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Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
Gen bio unit 3 part 1
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Gen bio unit 3 part 1

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  • 1. PLANTS AND ECOLOGY PART 1
  • 2. <ul><li>Plant Biology </li></ul><ul><ul><li>Photosynthesis (Chapter 8) </li></ul></ul><ul><ul><li>Plant Organization and Function (Chapter 9) </li></ul></ul><ul><ul><li>Plant Reproduction and Responses (Chapter 10) </li></ul></ul><ul><li>Ecology </li></ul><ul><ul><li>Nature of Ecosystems (Chapter 34) </li></ul></ul><ul><ul><li>The Biosphere (Chapter 35) </li></ul></ul><ul><ul><li>Environmental Concerns (Chapter 36) </li></ul></ul>
  • 3. <ul><li>CHAPTER 8 </li></ul><ul><li>UNIT 3 LESSON 1 </li></ul>
  • 4. <ul><li>Photosynthesis converts solar energy into chemical energy. </li></ul><ul><li>Organisms that carry on photosynthesis are called autotrophs. </li></ul><ul><li>Heterotrophs are organisms that feed on other organisms. </li></ul>
  • 5. <ul><li>Autotrophs and heterotrophs use organic molecules produced by photosynthesis </li></ul><ul><li>THUS THE MAJORITY OF LIFEFORMS ARE DEPENDENT ON PHOTOSYNTHESIS. </li></ul>
  • 6. <ul><li>Photosynthetic Reaction </li></ul><ul><ul><li>Solar energy + 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 </li></ul></ul><ul><li>Glucose and oxygen are the products of photosynthesis </li></ul><ul><li>The oxygen given off comes from water </li></ul><ul><li>CO 2 gains hydrogen atoms and becomes a carbohydrate </li></ul>
  • 7. <ul><li>Photosynthesis consists of two sets of reactions </li></ul><ul><ul><li>Photo refers to capturing light </li></ul></ul><ul><ul><li>Synthesis refers to producing a carbohydrate </li></ul></ul><ul><li>The two sets of reactions are called the: </li></ul><ul><ul><li>Light Reactions - thylakoids </li></ul></ul><ul><ul><li>Calvin Cycle Reactions - stroma </li></ul></ul>
  • 8. <ul><li>Electromagnetic Spectrum </li></ul><ul><ul><li>Visible light is used to drive photosynthesis </li></ul></ul>
  • 9. <ul><li>Visible Light </li></ul><ul><ul><li>The photosynthetic pigments in chlorophylls a and b and the carotenoids can absorb specific portions of visible light </li></ul></ul><ul><ul><ul><li>Chlorophyll a and b absorb violet, indigo, blue and red light </li></ul></ul></ul><ul><ul><ul><li>Carotenoids absorb violet-blue-green range </li></ul></ul></ul>
  • 10. <ul><li>Light Reactions </li></ul><ul><ul><li>Photosynthesis takes place in chloroplasts. </li></ul></ul><ul><ul><li>Light reactions consist of two alternate electron pathways: </li></ul></ul><ul><ul><ul><li>Noncyclic electron pathway </li></ul></ul></ul><ul><ul><ul><li>Cyclic electron pathway </li></ul></ul></ul><ul><ul><li>Both pathways transform solar energy to chemical energy </li></ul></ul><ul><ul><li>Both pathways produce ATP </li></ul></ul><ul><ul><li>The noncyclic pathway also produces NADPH </li></ul></ul>
  • 11. <ul><li>Noncyclic Electron Pathway </li></ul><ul><ul><ul><li>A photosystem consists of a pigment complex and electron acceptor molecules within the thylakoid membrane. </li></ul></ul></ul><ul><ul><ul><li>The pigment complex can be described as a “antenna” for gathering solar energy. </li></ul></ul></ul>
