TLS Online TPP Program

#Question id: 10146


Light-dependent ion movements modulate enzymes of the Calvin–Benson cycle such as : rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase, and phosphoribulokinase what will happen Upon illumination;

#Unit 6. System Physiology – Plant
  1. flow of protons from the thylakoid lumen  into the stroma is coupled to release of Mg2+ from the intrathylakoid space to the stroma
  2. light actuated ion fluxes decrease the stromal concentration of protons (the pH increases from 7 to 8) and decrease that of Mg2+ by 2 to 5 mM
  3. The light-mediated decrease of pH and the concentration of Mg2+ activate enzymes of the Calvin–Benson cycle that require Mg2+ for catalysis and are more active at pH 7 than at pH 8
  4. The modifications of ionic composition of the chloroplast stroma are reversed rapidly upon darkening