LIFE 103 (Erik Arthun) Week 5 Notes
LIFE 103 (Erik Arthun) Week 5 Notes LIFE 103
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This 9 page Class Notes was uploaded by Lauren Caldwell on Friday February 19, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Erik Arthun, Tanya Dewey in Spring 2016. Since its upload, it has received 15 views. For similar materials see Macrobiology; Plants and Animals in Biology at Colorado State University.
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Date Created: 02/19/16
2/15 Chapter 30 (cont.) Angiosperms are defined by two features; fruit and flowers Life cycle Ploidy o Egg and sperm are both (n) - haploid o Embryo is (2n) - diploid o Seed coat is (2n) - diploid o Endosperm is (3n) - triploid This develops into the fleshy part of the fruit Cotyledons - first two leaves - not photosynthetic o Primary function is to help the organism develop o Its green just because it has chloroplasts It already has a TON of sugars so there's no need for photosynthesis Diversity o 250k extant species live today o Greater specialization allows plant traits to more closely match environments and needs High angiosperm diversity mean angiosperm style of life has specialized successfully in many unique environments o Originally divided into two groups Monocots One cotyledon Dicots Two cotyledons People are generally more familiar with dicots than monocots o Now four groups Eudicots 'true' dicots (includes the dicots group, for the most part) Basal Flowering plants with the oldest lineages angiosperms Ex: water lilies Magnoliids Shares some traits with basal angiosperms but evolved later Ex: magnolias Monocots About 25% of all flowering plants on the planet Has 1 cotyledon Parallel veins On the leaves, they don’t fan out from main veins Vascular tissue scattered through the stem Xylem and phloem scattered throughout the stem No given pattern to the arrangement through the stems Roots are fibrous and there is no main root Pollen grain has a single opening Floral organs are all in multiples of three This refers to the pattern and arrangement of the petals Ex: orchids, grasses, palms Eudicots About 75% of all flowering plants on the planet Has two cotyledons Netlike or spreading out veins on leaves Vascular tissues arranged in a ring Roots stem from a main taproot Pollen trains with three openings Floral organs in multiples of four or five Ex: roses, pear trees, strawberry plants, walnut trees Includes legumes too Five traits of seed plants o Reduced gametophytes o Heterosporus Micro and mega spores o Ovules o Pollen o Seeds How seed plants impact humans o Key sources for food, fuel, wood products, and medicine o Preservation of plant diversity is critical o Most of our food comes from angiosperms Six crops (wheat, rice, maize, potatoes, cassava, and sweet potatoes) yield 80% of calories consumed by humans o Modern crops products of genetic changes resulting from artificial selection We have expanded the physical sizes of plants o Many seed plants create would Tree rings are xylem only 2/17 Examples of seed-plant based medicine Asprin Eye pupil dilator o Note: our teacher is allergic to this Heart medication Throat soother Malaria preventive o Quinine: in tonic water o Put into gin and alcohol for the British colonials in India to drink Ovarian cancer drug Muscle relaxant Leukemia drug Threats to Plant Diversity Extinction of these plants are being led by humans In the tropical rainforest, 55,000 kilometers of rain forest are cleared every year o At this rate, within two hundred years, there will be no remaining tropical rainforest o Great contribution to the accumulation to Global Warming Loss of plant habitats are leading to major animal extinction o At this rate, about 50% of earth's species will become extinct within the next 100-200 years Chapter 35: Plant Structure, Growth, and Development Organs o Each has specialized tissue composed of specialized cell types Required in order to carry out particular functions Most basic breakdown of organ systems o Two systems for the three organs: Root system and Shoot system Root system -> underground: gathers water and minerals Shoot system -> above ground: produces sugar through photosynethsis o Leaf Main tool for photosynthesis Intercepts light, exchanges gas, dissipates heat, and defends the plant form herbivores and pathogens Anatomy Blade Flattened section - aka, the leaf itself Petiole Stalk that connects the leaves to the stem So, honestly, each branch is a petiole Variations Simple leaf A single leaf Prevents the entire leaf from being torn of Compound leaf Several leaves attached to a single petiole We know this is different from an actual stem since there is no axillary bud attached to these guys Spines Spikes, like on cacti Tendrils The little twin that comes from bean plants Will actually, when it comes into contact with support structures around it, will grow to wrap itself around it Reproductive leaves On succulents Each time one of these little flowering leaves falls, it develops into a new plant Storage leaves Onions Looks like a solid little plump plant, but is actually the leaf surrounding the stem o Stem Alternating system of nodes, aka the place where leaves are attached Internodes are the places between nodes Aka, stretches of the stem that do not have leaves or branches rising of Apical bud The very top point of any shoot that is growing This can be either the very, very top of the plant, or the tips of laterally growing branches IF an apical bud is cut of, axillary buds will continue to grow This helps a plant become bushier Axillary bud Structure that has the potential to develop into lateral branches, thorns, or flowers Tucked into the little cleft just above a branch Modified stems (NOTE: each variation below is a genetic clone of the original organism - each time it expands and grows out, it is through asexual reproduction) Rhizome The stem actually is underground, and roots still grow of of it Stolon Allows asexual reproduction for plants The stems are modified to, instead of moving laterally and horizontally underground, it grows on the surface Each "runner," little ofshoots