  • 12. <ul><li>Noncyclic Electron Pathway </li></ul><ul><ul><li>The noncyclic electron pathway uses two photosystems (PS I and PS II) </li></ul></ul><ul><ul><ul><li>PS II captures light energy </li></ul></ul></ul><ul><ul><ul><li>Energized electrons (taken from water) leave PSII and pass down an electron transport chain to PSI </li></ul></ul></ul><ul><ul><ul><li>This forms ATP </li></ul></ul></ul><ul><ul><ul><li>PS I captures light energy and ejects an electron that is transferred to NADP+ </li></ul></ul></ul><ul><ul><ul><li>NADP+ combines with H+, forming NADPH. </li></ul></ul></ul>
  • 13. <ul><li>The Cyclic Electron Pathway </li></ul><ul><ul><li>Uses only photosystem I (PS-I) </li></ul></ul><ul><ul><li>Begins when PS I complex absorbs solar energy </li></ul></ul><ul><ul><ul><li>Electrons escape from the reaction center and travel down electron transport chain </li></ul></ul></ul><ul><ul><ul><li>Released energy is stored in the form of a H+ gradient, which causes ATP production </li></ul></ul></ul><ul><ul><li>Electrons return to PS-I (cyclic) </li></ul></ul><ul><ul><li>Pathway only results in ATP production </li></ul></ul>
  • 14. <ul><li>The Calvin Cycle </li></ul><ul><ul><li>Series of reactions that use CO2 from the atmosphere to produce carbohydrate </li></ul></ul><ul><ul><li>Includes </li></ul></ul><ul><ul><ul><li>Carbon dioxide fixation </li></ul></ul></ul><ul><ul><ul><li>Carbon dioxide reduction </li></ul></ul></ul><ul><ul><ul><li>RuBP regeneration </li></ul></ul></ul>
  • 15. <ul><li>Fixation of Carbon Dioxide </li></ul><ul><ul><li>CO2 is attached to 5-carbon RuBP molecule </li></ul></ul><ul><ul><ul><li>This results in a 6-carbon molecule that splits into two 3-carbon molecules (3PG) </li></ul></ul></ul><ul><ul><li>Reaction accelerated by RuBP Carboxylase </li></ul></ul>
  • 16. <ul><li>Reduction of Carbon Dioxide </li></ul><ul><ul><li>Each 3PG molecules undergoes reduction to G3P in two steps </li></ul></ul><ul><ul><li>Energy and electrons needed for this reaction are supplied by ATP and NADPH. </li></ul></ul>
  • 17. <ul><li>Regeneration of RuBP </li></ul><ul><ul><li>RuBP used in CO2 fixation must be replaced </li></ul></ul><ul><ul><li>Every three turns of Calvin Cycle, </li></ul></ul><ul><ul><li>Five G3P (a 3-carbon molecule) used </li></ul></ul><ul><ul><li>To remake three RuBP (a 5-carbon molecule) </li></ul></ul><ul><ul><li>5 X 3 = 3 X 5 </li></ul></ul>
  • 18. <ul><li>Importance of the Calvin Cycle </li></ul><ul><ul><li>G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules </li></ul></ul><ul><li>The hydrocarbon skeleton of G3P can form: </li></ul><ul><ul><li>Fatty acids and glycerol to make plant oil </li></ul></ul><ul><ul><li>Glucose phosphate (simple sugar) </li></ul></ul><ul><ul><li>Fructose (which with glucose = sucrose) </li></ul></ul><ul><ul><li>Starch and cellulose </li></ul></ul><ul><ul><li>Amino acids </li></ul></ul>
  • 19. <ul><li>C3 Pathway </li></ul><ul><ul><li>When a three-carbon molecule is detected immediately upon CO2 fixation, this is called C3 photosynthesis. </li></ul></ul><ul><ul><li>RuBP can also bind with oxygen. </li></ul></ul><ul><ul><ul><li>This can be a wasteful reaction because it uses oxygen and releases carbon dioxide, decreasing the overall efficiency of the enzyme. </li></ul></ul></ul>
  • 20. <ul><li>C4 Pathway </li></ul><ul><ul><li>C4 photosynthesis bypasses this problem. </li></ul></ul><ul><ul><li>CO2 is initially fixed into a four-carbon molecule. </li></ul></ul><ul><ul><li>The four-carbon molecules is later broken down into a three-carbon molecule and CO2 </li></ul></ul><ul><ul><li>CO2 enters the Calvin cycle </li></ul></ul>
