Light Dependent reaction

• What is the photolysis of water?

  The photolysis of water is when light energy causes water to dissociate into protons and electrons and oxygen is produced.

  H2O ⇌ 2H+ + 2e- + ½O2

  These electrons from water replace those lost by chlorophyll in photoionisation.
• What is photoionisation?

  Photoionisation is when light energy excites chlorophyll electrons and raises them to higher energy levels, electrons are lost from chlorophyll which becomes positively charged.
• What is the electron transfer chain?

  Electrons pass down an electron transfer chain using REDOX reactions where electron carriers are reduced, energy is lost as they pass down the chain. These electrons reduce NADP to form NADPH.
• What is the chemiosmosis Theory?

  The energy from the electron transfer chain is used to transport protons across the membrane from the stroma to inside the thylakoid, creating a proton concentration gradient. Protons will then diffuse through ATP synthase into the stroma, ATP synthase spins releasing the energy to phosphorylate ADP with Pi forming ATP.
• The light dependent stage takes place in the thylakoid membranes of chloroplasts.
• What is the role of ATP from the light-dependent reaction in the light-independent reaction?

  ATP provides energy for glycerate 3- phosphate → triose phosphate and provides the inorganic phosphate for triose phosphate → ribulose bisphosphate.
• What is the role of NADPH from the light-dependent reaction in the light-independent reaction?

  NADPH provides electrons and protons for glycerate 3- phosphate → triose phosphate.
• During photosynthesis, which chemicals are needed for the light-dependent reaction?

  NADP, ADP, Pi and Water.