Unit 2 Plants and People BSC 1005 Dr George Bates Why study plants What is a plant o To help conserve endangered plants and threatened environments o To learn more about the natural wild o To better harness the abilities of plants to provide us with food and medicine o Plants are green mode of nutrition o Plants don t move cellular structure o Plants have flowers mode of reproduction Structure and organization have rigid cell walls Spores pinecones o Fungi are not plants Similar features cell walls can t move spores and mode of nutrition release enzymes Carl Linnaeus o 18th century Swedish doctor and naturalist laid the foundation for current biological classification systems The binomial system Classification of plants based on reproductive structures Kingdom Phylum Class Order Family Genus Species King plays chess on fine glass stools o Kingdoms Plant Animals Fungi Protists Bacteria Organisms are classified based on their evolutionary genetic relatedness Timeline of Life Life begins 3 5 bya o o Photosynthesis 3 bya o Bacteria separated from other groups 2 bya o Animal and fungi separate 1 bya o Green plants separate from others 1 bya o Plants invade the land 450 mya o Transport tissues 400 mya o o Seeds and pollen 350 mya Flowers and fruit 150 mya o Leaves 375 mya Using renewable energy sources reduce CO2 emissions but some sources are better Crop Product US Gas CO2 emissions of US crop land needed for half of US Corn Alcohol 85 Cell Theory than others demands Algae Biofuel 200 2 3 3 cells arise from preexisting cells o All organisms are composed of cells the cell is the basic unit of life and all o Scientific theory a well confirmed broad explanation of a natural phenomenon based on knowledge that has been repeatedly confirmed through observation and experimentation o Scientific Hypothesis Plant cells have 2 additional features that animal cells don t o Cell wall Gives plants shape and rigidity Holds neighboring cells together o Chloroplasts Photosynthesis Where chlorophyll is and where photosynthesis takes place o CO2 H20 sugars O2 o o During photosynthesis plants lose large amounts of water transpiration Light is needed for this equation to occur Xylem moves water from roots to leaves Phloem moves sugars from leaves to roots This allows the plant to grow o Stoma Holes that allow CO2 to come in from the air and allow water to exit when water is abundant Respiration Uses of the Corn crop Can swell up and contract to prevent water loss o Guard Cells o Plant cell walls are composed of long chains of sugars particularly cellulose o Sugars 02 CO2 H2O energy o US is the world s biggest producer of corn o Almost 50 goes into animal feed o Almost 1 3 is used for gas o In 2005 the federal government mandated for cars must be mixed with ethanol Almost 100 of this ethanol comes from corn Consequence is that beef and pork have gone up by 65 and 55 respectively Shoot Root o Above ground portion of a plant Stem leaf petiole shoot tip lateral bud tips o Below ground portion of a plant Root tips Plants grow by producing new cells at the tips of the shoot and the root Then the cells increase in size Removing the shoot tip causes the lateral buds to grow out makes the plant bushy Plants can be multiplied by making cuttings of branches and rooting them in water I Clicker Question Most plants that live more than one year perennials grow in width as well as length Reproduction Flowers Seeds and Fruits o Xylem moves water from roots to leaves o Cell divisions in the body of the stem and root increase thickness o When flowering starts the shoot tip makes flowers o Most flowers are hermaphroditic o Ovule Have male and female structures Contains an egg Can have one or more ovule After fertilization the ovule becomes the seed The ovary becomes the fruit o The egg becomes an embryo a young plant o Each pollen grain contains two sperm cells o When a pollen gain lands on the stigma a pollen tube grows out o The pollen tube delivers the sperm to the egg o Pollination Fertilization The process by which the pollen grain is delivered to the stigma Storage leaves Sperm and egg embryo o o Cotyledons o Endosperm o The nutrition we get from a bean seed comes from cotyledons o After fertilization the ovary becomes the fruit 35 of US population depends on insect pollination o 15 billion annually in the US Food for the young plant The purpose of flowers is to bring male and female reproductive cells together Wind Pollination Flowers of an oak o o No petals large stigmas to catch pollen lots of pollen o Corn is wind pollinated as are most grasses including wheat and rice Silk in the corn are stigmas Pollination by Animals flowers provide attractants and rewards o Rewards nectar and pollen o Attractants flower shape colors and scent o Some animals include bees butterflies and bats o Bee Pollination Bee flowers have a landing platform blue or yellow colors scented and Bees learn quickly to recognize colors odors and outlines have nectar as a reward Flowers pollinated by butterflies are similar to bee pollinated flowers o o Bees and butterflies are generalists visiting many kinds of flowers some o Bird pollinating flowers usually produce lots of nectar and are red and odorless o Bat pollinated flowers make lots of nectar open at night have strong musty interaction are more specific or fruity odors and dull colors Self Pollination vs Cross Pollination Darwin s Orchid o Many plants self pollinate much of the time offspring are genetically uniform o Cross pollination creates genetic variability which is important for species to o Pollinators promote cross pollination adapt to environmental change o Found a flower that hides its nectar 10 inches deep He predicts that a moth must have a tongue long enough that can reach the nectar and 50 years later he was proved to be correct After Fertilization the ovule develops into the seed the ovary wall develops into the fruit o The function of fruit is seed dispersal o o o Like flowers fruits are very diverse and use different ways to disperse their seeds Fruits may be fleshy Wind water animals and more Meant to be eaten Fruits may be dry some are dispersed by animals some wind or water or other ways I Clicker o A cucumber is a fruit Algae Milkweed fruit dries splits open and releases seeds that are disposed by wind Mistletoe plants eject their seeds Water dispersal o Coconuts o Simple photosynthetic aquatic organisms some unicellular some o Plankton microorganisms that live in
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