  • 21. <ul><li>C4 Pathway </li></ul><ul><ul><li>C4 plants tend to be found in hot, dry climates. </li></ul></ul><ul><ul><li>In these climates, stomata tend to close to conserve water. </li></ul></ul><ul><ul><li>Oxygen then builds-up in the leaves. </li></ul></ul><ul><ul><li>In C3 plants, the O2 would compete with CO2 for binding to RuBP. </li></ul></ul>
  • 22. <ul><li>CAM Pathway </li></ul><ul><ul><li>CAM plants partition carbon fixation by time </li></ul></ul><ul><ul><li>During the night CAM plants fix CO2 forming C4 molecules, </li></ul></ul><ul><ul><li>The C4 molecules are stored in large vacuoles </li></ul></ul><ul><ul><li>During daylight </li></ul></ul><ul><ul><li>C4 molecules release CO2 to Calvin cycle </li></ul></ul>
  • 23. <ul><li>CHAPTER 9 </li></ul><ul><li>UNIT 3 LESSON 2 </li></ul>
  • 24. <ul><li>Plant organ – a structure that contains different tissues and performs one or more specific functions </li></ul><ul><li>Vegetative Organs </li></ul><ul><ul><li>Roots </li></ul></ul><ul><ul><li>Stems </li></ul></ul><ul><ul><li>Leaves </li></ul></ul><ul><li>Reproductive Structures </li></ul><ul><ul><li>Flowers </li></ul></ul><ul><ul><li>Seeds </li></ul></ul><ul><ul><li>Fruits </li></ul></ul>
  • 25. <ul><li>See objectives 4-11 </li></ul>
  • 26. <ul><li>Flowering plants divided into 2 groups based on number of cotyledons (seed leaves) </li></ul><ul><ul><li>Monocots – one cotyledon </li></ul></ul><ul><ul><ul><li>Grasses, lilies, orchids, palm trees, etc. </li></ul></ul></ul><ul><ul><li>Eudicots – two cotyledons </li></ul></ul><ul><ul><ul><li>Larger group </li></ul></ul></ul><ul><ul><ul><li>dandelions, oak trees, etc. </li></ul></ul></ul>
  • 27.  
  • 28. <ul><li>Roots </li></ul><ul><ul><li>Generally, the root system is at least equivalent in size and extent to the shoot system </li></ul></ul><ul><ul><ul><li>Anchors plant in soil </li></ul></ul></ul><ul><ul><ul><li>Absorbs water and minerals </li></ul></ul></ul><ul><ul><ul><li>Produces hormones </li></ul></ul></ul><ul><ul><li>Root hairs: </li></ul></ul><ul><ul><ul><li>Projections from epidermal root hair cells </li></ul></ul></ul><ul><ul><ul><li>Greatly increase absorptive capacity of root </li></ul></ul></ul>
  • 29. <ul><li>Root Apical Meristem </li></ul><ul><ul><li>Protected by the root cap </li></ul></ul><ul><ul><li>Three Regions </li></ul></ul><ul><ul><ul><li>Zone of Cell Division </li></ul></ul></ul><ul><ul><ul><ul><li>Contains primary meristems </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Provides cells to zone of elongation as cells divide (mitosis) </li></ul></ul></ul></ul><ul><ul><ul><li>Zone of Elongation </li></ul></ul></ul><ul><ul><ul><ul><li>Cells lengthen and become specialized </li></ul></ul></ul></ul><ul><ul><ul><li>Zone of Maturation </li></ul></ul></ul><ul><ul><ul><ul><li>Contains fully differentiated (mature) cells </li></ul></ul></ul></ul>
  • 30. <ul><li>Tissue of a Eudicot Root </li></ul><ul><ul><li>Epidermis </li></ul></ul><ul><ul><ul><li>Outer layer of the root </li></ul></ul></ul><ul><ul><li>Cortex </li></ul></ul><ul><ul><ul><li>Loosly packed cells that permit water and minerals to move through </li></ul></ul></ul><ul><ul><ul><li>Cell contain starch granules to serve as food storage </li></ul></ul></ul><ul><ul><li>Endodermis </li></ul></ul><ul><ul><ul><li>Single layer of cells that form boundary between cortex and vascular cylindar </li></ul></ul></ul><ul><ul><ul><li>Casparian Strip – prevents water and minerals from moving to adjacent cells </li></ul></ul></ul><ul><ul><li>Vascular Tissue </li></ul></ul><ul><ul><ul><li>Xylem (water and minerals) and phloem (photosynthetic products) </li></ul></ul></ul><ul><ul><ul><li>Pericycle – development of branch roots </li></ul></ul></ul>
