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Photosynthesis Photosynthesis The process where light energy is converted into chemical energy Photosynthesis • Autotrophs change light energy into chemical energy in the process of photosynthesis. • Plants use light energy to convert water and carbon dioxide into oxygen and carbohydrates (sugars and starches) Process of Photosynthesis • Photosynthesis is a process used by green plants • The is a type of autotrophic nutrition. • Photosynthesis is carried out by chloroplasts, which contain chlorophyll • In the chloroplasts, CO2 and H2O are used to form C6H12O6 and O2 Process of Photosynthesis 6 CO2 + 6 H2O C6H12O6 + 6 O2 = light energy trapped in the chloroplast makes this process happen Process of Photosynthesis Photosynthesis Equation 6CO2 + 6H2O carbon water C6H12O6 + 6O2 light energy dioxide sugar oxygen (glucose) • Requirements: – 6CO2 – carbon dioxide is absorbed from the environment – 6H2O – water absorbed from the environment – Energy – energy from the sun is trapped by the chlorophyll in the chloroplasts • Products/Wastes: – C6H12O6 – organic sugar (glucose) is stored in the plant – 6O2 – oxygen is released as a waste product Factors Affecting Photosynthesis • Water or Carbon dioxide (wax prevent water loss) • Temperature (0-35°C for enzymes) • Light intensity (min and max) or water Adaptations for Photosynthesis • Autotrophic algae carries out photosynthesis • They are responsible for the large percentage of oxygen found on the Earth (in water) Adaptations for Photosynthesis • Terrestrial plants are complex organisms also adapted for photosynthesis • Photosynthesis may occur in the stems of some plants • Leaves are best adapted for the process of photosynthesis http://earthguide.ucsd.edu/earthguide/diagra ms/photosynthesis/photosynthesis.html Stomata • Pore-like opening on the bottom of plant leaf that allows carbon dioxide to diffuse in or oxygen to diffuse out. Light and Pigments • Energy from the sun travels to Earth in the form of light of different wavelengths of the visible spectrum as different colors • Plants gather the sun’s energy with lightabsorbing molecules called pigments. Chloroplasts • Chlorophyll in the chloroplast is the green pigment that captures light energy. • Oxygen is released through the leaves • Organic sugars made are used by the autotroph to grow/develop or stored as carbohydrates or lipids. Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Go to Section: Sugars + O2 Green Plants • Chlorophyll absorbs light in the red and blue regions of the visible spectrum, but does not absorb light in the green region. • Green light is reflected making plants appear green! • Plants also contain red and orange pigments (ex. Carotene) that absorb light in other regions of the spectrum. • Any compound that absorbs light absorbs energy from that light and transferred it directly to electrons in the pigment molecules, raising the energy level of the electrons. Figure 8-5 Chlorophyll Light Absorption Section 8-2 Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll b Chlorophyll a V Go to Section: B G YO R