Free Metabolism and Bioenergetics MCQs with Answers

• A. Glycolysis
• B. Gluconeogenesis
• C. Beta oxidation
• D. TCA cycle

Explanation: Phosphofructokinase-1 catalyses the major rate-limiting and committed step of glycolysis, converting fructose-6-phosphate to…

• A. Oxalocetate
• B. Ornithine
• C. Alpha ketoglutarate
• D. Glycine

Explanation: Alpha-ketoglutarate accepts amino groups to form glutamate, and glutamate then binds ammonia to form glutamine for safe transport in the…

• A. Isocitrate
• B. Glutarate
• C. Oxalocetate
• D. Cisaconitate

Explanation: Aconitase first removes water from citrate to form cis-aconitate, then adds water to produce isocitrate.

• A. Thiokinase
• B. Malonate reduction
• C. Succinate dehydrogenase
• D. None of the above

Explanation: Substrate-level phosphorylation in the TCA cycle occurs when succinyl-CoA is converted to succinate by succinyl-CoA synthetase, also…

• A. Pyruvic acid
• B. Lactic acid
• C. Acetoacetic acid
• D. Oxaloacetic acid

Explanation: When oxygen is insufficient, pyruvate is reduced to lactate so NAD+ is regenerated and glycolysis can continue.

• A. ATP
• B. TTP
• C. ITP
• D. GTP

Explanation: Succinyl-CoA synthetase produces GTP from GDP and inorganic phosphate by substrate-level phosphorylation in the citric acid cycle.

• A. Oxaloacetic acid
• B. Glutamic acid
• C. Nitric acid
• D. None of the above

Explanation: Oxaloacetic acid is regenerated at the end of the citric acid cycle when malate is oxidized.

• A. Anaerobic
• B. Aerobic
• C. Microaerophilic
• D. Aerobic and anaerobic

Explanation: The citric acid cycle is considered aerobic because it depends on oxygen indirectly through the electron transport chain, which reoxidizes…

• A. Glucose 6 phosphatase
• B. Hexokinase
• C. Glucokinase
• D. Adenylate kinase

Explanation: Insulin increases hepatic glucokinase expression and activity, promoting glucose phosphorylation and glycolysis after a meal.

• A. Glucokinase
• B. Hexokinase
• C. Glucose diphosphatase
• D. Phosphorylase

Explanation: Adrenaline stimulates glycogen phosphorylase through the cAMP-dependent phosphorylation cascade, causing glycogen breakdown.

• A. Fat
• B. Muscle
• C. Heart
• D. Kidney

Explanation: Gluconeogenesis occurs mainly in the liver and, especially during fasting, in the kidney cortex.

• A. Muscle lacks glucose 6 phosphatase
• B. Muscle lacks phospho gluco isomerase
• C. Absence of glucokinase
• D. Muscle does not contain glycogen phosphorylase

Explanation: Muscle can break glycogen down to glucose 6-phosphate, but it lacks glucose 6-phosphatase.

• A. ATPase
• B. Enolase
• C. Pyruvate Kinase
• D. Fructose 6 phosphatase

Explanation: Fluoride inhibits enolase, the glycolytic enzyme that converts 2-phosphoglycerate to phosphoenolpyruvate.

• A. It is present in cytoplasm
• B. Catalyzes the conversion of pyruvate to oxaloacetate
• C. Requires TPP as cofactor
• D. Catalyzes a reversible reaction

Explanation: Pyruvate dehydrogenase is a mitochondrial complex that irreversibly converts pyruvate to acetyl-CoA, not oxaloacetate.

• A. Mitochondria
• B. Nucleus
• C. Ribosomes
• D. Non-particulate cytoplasm

Explanation: Most citric acid cycle enzymes are located in the mitochondrial matrix, while succinate dehydrogenase is embedded in the inner…

• A. HMG-Co A synthase
• B. Malic enzyme
• C. Malonyl CoA synthetase
• D. Fatty acid synthetase

Explanation: Malic enzyme uses malate and NADP+ to form pyruvate, so acetyl-CoA is not its substrate.

• A. Dopamine hydroxylase
• B. Dopa decarboxylase
• C. O-methylation
• D. N-methylation

Explanation: Norepinephrine becomes epinephrine when a methyl group is added to its amino group by phenylethanolamine N-methyltransferase.

• A. Tyrosine to dopa
• B. Phenylalanine to tyrosine
• C. Dopa to dopamine
• D. Dopamine to nor epinephrine

Explanation: Tyrosine hydroxylase converts tyrosine to DOPA and catalyses the rate-limiting step of catecholamine synthesis.

• A. Insulin
• B. GH
• C. Glucagon
• D. Androgen

Explanation: Glucagon promotes fatty-acid breakdown and hepatic ketone-body formation during fasting, so it has a ketogenic effect.

• A. Metabolic acidosis
• B. Smell of acetone in breath
• C. Rothera's test is +ve
• D. Benedict's test +ve

Explanation: Starvation ketoacidosis causes metabolic acidosis, acetone-smelling breath, and a positive Rothera test for ketone bodies.