Plantae-Adaptations

Plantae-Adaptations - 5 STAGES OF LAND PLANT EVOLUTION...

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Unformatted text preview: 5 STAGES OF LAND PLANT EVOLUTION Which of these statements is probably true for the first land plants? A) They had xylem B) The sporophyte generation was dominant C) They had chlorophyll a & c D) They had swimming sperm E) They had plasma membranes but lacked cell walls Clicker Question Land Plants Review Bryophytes= Mosses, Liverworts, Hornworts Moist environments Swimming sperm Homosporous Single gametophyte Gametophyte (n) haploid stage is dominant Embryo (2n) is parasitic on gametophyte Lack xylem & phloem Small plants Tracheophytes= e.g. Ferns, conifers, Land Plants Review flowering plants Moist Dry environments 1) Swimming sperm (club moss, horsetails, ferns) 2) Airborne pollen + swimming sperm (few gymnosperms) 3)Airborne pollen (gymnosperms & Land Plants Review Homosporous 1 gametophyte Mosses & Ferns One type of spore Two types of spores Heterosporous 2 gametophytes Gymnosperms & Angiosperms Tracheophytes Cont'. Land Plants Review Sporophyte (2n) dominant Gametophyte is tiny and may be in pollen grain Xylem & Phloem Large plants Land Plants Review Tracheophytes Cont'. Seeds= embryo + endosperm + seed coat SEEDS Plant Adaptations to Land Selective advantages to land Less competition for light and nutrients Less predation Problems with new environment Physical support Water loss and availability Reproduction Temperature fluctuations How Plants Deal with Problems Problem: Physical support Solution: Internal support Roots: anchor plants in soil & acquire nutrients & H2O How Plants Deal with Problems Problem: Physical support Solution: Internal support Stems: Turgor pressure in cells with cell walls Lignin = "wood" Secondary growth--i.e. growth in width (Rings of Xylem) How Plants Deal with Problems Problem: Water loss & availability Solution: Conserve & acquire H20 Conserving H20--problem large surface area for photosynthesis (leaves) Waxy cuticle on leaves Deciduous leaves Hooks & hairs on leaves reduce evaporation How Plants Deal with Problems Problem: Water loss & availability Solution: Conserve & acquire H20 Conserving H20--problem large surface area for photosynthesis (leaves) Stomates & guard cells How Plants Deal with Problems Problem: Water loss & availability Solution: Conserve & acquire H20 Conserving H20--problem large surface area for photosynthesis (leaves) Stomates & guard cells How Plants Deal with Problems Problem: Water loss & availability Solution: Conserve & acquire H20 Acquire H20 H20 from soil via root Transport via xylem How Plants Deal with Problems Problem: Water & reproduction Solutions: Pollen= nonswimming sperm with tough water resistant coat How Plants Deal with Problems Problem: Water & reproduction Solutions: Seeds = Embryo + nutrition (endosperm) + protective seed coat SEED EVOLUTION Seeds evolved 365 MYA in Gymnosperms (Seed Ferns) Angiosperm invention of double fertilization gives rise to triploid endosperm as a food supply. Much larger food supply than in gymnosperms. SEED EVOLUTION In the earliest seeds the embryo is small and the endosperm large. The trend throughout the Angiosperms is to increase the embryo and decrease the endosperm, transferring the stored food to the cotyledons. Endosperm Embryo How Plants Deal with Problems Seed Dispersal Wind Large surface area to catch the breezes How Plants Deal with Problems Seed Dispersal Wind Large surface area to catch the breezes How Plants Deal with Problems Seed Dispersal Water Seeds must float Coconuts How Plants Deal with Problems Seed Dispersal Animals Caught on fur or body Cockleburs How Plants Deal with Problems Seed Dispersal Animals Fruit eaten by animals & the seeds dropped at a distance from the parent plant Fruits whose seed dispersers are extinct. Osage orange "Anachronistic Fruits" = How Plants Deal with Problems Seed Dispersal Osage Orange Mastodon The Honey Locust "Anachronistic How Plants Deal with Problems Seed Dispersal Fruits" = Fruits whose seed dispersers are extinct. Devil's foot gourd Leaf Evolution & Adaptations Microphyll Evolution (Club Mosses) Megaphyll Evolution Why Are There Different Leaf Shapes? Leaf Evolution & Adaptations WHY? Why do plants have different shaped leaves? 1) To lose heat effectively 2) They are adapted to specific predators 3) They are adapted to absorb the maximum sun 4) Genetic drift 5) To reduce wind resistance Clicker Question Here's Two We Know Pitcher plant captures insects in leaf Cactus leaves are spines Root Adaptations Why are there different root shapes? Stem Adaptations Why differences in stems? Stem Adaptations One Summary of Plant Evolution One Summary of Plant Evolution Why Does This Trend Occur? 1) It is because fertilization produces 2n 2) 2n has a selective advantage because there is a back up copy of genes 3) 2n can respond faster to environment stress with two copies of genes 4) Pollen & seed formation require 2n 5) Because of artificial selection 6) All are correct 7) Answers 2 & 3 make most sense Why does diploidy come to dominate in later species? Clicker Question But Whatever Your Hypothesis, Answer This: If d adv iploid why anta y is g d spe on't t eous, cies he o t ad opt her it? But Whatever Your Hypothesis, Answer This: I don't know! I DON'T KNOW! Tell me about flowers and the bees Be patient. The flowers and the bees are the next lecture! ...
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