​Photorespiration or the C2 cycle takes place in three distinct organelles in plant cells: the chloroplast, peroxisome, and mitochondrion. The following statements relate to the C2 cycle:

A. Reduced ferredoxin and ATP are required for photorespiration and assimilation of the resulting NH₃.

B. Photosynthetic electron transport provides energy-rich ATP and NADPH for photorespiration.

C. Glutamate is translocated from the chloroplast to the peroxisome, while α-ketoglutarate is translocated from the peroxisome to the chloroplast.

D. The action of the enzyme serine hydroxymethyltransferase takes place in the peroxisome.

Which one of the following combinations contains all correct statements?

Correct option is B

​Explanation:

Statement A: Correct

• Photorespiration requires reduced ferredoxin and ATP during the recycling of NH₃ (ammonia) in the chloroplast.
• Ammonia (NH₃) is released during glycine-to-serine conversion in mitochondria and needs to be reassimilated in the chloroplast using ATP and reduced ferredoxin.
• This process ensures efficient nitrogen use and prevents nitrogen loss.

Statement B: Incorrect

• ATP and NADPH produced during photosynthetic electron transport are used in the Calvin cycle, not directly in photorespiration.
• Photorespiration does not depend on ATP and NADPH from photosynthetic electron transport but instead uses energy indirectly from other metabolic reactions.
• Thus, this statement is incorrect.

Statement C: Correct

• Glutamate (Glu) and α-ketoglutarate (α-KG) act as shuttle molecules between organelles during photorespiration.
• Glutamate moves from the chloroplast to the peroxisome, while α-ketoglutarate moves in the opposite direction.
• This exchange is crucial for nitrogen metabolism during the glycine-to-serine conversion step in mitochondria.

Statement D: Incorrect

• Serine hydroxymethyltransferase (SHMT) is primarily active in mitochondria, not in the peroxisome.
• It plays a key role in converting glycine into serine in photorespiration.
• Thus, this statement is incorrect.