Photosynthesis

PHOTOSYNTHESIS What is Light Reactions Photosynthesis? Photosynthesis is how plants use light energy to power their growth. They Light energy from the sun is converted to chemical energy through a series of complex chemical reactions. The ultimate beginning and end products are: serve as an energy source for life on Earth and 6 CO2 + 6 H20 –→ C6H2O2 + 6 02 therefore plants are a vital part of our lives. So plants start with carbon dioxide and water and in return we get carbohydrates and oxygen. Light Photons ADP ATP NADP+ NADPH Light Photons Н+ Cytochrome Complex H20 O, + H* CO, H20 (1) chlorophyll molecules excited Electrons from Glucose are into Ribulose-i-s bisphosphate higher energy state by absorbed light energy in Photosystem II. The electron moves back down its energy state in the Cytochrome Complex which drives the production of ATP, the chemical energy used by cells. The electron then moves on to Photosystem I where it is excited again and this time drives the production of NAPDH which is an electron carrier used in the next Calvin Cycle A ADP the NADPH NÁDP+ ATP Why are plants green? нt G3P" Plants are green because of light absorbing pigments called chrorophyll. They absorb mostly red (650nm) and blue (430nm) light wavelengths and reflect green, which is what our eyes see! phase, the Calvin Cycle. (2) In the Calvin Cycle, the products ATP and NADPH are used in reactions to create carbohydrates or sugars, energy sources used by other organisms. 430 nm 650nm 380 nm 750nm hkchin may 2011 Pea Plant Pisum sativum