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Lecture 10

BIOL 1902 Lecture 10: Lecture 10 Notes

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Carleton University
BIOL 1902
Michael Runtz

Lecture 10 o Photopigment: a pigment that reacts to sunlight o Geese fly in a V-formation while migrating to conserve energy o Banding: Attached a metal band to the legs of birds to track migration patterns o Songbirds caught in “mist nets” for banding (measure fat content first) o Geolocators: little computers put on the back of bird’s legs to measure daylight and night time ratios for better migration data o MOTUS: Towers pick up signals from nanotags (mini computers) on birds to pick up geolocation data with a 50-km radius o Half the birds who migrate don’t return (They die) buildings, habitat loss Subzero Temperatures pose problems for Plants • Many plants go dormant under the soil • Plants become Cold Hardy (similar to Freeze Tolerance) o Excess water is evaporated from leaves o Water is removed from cells & Protective sugars added to cells o which increase solute concentration o Increase flexibility of cell membranes o Ice forms between the cells not inside Plants become Cold Hardy through Acclimation o 1 Stage of Acclimation triggered by change in Photoperiod (less sun) o Phytochromes: light-sensitive photopigments which cause cells to go dormant and become more responsive to low temps nd o 2 Stage of Acclimation is triggered by cold (not sub-zero) temps o Coniferous trees retain needles that enable chlorophyll to use sun’s energy to create heat o Skunk Cabbage generates own heat for winter o Cold winters can cause Desiccation (drying out for plants) o Conifers retain leaves so size and shape is important (small surface area, close stomata, thick cuticles) o Hairs on undersides of leaves (trap area near stomata for moisture retention) o Reduce leaf surface area by curling up (Rock Podoly) o Deciduous trees drop their leaves for winter (lose chlorophyll) o Female maple trees turn yellow while males turn red o Leaf loss helps solve precipitation issues and snow buildup o Spire and spindly trees (firs and spruces) help shed snow o Extreme Heat can cause desiccation (plants curl leaves, close stomata o Dragonflies can reduce surface area by body posture puts abdomen in the air to cast shade(Obelisk) o Stilting: raise their bodies up (Tiger Beetles on hot sand) o Rete Mirabelle is bypassed and more blood shunted to extremities (feet is hotter) o Rete Mirabelle: tightly packed blood vessels that help keep feet warm in winter o Beavers lose more heat through tail when rete mirabelle is functioning
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