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Photosynthesis Using light to make food. . 8-1 Energy and life • Energy – the ability to do work • In living things it is needed to move and also to build new proteins and amino acids. • Where does energy that living things need come from? Autotroph • "self-feeding“ – any organism that makes its own food • without eating • decomposing • absorbing other organisms or organic molecules. Auto – self Troph – to feed Photosynthetic autotrophs • "feed" themselves with light energy – include plants – photosynthetic protists (algae) – photosynthetic bacteria Cyanobacteria Algae & bacteria Heterotrophs • Get their food from eating autotrophs or from eating other heterotrophs Hetero - other Chemical Energy and ATP • Energy comes in many forms (heat, light, electricity) • It can be stored in molecules such as carbohydrates and lipids • The chemical fuel for cells though is ATP • Adenosine Triphosphate Tri- three This is how it works • Energy from food is used to convert ADP to ATP. As a result of adding a phosphate a small amount of energy is stored. Di - two Using biochemical energy • This energy can be used to do all kinds of cell work • Active transport – Pumps – Motor Proteins – Synthesis of proteins and nucleic acids 8-2 Photosynthesis Overview • During Photosynthesis light energy is used to convert water and carbon dioxide into sugar(glucose) and oxygen Photo – Syn – to put together Chlorophyll • green pigment that absorbs light energy • located in the membranes of chloroplasts – thylakoids in stacks, called grana – In stroma • carbon dioxide is built into sugars. The absorption spectrum • White light is composed of the colors of the rainbow • ROYGBIV 8-3 The reactions of Photosynthesis Step 1 • The light energy strikes the leaf – passes into the leaf – hits a chloroplast inside an individual cell. Step 2 • light energy enters the chloroplasts – captured by the chlorophyll inside a grana. Step 3 Inside the grana -part of the energy is used to split water into hydrogen and oxygen Step 4 • Releasing of excess (waste) – As oxygen into the air. Stomata of cactus plant Step 5 • hydrogen – taken to the stroma along with the grana’s remaining light energy. Step 6 • Carbon dioxide enters the leaf – passes into the chloroplast. Step 7 • Stroma the remaining light energy – used to combine hydrogen and carbon dioxide • making Carbohydrates. Step 8 • The energy rich carbohydrates are carried to the plant’s cells. Step 9 • Energy rich carbohydrates – used by the plants cells to drive all its life processes – Holds energy in chemical bonds Summary of Photosynthesis Photosynthesis and Respiration