chapter 23 roots, stems, & leaves. specialized tissues seed plants are organized into different...

Download Chapter 23 Roots, Stems, & Leaves. Specialized Tissues Seed plants are organized into different tissues and organs Three principal organs are: 1. Roots

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Chapter 23 Roots, Stems, & Leaves

Chapter 23 Roots, Stems,& LeavesSpecialized TissuesSeed plants are organized into different tissues and organsThree principal organs are:1. Roots2. Stems 3. LeavesEach work together to at a slow efficient pace to ensure the plants survivalRootsFunctions:1. absorb water and dissolved nutrients2. anchor plants to ground; prevent erosion3. Protect plant from harmful bacteria and fungi4. transport water and nutrients to rest of the plant

StemFunctions:1. support system that maintains or hold leaves and branches2. transport system that carries nutrients3. defense system against predators and disease

LeavesFunctions:1. primary photosynthetic organ of the plant2. contains subsystems that prevent water loss3. Gas exchange (CO2 and O2)

Plant Tissue SystemsThree main tissue systems:1. Dermal tissue outer layer much like skin2. Vascular tissue bloodstream for transport of water and nutrients3. Ground tissue layers of plant in between dermal and vascular tissue

Dermal TissueEpidermal cells make up the outer layer of plantCuticle - outer waxy covering of the epidermal cells that protects the plant from water loss and injuryDermal tissue appears in different ways throughout structure of the plantEx: root hairs that increase water absorption- guard cells on the leaf that regulate gas exchange and water loss

Vascular TissueForms that transport system that moves water and nutrients throughout the plant- much like circulatory system in humansTwo tissues of vascular system:1. Xylem water conducting tissue- composed of tracheids & vessel elements2. Phloem food conducting tissue- composed of sieve tubes & companion cells

Ground TissueFound between dermal and vascular tissue- Parenchyma cells with thin cell walls and large vacuoles that help with storage in leaf- Collenchyma strong flexible cell walls that help with support in stem- Sclerenchyma thick, rigid cell walls for support in stemGrowth and Meristematic TissueMeristematic tissue is only plant tissue that produces new cells by mitosis- tissue is undifferentiated or does not have a function yet- forms cluster of cells that will contribute to growth of roots and stem- Apical meristem found at the end or tip and will increase length of stem and roots when the cells divideTypes of RootsTwo main types of roots:1. Taproots primary root grows long and thick, while others are smallEx: carrots, beets, radishes, oak trees*Mainly Dicots2. Fibrous roots branch out so that each root is about the same size- prevents topsoil from washing awayEx: grasses*Mainly Monocots

Monocots vs. Dicots

Root Uptake and NutrientsPart of the roots function is to absorb water and nutrients- plants expend energy to do this - nutrient uptake help facilitate other processes that will aid in growth, reproduction and flowering- Nitrogen, phosphorus, potassium, magnesium, and calcium are essential nutrients- sulfur, iron, zinc, chlorine, boron, copper, manganese, and molybdenum are trace elementsStemStems can be any shape or sizeStems can grow entirely underground or high into the airNodes distinct regions where leaves attach to the stemBuds undeveloped tissue that can produce new stems and leavesVascular BundlesVascular bundles carry out the transport of materials from the roots to the leaves- includes xylem and phloem tissue- Monocots have bundles scattered throughout the stem- Dicots have bundles arranged in a ring

Growth of StemsPrimary growth occurs with cell divisions of the apical meristemAs most plants grow they must also increase in thickness to support more branches and leavesSecondary growth occurs by expansion of 2 kinds of tissue in the lateral meristem- vascular cambium thickens by producing new layers of xylem and phloem- cork cambium tissues that form outer protective covering

Formation of Wood Wood is simply older layers of xylemWhen xylem at the center of the stem has stopped conducting water it is known as heartwood (dark wood)Sapwood surrounds heartwood, and is active in fluid transport (lighter wood)Alteration of dark and light wood produces tree rings which are used to estimate age of tree

BarkBark is formed from vascular cambium, phloem, cork cambium, and corkEach layer expands to accommodate the otherOutermost cork contains cells with thick cell walls and usually contains fats, oils, and waxes (waterproofing)Dead cells of cork (bark) crack and flake off in patches or stripsWood and Bark

LeavesConsidered the most important manufacturers of food that directly or indirectly affect all organismsBlades are the flattened sections of the leaf that collect sunlightPetiole connects the blade to the stemNo matter the shape, same structures in all leaves

Leaf StructureIn order to carry out photosynthesis the leaf depends on specialized ground tissue called mesophyllPalisade mesophyll contains the chloroplasts to absorb sunlightSpongy mesophyll connects to exterior through the stomata (pores)

Leaf FunctionsGuard cells regulate the opening and closing of stomas in response to water pressure- Water pressure high guard cells pull away from each other opening the stomata to relieve pressure- Water pressure low guard cells move together to conserve- acts same in both cases of water conservation and gas exchangeTranspiration - loss of water through the leavesTransport Xylem is the main tissue of water transport that spans from roots to leavesActive transport draws water into the rootsCapillary action is the tendency of water rise in thin tubes - xylem network changes to thinner transport tubes as it reaches leaf


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