PHOTOSYNTHESIS

1 EJC H2 Biology T3W5 Photosynthesis Energy & Equilibrium – Photosynthesis 1. Overview of Topic All living things require energy to grow and survive. Most living organisms get their energy either directly or indirectly from sunlight. Producers derive their energy from the sun via photosynthesis while consumers such as herbivores, carnivores and omnivores get their energy from eating other organisms. Photosynthesis is the process by which plants, some bacteria and some protists use light energy to produce glucose from CO2 and water. The oxidation of glucose during respiration can yield ATP to fulfil an organism’s energy needs. Photosynthesis is also a source of carbon, which is needed for the synthesis of other organi c compounds, e.g. pro teins, lipids and nucleic acids. In this chapter , we will look at the location, importance and mechanisms of photosynthesis. 2. Learning Outcomes a. Identify components of chloroplasts an d mitochondria in drawings, photomicrographs and electron micrographs. b. Explain the absorption and action spectra of photosynthetic pigments. c. With reference to the chloroplast structure, describe and explain how light energy is harnesses and converted into chemical energy during the light-dependent reactions of photosynthesis. d. Outline the three phases of the Calvin cycle in C3 plants: i. CO2 fixation, ii. PGA reduction and iii. Ribulose bisphosphate (RuBP) regeneration, indicating the roles of rubisco, ATP and reduced NADP in these processes that ultimately allow synthesis of sugars. e. Discuss limiting factors in photosynthesis and carry out investigations on the effect of limiting factors such as temperature, light intensity and carbon dioxide concentration on the rat e of photosynthesis. 3. References Campbell, N.A. and Reece, J.B. (2008). Biology, 9th edition. Pearson.

2 EJC H2 Biology T3W5 Photosynthesis Contents 1. Overview of Topic ...................................................................................................... 1 2. Learning Outcomes.................................................................................................... 1 3. References ................................................................................................................. 1 4. Introduction ............................................................................................................... 3 5. Chloroplast – The Site of Photosynthesis .................................................................. 3 6. Light & Photosynthetic Pigments .............................................................................. 4 7. Absorption & Action Spectrum.................................................................................. 6 8. Photoactivation of Photosynthetic Pigments ............................................................ 7 9. Photosystems ......................................................................