Biology Photosynthesis

Carbon dioxide + water --> Oxygen + glucose

Leaf adaptations

• numerous stomata
• large SA
• cytoplasmic streaming

Stomata

•  Potassium ions actively transported in, water moves in (stomata open)
• Chloride ions pumped out, potassium ions follow, water moves out (stomata close)

Chloroplasts

• absorbs red/blue light, reflects green light
• thylakoids provide large SA
• contain DNA and ribosomes
• granal membrane selectivelt permeable due to ATP synthase

Light dependent reaction

• occurs in thylakoid 
• Photoionisation - chlorophyll oxidised by light
• Electrons move down electron transfer chain by redox reactions
• Energy released from electrons used to actively transport protons into thylakoid lumen
• Electrons joined to NADP with hydrogen ions to form NADPH
• Proton gradient. Hydrogen ions diffuse through ATP synthase
• ADP + Pi --> ATP
• Photolysis of water: 2H₂O --> 4H⁺ + 4e^- + O₂

Light independent reaction

• occurs in stroma
• Carbon dioxide combines with Ribulose bisphosphate catalysed by rubisco
• Produces two glycerate phosphate
• GP reduced by NADPH into triose phosphate using energy from ATP
• NADP and ADP and pi go back to Light dependent reaction
• TP converted into organic substances and RuBP
• 6 cycles required to make glucose

Limiting factors

• light intentisty
• carbon dioxide concentration 
• temperature
• water concentration

Compensation point

• rate of respiration = rate of photosynthesis 
• plants in lower light intensities reach compensation point faster due to higher chlorophyll numbers.