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Plants/The Importance Of Leaves
Chapters 6 & 19
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Plant Classification Plant features Common traits in all plants:
All plants have chloroplasts Contain chlorophyll: a chemical that gives plants their green color and traps light energy Light energy is used in photosynthesis: the process in which plants use water, carbon dioxide, and energy from the sun to make food Releases oxygen Occurs in the chloroplast All plants contain a stiff cell wall Many different kinds of plants 250, ,000. cell wall gives support and structure
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Plant Classification Two groups of plants
Based on whether or not they have cells that make up tubes throughout the length of the plant Vascular plants: plants that have tube like cells in their roots, stems, & leaves like a straw Like an elevator- these tube like cells carry things up and down the length of the plant Carries: *water and minerals *food made by the leaves Nonvascular plants: do not have tube like cells in their roots, stems, & leaves Shorter & grow close to the ground Use osmosis to take up water Like elevators in buildings. Tall ones have elevators short ones don’t… needed to travel up and down quicker. **Draw Picture*** leaves (where the food is made), stems (carry water to all parts of the plant- hold leaves up), roots organs
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Nonvascular Plants Mosses & Liverworts
Moss: small, nonvascular plant that has both stems and leaves but no roots Liverworts: found in small patches that appear wet and slippery Both are similar
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Nonvascular Plants Mosses & Liverworts Neither have roots Mosses
Hair like cells used to attach to the ground or tree trunk Take up water Only a few cm tall Common in wet or damp areas Mosses Stems grow upright Fine & soft Stems that creep across the ground Appear like longer, tangled, wavy hair Mosses stems fine & soft
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Nonvascular Plants Mosses & Liverworts Mosses cont.
Leaves= 1 or 2 cells thick Easily dry out Liverworts Many don’t have roots, stems, or leaves Body is flat slippery layer of green cells Leaves grow in 2 or 3 flattened rows along the stem Mosses stems fine & soft. Liverworts sometimes appear like mosses
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Nonvascular Plants Mosses & Liverworts Uses Food
Snails & worms Help hold soil in place Prevents soil from washing away Some mosses that live on rocks-cause them to break down and form soil Sphagnum moss used in hanging baskets or flowers Aka peat moss Increases the amount of water that can be held
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Nonvascular Plants Life cycle of a moss
***Need constant source of water to survive*** Used in sexual reproduction Sexual Reproduction: the forming of a new organism by the union of two reproductive cells Female reproductive cell: egg Male reproductive cell: sperm Fertilization: joining of the sperm and egg cell Occurs in most plants and animals Sperm & eggs of mosses form at the tips of the leafy stems
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Nonvascular Plants Hair like structures Life cycle of a moss
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Vascular Plants Majority of plants Two types of tube like cells
Xylem: carry water and dissolved minerals from roots to the leaves Phloem: carry food that is made in the leaves to all parts of the plant
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Vascular Plants Ferns: vascular plant that reproduces with spore
Can grow much taller than mosses or liverworts In tropical forest can grow to 25 meters! During part of its life ferns do not have a vascular system at all Often grow in moist, shaded areas Some can live in drier areas and some actually grow in water 12,000+ species- most live in tropical forests
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Vascular Plants Ferns cont.
Leaves grow from a horizontal stem that lies underground Stem stores food and water Roots Anchor plant Take up water and minerals from the soil Fern leaves are divided into many leaflets Many lose their leaves at the end of the growing season New leaves form in the spring Named by the shapes of their leaves Reproduce with spores Found on the underside of the leaves Brown/orange “spots”- spore cases: hold the spores
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Vascular Plants Ferns cont.
