C.PlantsF11 - Plants The Secret World of The Producers...

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Unformatted text preview: Plants The Secret World of The Producers Plants Photosynthesis • Produce the food (photosynthesis) • Condition the environment • Create shelter and habitat Ecological communities are often named for the dominant producers • Glucose for energy fuel, organic chemical monomers, structural polymers. • Oxygen for aerobic respiration. • Not all producers are plants Photosynthetic Protists Photosynthetic bacteria Cyanobacteria — “blue-green algae ” use chlorophyll Phytoplankton — earth ’s dominant producers! • Diatoms • Dinoflagellates Halophilic archaea — “purple bacteria ” use bacteriorhodopsin Heyer 1 Plants Plants Cells Alternation of Generations in Plant Reproduction Plant Cells / Tissues / Organs Alternation of Generations in the Green Algae ( Chlorophyte) Ulva MITOSIS MITOSIS MALE & FEMALE FLAGELLATED ZOOSPORES (1N) MITOSIS MALE & FEMALE FLAGELLATED GAMETES (1N) ZYGOTE (2N) Changing definitions of the Kingdom Plantae Kingdom Plantae 1. Classical: everything photosynthetic / not an animal 2. Whitaker’s 5-kingdom model: all eukaryotic multicellular photosynthetic organisms ? ? 4. Cladistic: Viridiplantae (“green plants”) — embryophyta + chlorophyta (“green algae”) Heyer Embryophyta = Embryophyta: dependent embryo, meristem growth & differentiation, cuticle Viridiplantae 3. Phylogenetic: “land plants” — exclude the algae Plantae Plantae (eukaryotic photoautotrophs ) photoautotrophs Changing definitions of the 2 Plants Algae — Aquatic Plants • Three Divisions (Phyla) Chlorophyta “Green Algae ” Rhodophyta “Red Algae” Kelp Life Cycle Phaeophyta “Brown Algae ” { including the “kelp” family } • Not directly related to each other, nor to terrestrial vascular plants. • Accessory pigments allow greater light sensitivity at depth. Contrast between terrestrial vascular plant form and aquatic algal form. “Dependent embryo” — analogous to embryophytes Bryophytes: Mosses • Land plants – Photosynthesis and gas exchange in leaves. – Nutrient and water uptake from soil by roots. – Vascular system transports between leaves & roots. – Woody tissues provide erect support. – Waxy cuticle resists drying. • Algae – Bathed in medium providing water, nutrients, and dissolved gases — roots, stomata, cuticle, and vascular systems not needed – Photosynthesis occurs all over plant body — no leaf specialization – Water environment provides buoyancy / woody tissue not needed Vascular Plants (Tracheophytes) Xylem - up! Phloem - down! • Haploid gametophytes are the dominant, conspicuous phase • Sperm “swim” to female gametophyte; require moist habitat • Spores may be dispersed by wind Pterophytes: Ferns • Diploid sporophyte is the dominant, conspicuous phase • Sperm “swim” to female gametophyte; require moist habitat • Spores are dispersed by wind Heyer 3 Plant Biology Fern Life Cycle Seed-bearing plants (Spermatophytes) • The visible plant body is the Two Clades: diploid sporophyte • Gymnosperms “naked seeds” • The gametophytes are transient – Phylum: Conifers “cone microscopic structures bearers” – Female gametophyte within the ovule – Male gametophyte within the pollen grain • Pollen grains resist desiccation • Angiosperms “vessel seeds” — allow transport of sperm – Phylum: Anthophytes independent of water “flowering • After fertilization, ovule develops into seed bearing the plants” embryo Gametophytes & Sporophytes Gymnosperms “naked seeds” Conifers “cone bearers” World ’s largest biome: boreal coniferous forest [taiga] World ’s largest organisms: sequoia & coast redwood Conifers include the world’s largest organisms Tallest — coastal redwoods Most massive — giant sequoia Angiosperms — the flowering plants >250,000 known living species = 90% of all plant species Heyer 4 Plant Biology Vascular Plants Xylem - up! Phloem - down! Vascular-plant structure Gas exchange in vascular plants Leaf Anatomy in Dicot Angiosperms • CO2 taken in and O2 given out by leaves for/from photosynthesis. • Dissolved O2 taken in with H2O from soil by roots for tissue respiration. • During daylight: O2 out > O2 in • In dark of night: O2 out < O2 in Leaf Anatomy Stomata — “little mouths” — adjustable openings for gas exchange on the undersides of leaves O2 bubbles forming from stomata Heyer 5 Plant Biology Two main classes of angiosperms: • Monocots — grasses & grains (~70,000 spp.) • Dicots —non-grasses (~180,000 spp.) Secondary xylem & phloem in woody plants Vascular Plants Xylem - up! Phloem - down! Annual growth rings in woody plants Gymnosperms “naked seeds” Conifers “cone bearers” Seed-plant reproduction Spermatophytes Heyer 6 Plant Biology Gymnosperm Life Cycle Gymnosperm Seed Development Angiosperms — the flowering plants Flowers — the sex organs • Non-reproductive perianth >250,000 known living species = 90% of all plant species Style – Sepals form calyx – Petals form corolla • Male organ: Stamen – Filament & Anther – Anther produces pollen • Female organ: Carpel – Stigma , Style & Ovary – Stigma collects pollen – Ovary produces ovules Receptacle Reproductive Phase Changes of Meristem and Floristic Development • Floral Anatomy Heyer Meristem identity genes: leaf primordia Æ floral primordia • Organ identity genes: which floral primordia