BIO120H1 Lecture Notes - Lecture 16: Crassulacean Acid Metabolism, C4 Carbon Fixation, C3 Carbon Fixation
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Plants can"t evade stress by moving, but can make own food, have to tolerate environmental stresses. Photosynthesis requires light, water, co2, reasonable temp. Leaf, stem, root traits reflect adaptation to environments. They are sessile, little scope for behavior, must tolerate adverse conditions. All plants need same things: light, co2, water, soil nutrients (npk) Co2 + h2o ---> carbs + o2. Need more c through photosynthesis than lose in respiration, so carbon balance is important for growth. Photosynthetic structures embody adaptation to environmental stresses. Green (bc of chlorophyll) structures (usually leaves, can be stems) Take in co2 through stomata, also lose water through stomata (singular stoma) Benefits of large leaf sa: good for harvesting light and co2. Costs: overheating, water loss by transpiration through stomata. At high temps, rubisco gets o2 instead of co2 (photorespiration) Pep carboxylase: enzyme accepts co2, reducing photorespiration (better than rubisco at its job)
