Acquired proteinopathies
Inborn errors of metabolism
A patient presents with chest pain. Which reasoning process would best use plasma enzyme changes to evaluate myocardial damage?
Which condition results from mutation in phenylalanine hydroxylase causing phenylalanine accumulation?
Homocystinuria
Tyrosinemia
Maple syrup urine disease
Phenylketonuria
Clinical enzymology primarily focuses on changes in enzyme levels for diagnosis, differential diagnosis, and monitoring. Fill in the blank: Tracking disease progression and treatment response is called (a) .
Elevated serum creatine phosphokinase (CPK2) supports which clinical application when ECG changes are inconclusive?
Prognosis of chronic liver disease
Therapeutic monitoring of chemotherapy
Diagnosis of myocardial infarction
Screening for pulmonary embolism
A patient shows elevated serum glutamate-oxaloacetate transaminase (GOT) and lactate dehydrogenase (LDH). Which diagnosis is most supported?
Myocardial infarction
Acute pancreatitis
Pulmonary embolism
Hepatic failure
Pulmonary embolism is best indicated by elevation of which single serum enzyme?
Amylase alone
LDH alone
ALT alone
CPK2 alone
During chronic antidepressant or chemotherapy use, elevations in which serum enzymes are commonly monitored?
Amylase or lipase
Isocitrate dehydrogenase or ornithine carbamoyl-transferase
Creatine phosphokinase or troponin
GGT or alkaline phosphatase
Functional plasma enzymes are synthesized by the liver and act within plasma. Which is the best example category?
Transaminases and dehydrogenases
Mitochondrial respiratory enzymes
Coagulation and lipoprotein-metabolizing enzymes
Digestive and lysosomal enzymes
Non-functional plasma enzymes are normally intracellular and present at low plasma levels. Which finding most suggests cell damage?
Elevated plasma levels
Normal low plasma levels
High urinary excretion
Absence in plasma
Classify plasma enzymes into functional and non-functional types and describe their clinical significance.
Which statement best describes secretory enzymes in plasma?
Produced by hepatocytes exclusively for metabolism
Converted from inactive zymogens within plasma
Synthesized by glands and secreted into body lumens
Released after cell damage into circulation
Pancreatitis commonly elevates which pair of secretory enzymes?
Alkaline phosphatase and GGT
AST and ALT
LDH1 and LDH2
Pancreatic amylase and lipase
Elevated alanine transaminase (ALT) most strongly indicates damage in which organ?
Kidney tissue
Skeletal muscle
Liver parenchyma
Pancreatic ducts
Which mechanism explains increased plasma enzyme levels from apoptosis or necrosis?
Reduced hepatic synthesis due to mutations
Increased release from damaged cells raising membrane permeability
Enhanced renal clearance leading to rapid excretion
Inhibition by insecticides causing enzyme blockade
Name one condition where impaired clearance increases plasma enzymes.
(a)
Low ceruloplasmin levels are characteristic of which disease?
Obstructive jaundice
Myocardial infarction
Paget’s disease
Wilson’s disease
Insecticide poisoning that affects pseudocholinesterase primarily causes which change?
Cofactor excess increasing activity
Enhanced enzyme synthesis
Enzyme inhibition or deficiency
Accelerated hepatic clearance
Define isoenzymes in one precise sentence.
Which statement about lactate dehydrogenase (LDH) isoenzymes is accurate?
LDH isoenzymes cannot indicate tissue-specific injury
LDH isoenzymes all share identical tissue localization
LDH has five isoenzymes (LDH1–LDH5) linked to different tissues
LDH has two isoenzymes specific to bone and brain
Match LDH isoenzymes to their predominant tissue association.
LDH5—brain and kidney
LDH1/LDH2—liver and skeletal muscle
LDH5—heart and red blood cells
LDH1/LDH2—heart and red blood cells
A patient presents with obstructive jaundice. Which enzyme is most likely elevated due to impaired clearance?
