Photorespiration (C2 cycle) involves a cooperative metabolic pathway spanning which three subcellular organelles in sequential order?

Answer and explanation

Correct answer: A. Chloroplast, Peroxisome, and Mitochondrion

  1. Step 1: In chloroplasts, oxygenation of RuBP yields 2-phosphoglycolate, which is dephosphorylated to glycolate.
  2. Step 2: Glycolate is transported into the peroxisome, where glycolate oxidase oxidizes it to glyoxylate (producing , broken down by catalase), which is then transaminated to glycine.
  3. Step 3: Glycine enters the mitochondrion, where two glycine molecules are decarboxylated and deaminated to form one molecule of serine, releasing and .
  4. Step 4: Serine returns via peroxisome to chloroplast to regenerate 3-PGA.
Answer
Chloroplast, Peroxisome, and Mitochondrion
Why not the others: 'Chloroplast, Golgi apparatus...' includes endomembrane organelles that do not participate in photorespiratory glycolate metabolism; 'Mitochondrion, Vacuole...' lists the vacuole, which acts as a storage organelle and lacks photorespiratory enzymes; 'Chloroplast, Nucleus...' lists organelles involved in genetic control and protein synthesis rather than carbon recycling.

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