In a healthy young adult, arterial oxygen saturation (SaO2) during moderate exercise (vs. rest) is usually:

In a normal person, arterial oxygen tension (PaO2) in the aorta during sleep vs. quiet wakefulness is generally:

A finger pulse oximeter is placed on a patient. Which parameter is NOT directly measured by the device?

Which change most directly increases O2 delivery to exercising skeletal muscle?

JinnY’s pulse oximeter reads 60% SpO2, but she’s walking briskly and talking normally. Which explanation is most likely?

Which parameter is actually increased in JinnY during brisk walking and helps improve O2 delivery?

Which factor in exercising muscle shifts the O2–Hb dissociation curve to the right, enhancing O2 unloading?

Which histidine residue is absent in fetal hemoglobin (HbF), contributing to its left-shifted O2 dissociation curve (higher O2 affinity)?

Myoglobin has high affinity for oxygen (and even carbon monoxide). Which structural feature promotes tight ligand binding?

In a patient with end-stage renal disease, which hormone–manifestation pair is correct?

Which enzyme of carbohydrate metabolism is present in the renal cortex (and liver) and allows the kidney to perform gluconeogenesis during prolonged fasting?

During prolonged fasting, what role does the kidney play in glucose metabolism?

How do the kidneys help regulate intracellular fluid (ICF) osmolarity?

A diabetic patient is started on an SGLT2 inhibitor. What is the most characteristic urinalysis finding?

Which mechanism in the kidney is a major ATP consumer?

Who has the lowest percentage of total body water relative to body weight?

A triathlete wants to stay hydrated pre-race but avoid frequent urination. Which beverage would best achieve this?

A patient with nephrogenic diabetes insipidus has a mutation in aquaporin-2. What is the main physiologic consequence?

Bonita is dehydrated with metabolic acidosis. Correcting which parameter most directly restores her acid–base status?

At what relationship between pH and pKa does a buffer work best?

At pH equal to pKa, which statement about a weak acid buffer is most accurate?

Which feature makes the bicarbonate buffer effective in blood?

A patient retains CO2 due to hypoventilation. What primary acid–base disorder results?

Loss of gastric contents from vomiting most likely causes which disorder before compensation?

Which immediate physiologic response helps raise pH during metabolic acidosis?

During exercise, which reaction chiefly links rising CO2 to H+ generation in capillaries?

An ABG shows low HCO3− with low PaCO2 and near-normal pH. What pattern fits best?

Which change indicates respiratory compensation for metabolic acidosis on ABG?

In sepsis with lactic acidosis, labs show low HCO3− and low PaCO2. Which description fits?

Which compound is the conjugate base of a weak dicarboxylic acid such as methylmalonate?

Which extrahepatic reaction lowers circulating ammonia by forming a nontoxic carrier?

Which enzyme catalyzes conversion of glutamate and NH3 to glutamine using ATP?

During starvation, which amino acid transports carbon and nitrogen from muscle to liver for gluconeogenesis and urea formation?

Under normal physiology, what is the primary fate of phenylalanine in catabolism?

Which amino acid yields both acetoacetate and fumarate upon catabolism?

Which amino acid is catabolized to succinyl‑CoA, serving as a glucogenic substrate during fasting?

Which amino acid is degraded via the kynurenine pathway and can be used to synthesize NAD+?

A 40‑year‑old with seizures after aspartame ingestion likely has deficiency of which enzyme?

Which intermediate of the urea cycle also participates directly in the TCA cycle?

Which enzyme cleaves argininosuccinate to produce arginine and fumarate in the urea cycle?

Which mitochondrial enzyme catalyzes the committed, rate-limiting step of the urea cycle?

Which compound is the immediate precursor of ornithine formation in the urea cycle?

A 2‑day‑old infant has hyperammonemia, respiratory alkalosis, and markedly elevated orotic acid. Which urea‑cycle enzyme is most likely deficient?

Which therapy most directly lowers blood ammonia in ornithine transcarbamylase deficiency?

After a very high‑fat meal, which substrate–pathway pair best explains increased triacylglycerol (TAG) synthesis?

In obesity with metabolic syndrome, which mechanism explains TNF‑alpha–induced hyperglycemia?