Alkaline phosphatase (ALP)
Ceruloplasmin
Amylase
ALT
Explain how measuring isoenzymes can aid clinical diagnosis.
Which enzyme pattern most specifically indicates liver damage when elevated in plasma?
High amylase isoenzymes levels
High lactate dehydrogenase levels
High creatine kinase total levels
High alanine transaminase levels
Elevated aspartate transaminase in plasma may suggest involvement of which tissue besides liver?
Heart muscle involvement
Pancreatic acinar involvement
Renal tubular involvement
Intestinal mucosa involvement
Which simple calculation helps differentiate liver diseases from other conditions using plasma enzymes?
LDH to CK ratio
Total protein to albumin ratio
Amylase to lipase ratio
ALT to AST ratio
Why does measuring more than one enzyme improve diagnostic precision?
In the liver, which two enzymes are abundant and commonly estimated?
(a)
What term describes multiple forms of an enzyme that differ in physical or chemical properties?
(a)
Which enzyme is present in both skeletal and cardiac muscle and has isoenzymes useful in diagnosis?
Lactate dehydrogenase
Aspartate transaminase
Alanine transaminase
Creatine kinase
A patient presents with chest pain. Serial estimations show a rise and fall of CK-MB over time. What does this pattern most likely indicate?
Which factor enhances the diagnostic value of enzyme measurements by showing the balance between enzyme entry and clearance?
Number of enzyme isoforms present
Total daily enzyme protein concentration
Rate of change in plasma enzyme activity
Baseline fasting plasma glucose level
Persistently raised plasma enzyme activity most likely indicates which condition?
A chronic disorder or impaired clearance
Recent meal causing transient elevation
Excess vitamin intake without disease
Laboratory calibration error only
Which statement best describes the diagnostic insight from intracellular distribution of enzymes?
Enzymes act only in the bloodstream
Extracellular matrix binds all enzymes equally
Serum albumin levels determine enzyme type
Location within cells informs tissue damage
ALT and lactate dehydrogenase (LDH) are predominantly located in which cellular compartment?
(a)
Glutamate dehydrogenase (GLDH) is primarily found in which organelle?
(a)
Which enzyme’s presence in both cytoplasm and mitochondria provides broader diagnostic information regarding cellular damage?
AST
LDH
CK
ALT
Which is NOT a function of creatine kinase (CK) in muscle cells?
Catalyzes ATP regeneration during contraction
Stores high-energy creatine phosphate
Helps maintain muscle ATP levels
Initiates glycogen breakdown for glucose
Which tissue has high concentrations of CK?
Bladder, liver, pancreas
Kidney, lung, intestine
Skeletal muscle, heart, brain
Skin, adipose tissue, spleen
Which CK isoenzyme is specific for myocardial damage and elevated in acute myocardial infarction?
CK-MB (hybrid type)
CK-MM (muscle type)
CK-BB (brain type)
LDH-1 (cardiac type)
After an acute myocardial infarction, CK-MB levels typically rise within how many hours and peak by what time?
Rise 24–36 hours, peak 48–60 hours
Rise 8–12 hours, peak 36–48 hours
Rise 4–8 hours, peak 12–24 hours
Rise 1–2 hours, peak 6–8 hours
Which CK isoenzyme is elevated in CNS damage, tumors, and certain cancers?
CK-BB (brain type)
CK-MB (hybrid type)
GLDH (mitochondrial type)
CK-MM (muscle type)
List two non-disease factors that can influence CK levels.
Provide the reference range for CK in males and females.
Which reaction is catalyzed by lactate dehydrogenase (LDH) in human metabolism?
Citrate to isocitrate via aconitase
Lactic acid to pyruvic acid using NAD+
Pyruvate to acetyl-CoA via CoA transfer
Glucose to glucose-6-phosphate via ATP
LDH is found in multiple tissues. Which list best represents common LDH tissue sources relevant to diagnostics?
