TCA and Oxidative Phosphorylation PDF

Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA in the link reaction? A) Pyruvate dehydrogenase B) Hexokinase C) Citrate synthase D) Malate dehydrogenase o Answer: A) Pyruvate dehydrogenase The link reaction occurs in which part of the cell? A) Cytoplasm B) Inner mito...

Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA in the link reaction? A) Pyruvate dehydrogenase B) Hexokinase C) Citrate synthase D) Malate dehydrogenase o Answer: A) Pyruvate dehydrogenase The link reaction occurs in which part of the cell? A) Cytoplasm B) Inner mitochondrial membrane C) Mitochondrial matrix D) Nucleus o Answer: C) Mitochondrial matrix During the link reaction, one molecule of pyruvate produces how many molecules of NADH? A) 1 B) 2 C) 3 D) 4 o Answer: A) 1 Which of the following is released as a byproduct during the conversion of pyruvate to acetyl-CoA? A) Oxygen B) CO₂ C) ATP D) FADH₂ o Answer: B) CO₂ The TCA cycle begins with the reaction between acetyl-CoA and which molecule? A) Succinate B) Oxaloacetate C) Citrate D) Malate o Answer: B) Oxaloacetate Which enzyme catalyzes the first reaction of the TCA cycle? A) Citrate synthase B) Aconitase C) Isocitrate dehydrogenase D) Succinate dehydrogenase o Answer: A) Citrate synthase How many NADH molecules are produced per acetyl-CoA molecule in one round of the TCA cycle? A) 1 B) 2 C) 3 D) 4 o Answer: C) 3 Which intermediate in the TCA cycle is the direct precursor for the synthesis of fatty acids? A) Citrate B) Succinate C) Fumarate D) Malate o Answer: A) Citrate The only enzyme in the TCA cycle that is embedded in the inner mitochondrial membrane is: A) Citrate synthase B) Aconitase C) Succinate dehydrogenase D) Malate dehydrogenase o Answer: C) Succinate dehydrogenase In the TCA cycle, how many GTP (or ATP) molecules are produced per turn of the cycle? A) 0 B) 1 C) 2 D) 3 o Answer: B) 1 Which TCA cycle enzyme is inhibited by high levels of ATP and NADH? A) Citrate synthase B) Isocitrate dehydrogenase C) Succinate dehydrogenase D) Fumarase o Answer: B) Isocitrate dehydrogenase Which complex in the electron transport chain is responsible for pumping protons and producing water? A) Complex I B) Complex II C) Complex III D) Complex IV o Answer: D) Complex IV The primary role of oxygen in oxidative phosphorylation is to: A) Act as an electron donor B) Act as the final electron acceptor C) Generate ATP directly D) Transport electrons to the TCA cycle o Answer: B) Act as the final electron acceptor Which molecule directly drives the synthesis of ATP by ATP synthase? A) NADH B) FADH₂ C) Proton gradient D) Oxygen o Answer: C) Proton gradient Which complex of the electron transport chain does NOT pump protons across the membrane? A) Complex I B) Complex II C) Complex III D) Complex IV o Answer: B) Complex II What is the total number of ATP molecules produced from one molecule of NADH in oxidative phosphorylation? A) 1 B) 1.5 C) 2 D) 2.5 o Answer: D) 2.5 Which organ is the primary site of gluconeogenesis in the body? A) Muscle B) Liver C) Kidney D) Brain o Answer: B) Liver In gluconeogenesis, pyruvate is first converted to which intermediate before entering the gluconeogenic pathway? A) Oxaloacetate B) Acetyl-CoA C) Malate D) Fumarate o Answer: A) Oxaloacetate Which enzyme converts oxaloacetate to phosphoenolpyruvate in gluconeogenesis? A) Phosphofructokinase B) Pyruvate carboxylase C) Phosphoenolpyruvate carboxykinase (PEPCK) D) Pyruvate dehydrogenase o Answer: C) Phosphoenolpyruvate carboxykinase (PEPCK) Which of the following hormones promotes gluconeogenesis? A) Insulin B) Glucagon C) Oxytocin D) Prolactin o Answer: B) Glucagon Which energy molecules are consumed during gluconeogenesis? A) ATP and NADH B) ATP and FADH₂ C) GTP and NADH D) GTP and NAD+ o Answer: A) ATP and NADH