BIOL 1902 Lecture Notes - Lecture 9: Herbivore, Filter Feeder, Hyoid Bone
24 Mar 2016
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Document Summary
Subzero temperatures also pose problems for plants: ice inside their cells kills plants, many plants go dormant in the soil under the snow. Plants become cold hardy through acclimation: the first stage of acclimation is triggered by a change in the photoperiod. Photoperiod of the ratio of daylight to darkness: phytochromes = light-sensitive photo pigments. Make plant more responsive to low temperatures: second stage is triggered by cold (not sub-zero/10-0 0c) temperatures. Some trees are cold hardy to -800c. Retaining needles creates new problem = damage by solar radiation: solution: xanthophyll pigments, enable chlorophyll to use sun"s energy to create heat, not photosynthesize. Skunk cabbage has an unusual adaptation for the cold: it turns up the heat. Desiccation is another problem drying out. Conifers retain their leaves so size & shape is very important: leaf surface area is small. Reduces leaf surface area by rolling them up. Weight of snow: some shapes shed snow.
