9Medicinal Uses 25% of prescription medicines contain plant extracts Rosy periwinkle (vincristine andvinblastine) – childhood leukemia and Hodgkin’s. Survival rates have gone from 20% to 90% with these 2 compoundsGoldenseal – colds and sore gumsGinseng – immune system function
10BiofuelsMost biofuels come from corn (ethanol). What are some pros and cons of this method?Research is being done to get fuel from cellulose and oil from algaeRead Quirks and Quarks on page 542
11Erosion ControlThe paradox of farming: farmers need good soil to farm, yet farming destroys good soil.2.5 million acres each year are lost to urbanization and soil erosion.About 1/3 of the country's topsoil has been lost due to urbanization and soil erosion.
13KINGDOM PLANTAEPlants evolved about 500 million years ago from simple green algae that lived in the ocean.All plants are autotrophic and some, like the famous Venus fly-trap, can also be heterotrophic.All plants are eukaryotic and multicellular.
14PLANT CELLSLike animal cells, plant cells contain a nucleus and organelles, but they have two distinguishing features:Cell wall (made of cellulose, a complex carbohydrate, provides rigid structural support; difficult to digest)Chloroplast (organelle that conducts photosynthesis)Animal cells have lysosomes that release the cellular equivalent of digestive enzymes. Why don’t plants need these?
15PLEASE... CONSIDER THE FOLLOWING: How can plants stand up straight without a skeleton?15
16PLANT DIVERSITY Currently over 350 000 species of plants, including: MossesFernsConifersFlowering plantsMost plants live on land and can withstand a wide variety of climates. Cacti live in arid, dry areas whereas mosses need to be in moist environments to survive.
18CLASSIFYING PLANTSPlants are classified based on the presence or absence of vascular tissueVascular tissue can be compared to arteries and veins: a network of specialized cells that allows plants to transport water, minerals and sugar throughout the plantWhat would you expect a non-vascular plant, without vessels to transport nutrients and water, to look like?
19Non-vascular (ex. moss) Vascular (ex. tree, sunflower) PlantsNon-vascular (ex. moss)Cannot transport foot or water between plant partsTransport of fluid is through simple absorption or osmosisMust live in moist environments; need water for reproductionVascular (ex. tree, sunflower)Contain a vascular system allowing for transportation of nutrients / water throughout the plant
21FUNCTION OF STEMS Support system for plant body Transport system carries water & nutrients (through vascular tissue!)Holds leaves & branches uprightLooking at the picture below:What years had the most rain?What years experienced the worst drought?
22FUNCTION OF LEAVES Main photosynthetic organ Broad, flat surface increases surface area for light absorptionHave systems to prevent water lossStomata open in day but close at night or when hot to conserve waterWaxy cuticle on surfaceSystem of gas exchangeAllow CO2 in and O2 out of leafElephant Ear Plant
23LEAF STRUCTURES Cuticle: waxy layer; covers upper surface Leaf Cross-SectionCuticle: waxy layer; covers upper surfaceProtects leaf against water lossVeins: transports water, nutrients and foodMade of xylem and phloem vascular tissueMesophyll: contains cells that perform photosynthesisb/c they contain chloroplasts.CuticleVeinsMesophyllStoma(Opening)2 Guard CellsSurroundeachStoma
24LEAF STRUCTURES Guard cells: Cells that open and close the stoma Conserve water by preventing excess water transpirationStomata: openings in leaf’s surface; when open:GAS EXCHANGE: Allows CO2 in & O2 out of leafTRANSPIRATION: Allows excess H2O out of leafGuard CellsStoma
25FUNCTION OF ROOTS Anchor & support plant in the ground Absorb water & mineralsHold soil in placeFibrous RootsRoot Hairs
26STRUCTURE OF ROOTSRoot HairsRoot Hairs: increase surface area for water & mineral absorptionMeristem: region where new cells are producedRoot Cap: protects tip of growing rootMeristemRoot Cap
27QUIZ TIME! BEFORE WE CONTINUE… VASCULAR OR NON-VASCULAR?
28VASCULAR PLANTS http://dendro.cnre.vt.edu/forsite/idtype.htm Gymnosperms“Naked seeds” are not enclosed in an ovule (like a pine cone).Plants are usually evergreens.Ex. pines, cedars, spruces and firs.AngiospermsMature seed is surrounded by the ovule (think of an apple).Angiosperms are trees/plants that shed leaves every autumn.Ex. Oaks, maples and dogwoods are examples of deciduous trees.Contain a vascular system allowing for transportation of nutrients / water throughout the plant
29QUIZ TIME! BEFORE WE CONTINUE… GYMNOSPERM OR ANGIOSPERM ?