BIO120H1 Chapter 5: Struggle for Existence Part Vb

• School: UTSG
• Department: Biology
• Course: BIO120H1
• Professor: Spencer Barret

Document Summary

Part vb: physiological ecology as a way of thinking about organisms. Plant physiological ecology (tangle of constraints and tradeoffs): higher plants! Plants are autotrophs (they harvest their own energy by photosynthesis): other than cacti, most terrestrial plants photosynthesize in their leaves! Sa/v ratio is extremely important: large surface areas in leaves to harvest sunlight photon, large surface areas for gas exchange (co2 in, o2 out) , large surface areas are at risk for overheating and denaturing the enzymes! Heat balance and water balance: evaporative cooling ties the two together! Gas exchange in the stomata, water from inside the leaves can be evaporated through stomata! Leaves can stay cool under full sun if there"s enough water! Photosynthetic pathways: co2 is incorporated into a 3-carbon molecules (c3): photorespiration! Cam: crassulacean acid metabolism: provides extreme water conservation in succulent plants (cacti, epiphytes), eliminates tradoff, plants keep they stomata closed during sunny periods to minimize water loss!