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Photosynthesis. Photosynthesis Overview. Defined : Production of sugar & oxygen from CO2, water, & sunlight Endergonic reaction: Requires energy Who : Plants, algae, some bacteria End Result : Sugar for food and oxygen (waste) 2 step process. Step 1 : Light Reaction.
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PhotosynthesisOverview • Defined: Production of sugar & oxygen from CO2, water, & sunlight • Endergonic reaction: Requires energy • Who: Plants, algae, some bacteria • End Result: Sugar for food and oxygen (waste) • 2 step process
Step 1: Light Reaction • Where: Thylakoid membranes of chloroplast • What happens? • 1) Light energy converted into chemical energy (ATP) • 2) Water (H2O) broken apart and the oxygen is released as a waste product • How: Chlorophyll absorbs light energy and electrons become excited • Excited electrons bond ADP + P to create ATP • Sunlight energy has been converted into chemical energy (ATP) • No sugar created…yet!!!
Step 2: Dark Reaction • Where: Stroma (fluid interior) of chloroplast • What happens? ATP (from light reaction) creates sugars • How? • ATP breaks apart CO2 + H2 from water • Atoms recombine into glucose and other sugars • Sugar is used by plants, algae, and some bacteria as a food source (autotrophs)
The Big Picture • Reasons I love autotrophs! • All food energy on earth can be traced back to photosynthesis • Autotrophs absorb CO2 • Problem: Greenhouse Effect • The Good: GHE naturally warms Earth by trapping heat • The Bad: CO2 from fossil fuels traps excess heat near Earth’s surface • AKA: Global Warming • Solutions: Regrow plants to absorb the extra CO2, reduce use of fossil fuels
QuickReview • CO2, Water, Sunlight are used during photosynthesis • Sugar and Oxygen are created as a result of photosynthesis • Photosynthetic life forms the basic of life on earth