Heart, liver, skeletal muscle, kidney, erythrocytes, lungs
Adipose tissue, endocrine glands, cornea, marrow
Pancreas, thyroid, spleen, skin, retina, bone
Intestine, placenta, hair follicles, nails, cartilage
Total LDH levels are nonspecific. Which approach increases diagnostic value for LDH testing?
Measuring only LDH in urine samples
Repeating tests every hour for two days
Analyzing LDH isoenzymes LDH-1 to LDH-5
Using fasting status to reduce variability
Which LDH isoenzymes are typically elevated in acute myocardial infarction (AMI) and hemolysis?
LDH-1 and LDH-2 fractions
LDH-5 fraction only
LDH-3 fraction only
LDH-4 and LDH-5 fractions
Elevations of LDH-3 are most associated with which condition?
Pulmonary disorders and carcinomas
Acute viral hepatitis episodes
Renal failure with uremia
Thyroid storm crises
The LDH isoenzymes LDH-4 and LDH-5 are indicative of disorders in which tissues?
Pulmonary parenchymal fibrosis
Liver and skeletal muscle disorders
Cardiac conduction system issues
Renal glomerular diseases
Provide the typical reference range for total LDH activity.
(a)
Aspartate aminotransferase (AST) primarily performs which biochemical role?
Phosphorylates fructose in hepatic metabolism
Oxidizes ethanol via NAD+ dependent pathway
Hydrolyzes peptide bonds in serum proteins
Transfers amino groups between aspartate and α-keto acids
Which tissues show high concentrations of AST under normal physiology?
Pancreas, thyroid, and spleen
Kidney, lung, and intestine
Heart, liver, and skeletal muscle
Skin, bone, and cartilage
In acute viral hepatitis, which enzyme typically shows the highest levels indicating acute liver damage?
AST shows highest elevations
Alkaline phosphatase spikes first
ALT shows lowest changes
LDH decreases markedly
State the typical reference range for AST activity.
(a)
Which statement best describes alanine aminotransferase (ALT) compared with AST?
Catalyzes similar transamination and is more liver-specific
Acts mainly in renal gluconeogenesis pathways
Primarily a cardiac enzyme with minimal liver presence
Functions in lipid oxidation and ketone formation
Where is ALT primarily found, making it a key marker for hepatocellular injury?
Liver tissue predominantly
Skeletal muscle predominantly
Pulmonary tissue predominantly
Renal cortex predominantly
In acute liver inflammation, how do ALT elevations typically compare with AST?
ALT elevations are higher and longer-lasting
ALT and AST remain unchanged together
ALT decreases while AST rises quickly
ALT rises briefly then normalizes faster
Provide the typical reference range for ALT activity.
(a)
Which reaction is catalyzed by alkaline phosphatase (ALP)?
Hydrolyzes phosphate esters at alkaline pH
Forms phosphate esters at neutral pH
Transfers phosphate groups at acidic pH
Oxidizes phosphate esters at basic pH
Identify two major tissue sources of ALP used clinically.
Thyroid
Pancreas
Bone
Liver
Skeletal muscle
An adult with cholestasis presents with elevated ALP. Which site most likely accounts for the increase?
Renal tubular secretion impaired
Placental production in late pregnancy
Bone resorption due to osteoporosis
Liver synthesis increased by cholestasis
During normal pregnancy, ALP can rise. Which statement best explains this physiological change?
Bone isoenzyme is suppressed by estrogen
Kidney reabsorption of ALP increases markedly
Erythrocyte breakdown releases ALP into plasma
Placental isoenzyme contributes to higher levels
Acid phosphatase (ACP) functions optimally at approximately which pH?
Around pH 5.0 acidic conditions
Near pH 7.4 physiological range
Above pH 9.0 alkaline conditions
Exactly pH 6.5 mildly acidic
Historically, which disease was ACP used to help detect before PSA became standard?
