Textbook Notes (368,432)
Canada (161,877)
Biology (396)
BI111 (135)
Tristan Long (112)
Chapter 27

Chapter 27 Detailed Notes.docx

26 Pages
Unlock Document

Tristan Long

Chapter 27: The Plant Body 27.1 Plant Structure and Growth: An Overview • Photosynthetic shoot system extending upward into the air and a  nonphotosynthetic root system extending down into the soil Growth in Plants  Determinate growth common in animals  Indeterminate growth in plants  Plant grows throughout life  Meristems give rise to plant body  Why would this be adaptive?  Plasticity of growth gives some flexibility since plants cannot move around  Plants grow by:  Increase in number of cells  Increase in size of cells Shoot Systems: Functions  Stems, leaves, buds, flowers  Highly adaptive for photosynthesis & positions flowers for pollination  Vegetative (nonreproductive) shoot  Stem with attached leaves and buds  Bud gives rise to extension of shoot or new, branching shoot  Reproductive shoot  Produces flowers which later develop fruits containing seeds Root Systems: Functions  Usually grows below ground  Anchors plant and supports upright parts  Absorbs water and dissolved minerals from soil  Stores carbohydrates 27.1a Cells of All Plant Tissues Share Some General Features • Organs: body structures that contain two or more types of tissues and have a  definite form and function o Includes leaves, stems, roots • Tissue is a group of cells and intercellular substances that function together in one  or more specialized tasks • Primary cell walls surround the plasma membrane and cell contents(cytoplasm  and organelles) o Made of cellulose • Plasmodesmata is a cytoplasmic connection between adjacent cells that allows  solutes such as amino acids and sugars to move from one cell to the next o Space between primary walls and adjacent cells is filled with  polysaccharide layer called middle lamella • As a plant grows, different types of cells deposit additional cellulose and other  materials inside primary wall, forming secondary cell wall o Contain lignin: makes walls o strong and impermeable to water • the ability of almost any cell to give rise to all other parts of a plant is totipotency o allows plants to heal wounds o one mean of asexual reproduction 27.1b Shoot and Root Systems Perform Different but Integrated Functions • a stem with its attached leaves and buds is a vegetative shoot (nonreproduuctive) • a reproductive shoot produces flowers, which later develop fruits containing seeds 27.1c Meristems Produce New Tissues throughout a Plant’s Life • determinate growth: growing to a certain size and then growth stops • indeterminate growth: growing throughout lives • meristems produce new tissues more or less continuously while the plant is alive 27.1d Meristems Are Responsible for Growth in Both Height and Girth • all plants have apical meristems: clusters of self­perpetuating tissue at the tips of  their buds, stems, and roots • tissues that develop from apical meristems are called primary tissues, and they  make up the primary plant body • growth of the primary plant body is called primary growth • secondary growth originates at cylinders of tissue called lateral meristems and  increases the diameter of older roots and stems • tissues that develop from lateral meristems are secondary tissues Primary Growth  Apical meristems at root and shoot tips  Self-perpetuating clusters of cells  Increases height of shoot, length of roots Secondary Growth (in some species)  Lateral meristems at root and shoot tips  Self-perpetuating cylinder of tissue  Increases diameter of stems and roots Primary Growth and Stems  Primary growth produces primary plant body Derivatives of theApical Meristem: Three Primary Meristems  Protoderm  Produces stem’s epidermis  Procambium  Produces primary xylem and phloem  Ground meristem  Produces ground tissue Modifed Stems Spatial & temporal variation in temperature • Ocean environments are less variable than those on land Primary Growth and Leaves  Leaf Primordia gives rise to leaves 27.1e Monocots and Eudicots Are The Two General Structural Forms of Flowering Plants • eudicots: trees, shrubs, non woody plants • monocots: grasses, lilies, cattails, corn, rice • monocot seeds have one cotyledon, eudicot has two o cotyledon: leaves produced by the embryo 27.1f Flowering Plants Can Be Grouped According to Type of Growth and Lifespan • annuals are herbaceous plants in which the life cycle is completed in one growing  season with minimal or no secondary growth o animals typically only have apical meristems • biennials such as carrots complete their life cycle in two growing seasons and  limited secondary growth occurs in some species • perennials, vegetative growth and reproduction continue year after year 27.2 The Three Plant Tissue Systems • simple tissues have only one type of cell • complex tissues are organized with arrays of two or more types of cells • ground tissue system (makes up most of the plant body) functions in metabolism  (including photosynthesis), storage, and support • vascular tissue system consists of xylem and phloem, which transport water and  nutrients throughout the plant o cylinders of vascular tissue are embedded in ground tissue • dermal tissue system is a shin like protective covering for the plant body Vascular Plant Body  3 Tissue Systems: Ground, Vascular & Dermal  Organ/Tissue system: Body structure that contains two (or more!) types of tissues and have a definite form and