BioStudyNotesChristmasFinal2 - Evolution...

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Evolution 1.1 adaptive radiation 1.1.1 Adaptive radiation of plants Adaptive Radiation Of Plants - chloroplasts: autotrophic - important step - oxygen in water and in air, think of consequences for life and for organisms that are autotrophic - moved onto land at end of devonian, scientists found plants with - gametangia: specialized sexual organs - stems: with fluid transport mechanisms can move from roots to the leaves - structural elements: e.g. wood - leaves: centres for photosynthesis - roots: hold to ground, provide access to nutrients and water - stomata: for gaseous exchange - sporangia, seeds Movement onto land requires - stoma - a guard cell adjusts amount of air and CO2 that gets in and out of plant - waterproof: - thick cuticle on surface to prevent evaporation and maintain internal balance - transport - tracheid cells in plants (a) moss (b) s type (c) G type (d) p type - tracheid cell: elongated closed cell of wood having secondary thickening and conducting water. cells are involved in wood, structural and transport Nitrogen - lots of N2 but they are in the form of triple covalent bonds that are hard for organisms to get a hold of - accessible Nitrogen by nitrogen fixation, ammonification, nitrification, denitrification - nitrogen fixation: capture and conversion of atmospheric nitrogen gas into nitro- gen compounds, stored in soil, that can be used by plants - ammonification: bacteria decomposers breaking down amino acids from dead animals and animal wastes into NH4OH - nitrification: process whereby ammonia in wastewater is oxidized to nitrite nad then to nitrate by bacterial or chemical reactions - denitrification: bacterial reduction of nitrite to gaseous nitrogen under anaerobic conditions - Haber-Bosch process made it possible for nitrogen fertilizers to be produced Carnivorous Plants
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Many species of plants are carnivorous, eating insects to obtain additional nutrients. Their approaches: - pitfall traps: attract and drown. e.g. pitcher plant - fly paper: butterwort, drosera - snaptraps: venus flytrap Carnivorous plants: recurring evolutionary theme - thus we cannot use the presence of pitchers or trap apparatus as a good taxonomic feature because they are different evolutionary lines of plants Example: Nepenthes Species - peristome: surrounding entrance to the trap, the “lip”. This is slippery and colourful, at- tracting prey but offering an unsure footing - operculum: lid above peristome. Keeps rain from diluting within pitcher - nectar: underside of pitcher contains nectar glands that attract prey - one way valves and elongated trichomes: prevents insects from crawling out - waxy zone - glandular zone: produces adhesive secretions - digestive glands - target: fruitflies and ants - ultimate goal: get nitrogen from captures Convergence Venus Flytrap (Dionaea) and waterwheel (aldrovanda) evolved from a common ancest- or NB: - dionaea is terrestrial, occurs in south east USA - aldrovanda is aquatic, occurs in Asia - using sequence from nuclear analysis, it was shown that the two species of plants use
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This note was uploaded on 10/23/2008 for the course BIO 1222 taught by Professor Maxwell during the Spring '08 term at UWO.

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BioStudyNotesChristmasFinal2 - Evolution...

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