Prostate cancer detection historically
Paget's disease of bone primarily
Cholestatic liver disease routinely
Pancreatic carcinoma screening
Name one key physiologic role of gamma-glutamyltransferase (GGT).
(a)
Which tissues are common sources of GGT measured in clinical evaluations?
Prostate
Pancreas
Brain
Kidney
Liver
Why is GGT particularly useful in assessing biliary tract obstruction compared to ALP alone?
List two non-disease factors that can increase GGT levels.
Which enzyme primarily catalyzes the breakdown of starch and glycogen and requires calcium and chloride ions for activation?
Lipase in gastric and intestinal tissues
Amylase from pancreatic acinar cells
G6PD in erythrocyte cytosol
Cholinesterase in neuromuscular junctions
Identify the major tissue sources of amylase relevant to diagnostic testing.
Fallopian tubes and stomach lining
Erythrocytes and cardiac myocytes
Skeletal muscle and small intestine
Pancreatic acinar cells and salivary glands
Elevated serum amylase is most strongly associated with which clinical condition in emergency diagnostics?
Renal tubular necrosis
Acute pancreatitis episodes
Chronic obstructive bronchitis
Hepatic cirrhosis flare
Which statement best describes the diagnostic value of lipase compared with amylase in acute pancreatitis?
Amylase is unaffected by intestinal perforations
Lipase is more specific for pancreatitis diagnosis
Amylase is uniquely specific for salivary lesions
Lipase primarily reflects salivary gland obstruction
Where is lipase primarily sourced for clinical measurement when evaluating pancreatic injury?
Salivary glands predominantly
Skeletal muscle predominantly
Erythrocytes predominantly
Pancreas predominantly
A patient presents with mumps and elevated amylase. Which tissue involvement explains the enzyme rise?
Erythrocyte membrane instability increases
Skeletal muscle fiber breakdown predominates
Pancreatic beta-cell insulin secretion changes
Salivary gland lesions causing enzyme release
Deficiency of glucose-6-phosphate dehydrogenase most directly leads to which clinical outcome?
Drug-induced hemolytic anemia
Cholinergic crisis in neuromuscular junctions
Obstructive salivary sialadenitis
Acute bacterial pancreatitis
What product of G6PD activity helps maintain erythrocyte redox status?
(a)
Which enzyme is known as true cholinesterase or acetylcholine acetylhydrolase?
Pseudocholinesterase enzyme variant
True cholinesterase acetylhydrolase
Pancreatic trypsinogen precursor
Serum alkaline phosphatase isoform
Identify one tissue source where true cholinesterase is found.
Bone marrow exclusively
Renal tubules primarily
Erythrocytes among others
Adipose tissue mainly
Decreased true cholinesterase activity is most associated with which condition?
Hepatic disease presentation
Acute pancreatitis flare
Nephrotic syndrome onset
Recovery from liver injury
Increased true cholinesterase levels can indicate which scenario?
Acetylcholine receptor deficit
Severe hepatic failure episode
Recovery from liver damage period
Organophosphate poisoning exposure
Provide the reference range for true cholinesterase listed on the page.
(a)
Glutamate dehydrogenase catalyzes which reaction?
Hydrolysis of peptide bonds
Reduction of disulfide bridges
Oxidative deamination of glutamate
Phosphorylation of glucose
Which organs are primary tissue sources of glutamate dehydrogenase?
Bone cartilage tendon mostly
Pancreas spleen lung chiefly
Liver heart kidneys mainly
Brain gray matter predominantly
Elevated glutamate dehydrogenase is diagnostically useful for what?
Evaluating cholinergic synapse function
Confirming nephrotic syndrome diagnosis
Detecting pancreatic enzyme activation
Assessing liver cell necrosis severity
State the GLD reference range at 37°C for men.
(a)
Why can organophosphate poisoning lead to decreased true cholinesterase activity?
Which inflammatory response effect is noted on enzyme levels after cellular injury?