  • 31. <ul><li>Monocot Roots </li></ul><ul><ul><li>Ground tissue of root’s pith is surrounded by vascular ring </li></ul></ul><ul><ul><li>Have the same growth zones as eudicot roots, but do not undergo secondary growth </li></ul></ul>
  • 32. <ul><li>Root Diversity </li></ul><ul><ul><li>Primary root (taproot) - Fleshy, long single root, that grows straight down </li></ul></ul><ul><ul><ul><li>Stores food </li></ul></ul></ul><ul><ul><li>Fibrous root system - Slender roots and lateral branches </li></ul></ul><ul><ul><ul><li>Anchors plant to the soil </li></ul></ul></ul>
  • 33. <ul><li>Root Diversity </li></ul><ul><ul><li>Root Specializations </li></ul></ul><ul><ul><ul><li>Adventitious roots - Roots develop from organs of the shoot system </li></ul></ul></ul><ul><ul><ul><ul><li>Prop roots </li></ul></ul></ul></ul>
  • 34. <ul><li>Root Diversity </li></ul><ul><ul><li>Root Specializations </li></ul></ul><ul><ul><ul><li>Haustoria: </li></ul></ul></ul><ul><ul><ul><ul><li>Root like projections that grow into host plant </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Make contact with vascular tissue and extract water and nutrients </li></ul></ul></ul></ul><ul><ul><ul><li>Mycorrhizas: </li></ul></ul></ul><ul><ul><ul><ul><li>Associations between roots and fungi </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Assist in water and mineral extraction </li></ul></ul></ul></ul><ul><ul><ul><li>Root Nodules - Contain nitrogen-fixing bacteria </li></ul></ul></ul>
  • 35. <ul><li>Woody twigs provide a good example for studying stem organization. </li></ul><ul><ul><li>Terminal Buds – bud that develops at the apex of a shoot </li></ul></ul><ul><ul><li>Bud Scale – modified leaves that protect shoot tip </li></ul></ul><ul><ul><li>Leaf Scars / Bundle Scars – mark location of leaves that have dropped </li></ul></ul><ul><ul><li>Axillary Buds – bud located in the axil of a leaf; give rise to branches or flowers </li></ul></ul><ul><ul><li>Lenticle – permits gas exchange </li></ul></ul>
  • 36. <ul><li>Stems </li></ul><ul><ul><li>The main axis of a plant that elongates and produces leaves </li></ul></ul><ul><ul><li>Nodes occur where leaves are attached to the stem </li></ul></ul><ul><ul><ul><li>Internode is region between nodes </li></ul></ul></ul><ul><ul><li>Stems have vascular tissue that transports water and minerals </li></ul></ul><ul><ul><li>In some plants, stems carry on photosynthesis, or store water and nutrients. </li></ul></ul>
  • 37. <ul><li>Herbaceous Stems </li></ul><ul><ul><li>Mature nonwoody stems exhibit only primary growth </li></ul></ul><ul><ul><li>Outermost tissue covered with waxy cuticle </li></ul></ul><ul><ul><li>Stems have distinctive vascular bundles </li></ul></ul><ul><ul><ul><li>Herbaceous eudicots - Vascular bundles arranged in distinct ring </li></ul></ul></ul><ul><ul><ul><li>Monocots - Vascular bundles scattered throughout stem </li></ul></ul></ul>
  • 38. <ul><li>Woody Stems </li></ul><ul><ul><li>Woody plants have both primary and secondary tissues </li></ul></ul><ul><ul><li>Primary tissues formed each year from primary meristems </li></ul></ul><ul><ul><li>Secondary tissues develop during first and subsequent years from lateral meristems; increases girth of trunks, stems, branches, and roots </li></ul></ul><ul><li>Woody Stems </li></ul><ul><ul><li>Woody stems have no vascular tissue, and instead have three distinct regions </li></ul></ul><ul><ul><ul><li>Bark </li></ul></ul></ul><ul><ul><ul><li>Wood </li></ul></ul></ul><ul><ul><ul><li>Pith </li></ul></ul></ul>
