Directions : In the following question more than one of the answers given may be correct. Select the correct answer and mark it according to the code:
Which of the following chemical reactions are associated with photorespiration? (1) \[\text{RuBP+O2}\,\xrightarrow{\text{RuBP}\,\text{oxygenase}}\underset{\text{+Phosphoglycolate}}{\mathop{\text{PGA}}}\,\] (2) \[\text{Glycolate+}{{\text{O}}_{\text{2}}}\,\xrightarrow{\text{Oxidase}}\text{Glyoxylate+}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}\] (3) \[\text{Glycolate+ATP}\,\xrightarrow[{{H}_{2}}]{Kinase}\] 3Phosphoglycerare+ADP (4) \[\text{RuBP+C}{{\text{O}}_{\text{2}}}\xrightarrow[\text{Carboxylase}]{\text{RuBP}}\text{2PGA}\]A) 1,2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 4 are correct
D) 1 and 3 are correct
Correct Answer: A
Solution :
Photorespiration occurs in peroxisome but is the combined activity of chloroplast peroxisome and mitochondria following reactions occur in photorespiration \[\text{RuBP}\,\text{+}{{\text{O}}_{\text{2}}}\,\xrightarrow[\text{Oxygenase}]{\text{RuBP}}\text{PGA}\,\text{+Phosphoglycolate}\] \[\begin{align} & \text{Phosphoglycolate}\,\text{+}\,{{\text{H}}_{\text{2}}}\text{O}\,\xrightarrow[\text{Oxygenase}]{\text{Phosphatase}} \\ & Glycolate\,+\,{{H}_{3}}P{{O}_{4}} \\ \end{align}\] \[\,\text{Glycolate}\,\text{+}\,{{\text{O}}_{\text{2}}}\,\xrightarrow[{}]{\text{Oxidase}}\text{Glyoxylate}\,\text{+}\,{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}\] \[\,\text{2}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}\,\xrightarrow[{}]{\text{Catalase}}\text{2}{{\text{H}}_{\text{2}}}\text{O+}{{\text{O}}_{\text{2}}}\] \[\,\text{Glyoxylate}\,\text{+}\,\text{Glutamate}\,\xrightarrow[{}]{\text{Transaminase}}\] \[\text{Glycine}\,\text{+ }\!\!\alpha\!\!\text{ -}\,\text{ketoglutarate}\] \[\text{2Glycine}\,\text{+}\,\text{NAD}\,\text{+}\,\xrightarrow[{}]{\text{Decarboxylase}}\] \[\text{1}\,\text{serine}\,\text{+}\,\text{C}{{\text{O}}_{\text{2}}}\,\text{+}\,\text{N}{{\text{H}}_{\text{3}}}\text{+NADH}\] \[\text{Serine}\,\text{+}\,\text{ }\!\!\alpha\!\!\text{ -ketoglutarate}\,\xrightarrow[{}]{\text{Transaminase}}\] \[\text{Hydroxypyruvate}\,\text{+}\,\text{Glutamate}\] \[\text{Hydroxypyruvate}\,\text{+}\,\text{NADH}\xrightarrow{\text{Reductase}}\] \[\text{Glycerate}\,\text{+}\,\text{NA}{{\text{D}}^{\text{+}}}\] \[\text{Glycerate}\,\text{+ATP}\,\xrightarrow{\text{Kinase}}\] \[\text{3-phosphoglycerate}\,\text{+ADP}\]
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