BIOL 2061 1st Edition Lecture 11Outline of Last Lecture I. Drawing of the Alternation of generationsII. Sporophyte/gametophyteIII. Growth and developmentIV. Plant organsV. GerminationVI. Plant Stem cellsVII. Vegetative growthVIII. Reproductive developmentIX. Seed life timeX. Comparing monocots & DicotsOutline of Current Lecture I. Plant growth and developmentII. Distinctive architectureIII. Maintenance of Stem cellsIV. Primary meristemsV. Expansions of cells by waterVI. Modular structureVII. StemsThese 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.VIII. LeavesIX. Roots Current LectureI. Plant growth and development-a. Four essential parts:i. Cell divisionii. Growthiii. Cell specializationiv. Apoptosis (A death of cells that occurs as a normal and controlled part of an organism growth or development)b. Cell migration DOES NOT occur in plants.c. Development and maintenance of a distinctive architecture throughout lifed. Increase in length is due to the activity of primary meristemse. Maintenance of a population of a young stem cells in meristemsf. Expansion of cells in controlled directions, by water uptakeII. Distinctive Architecture-a. Apical Pole= upperb. Basal Pole= lowerc. SAM is the upper poled. RAM is the basal polee. Plants have RADIAL symmetryi. Stem and root cylindricalf. Leaves and flower parts are on whorls or spiralsIII. Maintenance of Stem Cells-a. Stem Cell- plant meristem cells that remain undifferentiated but can produce new tissues.b. Stem cell divides to produce one cell that is not specialized and one that can differentiate.i. One can have a specific job where the other can become anything that the plant needs it to be.IV. Primary Meristems-a. SAM and RAM produce additional meristem tissues the increase plant length andproduces new plant organsb. Primary meristems produce primary tissues.i. Protoderm- generates dermal tissues (epidermis)ii. Procambium- produces vascular tissues (primary xylem and phloem)iii. Ground meristem- produces ground tissues defined by location (cortex and pith)V. Expansion of cells by water uptake-a. Growth includes producing new cells and cell expansion.b. Occurs when water enters the central vacuole by osmosis VI. Modular Structure-a. Module has 4 parts:i. Leaf- source of photosynthesisii. Node- where leafs emergeiii. Internode- the stem section between 2 nodesiv. Axillary meristem- a bud with a meristem that can produce new flowers or branchesb. You can tell a plants age by the number of bod scale scars!VII. Stems-a. Provides the plant stability and reproductive structuresb. Provides transportation between roots and leavesc. Act as a food storaged. New primary stems tissues arise by the cell divisions at the base of the SAMe. Epidermis develops at the stem surfacei. Produces a WAXY CUTICLE (reduces water loss)f. Cortex- made of parenchyma tissuei. Parenchyma has ability to undergo cell division to repair damages.ii. Stores starch in plastidsg. Vascular tissue made of xylem and phloem arranged in vascular bundlesi. Eudicot= ringii. Monocot= spread outh. Has collenchyma- made of collenchyma cellsi. Has Sclerechyma- made of fibers and scleridsj. Adaptations pf stems-i. Rhizomes- forms new roots and stems (underground)ii. Tubers- plants that are enlarges to store nutrients (potatoes)iii. Stolons- horizontal connections between organisms (above ground)k. Primary V. Secondary Growthi. Herbaceous plants produce mostly primary vascular tissuesii. Woody plants produce primary and secondary vascular tissues1. Woody plants begin as herbaceous seedlings with only primary vascular systems.Vascular Cambium- is a ring of dividing cells that produces secondary xylem to itsinterior and secondary phloem to its exterior. Secondary xylem conducts most of a woody plant's water and minerals.Secondary xylem- conducts most of a woody plant's water and minerals. Cell divisions that occur in secondary meristems increase the girth of woody stems. During each new growing season, the vascular cambium produces new cylinders of secondary xylem and secondary phloem. In temperate trees, each year's addition of new secondary xylem forms growth rings that can be observed on the cut stem surfaces. If environmental conditions favor plant growth, the growth rings formed at that time will be wider than those formed during stressful conditions.VIII. Leaves-a. Photosynthesisb. Cellular respirationc. Transpirationd. Animal foode. Flower reproductionf. Why flat? More surface area for light absorptionWhy do tree trunks have a thicker layer of wood (secondary xylem) than of inner bark (secondaryphloem)? Secondary xylem may transport water for several years, but usually only the current year's production of secondary phloem is active in food transport. This is because thin-walled sieve elements typically live for only a year. Cork- is produced by a secondary meristem called the cork cambium, another ring of actively dividing cells. The cork cambium surrounds the secondary phloem (see Figures 35.20 and 35.22). Cork cells are dead when mature, and their walls are layered with suberin, a material that helps to prevent both attacks by microbial pathogens and water loss from the stem surface.g. Why thin? Better for heat sheddingh. Young leaves are produced at the side of SAMs in leaf primordiai. hormones also influence the transformation of primordia into leaves. The cells of leaf primordia do not produce a protein known as KNOX, which is produced by other shoot meristematic cells. KNOX is a transcription factor, a protein that regulates gene transcription. The absence of KNOX proteins induces leaf primordia to produce a plant hormone known as gibberellic acid. This hormone stimulates both cell division and cell enlargement, causing young leaves to grow.i. The cuticle faces the sun because it helps prevent drying outj. The stomata are on the bottom to help aid in gas exchange of CO2 and O2 also preventing the plant from losing too much water.k. Leaf surface features-i. Cuticle- helps from drying outii. Trichomes- offers extra protection from excessive light, temperature and herbivoresiii. Leaf form-1. Simple- only one blade, advantageous in shade by providing maximal light absorption (node at base of leaf)a. Simple leave example 2. Complex/ compound- dissected into leaflets, common in hot environments for heat dissipationa. Complex/compound leaf exampleiv. Leaf venation-1.