Suppresses cytokines with no enzyme level change
Increases only lipase while amylase stays unchanged
Triggers pro-inflammatory cytokines affecting enzyme levels
Reduces α-amylase and lipase activity markedly
For α-amylase (EC 3.2.1.1; AML), which condition is associated with a marked increase at 5–10× the upper reference limit?
Perforated peptic ulcer with slight change
Intestinal obstruction with transient rise
Acute pancreatitis with major elevation
Acute cholecystitis causing mild elevation
What is the stated diagnostic utility of lipase in pancreatic disease?
Liver enzymes are categorized into three main groups. Fill in the blank: Markers of (a) include ALT and AST.
Alanine transaminase (ALT; EC 2.6.1.2) is described as highly specific to which tissue due to its abundance?
Renal cortex in glomerular function
Skeletal muscle with protein turnover
Hepatocytes showing tissue specificity
Myocardium due to high energy demand
Which condition is associated with marked increase (10–100× upper reference limit) of ALT?
Cholestatic jaundice with slight elevation
Infectious mononucleosis causing mild rise
Cirrhosis producing moderate increase
Acute viral or toxic hepatitis
A patient presents with right upper quadrant pain. Explain how combined amylase and lipase testing aids diagnosis.
Which statement best explains why AST is less specific for liver pathology?
Present in cardiac and skeletal muscle
Exclusive mitochondrial localization
Rapidly cleared by the kidneys
Only synthesized in hepatocytes
A 15-fold rise in AST most strongly aligns with which condition?
Acute viral hepatitis
Uncomplicated gallstones
Chronic autoimmune thyroiditis
Iron deficiency anemia
Marked AST elevation may occur in myocardial infarction because AST is also found in cardiac muscle.
(a)
Which tissue sources contribute to alkaline phosphatase activity measured in serum?
Liver, bone, intestines, placenta
Brain, lung, pancreas, spleen
Kidney, retina, prostate, thymus
Adipose, cartilage, cornea, uterus
In which physiological state is ALP expected to be elevated without disease?
Sedentary lifestyle
Fasting
Dehydration
Pregnancy
Why is lactate dehydrogenase considered a non‑specific marker of cell damage?
Has only one tissue isoenzyme
Rapidly degraded in circulation
Exclusively produced in the liver
Widely distributed across body tissues
Elevated LD is most consistent with which pattern of tissue injury?
Restricted to placental pathology
Isolated pancreatic and adrenal necrosis
Only biliary obstruction and cholestasis
Cardiac and skeletal muscle; liver, kidney, erythrocyte damage
Which cardiac enzyme fraction exceeding 6% of total CK supports early myocardial infarction diagnosis 4–6 hours after symptom onset?
CK-MB isoenzyme fraction
LDH overall activity
Total CK activity level
Troponin T concentration
Elevated levels of which proteins are specific markers for myocardial injury and predict adverse outcomes in angina and myocardial infarction?
Troponins T and I
CK-MB fraction
Plasma myoglobin
Creatinine levels
In cardiac damage, which enzyme is used alongside CK-MB and clinical findings to aid diagnosis?
Alkaline phosphatase
ALT activity
LDH measurement
Amylase test
Fill the blank: In malignancy, common changes include elevated plasma total enzyme activity and detection of abnormal (a) .
In liver metastasis and leukemia, which enzyme level is typically increased and may assist in monitoring disease?
Troponin I
Serum lipase
LDH activity
CK-MB
Niemann-Pick disease involves deficiency of which enzyme, leading to sphingomyelin accumulation in lysosomes?
Glucocerebrosidase
Hexosaminidase A
Sphingomyelinase
Galactosidase
Homocystinuria is caused by deficiency of which enzyme, resulting in homocysteine accumulation and associated connective tissue abnormalities?
Ornithine transcarbamylase
Tyrosinase
Phenylalanine hydroxylase
Cystathionine β-synthase
Where are enzymes mainly synthesized within the cell, considering their eventual targeting or export?