Which sequence best reflects liver metabolism from 7 AM after breakfast to 7 AM the next day during overnight fast?

During overnight fasting, which event occurs in adipose and peripheral tissues?

On day 3 of total fasting, which substrate contributes most to hepatic gluconeogenesis to maintain blood glucose?

A patient with a glucagon‑secreting pancreatic tumor is most likely to show which clinical course?

Approximately what percent of circulating free fatty acids released from adipose TAGs are re‑esterified back to TAGs in adipose tissue rather than oxidized?

Paper‑partition chromatography separates amino acids primarily based on which property?

In cation‑exchange chromatography, the stationary phase typically carries which functional group?

If the pH is raised above the pKa of an amino acid side chain, that group tends to become which charge state?

Which gradient is commonly used to elute bound cations from a cation‑exchange column?

The retention factor Rf in paper chromatography is defined as which ratio?

In an ascending paper chromatography experiment, an amino acid migrates 4 cm while the solvent front migrates 5 cm. What is the Rf value?

Using an ethanol‑rich mobile phase in paper chromatography, which amino acid type is expected to travel the farthest?

Which glycolytic enzyme deficiency in erythrocytes most commonly causes chronic hemolytic anemia due to low ATP?

Glucokinase is predominantly expressed in which tissues to buffer postprandial hyperglycemia?

Compared with hexokinase, glucokinase characteristically exhibits which kinetic profile?

In the Cori cycle, what metabolite is transported from anaerobic muscle to the liver for conversion back to glucose?

The first committed step of glycogenesis is best described as which reaction?

Which enzyme elongates glycogen by forming alpha‑1,4 glycosidic bonds at non‑reducing ends?

The branching enzyme creates which linkages to increase glycogen solubility and rapid mobilization?

What is the rate‑limiting enzyme of glycogenolysis that releases glucose‑1‑phosphate?

Skeletal muscle cannot export free glucose during glycogen breakdown because it lacks which enzyme?

During an overnight fast of approximately 8–12 hours, which organ is the primary source of blood glucose?

A deficiency of muscle glycogen phosphorylase presents as exercise intolerance and myoglobinuria. What disorder is this?

Which hormone most directly stimulates hepatic glycogenolysis via cAMP signaling?

Which substrate is NOT a major carbon source for gluconeogenesis?

Which enzyme pair bypasses the irreversible pyruvate kinase step during gluconeogenesis?

Pyruvate carboxylase requires which covalently bound cofactor to carry CO2?

Which clinical finding suggests impaired gluconeogenesis during fasting?

In hepatocytes, fructose‑2,6‑bisphosphate acts primarily to do what?

During prolonged fasting, which amino acid is most important for renal gluconeogenesis and acid excretion?

Ethanol intoxication elevates hepatic NADH. Which reaction is driven forward, lowering gluconeogenic precursors and causing hypoglycemia?

In the fed state with high insulin, which pathways in liver are most active?

Which enzyme is inhibited by ATP and citrate in glycolysis?

In a well-oxygenated resting muscle, most pyruvate from glycolysis is converted to:

Which glycolytic intermediate is also a precursor of 2,3-BPG in RBCs?

In liver, glucagon via cAMP leads to phosphorylation that:

The net ATP gain from anaerobic glycolysis (glucose → 2 lactate) is:

A drug inhibiting enolase would cause accumulation of:

Von Gierke disease (type I glycogen storage disease) is caused by deficiency of:

The main site of de novo fatty acid synthesis is:

The immediate precursor for fatty acid synthesis is:

Cytosolic acetyl-CoA for FA synthesis is derived from mitochondrial acetyl-CoA via export of:

Malonyl-CoA inhibits:

Which hormone profile promotes lipogenesis?

In uncontrolled type 1 diabetes, increased lipolysis in adipose tissue is due to:

Which tissue is the primary producer of ketone bodies?

In prolonged fasting, ketone bodies are used as major fuels by:

Ketone body synthesis is favored when:

The primary ketone body measured in blood (and correlated with severity) is:

In diabetic ketoacidosis, which statement is true?

During an overnight fast, which source provides glycerol for gluconeogenesis?

Which enzyme is shared by both FA synthesis and degradation pathways?

