YIJC [H2] CI3.1_Photosynthesis (N)(S)

2025 JC2 BIOLOGY LECTURE NOTES 1 CORE IDEA 3: ENERGY AND EQUILIBRIUM TOPIC 3.1 PHOTOSYNTHESIS Learning Outcomes: (a) Identify components of chloroplasts in drawings, photomicrograph 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 harnessed and converted into chemical energy during the light-dependent reactions of photosynthesis. (d) Outline the three phases of Calvin cycle in C3 plants: (i) CO 2 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 rate of photosynthesis. (l) Outline chemiosmosis in photosynthesis. (names of complexes in the ETC are not required.) References: Campbell and Reece. Biology. (11th edition). Chapter 11: Photosynthetic Processes, pg.259 – 283 (or corresponding chapter in other editions) Note: This textbook is available in our library. You may wish to borrow it to supplement your reading when necessary. 1) Introduction • The Chloroplast • Photosynthetic Pigments • Absorption and Action Spectra • Stages of Photosynthesis 2) Light-Dependent Stage • Non-cyclic Photophosphorylation • Cyclic Photophosphorylation • Chemiosmosis 3) Light-Independent Stage 4) Factors Affecting Rate of Photosynthesis • Light Intensity • Carbon Dioxide Concentration • Temperature H2

2025 JC2 BIOLOGY LECTURE NOTES 2 1 INTRODUCTION • Most plants synthesise their own organic molecules from carbon dioxide and other inorganic raw materials (such as water and minerals) obtained from the environment. • They use light as a source of energy to synthesise these organic compounds. This light is absorbed by photosynthetic pigments present in the chloroplasts of leaf cells or green organs of the plant. • Photosynthesis is the conversion of light energy to chemical energy that is stored in sugars or other organic compounds • The process of photosynthesis can be summarised by the following equation: light 6 CO2 + 6 H2O → → → C6H12O6 + 6 O2 chlorophyll Fig. 1.1: Plants as autotrophs chlorophyll absorbs mostly violet-blue and red wavelengths of light light energy water water is absorbed through the roots and carried through the stem to all parts of the plant. oxygen excess sugar synthesised in the leaf cells are stored. carbon dioxide

2025 JC2 BIOLOGY LECTURE NOTES 3 1.1 THE CHLOROPLAST Learning Outcome (a): Identify components of chloroplasts in drawings, photomicrograph and electron micrographs. • Chloroplasts, found in plants and algae, a