Mitochondria only
Cytosol or ER
Golgi apparatus
Lysosomes alone
Briefly describe the intracellular distribution of enzymes and mention two organelles involved.
Fill the blank: A relatively small number of enzymes are synthesized in the (a) , and these enzymes stay within this space.
Which factor directly influences plasma enzyme levels by determining how quickly enzymes enter circulation from damaged cells?
Rate of release from damaged cells
Renal filtration of small peptides
Dietary protein intake per day
Temperature of the clinical laboratory
Identify the two primary determinants of plasma enzyme levels when active tissue damage is present.
Rate of release from damaged cells
Extent of cell damage
Rate of enzyme clearance
Degree of enzyme synthesis induction
Half-life of the enzyme
When there is no cell damage, which processes most affect changes in plasma enzyme levels?
Extent of cell lysis
Degree of induction of enzyme synthesis
Temperature-dependent denaturation
Rate of release from necrotic cells
Rate of cell proliferation
Which balancing factor helps determine the measured concentration of enzymes in plasma over time?
Number of assay calibration points
Volume of patient plasma sample
Rate of enzyme clearance from circulation
Presence of unrelated lipids in plasma
Choose the best definition of isozymes relevant to clinical diagnostics.
Synthetic enzymes used in assays
Denatured enzymes lacking activity
Different forms catalyzing the same reaction
Unrelated proteins with distinct reactions
Which enzyme is preferred to indicate hepatocellular damage due to its specificity compared with AST?
ALT (SGPT)
LDH (isoenzyme 1)
CK-MB
Amylase
In acute pancreatitis, which plasma enzyme level is expected to rise?
Acid phosphatase
CK-MM
ALT
Amylase
During myocardial infarction, how does LDH behave temporally?
Rises within 24 hours and returns to normal in 5–6 days
Remains unchanged for 7–10 days
Peaks only after 14 days of recovery
Falls immediately and normalizes in 12 hours
Which LDH isoenzyme pattern is typically seen in liver disease?
LDH 3 becomes undetectable
LDH 5 increases
LDH 1 predominates
LDH 2 decreases only
Cholinesterase activity is normally involved in which physiological function?
Neuromuscular conduction
Renal acid-base regulation
Hepatic bile synthesis
Pancreatic bicarbonate secretion
Which enzyme is routinely used to estimate blood glucose by producing gluconic acid and hydrogen peroxide?
Glycerol kinase
Urease enzyme
Glucose oxidase
Alcohol dehydrogenase
In the glucose oxidase-peroxidase method, which substance acts on the generated hydrogen peroxide to form a measurable colored compound?
Peroxidase enzyme
Renin catalyst
Thrombokinase dye
Lysozyme reagent
Name the enzyme used to estimate the amount of urea in blood.
(a)
Which pair of enzymes assists in estimating triacylglycerol by acting on glycerol and its phosphate?
Urokinase and lysozyme
Glycerol kinase and glycerol phosphate dehydrogenase
Pepsin and renin
Thromboplastin and peroxidase
Cholesterol levels are commonly determined using which specific oxidase?
(a)
Alcohol levels are assessed using an assay based on which enzyme?
Urease enzyme
Streptokinase
Alcohol dehydrogenase
Glucose oxidase
Explain why colorimetric measurement in enzyme-based assays yields a signal proportional to analyte concentration.
Which therapeutic enzyme is used to treat pulmonary embolism and some myocardial infarctions by lysing clots?
Lysozyme enzyme
Renin protease
Thromboplastin factor
Urokinase agent
Streptokinase is clinically indicated primarily for which purpose?
Treat gastric achylia
Dissolve clot in myocardial infarction
Manage eye infections
Correct blood coagulation abnormalities
Identify the two gastric enzymes employed in managing gastric achylia.
(a)
Eye infections can be treated with which enzyme known for its bacteriolytic activity?
(a)
