Respiration in Plants MCQs

Statement analysis on carbon counts of TCA cycle intermediates:

I. Citric acid = 6 carbons.
II. α-Ketoglutaric acid = 5 carbons.
III. Succinic acid = 4 carbons.
IV. Oxaloacetic acid = 4 carbons.

Which option contains correct carbon counts?

Consider the total ATP generated directly via Substrate Level Phosphorylation from ONE Glucose in Mitochondria:

I. Two GTP (equivalent to two ATP) are produced during conversion of two Succinyl-CoA molecules to two Succinic acid molecules.
II. Six ATP are produced during the link reaction.
III. Substrate-level phosphorylation in the TCA cycle yields two ATP per glucose.
IV. Twelve ATP are generated directly without ETS.

Which statements are correct regarding substrate-level ATP?

Read the following statements about FADH₂ generation in Krebs Cycle:

I. Formed during conversion of Succinic acid (Succinate) to Fumarate.
II. Catalyzed by Succinate dehydrogenase (Complex II).
III. Oxidation of one FADH₂ via ETS yields two ATP molecules.
IV. Formed during condensation of Acetyl-CoA with Oxaloacetic acid.

Which statements are correct?

Statement analysis on oxidative steps of Krebs Cycle:

I. Isocitrate → α-ketoglutarate (yields NADH + H⁺).
II. α-ketoglutarate → Succinyl-CoA (yields NADH + H⁺).
III. Succinate → Fumarate (yields FADH₂).
IV. Malate → Oxaloacetate (yields NADH + H⁺).

Select the option listing all four correct oxidation steps.

Consider the net output of Link Reaction + TCA cycle for ONE Glucose molecule:

I. 8 NADH + H⁺ molecules.
II. 2 FADH₂ molecules.
III. 2 GTP / ATP molecules.
IV. 6 CO₂ molecules.

Which option gives the correct total yield?

Which step in Krebs cycle is catalyzed by Citrate Synthase?

I. Condensation of Acetyl-CoA + Oxaloacetic acid + H₂O.
II. Conversion of Citrate to Isocitrate.
III. Synthesis of Succinyl-CoA from α-ketoglutaric acid.
IV. Conversion of Malic acid to Oxaloacetic acid.

Select the correct statement.

Statement analysis on the fate of carbon atoms of glucose during aerobic respiration:

I. All six carbon atoms of glucose are completely released as 6 CO₂.
II. Two CO₂ molecules are released during the link reaction in the mitochondrial matrix.
III. Four CO₂ molecules are released during two turns of the TCA cycle.
IV. Two CO₂ molecules are released during glycolysis in the cytoplasm.

Which statements are correct?

Why is replenishment of Oxaloacetic Acid (OAA) essential for continuous function of the TCA cycle?

I. OAA acts as the initial acceptor of Acetyl-CoA.
II. If OAA is drained for amino acid synthesis without replenishment, the TCA cycle stops.
III. OAA is consumed permanently and transformed into CO₂ gas.
IV. Regenerated OAA combines with fresh Acetyl-CoA in each cycle turn.

Which statements are correct?

Consider the location of enzymes of the TCA cycle:

I. Most TCA cycle enzymes are soluble in the mitochondrial matrix.
II. Succinate dehydrogenase is bound to the inner mitochondrial membrane (Complex II).
III. All TCA enzymes are located in the outer mitochondrial membrane.
IV. Pyruvate dehydrogenase is located in the intermembrane space.

Which statements are correct?

Read the following statements regarding the role of Oxygen in the Krebs cycle:

I. Oxygen is a direct reactant entering into TCA cycle reactions.
II. Oxygen acts as the terminal electron acceptor in ETS, regenerating NAD⁺ and FAD.
III. In the absence of oxygen, NADH and FADH₂ accumulate, halting the TCA cycle.
IV. TCA cycle can operate indefinitely under strictly anaerobic conditions.

Which statements are correct?