Question

During photorespiration the oxygen consuming reaction occur in

• A. Grana of chloroplast and peroxisomes
• B. Stroma of chloroplasts
• C. Stroma of chloroplasts and mitochondria
• D. Stroma of chloroplasts and peroxisomes

Answer 1

The correct option is D Stroma of chloroplasts and peroxisomes

The process of photorespiration occurs in plants when the concentration of the oxygen increases and the Ribulose bisphosphate Carboxylase enzyme combines with oxygen, instead of carbon dioxide and functions as an oxygenase enzyme. This process is considered wasteful for plants because it deviates the C${}_3$ cycle. This process needs three organelles, chloroplast, peroxisomes, and mitochondria to be completed. It occurs in Chloroplast where oxygen is utilized by combining with RuBiSCO and glycolate is formed. This Glycolate then moves to the peroxisomes and glycolate is converted to glyoxylate using oxygen. Glyoxylate then moves to the mitochondria and glycine is formed. From glycine, serine is formed in mitochondria which goes to peroxisomes again where the hydroxypyruvate and glycerate are formed and the gluycerate finally arrives back to the chloroplas to take part in glucose formation. So, photorespiration is adeviation of C${}_3$ cycle. The oxygen-consuming reactions have occurred in the stroma of chloroplast and peroxisomes.

So, the correct answer is 'Stroma of chloroplast and peroxisomes.'