  • 39. <ul><li>Bark </li></ul><ul><ul><li>Bark of a tree contains cork, cork cambium, and phloem </li></ul></ul><ul><ul><ul><li>Cork cambium produces tissue that disrupts the epidermis and replaces it with cork cells. </li></ul></ul></ul><ul><ul><ul><li>Cork cells provide waterproofing </li></ul></ul></ul><ul><ul><ul><ul><li>Lenticels are pockets of loosely arranged cork cells that allow gas exchange </li></ul></ul></ul></ul><ul><ul><ul><li>Phloem transports organic nutrients </li></ul></ul></ul>
  • 40. <ul><li>Wood </li></ul><ul><ul><li>Wood is secondary xylem that builds up year after year </li></ul></ul><ul><ul><li>Vascular cambium dormant during winter </li></ul></ul><ul><ul><li>Annual ring is made up of spring wood and summer wood </li></ul></ul><ul><ul><li>In older trees, inner annual rings no longer function in water transport </li></ul></ul><ul><ul><li>Annual rings can provide a growth record. </li></ul></ul>
  • 41. <ul><li>Stem Diversity </li></ul><ul><ul><li>Stolons: </li></ul></ul><ul><ul><ul><li>Above-ground horizontal stems </li></ul></ul></ul><ul><ul><ul><li>Produce new plants when nodes touch the ground </li></ul></ul></ul><ul><ul><li>Rhizomes: </li></ul></ul><ul><ul><ul><li>Underground horizontal stems </li></ul></ul></ul><ul><ul><ul><li>Contribute to asexual reproduction </li></ul></ul></ul><ul><ul><ul><li>Variations: </li></ul></ul></ul><ul><ul><ul><li>Tubers - Enlarged portions functioning in food storage </li></ul></ul></ul><ul><ul><ul><li>Corms - Underground stems that produce new plants during the next season </li></ul></ul></ul>
  • 42. <ul><li>Leaves </li></ul><ul><ul><li>Major part of the plant that carries on photosynthesis </li></ul></ul><ul><ul><li>Deciduous plants are those that lose their leaves every year. </li></ul></ul><ul><ul><li>Evergreens retain their leaves for two to seven years. </li></ul></ul><ul><ul><li>Foliage leaves are usually broad and thin </li></ul></ul><ul><ul><ul><li>Blade - Wide portion of foliage leaf </li></ul></ul></ul><ul><ul><ul><li>Petiole - Stalk attaches blade to stem </li></ul></ul></ul><ul><ul><ul><li>Leaf Axil - Axillary bud originates </li></ul></ul></ul>
  • 43. <ul><li>Leaves are the organs of photosynthesis </li></ul><ul><ul><li>Photosynthesis occurs within the chloroplasts in the mesophyll tissue of the leaves </li></ul></ul><ul><ul><li>Epidermal cells are covered with waxy cuticle to protect the leaf </li></ul></ul>
  • 44. <ul><li>Leaves are the organs of photosynthesis </li></ul><ul><ul><li>Trichomes (leaf hairs) are protective structures </li></ul></ul><ul><ul><li>Veins – contain xylem (water and mineral transport) and phloem (organic solutes) </li></ul></ul><ul><ul><li>Stoma – opening in the epidermis for gas exchange </li></ul></ul>
  • 45. <ul><li>Identify the following on the diagram </li></ul><ul><ul><li>Trichomes </li></ul></ul><ul><ul><li>Cuticle </li></ul></ul><ul><ul><li>Epidermis </li></ul></ul><ul><ul><li>Mesophyll </li></ul></ul><ul><ul><li>Vascular tissue </li></ul></ul><ul><ul><ul><li>Xylem </li></ul></ul></ul><ul><ul><ul><li>Phloem </li></ul></ul></ul><ul><ul><li>Stoma </li></ul></ul>
  • 46. <ul><li>Identify the following leaf arrangements </li></ul>
  • 47. <ul><li>Spines – catus spines are modified leaves that protect the fleshy stem </li></ul><ul><li>Tendrils - allow attachment to a physical support </li></ul><ul><li>Bulbs - Leaves that store food </li></ul><ul><li>Some leaves are designed to protect buds, and in some cases leaves capture insects. </li></ul>
