AQA A LEVEL BIOLOGY – PHOTOSYNTHENSIS
EXAM QUESTIONS AND CORRECT ANSWERS
100%!!
What are the two stages of photosynthesis called>?The Light Dependent reaction The Light Independent reaction (The Calvin cycle)
What is the purpose of photosynthesis?To energy from light is used to make glucose
What is the general equation for photosynthesis?6H2O + 6CO2 + energy --> C6H12O6 + 6O2
Describe what happens during photoionization of PSII Chlorophyll absorbs light Electrons excited and move to higher energy level Electrons move down electron transport chain to PSI
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Describe what happens during photolysis of water Light energy splits water molecules into H+, e- and oxygen The electrons replace those lost from PSII during photoionisation
Explain how H+ ions are moved across the thylakoid membrane The excited electrons from photoionisation lose energy as they move down the electron transport chain The energy is used to actively transport H+ into the chloroplast
Explain how H+ are involved in the synthesis of ATP in chloroplasts H+ move down their concentration gradient into the stroma This is via ATP synthase in the thylakoid membrane The energy synthesises ATP from ADP and Pi
Explain why the photoionisation of PSI is important The excited eletrons are transferred to NADP with H+ to form reduced NADP This is needed for the light-independent reaction
What is chemiosmosis ?Electrons move down the electron transport chain and creating a proton gradient This drived ATP synthesis
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