Plantae Seed Plants Vascular Plants • Formation of vascular tissue – Xylem (water) – Phloem (food) – True leaves, roots, and stems • Lignin • ____________ generation dominate Alternation of Generation Alternation of Generation • Sporophyte dependent on gametophyte – mosses • Large sporophyte and small independent gametophyte – ferns • Gametophyte dependent on sporophyte – seed plants Why be Sporophyte Dominant? • Reduced mutations – UV light harmful to DNA – Diploid (2n) form copes better with mutations • two alleles Why Retain Gametophyte Generation? • Ability to screen alleles – doesn’t require a large amount of energy • Sporophyte embryos rely on some gametophyte tissue Seeds • A seed is a sporophyte in a package – spores are only single cells – packaged with food • All seed plants are _____________ (more than one kind of spore) – megasporangia – microsporangia From Ovule to Seed Develops from megaspore Whole structure Embryo, food supply, protective coat Overview of Seed Plants • Produce Seeds – Can remain dormant for years – Pollination replaces swimming sperm • Gametophyte generation reduced – Gymnosperms lack antheridium – Angiosperms lack both archegonium and antheridium Phylogeny Gymnosperms (Naked Seed) • Division: Cycadophyta • Division: Ginkgophyta • Division: Gnetophyta • Division: Coniferophyta Ginkgophyta • Ginkgo or Maidenhair Tree • Characteristic leaves • Only one species • Only ______ are planted Cycadophyta • Cycads • Palm-like plants – Sago Palms • Leaves in cluster at top of trunks • True __________ Gnetophyta • 3 Genera • Ephedra • Mormon Tea – ____________ • raises heart rate • raises blood pressure Coniferophyta Coniferophyta • Pine tree is the sporophyte generation • Contains both male and female cones – Pollen (___________) cones (low in tree) • produces pollen – Ovulate cones (high in tree) with scales • produces seeds Pine Life Cycle • No Antheridium (microsporangia) produce pollen grain (4 cells) –2 prothallial cells –1 generative cell »produces 2 sperm –1 tube cell –__________ for dispersal Pine Life Cycle • Ovule in a ovulate cone – integument (seed coat) (2n) – megasporangia or nucellus (nutrition) (2n) – 4 _______________ from female gametophyte (3 die) • develops into female gametophyte –archegonium with eggs (n) Angiosperms Angiosperm Flower • Sepals • Stamen • Petals – Anther – Filament • Receptacle (part of the stem) • Carpel – Stigma – Style – Ovary with ovule Angiosperm Life Cycle Angiosperm Life Cycle • No Antheridium (microsporangia - diploid) • produce pollen grain –1 ___________ cell »produces 2 sperm –1 tube cell Angiosperm Life Cycle • Ovule in Ovary – megasporangia – produces 4 megaspores (3 die) • remaining one develops into female gametophyte called the _____________ Angiosperm Life Cycle • Embryo sac (Female Gametophyte) consists of: – 7 cells (eight nuclei) due to 3 mitotic divisions • 3 ___________ • 2 polar nuclei (one cell) • 2 __________ • 1 egg Angiosperm Life Cycle • Double fertilization – one sperm unites with egg – one sperm unites with polar nuclei • develops into endosperm (3n) • Fruit and Seed development – ovule = seed – ovary = fruit Angiosperm Life Cycle Cross Pollination • Most flowers do not self-pollinate – stamen and carpal may develop at different times – stamen and carpal may be arranged in flower to avoid contact Angiosperm Radiation • Begins the Cenozoic era (65 mya) • Most closely related to the Gnetophyta • __________ – the mutual influence of two species on each other – plants and animals (insects, birds, bats) Pollination Dispersal The Global Impact • Transformed atmosphere – reduced carbon dioxide – cooled the earth • Nonrenewable/Renewable resource Plant Structure And Growth The Plant Body is Composed of Cells and Tissues •Tissue systems (Like Organs) –made up of tissues •Made up of cells Plant Tissue Systems • ____________________ Øphotosynthesis Østorage Øsupport • ____________________Vascular Tissue System Øconduction Øsupport • ___________________Dermal Tissue System ØCovering Dermal Tissue System • Epidermis – Single layer, tightly packed cells – Complex Tissue – Does different things in different areas (roots vs. leaves) – usually transparent – secretes cuticle • ___________Periderm – – replaces epidermis in woody plants – protection • ____________Root System – Tap Root – Lateral Roots • ____________Shoot System – Stems • Nodes (leaves are attached) • Internodes – Leaves • blades • petioles – Buds • Terminal (apical) Plant • Axillary Systems Plant Growth • ______________Meristematic Tissue –generates cells for new growth (like stem cells in animals) •apical meristems •lateral meristems Apical Meristems • increases length called primary growth –___________Protoderm - gives rise to dermal tissue –________________Ground Meristem - gives rise to ground tissue –_____________ - gives rise to vascular tissue Lateral Meristems • increases girth called secondary growth –__________________- produces secondary xylem and secondary phloem –______________Cork Cambium - produces cork (outer most layer of bark) Pine Tree w/ 8 Cotyledons! The Root System • Functions – anchor plant – absorb minerals, water and nutrients – store food • Systems – ____________ - one large root with smaller lateral roots (dicots) – ____________Fibrous roots - threadlike roots (monocots) Root Tissue • Protoderm - gives rise to the epidermis • Ground Meristem – Cortex (external to vascular tissue) • Procambium - gives rise to the _______Stele (the vascular tissue of a root or stem) – xylem and phloem – may include pith (parenchyma cells surrounded by vascular tissue) Dicot Root vs. Monocot Xylem (larger, in red) Endodermis Phloem (smaller, greenish) Pericycle – one layer IN from endoderm, gives “Pith” – central core of rise to lateral roots parenchyma cells surrounded by xylem and phloem Modified Roots • Food Storage • Pnematophores – carrots, sweet – mangroves potatoes, yams • Aerial Roots • Water Storage – orchids – pumpkin family • Buttress Roots • Propagative – tropical trees Roots • Haustoria – cherries, pears – dodder Shoot System Stems (Primary Growth) • Protoderm - gives rise to the epidermis • Procambium - gives rise to the stele – xylem and phloem in vascular bundles •dicots - found in ring •monocots - scattered throughout – includes “pith” in dicots • Ground Meristem – Cortex ____________ – stele (vascular tissue) divided into strands in stems and leaves Sclerenchyma cells Phloem Xylem Dicot Stem Vs. Monocot (35.16) Vascular Bundle Ground Tissue (Pith) (Cortex) How can you tell root from stem? Stems (Secondary Growth) • Occurs to increase girth (thickness) – Vascular Cambium • produces secondary xylem and secondary phloem – Cork Cambium • produces cork and phelloderm (thin layer of parenchyma cells) • together these structures are called periderm (Cork Cambium, cork, phelloderm) Secondary Growth Derivative Vascular cambium Secondary Growth of a Stem Secondary Growth of a Stem (Inside to Outside) • Pith • Secondary Phloem • Primary Xylem • Primary Phloem • Secondary Xylem • Cortex (wood) • Phelloderm • Vascular • Cork Cambium Cambium Periderm • Cork (outer layer of bark) Older, inner layers of 2° Xylem – no longer transport water Younger, outer layers of 2° Xylem still function in transport All tissue outside vascular cambium Missing cortex and phelloderm! ___________ (Early) growth occurs more quickly. Cells are large and thin walled and have less strength. Summerwood (Late) growth occurs more slowly. Cells are thicker, more dense, and stronger. Modified Stems • __________ - horizontal stems above the ground (strawberries) • Rhizomes - horizontal stems below the ground (Irises) • Tubers - swollen areas of rhizomes or stolons (Potatoes) • Bulbs & Corms - vertical shoots under ground (onions, garlic w/ mod storage leaves) • _____________Cladophylls - cactus pads Leaf Structure Leaves • Epidermis – __________Stomata - openings on underside of leaf – Guard Cells - surround stomata – Cuticle - waxy coating excreted by epidermis • Mesophyll - middle of leaf – ___________Palisade Layer - photosynthesis – Spongy layer - gas exchange Modified Leaves • ___________Tendrils - attachment • Bracts –modified leaves that surround a group of flowers • Spines - protection • Storage Leaves - succulents Uptake of Nutrients _______________Hydroponic cultures used to determine which chemical elements are essential. 17 essential elements needed by all plants NEED TO KNOW THE CHART!!! Soil • Develops from weathered rocks – Anchors plants – Provides water – Provides dissolved minerals Soil Texture • Pertains to sizes of soil particles – includes the following: • sands (0.02 - 2 mm) • silt (0.002 - 0.02 mm) • clay (less than 0.002 mm) • Loams (40/40/20) Control Systems in Plants Plant Hormones • Coordinates growth • Coordinates development • Coordinates responses to environmental stimuli Auxins • Stimulates stem elongation • Stimulates root growth • Stimulates differentiation and branching • Stimulates development of fruit • Stimulates apical dominance • Stimulates phototropism and gravitropism Auxin Control • Auxin stimulates growth • Auxin block on right causes cells to elongate and the plant bends left • Auxin block on left causes cells to elongate the the plant bends right ___________Acid Growth Hypothesis • Proton pump stimulated by auxin lower pH of wall • H+ activates Enzyme • Enzyme breaks hydrogen bonds in cellulose • Wall takes up water and elongates Auxin Others • Promotes secondary growth by stimulating vascular cambium and secondary xylem • Promotes adventitious root at the base