  • 48. <ul><li>Tension created by evaporation (transpiration) at the leaves pulls water along the length of the xylem from the root hairs to the leaves </li></ul>
  • 49. <ul><ul><li>Water moves into root cells by osmosis; minerals by diffusion and active transport </li></ul></ul><ul><li>Transpiration-evaporation from the leaves creates a “sucking” force that pulls water upward through the xylem </li></ul><ul><li>Adhesion-water molecules interact with the walls of the xylem vessels to reinforce strength of column </li></ul><ul><li>Cohesion-water molecules are attracted to each other and form a continuous column within xylem from leaves to roots </li></ul><ul><li>Tension-created by transpiration; reaches from the leaves to the roots as long as column is continuous </li></ul>
  • 50. <ul><li>Role of Phloem </li></ul><ul><ul><li>Transports products of photosynthesis from the leaves to the site of storage </li></ul></ul><ul><li>Pressure-flow Model of Phloem Transport </li></ul><ul><ul><li>Sugar is actively transported into sieve tunes at a source </li></ul></ul><ul><ul><li>Water follows by osmosis </li></ul></ul><ul><ul><li>A positive pressure causes phloem contents to flow from the source to a sink </li></ul></ul><ul><ul><li>Sugar is actively transported out of sieve tubes, and cells use it for cellular respiration; water exits by osmosis </li></ul></ul><ul><ul><li>Some water returns to the xylem, where it mixes with more water absorbed from the soil </li></ul></ul><ul><ul><li>Xylem transports water to the mesophyll of the leaf </li></ul></ul><ul><ul><li>Most of the water is transpired, but some is used for photosynthesis, some reneters the phloem by osmosis </li></ul></ul>
  • 51. <ul><li>CHAPTER 10 </li></ul><ul><li>UNIT 3 LESSON 3 </li></ul>
  • 52. <ul><li>Plants have two stages in their life cycle. </li></ul><ul><ul><li>A diploid stage alternates with a haploid stage. </li></ul></ul><ul><ul><ul><li>The diploid plant is called the sporophyte. </li></ul></ul></ul><ul><ul><ul><li>The haploid plant is called the gametophyte. </li></ul></ul></ul><ul><li>Flowers are the reproductive structures of angiosperms. </li></ul><ul><li>Flowers produce two kinds of spores. </li></ul><ul><ul><li>Microspores develop into the male gametophyte. </li></ul></ul><ul><ul><ul><li>The male gametophyte produces sperm. </li></ul></ul></ul><ul><ul><li>Megaspores develop into the female gametophyte. </li></ul></ul><ul><ul><ul><li>The female gametophyte produces an egg. </li></ul></ul></ul>
  • 53. <ul><li>Upon fertilization, a zygote is formed. The zygote develops into an embryo. </li></ul><ul><li>A seed contains the embryo and stored food. </li></ul><ul><li>When a seed germinates, a new sporophyte emerges. </li></ul>
  • 54. <ul><li>Parts of a Flower </li></ul><ul><ul><li>Sepals - leaf-like structures that protect the developing bud </li></ul></ul><ul><ul><li>Petals - attract pollinators </li></ul></ul><ul><ul><li>Stamens - male portion of the flower </li></ul></ul><ul><ul><ul><li>Anther - produces pollen grains </li></ul></ul></ul><ul><ul><ul><li>Filament - a slender stalk that supports the anther </li></ul></ul></ul><ul><ul><li>Carpel - female portion of the flower </li></ul></ul><ul><ul><ul><li>Stigma - an enlarged stick knob </li></ul></ul></ul><ul><ul><ul><li>Style - a slender stalk </li></ul></ul></ul><ul><ul><ul><li>Ovary - encloses one or more ovules </li></ul></ul></ul><ul><ul><li>Flowers that have sepals, petals, stamens and carpels are called complete flowers. Flowers that do not are called incomplete. </li></ul></ul>