Which lipoprotein is most associated with transporting dietary TAG from intestine to tissues?

Which lipoprotein primarily returns cholesterol from tissues to liver?

In the post-absorptive state (3–5 h after a meal), which pathways are active in liver?

Which hormone directly activates lipoprotein lipase (LPL) in adipose tissue?

In a high-carbohydrate diet, excess glucose is converted to fatty acids. The key regulatory step in FA synthesis is catalyzed by:

Which metabolic state shows highest ketone body production?

During prolonged exercise, which source becomes increasingly important for muscle energy?

An aminotransferase uses which cofactor to transfer amino groups?

The typical pair in aminotransferase reactions is:

The reaction alanine + α-ketoglutarate ↔ pyruvate + glutamate is catalyzed by:

Which enzyme releases free NH3 directly from glutamate in liver mitochondria?

Which cofactor is required for glutamate dehydrogenase in oxidative deamination?

In extrahepatic tissues, most ammonia is transported to liver in the form of:

A neonate with lethargy and vomiting has hyperammonemia, low BUN, and elevated glutamine. Most likely defect:

Which amino acid provides the second nitrogen of urea (in argininosuccinate synthetase reaction)?

Urea synthesis occurs primarily in:

A patient has hyperammonemia and very low citrulline levels. The most likely enzyme defect is:

Elevated blood levels of argininosuccinate suggest deficiency of:

Which treatment helps urea cycle disorders by providing an alternative route for nitrogen excretion?

The energetic cost of forming one molecule of urea is approximately:

Branched-chain amino acid (BCAA) oxidation defects, like in Maple Syrup Urine Disease, primarily affect metabolism of:

A 6-month-old infant has musty odor, eczema, and seizures. Labs show elevated phenylalanine and low tyrosine. Which diet modification is appropriate?

In homocystinuria due to cystathionine β-synthase deficiency, which vitamin may partially improve symptoms?

In the glucose–alanine cycle, alanine released from muscle is converted in the liver to:

Which amino acid is both a neurotransmitter and a precursor to GABA?

The side chain of histidine can act as a good buffer near physiological pH because its imidazole group has a pKa near:

Which amino acid is precursor for serotonin?

Which amino acid is strictly ketogenic?

A deficiency in arginase will lead to:

Ornithine is structurally similar to which TCA intermediate?

A buffer is strongest when acid equals conjugate base. At this point, the pH:

The main extracellular buffer system is:

The major intracellular buffer in RBCs is:

Phosphate buffer is more important in:

The Henderson–Hasselbalch equation for the bicarbonate buffer is:

A patient has ABG: pH 7.50, PaCO2 30 mmHg, HCO3− 23 mEq/L. Tic-tac-toe shows pH alkalotic, PaCO2 alkalotic, HCO3− normal. What is the primary disorder?

ABG: pH 7.25, PaCO2 55 mmHg, HCO3− 24 mEq/L. Tic-tac-toe shows pH acidotic, PaCO2 acidotic, HCO3− normal. Primary disorder?

ABG: pH 7.10, PaCO2 20 mmHg, HCO3− 6 mEq/L. Tic-tac-toe shows pH acidotic, PaCO2 alkalotic, HCO3− acidotic. Interpretation:

ABG: pH 6.90, PaCO2 68 mmHg, HCO3− 13 mEq/L. Tic-tac-toe shows pH acidotic, PaCO2 acidotic, HCO3− acidotic. Best description:

For Bonita: pH 7.30, PaCO2 45 mmHg, HCO3− 15 mEq/L (given). The absolute difference in tic-tac-toe for HCO3− vs normal (24) is:

A patient with metabolic alkalosis (HCO3− 36 mEq/L) shows which expected compensatory change?

A mountain climber at high altitude develops pH 7.50, PaCO2 28 mmHg, HCO3− 20 mEq/L. This reflects:

In lactic acidosis, buffering by bicarbonate produces increased:

Which HCO3− level is most consistent with chronic respiratory acidosis (compensated)?

Diarrhea primarily causes:

Vomiting primarily causes:

A patient with salicylate intoxication initially shows:

The anion gap is calculated as:

High anion gap metabolic acidosis is seen in all EXCEPT:

In renal failure, metabolic acidosis occurs mainly due to: