* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 35 notes
Survey
Document related concepts
Plant defense against herbivory wikipedia , lookup
Plant breeding wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Plant ecology wikipedia , lookup
Plant nutrition wikipedia , lookup
Plant reproduction wikipedia , lookup
Plant physiology wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Plant morphology wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Transcript
Chapter 35: Plant Structure, Growth, and Development The plant body has a hierarchy of organs, tissues, and cells • Plants, like multicellular animals, have organs composed of different tissues, which are in turn are composed of cells The Three Basic Plant Organs: Roots, Stems, and Leaves • Basic morphology of vascular plants reflects their evolution as organisms that draw nutrients from below-ground and above-ground • Three basic organs are evolved: – Roots – Stems – Leaves • They are further organized into a __________________________ system and a __________________________ system Roots • Functions of roots: – __________________________ the plant – __________________________ minerals and water – Often storing organic nutrients • In most plants, absorption of water and minerals occurs near the root tips, – The vast numbers of tiny root hairs increase the __________________________ – Many plants have modified roots • Prop roots: arises from the stem, penetrates the soil, and helps support the stem; corn • Storage roots: modified for storage of food or water; carrots and beets • Strangling aerial roots: entirely above the ground; ivy • Buttress roots: large roots on all sides of a tall or shallowly rooted tree; rainforest trees • Pneumatophores: roots rising above the ground, especially above water, contain a large number of breathing pores for exchange of gases; mangrove genera Stems • A stem is an organ consisting of: – An alternating system of nodes and internodes • __________________________: points at which leaves are attached • __________________________: stem segments between nodes • __________________________ bud: structure that has the potential to form a lateral shoot, or branch • __________________________ bud: located near the shoot tip and causes elongation of a young shoot • Many plants have modified stems – Stolons: specialized type of above ground shoot, a colonizing organ that arises from an axillary bud near the base of the plant; strawberry – Bulbs: underground vertical shoot that has modified leaves that are used as food storage organs by a dormant plant; daffodil – Tubers: enlarged stems to store nutrients, used to survive the winter or dry months, means of asexual reproduction; potatoes – Rhizomes: horizontal stem that is usually found underground, often sending out roots and shoots from its nodes; ginger Leaves • The leaf is the main photosynthetic organ of most vascular plants • Leaves generally consist of – Flattened blade – Stalk – __________________________: joins the leaf to a node of the stem • Some plant species have evolved modified leaves that serve various functions – Tendrils: threadlike shape that is used for support and attachment, generally by twining around whatever it touches; clematis – Spines: sharp, pointy ends, used to protect themselves from herbivores; cactus – Storage leaves: serve as food storage organs; aloe – Bracts: associated with a reproductive structure such as a flower, poinsettia – Reproductive leaves: contain new plants at tips; walking fern The Three Tissue Systems: Dermal, Vascular, and Ground • Each plant organ has dermal, vascular, and ground tissues – The dermal tissue is the outside protect layer, specifically known as the __________________________ – Vascular tissue: carries out long-distance transport of materials between roots and shoots • __________________________: conveys water and dissolved minerals upward from roots into the shoots • __________________________: transports organic nutrients from where they are made to where they are needed – Ground tissue includes cells specialized for storage, photosynthesis, and support Common Types of Plant Cells • Like any multicellular organism, a plant is characterized by cellular differentiation, the specialization of cells in structure and function • Some major types of plant cells: – Water-conducting cells of the xylem – Sugar-conducting Cells of the phloem Types of Plant Cells 1. Water-conducting cells of the xylem – __________________________: long thin cells with tapered ends • Water moves through pits – Vessel elements: wider, shorter, less tapered cells • Aligned end to end, forming long pipes • Ends are perforated 2. Sugar-conducting cells of the phloem – Sieve-tube members: chains of cells • Ends are connected with __________________________, that have pores to allow nutrients through Meristems generate cells for new organs • Plants grow throughout their lives – __________________________: complete life cycle in 1 year or less – __________________________: complete life cycle in 2 years or less – __________________________: live many years • Plants can constantly grow because of meristems: perpetual embryonic tissue Root Meristems – Apical meristems are located at the tips of roots and in the buds of shoots • Elongate shoots and roots, a process called __________________________ Shoot Meristems • Lateral meristems add thickness to woody plants, a process called __________________________ – There are two layers of lateral meristems • __________________________ cambium: adds layers of vascular tissue called secondary xylem (wood) and secondary phloem • __________________________ cambium: replaces the epidermis with periderm, which is thicker and tougher Primary growth lengthens roots and shoots • Primary growth produces: – Primary plant body – Parts of the root – Parts of the shoot systems Primary Growth of Roots • The root tip is covered by a __________________________, which protects the apical meristem as the root pushes through soil • Growth occurs just behind the root tip, in three zones of cells: – Zone of cell division – Zone of elongation – Zone of maturation Primary Growth of Shoots • A shoot apical meristem is a dome-shaped mass of dividing cells at the tip of the terminal bud • It gives rise to a repetition of internodes and leaf-bearing nodes Tissue Organization of Leaves • The epidermis in leaves is interrupted by __________________________ – Allow CO2 exchange between the air and the photosynthetic cells in a leaf • Flanked by __________________________, which regulate opening • The ground tissue in a leaf is sandwiched between the upper and lower epidermis – This region is the __________________________ – Cells are loosely arranged to allow CO2 and O2 • The vascular tissue of each leaf is continuous with the vascular tissue of the stem Morphogenesis and Pattern Formation • Morphogenesis in plants, as in other multicellular organisms, is often controlled by __________________________ genes • Pattern formation is the development of specific structures in specific locations – It is determined by positional information in the form of signals indicating to each cell its location • __________________________ is one type of positional information • In the gnom mutant of Arabidopsis, the establishment of polarity is defective Gene Expression and Control of Cellular Differentiation • In cellular differentiation, cells of a developing organism synthesize different proteins and diverge in structure and function even though they have a common genome – A cell’s position in a developing organ determines its pathway of differentiation • Cellular differentiation to a large extent depends on positional information and is affected by homeotic genes Genetic Control of Flowering • Flower formation involves a phase change from __________________________ growth to __________________________ growth – It is triggered by a combination of environmental cues and internal signals • Transition from vegetative growth to flowering is associated with the switching-on of floral meristem identity genes • The __________________________ of flower formation identifies how floral organ identity genes direct the formation of the four types of floral organs • An understanding of mutants of the organ identity genes depicts how this model accounts for floral phenotypes