  • 55. <ul><li>Life Cycle of Flowering Plants </li></ul><ul><ul><li>During fertilization, one sperm nucleus unites with the egg nucleus, producing a zygote. </li></ul></ul><ul><ul><li>The other sperm unites with the polar nuclei, forming a 3n endosperm cell. </li></ul></ul>
  • 56. <ul><li>Development of the Eudicot Embryo </li></ul><ul><ul><li>The endosperm cell divides to produce endosperm tissue. </li></ul></ul><ul><ul><li>The zygote divides into two cells. </li></ul></ul><ul><ul><ul><li>One cell will become the embryo. </li></ul></ul></ul><ul><ul><ul><ul><li>Embryonic cells near the suspensor become the root, and those at the opposite end form the shoot </li></ul></ul></ul></ul><ul><ul><ul><li>The other cell will give rise to the suspensor. </li></ul></ul></ul><ul><ul><ul><ul><li>The suspensor anchors the embryo and transfers nutrients to it. </li></ul></ul></ul></ul>
  • 57. <ul><li>Development of the Eudicot Embryo </li></ul><ul><ul><li>The embryo changes from a ball of cells to a heart-shape </li></ul></ul><ul><ul><li>Cotyledons (seed leaves) appear </li></ul></ul><ul><ul><li>The embryo next becomes torpedo-shaped, and the root tip and shoot tip become visible </li></ul></ul><ul><ul><li>The epicotyl portion of embryo contributes to shoot development </li></ul></ul><ul><ul><li>The hypocotyl portion contributes to stem development </li></ul></ul><ul><ul><li>The radicle contributes to root development </li></ul></ul>
  • 58. <ul><ul><li>Eudicots (two cotyledons) </li></ul></ul><ul><ul><ul><li>Cotyledons store nutrients that the embryo uses </li></ul></ul></ul><ul><ul><li>Monocots (one cotyledon) </li></ul></ul><ul><ul><ul><li>Cotyledon absorbs food molecules from the endosperm and passes them to the embryo </li></ul></ul></ul>
  • 59. <ul><li>Fruit Types </li></ul><ul><ul><li>Fruits are derived from an ovary </li></ul></ul><ul><ul><li>Fruits protect and help disperse offspring </li></ul></ul><ul><ul><li>The ovary wall thickens to become the pericarp (may have three layers; exocarp, mesocarp, endocarp) </li></ul></ul>
  • 60. <ul><li>Fruit Types </li></ul><ul><ul><li>Simple fruits are derived from a simple ovary or from a compound ovary (several fused carpels). </li></ul></ul><ul><ul><ul><li>Dry fruits – ex. Legumes, cereal grains, etc. </li></ul></ul></ul><ul><ul><ul><li>Fleshy fruits – </li></ul></ul></ul><ul><ul><ul><ul><li>Peaches and cherries – mesocarp fleshy; endocarp hard </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tomatoes – pericarp fleshy </li></ul></ul></ul></ul><ul><ul><ul><li>Accessory fruits – bulk of fruit is from the receptacle instead of the ovary (ex. apple) </li></ul></ul></ul>
  • 61. <ul><li>Fruit Types </li></ul><ul><ul><li>Compound fruits develop from several individual ovaries. </li></ul></ul><ul><ul><ul><li>Aggregate fruits </li></ul></ul></ul><ul><ul><ul><ul><li>Many separate carpels of the same flower (straberry, raspberries) </li></ul></ul></ul></ul><ul><ul><ul><li>Multiple fruits – many different carpels from separate flowers (pineapple) </li></ul></ul></ul>
  • 62. <ul><li>Monocot Seed Structure and Germination </li></ul><ul><ul><li>Cotyledon does not have a storage function </li></ul></ul><ul><ul><li>Plumule and radicle are protected by sheaths </li></ul></ul><ul><ul><li>Plumule and radicle burst through the sheaths when germination occurs </li></ul></ul><ul><ul><li>Young shoot is straight, not hooked </li></ul></ul>
