Introduction to Photosynthesis

1. Introduction to Photosynthesis • define the terms autotroph and heterotroph; • state that light energy is used during photosynthesis to produce complex organic molecules; • explain how respiration in plants and animals depends upon the products of photosynthesis; • state that in plants photosynthesis is a two-stage process taking place in chloroplasts;

2. What is Photosynthesis? • Light energy from the sun is transformed into chemical energy and used to make organic molecules (containing carbon) from inorganic substances (no carbon) • Nearly all life on earth depends on it • Light energy turns into chemical potential energy available to consumers and decomposers • Releases oxygen, so aerobes depend on it for respiration

3. Autotrophs and Heterotrophs • Using Cambridge Biology 2 p65, define the terms autotroph and heterotroph Autotroph: organisms that use light energy or chemical energy and inorganic molecules (carbon dioxide and water) to synthesis complex organic molecules Chemoautotrophs are early prokaryotes that used exergonic (reactions that release heat) to make complex organic molecules Photoautotrophs use sunlight and inorganic molecules (carbon dioxide and water) Heterotrophs: organisms that ingest and digest complex organic molecules releasing the chemical potential energy stored in them e.g. humans

4. Does everything depend on Photosynthesis? • Task: Using Cambridge Biology 2 p65, explain why respiration in autotrophs and heterotrophs depends on photosynthesis (5)

5. Answer... • Respiration requires oxygen • Oxygen is the final electron acceptor • In the electron transport chain • Photosynthesis produces oxygen • Both photoautotrophs and heterotrophs release the chemical potential energy in complex organic molecules • Complex organic moloecules e.g. carbohydrates made in plants during photosynthesis

6. The Chloroplast • Photosynthesis takes place in specialised organelles called chloroplasts within plant cells • The equation for photosynthesis is: 6CO2 + 6H20  C6H12O6 + 602

7. Looking at Chloroplasts • explain, with the aid of diagrams and electron micrographs, how the structure of chloroplasts enables them to carry out their functions; • define the term photosynthetic pigment; • explain the importance of photosynthetic pigments in photosynthesis;

8. Task • Using Cambridge Biology 2 p65–68, and OCR biology p60-61 outline how the structure of chloroplasts enables them to carry out their functions • This must be completed as a poster or information resource/ PowerPoint etc. • You have 2 weeks to complete this task

9. Success Criteria • Your Resource must include: • The structure of chloroplasts • How chloroplasts are adapted to their role • Photosynthetic pigments • Accessory pigments • Rf values: what they are and how they are calculated