BIO120H1 Lecture Notes - Lecture 5: Leaf, Sclerophyll, Cactus
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BIO120H1 Full Course Notes
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Leaf has high sv/v ration: good for harvesting sunlight, but bad for overheating. Stresses are greater due to the fact the it cannot move. Tissues in plants need to keep the write water balance. Can counter heat by evaporative cooling using water. Stomato open open, co2 enters, water vapour escapes, and water evaporation stays cool. Can be closed, causes conservation of water: can"t photosynthesize though. When we have trees with branches and leaves on it, leaves tend to be small. Leaves tend to equilibrate with the temp, rather than over heat w/ the sun (small leaves on palo verde. A lot of desert plants gave up on leaves. Cactus does all photosynthesis in its stem. The structure that usually develop into leaves, develop into thornes that protect water filed structures. Not good at photosynthesis, but can hold a lot of water.