  • 63. <ul><li>Eudicot Seed Structure and Germination </li></ul><ul><ul><li>Cotyledons shrivel and degrade </li></ul></ul><ul><ul><li>Epicotyl produces immature leaves and is called a plumule </li></ul></ul><ul><ul><li>Young shoot is hook-shaped as it emerges through the soil </li></ul></ul>
  • 64. <ul><li>Germination of Seeds </li></ul><ul><ul><li>Some types of seeds remain dormant until conditions are favorable for growth. </li></ul></ul><ul><ul><ul><li>Temperature </li></ul></ul></ul><ul><ul><ul><li>Moisture </li></ul></ul></ul><ul><ul><ul><li>Regulatory Factors (stimulatory and inhibitory) </li></ul></ul></ul><ul><ul><ul><li>Mechanical Action (examples: water or fire) </li></ul></ul></ul><ul><li>Dispersal of Seeds </li></ul><ul><ul><li>Seeds may have hooks or spines that attach to fur or clothing </li></ul></ul><ul><ul><li>Seeds may pass through the digestive tract of animals </li></ul></ul><ul><ul><li>Seeds may be gathered and buried by animals </li></ul></ul><ul><ul><li>Seeds may be carried by wind or water </li></ul></ul>
  • 65. <ul><li>Hormones are small organic molecules that serve as chemical signals between cells and tissues. </li></ul><ul><li>Groups of Plant Hormones </li></ul><ul><ul><li>Auxins </li></ul></ul><ul><ul><li>Gibberellins </li></ul></ul><ul><ul><li>Cytokinins </li></ul></ul><ul><ul><li>Abscisic Acid </li></ul></ul><ul><ul><li>Ethylene </li></ul></ul><ul><li>Plant hormones bind to a specific protein in the plasma membrane. This brings about a physiological response. </li></ul>
  • 66. <ul><li>Auxins </li></ul><ul><ul><li>Auxins affect many aspects of plant growth and development. Auxins: </li></ul></ul><ul><ul><ul><li>Promote apical dominance </li></ul></ul></ul><ul><ul><ul><li>Increase the development of adventitious roots </li></ul></ul></ul><ul><ul><ul><li>Promote the growth of fruits </li></ul></ul></ul><ul><ul><ul><li>Are involved with phototropism and gravitropism. </li></ul></ul></ul>
  • 67. <ul><li>Gibberellins </li></ul><ul><ul><li>Gibberellins are growth-promoting hormones that promote elongation. </li></ul></ul>
  • 68. <ul><li>Cytokinins </li></ul><ul><ul><li>Promote cell division </li></ul></ul><ul><ul><li>Prevent senescence (aging) </li></ul></ul><ul><ul><li>Initiate growth </li></ul></ul><ul><ul><li>The ratios of auxins to cytokinins play a role regarding the differentiation of plant tissues. </li></ul></ul>
  • 69. <ul><li>Abscisic Acid </li></ul><ul><ul><li>Produced by green portions of plant </li></ul></ul><ul><ul><li>Closes stomata and maintains seed and bud dormancy </li></ul></ul><ul><ul><li>Considered a plant “stress” hormone </li></ul></ul><ul><ul><li>A decrease in abscisic acid and an increase in gibberellins breaks dormancy </li></ul></ul>
  • 70. <ul><li>Ethylene: </li></ul><ul><ul><li>Is a gas that moves freely through the air </li></ul></ul><ul><ul><li>Is involved with abscission (leaf drop) </li></ul></ul><ul><ul><li>Promotes the ripening of fruit </li></ul></ul>
  • 71. <ul><li>Plant Responses Are Influenced By: </li></ul><ul><ul><li>Light </li></ul></ul><ul><ul><li>Day length </li></ul></ul><ul><ul><li>Gravity </li></ul></ul><ul><ul><li>Touch </li></ul></ul><ul><li>Plant Tropisms: </li></ul><ul><ul><li>Phototropism: Growth in response to light </li></ul></ul><ul><ul><li>Gravitropism: Growth in response to gravity </li></ul></ul><ul><ul><li>Thigmotropism: Growth in response to touch </li></ul></ul>

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