of the stolon, will also take root in the earth beneath them Tuber A potato, actually A stem full of storage material - carbohydrates, etc New shoots grow out of an "eye" of the potato This is actually a node from the stem o Root 1. Anchors plant in place 2. Absorbs minerals and water 3. Stores carbohydrates Variations Taproot - a main, vertical root, helps tall plants stay upright Most dicots are taproots Lateral roots - branches that stem from the taproot, improves anchorages and water absorption Root hairs - grows of the lateral roots, very high surface area and high access to water and nutrients Radicle - embryonic root, aka, the first root to emerge for the baby plant Fibrous - the dead radicle and is replaced by a series of fine, adventitious roots These are for smaller plants The radicle does not develop into a taproot Instead, the roots grow from the stem/the base of the plant Much more difficult to completely uproot and destroy the plant when being graized on by meandering animals Udicots are generally fibrous Prop roots Kinda rises the plant up - roots are visible Comes from the stem, not the taproot Helps with preventing falling over Storage rots Beats, carrots, sweet potatoes Carbohydrates are stored here Pneumatophores "Arial roots" For Mangroves Roots rise up, so in low tide, absorbs oxygen Tissue o Each plant has dermal, vascular, and ground tissues o All are present in every organ in the plant o Each has own functions Dermal Protects from parasites and outside conditions Root hair Three parts Extensions of 1. Epidermis - outermost layer epidermal cells 2. Cuticle - waxy coating from the roots Prevents desication Single-cell-thick Vascular Transportation throughout the plant Rings of a tree Two parts Dead xylem 1. Xylem - water and minerals moving upward o Thickened Water conducting cells cell walls Two cell types stay behind Tracheids Vessel elements Essentially connected together like pipes Pits Cells that connect neighboring xylem together Perforation plates Kinda like grates through xylem that filters water through Both are dead upon maturity of the plant 1 Phloem - sugars transported throughout the stem Two elements Sieve-tube elements ALIVE No organelles present - simply because its so focused on transporting phloem sap Sieve plates Porus end walls that allow fluid motion between cells along the sieve tubes Ground Storage, support, photosynthesis, transport, etc. anything that is NOT Dermal or Vascular Pith o Tissue on the inside/between (of) the vascular system Cortex o Tissue on the outside of the vascular system Ground tissue in leaves is the place where photosynthesis occurs 2/19 Plant Anatomy (cont.) Three basic cell types o Parenchyma Synthesis and storage of sugar Least specialized type Most metabolic functions Cells that store starch, water, protein, etc o Collenchyma Flexible support for younger parts of the plant Thicker and uneven cell walls o Scleremchyma Rigid, found in mature stem pieces Strengthened by lignin Dead upon functional maturity Cannot lengthen - only in plant parts that have stopped growing Plant growth Meristems o Able to give rise to new tissues (essentially plant stem cells) Perpetually embryonic tissue Aka, can give rise to all cell types throughout their existence Two types of meristems - apical meristems and lateral meristems Apical meristems - the tips of a plant (roots and top) The growth directed towards LEGNTH is primary growth We CAN have primary xylem and primary phloem - this is the fundemental growth of both vascular tissues Lateral meristems - adds thickness to woody plants The growth directed towards width is secondary growth Two types: Vascular Cambium Adds layers of vascular tissue called secondary xylem (wood) and secondary phloem Cork cambium Replaces the epidermis of a plant with periderm, which is thicker and tougher o Indeterminate growth -> the ability to grow all throughout its life This applies to all plants o Some plant organs cease to grow at certain sizes This is the opposite and is called determinate growth Ex: leaves, thorns, and flowers - they all reach their biggest size and stop growing Primary v Secondary growth Primary growth Secondary growth Length - to get taller and Width - mostly for woody deeper plants Roots In woody plants, primary Root Cap growth and secondary growth occur o Protects the simultaneously but in different locations apical meristem tissue o Created BY the apical meristem o Growth occurs just behind this root tip in three zones of cells: Zone of cell division W here mitosis and cytokinesis produces new cells Zone of elongation C ells lengthen Zone of diferentiation C ells become distinct cell types Growth on the cellular level Plant growth occurs through cell division and cell elongation o Cell division mostly occurs in meristems Cell elongation accounts for most of the increase in plant size o Plant cells elongate by filling a large central vacuole with water o Literally can only go up down, not outwards Ground tissue - mostly parenchyma cells - fills with CORTEX, the space between vascular cylinder and epidermis o The innermost layer of the cortex is called the endodermis The endodermis regulates passage of substances from the soil into the vascular cylinder (like a bouncer, really) o Cortex - storage material For eudicots, xylem is more like a cross or star shape - phloem surroudnms it For monocot, it is in rings Lateral root formation Comes from within the pericycle, the outermost cell layer in the vascular cylinder o Forces its way out of the cortex and epidermise on its way out from the very center From it comes an apical meristem The closer an axillary bud is to the active apical bud, the more INHIBITED it is o If you remove or inhibit the apical meristem, the plant will grow outwards as the axillary blud meristems will continue to grow There will no longer be the hormonal inhibition preventing the plant from 'bushing out' Tissue organization of stems The vascular cylinder in roots is now a ring o In most eudicots, the vasuclar tissue is made up of vascular bundles arranged in a ring o For monocots, the vascular bundles are scattered throughout the ground tissue