AP Environmental Science · Unit 4 · Energy & Matter
Energy Flow & Nutrient Cycles: every key term you need (+ practice quiz)
20 flashcard terms for AP Environmental Science Unit 4, written to match the course framework. Study them here, then drill them as interactive flashcards, or test yourself with the 5-question quiz — free, no account needed.
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Photosynthesis Process converting CO₂ + H₂O + light → glucose + O₂; occurs in chloroplasts.
Respiration Process converting glucose + O₂ → CO₂ + H₂O + energy (ATP); occurs in mitochondria.
ATP Adenosine triphosphate; energy currency of cells; energy released when losing phosphate group.
Photosystem Light-harvesting complex in chloroplast; absorbs photons, transfers energy to electron transport chain.
Calvin Cycle Light-independent reactions fixing CO₂ into sugars; requires ATP and NADPH from light reactions.
Stomata Pores in leaf leaves opening for gas exchange; closed at night to conserve water.
C3 Photosynthesis Standard pathway; first stable product has 3 carbons; efficient in cool, moist climates.
C4 Photosynthesis Modified pathway; first stable product has 4 carbons; more efficient in hot, dry climates.
CAM Photosynthesis Crassulacean acid metabolism; opens stomata at night to conserve water; drought-adapted.
Enzyme Protein catalyst speeding reactions; lowers activation energy; not consumed in reaction.
Photosynthetic Efficiency Percentage of light energy converted to chemical energy; typically 1-2% in field conditions.
Cellular Respiration Metabolic process releasing energy from organic molecules; aerobic requires O₂, anaerobic does not.
Glycolysis Process splitting glucose into pyruvate; occurs in cytoplasm; produces small amount of ATP.
Krebs Cycle Aerobic respiration cycle producing NADH and FADH₂; occurs in mitochondrial matrix.
Electron Transport Chain Series of proteins transferring electrons, pumping protons, producing large amount of ATP.
Chemiosmosis ATP synthesis driven by proton gradient across mitochondrial membrane.
Fermentation Anaerobic respiration producing ATP without oxygen; produces lactate or ethanol and CO₂.
Nitrogen Fixation Conversion of N₂ → ammonia by bacteria; essential for protein synthesis.
Nitrogenase Enzyme catalyzing nitrogen fixation; requires energy (ATP) to break N≡N bond.
Root Nodules Structures on legume roots housing nitrogen-fixing bacteria; mutualistic relationship.
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