Plant Structure and Transport

1. Plant Structure and Transport

2. Basic Structure • Plants have different organs and tissues • Tissue- a group of cells consisting of one or more cell types that together perform a specialized function • Organ- consists of several types of tissues and serves a specific purpose in the plants • Plants grow (at different speeds) throughout their lives

3. Basic Plant Organs • Roots, stems, and leaves are the basic plant organs • Together they form a root system (below ground) and a shoot system (above ground) Shoot system Root system

4. Roots • The roots are part of the root system • The roots are an organ that anchors a vascular plant in the soil and absorbs minerals and water and often stores carbs • Gymnosperm and angiosperm have a taproot system that consists of one main vertical root – the taproot • The taproot gives rise to the lateral roots • Monocots, however, do not have taproots • Most absorption occurs at the tip of the roots (the root cap) • This root cap also serves as a protective barrier between the soil and the innards of the roots • Root hairs increase the surface area/volume ratio of the roots

5. Stems • Part of the shoot system • They are an organ that raises or separates leaves , exposing them to light • To do this they rely on their alternating systems of nodes- the points at which leaves are attached- and internodes- the stem segments between the nodes • Growth • The growth of stems forms an angle between the leaf and stem which is called the axillary bud- they form branches • Growth itself occurs at the tip, better known as the apical bud • Removal of the apical bud allows the axillary bud to grow node internode

6. Leaves • Part of the shoot system • They are the main photosynthetic organ in the plant • Consist of: • Blade (actual leaf) and a stalk (joins the leaf to the stem) • Differences between monocots and eudicots • Monocots have a parallel major vein (the vascular tissue of leaves) that runs the length of the leaf • Eudicots have a branched network of veins • Different leaves • Simple leaves – a single undivided blade that is deeply lobed on the side • Compound leaves – the blade has multiple leaflets which have no axillary bud • Doubly compound leaves – each leaflet is divided into smaller leaflets

7. Kinds of Leaves Simple leaf Compound leaf Doubly Compound leaf

8. Tissues • Three types of tissue systems • Dermal tissue system • Vascular tissue system • Ground tissue system

9. Dermal Tissue System • It serves as the plants outer protection against physical damage and pathogens • The root “derma-” means skin, so it is the outer layer of the tissue system • Differences between woody and non-woody plants • In woody plants it is called the epidermis • In non-woody plants it is called the periderm

10. Vascular Tissue System • It carries out the long distance transport for the plant between its root and shoot systems • 2 types of vascular tissue: • Xylem – conducts water and dissolved minerals UP from roots to shoots • Phloem – transports sugars from where they were made (leaves) to where they are needed (roots and sites of growth)

11. Ground Tissue System • The tissues in a plant that are neither dermal nor vascular • Two types of ground tissue: • Pith – ground tissue that is internal to the vascular tissue • Cortex – ground tissue that is external to the vascular tissue

12. Primary Growth of Roots • Cause by the apical meristems • The three zones: • Zone of differentiation • The place where cells complete their differentiation and become distinct cells • Zone of elongation • Growth of the root occurs here • Zone of cell division • New cells are produced here

13. Primary Growth of Shoots • Caused by the apical meristem • Leaves develop from the leaf primordial • Branching happens from the activation of axillary buds • Tissue organization of leaves • Stomata form in the epidermis – they allow the exchange of CO2 and O2 • Stomata are surrounded by guard cells that regulate the opening and closing of the stomata • Each vein is enclosed by bundle-sheath cells which protect them

14. Stomata Video • http://www.youtube.com/watch?v=BfPKjlfWPmQ • Once the video is finished, do not close the browser, just reopen the powerpoint

15. Secondary Growth of Roots and Shoots • There is an increase in the diameter of stems and roots in woody plants • All of the layers of the trunk of trees, for example, are formed

16. Shoot Architecture and Light Capture Factors • The arrangement of leaves on a stem is known as the phyllotaxy • Without it the leaves would not be able to catch light • Leaf orientation • Horizontal leaves are for low light places • Vertical leaves are for intense light places

17. Main Compartments of Tissues • There are two main compartments • The apoplast consists of everything external to the plasma membranes of living cells • The symplast consists of the entire mass of cytosol of all living cells in a plant, along with the plasmodesmata

18. Short Distance Transport of Water across a Membrane • The absorption or loss of water by a cell occurs by osmosis – the diffusion of free water across a membrane • The property that detects the high to low potential direction that water flows is called water potential High potential High potential Low potential Low potential

19. Long Distance Transport of Water across a Membrane • It occurs through a process called bulk flow which is the movement of liquid in response to a pressure gradient • It always occurs from higher to lower pressures • It is independent of solute concentration

20. Water Potential • Water Potential is abbreviated as the symbol Ψ pronounced “sigh” • The water potential equation is Ψ = ΨS + ΨP • The ΨS stands for solute potential • This number is always negative because an increase in solute has a negative effect on water potential • The ΨP stands for pressure potential • This number is negative and positive relative to the atmospheric pressure

21. Works Cited • http://extension.oregonstate.edu/mg/botany/images/fig1.gif picture of plant with organs labeled • http://extension.entm.purdue.edu/pestcrop/2009/issue10/index.html picture of plant on 3rd slide • http://teenstudents.wordpress.com/2011/11/04/plant-growth-and-development/ Plant growth picture on 2nd slide • http://utsa.edu/sombrilla/fall2009/story/plastic-surgery-plants.html picture of roots in root slide • http://darwin-online.org.uk/content/frameset?itemID=F836&viewtype=text&pageseq=1 picture of branch in stem slide • http://mayang.com/textures/Plants/html/Leaves/index.html simple leaf picture • http://scioly.org/wiki/Forestry/Leaf_Types compound leaf picture • http://www.google.com/imgres?hl=en&sa=X&biw=1280&bih=699&tbm=isch&prmd=imvns&tbnid=zgceJGtgPgmESM:&imgrefurl=https://163.120.6.2/univ/naturepark/natural%2520history/honey%2520locust.asp&docid=awcnUSw_ZW8EBM&imgurl=https://163.120.6.2/univ/naturepark/natural%252520history/images/honeylocust5.jpg&w=260&h=266&ei=VzeeT9eoCKayiQLrq6hu&zoom=1&iact=hc&vpx=599&vpy=150&dur=9093&hovh=212&hovw=208&tx=140&ty=114&sig=107450691717456364362&page=1&tbnh=153&tbnw=150&start=0&ndsp=16&ved=1t:429,r:2,s:0,i:74 picture of doubly compound leaf • http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/plant%20structure/plant%20structure.htm tissue diagram • http://www.youtube.com/watch?v=BfPKjlfWPmQ stomata video • http://www.cliffsnotes.com/study_guide/Root-Zones.topicArticleId-23791,articleId-23669.html primary growth of roots picture • http://askville.amazon.com/Trees-grow-ring-wood-year-inside-outermost/AnswerViewer.do?requestId=2406761 tree diagram • http://en.wikipedia.org/wiki/Apoplast diagram of apoplast and symplast pathways • Biology textbook p 738- 741 slides 1-7 • Biology textbook p 742- 743 slides 8-11 • Biology textbook p 746- 750 slides 12-16 • Biology textbook p 768- 770 slides 17-20