BIOL 240W 1st Edition Lecture 4 Outline of Last Lecture I. Cation Exchangea. Capturing nutrientsb. Soil pHc. Problems with phosphateII. The Nitrogen Cyclea. Rhizobium bacteriaIII. Mycorrizal fungiOutline of Current Lecture I. Plant Structure and GrowthII. Three Basic Plant OrgansIII. Dermal Tissue, Vascular Tissue, Ground TissueIV. Differences Between Plant and Animal CellsV. Three Major Types of Plant CellsVI. XylemVII. PhloemCurrent LectureI. Plant Structure and Growtha. Growing in response to what is happening in surrounding environmentb. “plastic”- plant responds to environmental cues.c. Monocots/dicots- associated with cotyledon. Both differ in structurei. Monocots- grasses, corn, cerealii. Dicots- what we think of when we think of a plantII. Three Basic Plant Organsa. Roots- involved with anchorage, water scavenging, mineral uptake. Non-photosynthetic, need sugar from shoots (reliance on stems and leaves above ground)i. Dicots- use a taproot that is a big, main root that allows for support and tall growth of plantii. Monocots- small, trailing plants with a fibrous root system. Early embryonic root dies, leaving adventitious roots.iii. Absorption from rootsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Root hairs are single cells projecting from roots that absorb water and minerals from their tips. iv. Remember- roots form mycorrhizal associationsb. Stems- contain vascular tissuei. Support, but mostly transportii. Node- stem where leaves or other lateral organs attachiii. Internode- region in between nodeiv. Apical Bud- “tip”/top of shoot. Also referred to as terminal bud (end). This is where organ differentiation occursv. Axillary bud- occurs on leaf/stem junction. Remains dormant because of apical dominance. Only receive signal if the apical bud is removedc. Leavesi. Blade- solar collector (collect energy from sun)ii. Petiole- joins blade to stem at internodeiii. Main site of photosynthesis. Green stems may also be photosynthetic, butleaves are primary contributor to photsynthesisiv. Monocots and dicots have differently arranged veins (vascular tissue of leaves)1. Monocots- parallel veins2. Eudicots/dicots- branching veinsv. Varieties of leaves- single, compound, doubly compound (depending on leaflets)vi. To determine if a structure is a leaf, locate axillary budd. Plants have evolved, we can see this by the fact that they have parts both above and below the ground.i. Stems and leaves depend on roots to obtain minerals underground. Rootsdo not have chloroplasts. ii. Roots depend on stems and leaves to supply photosynthetic products for energy. III. Dermal Tissue, Vascular Tissue, Ground Tissuea. Dermal tissue- outside layer of cellsi. Herbaceous (non-woody)- single cell layer thick of dermal tissue (epidermis)ii. Woody plants have multiple cell layers in dermal tissue (periderm)iii. Leaves and stems covered with waxy cuticle to prevent water lossb. Vascular Tissuei. Xylem- bring water and minerals up from roots into shootsii. Phloem- transport sugars made in leaves and stems to roots and other parts of the plantiii. Stele- stele of roots forms a solid, central vascular cylinder. The stele in the upper part of the plants (stems and leaves) becomes bundles with strands of both xylem and phloem together.c. Ground Tissuei. Everything that isn’t dermal or vascular tissueii. Pith- what happens inside vascular tissueiii. Cortex- outside of vascular tissue, especially stemIV. Differences of Plant cells and animal cellsa. Plant cells contain chloroplasts, vacuoles, cell walls, and plasmodesmatab. Cell wallsi. Primary- all plant cells contain a primary cell wall. It is thin and flexible and does not contain lignin.ii. Secondary- formed later in certain plant cell types. It is a thick and stiff structure containing ligninV. 3 Major types of plant cellsa. Parenchyma- i. Typical plant cell (ex: leaves). Contains only primary cell wall, is classified as ground tissue, photosynthetic, large central vacuole, relatively undifferentiated, totipotent (can turn into other types of cells)b. Collenchyma- i. mostly strand of cells just below the epidermis. Contains only primary cellwall, classified as ground tissue, thicker primary wall than parenchyma, living at maturity. c. Sclerenchyma-i. Rigid support cells. Contain secondary cell walls. Still classified as ground tissue. Dead at maturity.VI. Xylema. Tracheids-Dead at maturity. Conducts water. Part of vascular tissue. Contain thick, lignified secondary cell walls. Long, thin, hard tubes to allow water flow. Pits enable water movementb. Vessel Elements- dead at maturity, vascular, wider, thinner walls compared to tracheids, connected end to end to make “pipes”,VII. Phloema. Sieve-tube elements- alive at maturity, but do not have nucleus/ things needed for cell growthb. Companion cells, provide what sieve tube elements do not
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