function  Tissue: Group of one (or more!) types of cells and intercellular substances that function together in one (or more!) specialized tasks Primary Shoot System  Consists of main stem, leaves, and buds  Plus any attached flowers and fruits  Stems are adapted to provide  Mechanical support  House vascular tissues  Food and water storage  Buds and meristems for growth  Leaves carry out photosynthesis and gas exchange Lignin  Some plant cells have “lignified” secondary cell wall  Cellulose fibres anchored with lignin: stronger and more rigid  Creates waterproof barrier (hydrophobic)  Resistant to decay and attack by microbes Plant Tissue System: Form & Function  3 Tissue Systems: Ground, Vascular & Dermal  Ground tissues are all structurally simple but exhibit important differences  Vascular tissues are specialized for conducting fluids  The dermal tissue system protects plant surfaces Ground, Vascular, and Dermal Tissues 27.2a Ground Tissues Are All Structurally Simple but Exhibit Important Differences • 3 types of tissues: parenchyma, collenchyma, sclerenchyma • parenchyma: soft primary tissues o makes up bulk of primary growth of roots, stems, leaves, flowers, fruits o thin primary wall o permeable to water o large air spaces o storage, secretion, photosynthesis o alive and metabolically active when mature o Thin primary cell walls, pliable and permeable to water, often round o Air spaces (gas exchange, buoyancy) o Specialized for storage, secretion, photosynthesis  They are found in the cortex and pith of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds. o Metabolically active when mature o Capable of additional cellular division (meristematic) if stimulated • collenchyma: flexible support o strings in celery o strengthen plant parts o cellulose and pectin o walls stretch as the cell enlarges, growing organs o alive and metabolically active, continue to synthesize primary wall layers  as the plant grows o Thicker (uneven) primary cell walls (pectin) – especially at the corners o Elongated cells in strands or sheath like cylinder o Not uniformly thick walls o Strengthen plant parts still elongating  Found adjacent to outer growing tissues and the vascular cambium o Metabolically active & meristematic  Additional growth stimulated by mechanical stress • sclerenchyma: rigid support and protection o Thick, uniform, secondary cell walls (hemicelluslose & lignin) o No air spaces between them, large amount of strength o Adding lignin chokes off plants, and thus these cells are terminal o Dead at maturity as cut off from rest of organism o Found in stems, leaf veins and make up the hard outer covering of seeds & nuts. o Two major types  Sclereids (protective casings) • Cells are irregular in shape. Commonly found in fruit and seeds.  Fibres (support) • Cells are often needle-shaped with pointed tips – some elasticity Ground Tissues 27.2b Vascular Tissues Are Specialized for Conducting Fluids • xylem: transporting minerals and water o conducts water and dissolved minerals absorbed from the soil upward  from a plants roots to the shoot o types of conducting cells:  tracheid’s • elongated with tapered, overlapping ends • strong secondary walls to keep plants from collapsing when  water becomes scarce • water can move between through pits o seeps laterally between cells  vessel members • shorter, wider cells joined end to end in tubelike columns  called vessels • have pits • as they mature, enzymes break down portions of their end  walls, producing perforations • moves water more efficiently • phloem: transporting sugars and other solutes o transports solutes and sugars made in photosynthesis through the plant  body o main conducting cells are sieve tube members connected end to end  end walls called sieve plates, are studded with pores  immature sieve tube members contain the usual plant organelles,  but the cell nucleus and internal membranes in plastids break  down, mitochondria shrink, and cytoplasm is reduced to a think  layer lining the interior surface of the cell wall • specialized parenchyma cells known as companion cells are connected to mature  sieve tube members by Plasmodesmata Vascular Tissue: Xylem • Conducts water and dissolved minerals • Thick, lignified secondary walls • Dead when functional Types of Xylems: Tracheids and Vessel Members Tracheids • Elongated, tapered, overlapping ends • Lateral connections through pits Vessel members • Shorter, tubelike columns • Lateral connections through pits and perforations • Vessel members are better at quickly moving water, more easily blocked by air bubbles in water Vascular Tissue: Phloem • Conduct sugars and other solutes • Living* when functional Sieve Tube Members  Joined end to end in sieve tubes  Sieve tube cells assisted by “companion cells”  Parenchyma cells that load and unload organic compounds into sieve tube  End walls (sieve plates) studded with pores 27.2c The Dermal Tissue System Protects Plant Surfaces • epidermis covers primary plant body in single continuous layer or multiple layers  of packed cells • external surface of epidermal cell walls is coated with waxes that are embedded in  cutin, a network of chemically linked fats • epidermal cells secrete cuticle which resists water loss and helps protect against  attacks by microbes • guard cells contain chloroplasts and so can carry out photosynthesis o pore between guards is stomata
More Less

Related notes for BI111

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.