becomes which floral component – The ABC hypothesis 7 Plant Biology Flowers Flower Morphology • Complete flower – calyx+corolla+stamens+ carpels • Hermaphroditic: – Both male + female organs in same flower regular / radial symmetry irregular / bilateral symmetry • Monoecious : Lily [note non-green sepals!] – Separate male flowers & female flowers on the same plant • Dioecious : – Separate male flowers & female flowers on separate plants Staminate flower Carpellate flower Begonias Flower Morphology and Ovary Position Floral characters relevant to pollination Flies Wind dull white, green, purple Bats bright white, yellow, blue Bees dull white, green Beetles red, orange, white Birds red, orange, purple Butterflies dull brown, purple dull green, brown strong, fruity fresh, mild, pleasant fruity, spicy none spicy, none putrid none regular, bowlshaped. Closed during day tubular with shallow landing platform large, bowlshaped large, funnelshaped; perch support, but no landing platform narrow tube with wide landing pad shallow funnel or trap-like regular or petals reduced or absent; stigmata protruding night day day day day any time any time abundant; hidden usually present; not hidden sometimes present; not hidden abundant; deeply hidden abundant; deeply hidden usually none none FLOWER color odor Hypogynous flower with superior ovary • • • Perigynous flower with superior ovary Epigynous flower with inferior ovary Hypogynous (flower “below ovary ”): ovary positioned on the peak of the receptacle ( torus). Other flower parts arise below the base of the carpels. E.g., Pea. Perigynous (flower “around ovary ”): ovary positioned in cup-like torus. Other flower parts arise from edge of the cup. E.g., Rose. Epigynous (flower “above ovary ”): ovary completely embedded and fused within the receptacle. Other flower parts arise from the top of the ovary. E.g., Apple. Angiosperm Gametophyte Development Heyer shape bloom time nectar Angiosperm Gametophyte Development 8 Plant Biology Angiosperm Life Cycle Double Fertilization in Angiosperms Germinating pollen grains Angiosperm “vessel seeds” DicotAngiosperm Seed Development A fruit is a structure to protect and disperse the embryos within the seeds walls of ovary thicken to form fruit to carry the seeds Placentation • Attachment of ovules to ovarian wall – Becomes more conspicuous as ovary develops into fruit • Simple fruits develop from a single ovary of a single flower • Compound fruits develop from the fusion of many ovaries or many flowers Heyer 9 Plant Biology Fruit: vessel (angio-) containing seeds • Pericarp – derived from ovarian wall (carpel). Surrounds seeds while they develop – Endocarp – innermost layer Fruit: agents of seed dispersal • Autochory: self dispersed (explosive or recoil) • Anemochory (wind-) & Hydrochory (water-dispersed) – Mesocarp – middle layer – Exocarp – outermost layer Fruit: agents of seed dispersal • Autochory: self dispersed (explosive or recoil) • Anemochory (wind-) & Hydrochory (water-dispersed) • Zoochory (animal-dispersed) Fruit Types • Simple Fruit: derived from a single ovary – Dehiscent Fruit : fruit remains attached to plant. Splits open to release mature seeds • Pod; capsule; follicle – Synzoochory – stockpiling & sloppy feeding – Epizoochory – attach/adhere to fur/feathers/feet – Endozoochory – digestion-resistant seeds pass through gut Legume pod Fruit Types • Simple Fruit: derived from a single ovary – Indehiscent Fruit : fruit dispersed with seeds. • Dry Fruit : pericarp hardens – Grain (Caryopsis): pericarp thin, fused to seed coat – Achene : pericarp thin, not fused to seed – Nut: pericarp forms thick shell, not fused to seed Fruit Types • Simple Fruit: derived from a single ovary – Indehiscent Fruit : fruit dispersed with seeds. • Fleshy Fruit : mesocarp thick/pulpy/juicy (= sarcocarp ) – Berry: endocarp thin » Bacca (true berry) : exocarp Æ thin skin » Tomato, grape, coffee bean, cucumber » Hesperidium: exocarp Æ thick rind » Citrus Heyer 10 Plant Biology Fruit Types • Simple Fruit: derived from a single ovary – Indehiscent Fruit : fruit dispersed with seeds. • Fleshy Fruit : mesocarp thick/pulpy/juicy (= sarcocarp ) – Drupe : endocarp thickens/hardens Æ pit around single seed » Peach, cherry, plum, mango, olive, coconut Fruit Types • Simple Fruit: derived from a single ovary – Indehiscent Fruit : fruit dispersed with seeds. • Accessory Fruit (Anthocarp): pericarp thin; other flower parts contribute to much of fruit structure – Pome : papery pericarp from inferior ovary forms core around seeds; receptacle/ perianth form fleshy layer & skin » Apple, pear Fruit Types Fruit Types • Compound Fruit: derived from multiple ovaries or multiple flowers • Compound Fruit: derived from multiple ovaries or multiple flowers – Aggregate drupes : from flowers with multiple ovaries; each drupelet with tiny pit • Blackberry, raspberry – Aggregate achenes with accessory fruit : from flowers with multiple ovaries; multiple achenes on fleshy receptacle ( torus ) • Strawberry Seed Development Fruit Types Monocots vs. Dicots • Compound Fruit: derived from multiple ovaries or multiple flowers (inflorescence) – Multiple fruit : fusion of fruits from multiple flowers (2) • Pineapple, fig, mulberry (1) Heyer 11 ...
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