UMD BSCI 442 - Lecture 2 Plant body: form & function

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1Lec 2. Plant body: form & function1. Seed plants are the most successful land plants. Why?Main stages of a plant’s life cycle.2. Plants have developed appropriate structures to carry out the functions: leaf, stem, root, flower3. Organs are made of tissues. Tissues are made of different cell types4. How do plants develop organs, tissues and cells?5. Why do cell types differ in structure and function?Differential gene expression: DNA Æ RNA Æ protein Different enzymes/proteins are workingRef. BSCI 124, lec. 2 & 4The fossil records of some protist and plant groups. The width of the shaded space is an indicator of the number of species. Image from Purveset al., Life: The Science of Biology, 4th Ed.450 m200 m600 m65 mGeologic time: Fossil records indicate that higher plants evolved from algaeLand plants evolved from an algal ancestor.Plants developed adaptations to survive on land• 1. Surface to prevent drying out.• 2. Pores for gas exchange• 3. Support to give structure to plant body• 4. Plumbing system to distribute nutrients and water.• 5. Accomplish fertilization without an aqueous environment.• 6. Development of seed with dormant embryo.Angiosperms or flowering plantsare the most advanced and dominant plants.1. Monocot2. DicotDicotMonocot2Major stages in the life of a plantSeedlingAutotrophsVegetative PlantReproductive plantSeed -1. Seed germination3. Development of the reproductive organs (flower)4. Seed formation2. Development of the plant bodyHeterotrophsSeed GerminationDevelopment of the vegetative plant body.Plants develop appropriate structures to carry out special functions.Veg. plant body is made of 3 organs:•leaf•Stem•rootReproductive development involves formation of flowers1. Sepal2. Petal3. Stamen: male organ 4. Pistil: female organInsect or bird pollinated flowers are colored and fragrant.Reproductive development involves formation of flowersStamen: male organPistil: female organPollinationFertilizationFig. 1-2. TaizIn corn, male and female flowers are separated.3Grass Flower: WheatWheat spikeletSepal= PetalWind pollinated flowers are not showyReproductive OrgansFlower: produces egg and spermpromote pollination and fertilization4 organs: •Sepals•Petals•Stamens•pistilsFruit: protects embryo from harsh environment,protects embryo from animalspromotes seed dispersion? Difference between fruit and seed?1. A plant body is made up of cells, tissues and organs.ORGANS:Veg. body is made up of three organs: function?leaf,stemrootReproductive organs are:flowerfruitTissues: Each organ is made of several tissues.A tissue has a particular function.1. dermal2. ground3. vascular[4. Meristem]Cell typesTissues1. dermal2. ground3. vascularMain function is ?4Cell types: A tissue consists of one or more cell types.1. Dermal tissue includes the epidermis, guard cell (leaf)2. Ground tissue: includes cortex, mesophyll parenchyma 3. Vascular tissue includes xylem tracheids, phloem sieve tube, companion cellsCells are grouped in tissues and several tissues make up an organ.The ability of plants to grow and develop depends on the ability of individual cells to divide, differentiate and to carry out their intended functions.LS of Root shows different growth zonesRoot Cross-Section5How do plants develop organs & cell types?Plants development is characterized by permanent embryogenyUnlike animals, plants can grow indefinitely at the growing tips.• shoot apical meristem• root apical meristemGrowth and Development includes:•Cell Division•Enlargement (or Elongation)•Differentiation (or specialization)---> cell typesMeristems: cells can continuously divide•Shoot apical meristem--->leaf and stem•Root apical meristem--> root•Cambium --->increase girth of stemHow do roots grow?16-13. Shoot apical meristemShoot apical meristem Floral apical meristem6RecapName these foods: Organ?CarrotSpinachSugar caneTomatoBrocolliCorn on the cobTissues of a rootWhy do cell types look and behave differently?1-10.Differential GeneexpressionWhy do cells differ in form and function?1-4. Plant


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UMD BSCI 442 - Lecture 2 Plant body: form & function

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