Leaves grow from a horizontal stem that lies underground Stem stores food and water Roots Anchor plant Take up water and minerals from the soil Fern leaves are divided into many leaflets Many lose their leaves at the end of the growing season New leaves form in the spring Named by the shapes of their leaves Reproduce with spores Found on the underside of the leaves Brown/orange “spots”- spore cases: hold the spores
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Vascular Plants Ferns cont. Life cycle Spore case opens
Carried by water or wind If it lands in a moist place it grows into a small, flat, heart- shaped plant Heart-shaped plant produces sperm cells and egg cells Sperm swim through the water to fertilize the egg cell Fertilized egg develops into a new fern Vascular Plants
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Vascular Plants Seed: Part of a plant that contains an embryonic plant and stored food. Embryo: an organism in it’s earliest stages of growth Young root Embryo Stored food Young shoot Seed Coat 2 types of seed plants conifers and flowering plants Seeds with a hard outer covering=seed coatprotects the embryo seed coat and food stored allow seeds to survive for a long time even when conditions are not suitable for growth
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Vascular Plants Conifers: a type of seed plant that produces seeds in cones. Most common land plants Most do NOT lose their leaves Found in the northern areas Small needle-shaped leaves Examples: Evergreen Trees- sheds their leaves but not all at once Pine, Spruce, & Fir Loose their leaves each fall: Larch, Dawn Redwood, & Bald Cypress 2 types of seed plants conifers and flowering plants Sometimes called EVERgreens Evergreen sheds like a cat or dog
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Vascular Plants Conifers: Pine spruce fir
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Vascular Plants Conifers: Life cycle of a pine tree:
Produce male and female cones Small cones=male *produce pollen: tiny grains of seed plants that develop sperm *Found in early spring *Wind is used to carry the pollen Large cones=female *contain egg cells *when seeds are ripe the cones dry and the wood like scales open **seeds fall to the ground **if conditions are right the seeds grow into a new plant Some conifers don’t have cones
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Vascular Plants Conifers: Some conifers don’t have cones
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Vascular Plants Conifers: Roots and Stems are woody
Xylem cells have thick cell walls Leaves are tough and needle like Some can be scale like Can live in a variety of places Wet areas, dry areas, high mountain slopes, close to sea etc. Wood is mainly made of xylem cells\ Paper, pencils, lumber, Important shelter and food for animals Bark, buds, and seeds are eaten by insects, birds, squirrels, rabbits, and more! Wet areas like swamps Some in deserts
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Vascular Plants Flowering Plants: vascular plant that produces seeds inside a flower Flower: the reproductive part of the plant Male part: produces pollen Sperm produced in the pollen Must join with egg to reproduce Carried by insects, wind, or other animals Female part: produces eggs Develops into a fruit that protects the seeds More flowering plants than non Better seed protection Adaptive to many environments Not all flowering plants have big sweet smelling flowers- ex the maple small flowers
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Vascular Plants Flowering Plants: Examples:
Most broadleaved trees, vegetables, grasses, weeds, thorn bushes, and of course flowers like roses etc. Only produce flowers at certain times during the year Uses: Decoration Food source Can you name some examples? Which parts do you eat? (stems, leaves, fruit, or seed?) Provides us with Oxygen Removes carbon dioxide Not all flowering plants have big sweet smelling flowers- ex the maple small flowers
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Leaf Traits Most are flat and green Blade: thin, flat part of the leaf
Many different shapes: Round, heart-shaped, long and narrow, short and broad May not even look like a leaf Example: needles Stalk attaches the leaf to the stem Many lengths and thicknesses Example: celery stalk- the part you eat Some plants do not have this Examples: Grass & corn Leaves NOT attached to the stem by stalks Leaves directly attached to the stem Contains xylem and phloem Not all flowering plants have big sweet smelling flowers- ex the maple small flowers
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Leaf Traits Midrib: the main vein of the leaf Continues off the stalk
Small veins branch off the midrib Also contain xylem and phloem Not all flowering plants have big sweet smelling flowers- ex the maple small flowers Stalk
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Leaf Traits Used to identify plants
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Leaf Cells Arranged in layers
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Leaf Traits Waxy layer: Epidermis: outer layer of the cells of a plant
Protects from water loss and from insects Epidermis: outer layer of the cells of a plant Only one cell thick Palisade Layer: layer of long, green cells below the upper epidermis Make most of the food for the plant Contain many chloroplast Chlorophyll green pigment
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Leaf Traits Spongy Layer: below the palisade layer, made of round green cells Loosely arranged- in between filled with water and air Also make food Veins are found here
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Leaf Traits Another layer of epidermis with waxy layer, called lower epidermis Stoma: small pore or opening in the epidermis (both lower and upper) of a leaf Stomata=plural word for stoma Allow gas exchange Including water vapor Open during the day lets in CO2 Closed during the night Guard Cells: green cells that change the size of the stoma in a leaf Works by taking in or releasing water through osmosis
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Water Loss Transpiration: the process of water passing out through the stomata of the leaves Plants may loose up to 90% of the water they take up through their roots each day Wilting: when plant loses water faster than it can be replaced Plant cells are mostly water Water keeps the plant cells firm Water loss is greater during warm days
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Photosynthesis Product: Sugar
Serves as food for the plant 6CO2 + 6H2O Sunlight trapped by the chlorophyll C6H12O6 + 6O2 Previously thought that Plants got their food from the soil
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Photosynthesis Chlorophyll is used to trap the light energy
Waste product: Oxygen
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Sugar Sugar made during photosynthesis:
Broken down and used to make other molecules used by the plant to grow This releases energy We use oxygen CO2 and H2O are the by products
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Plants for food Leaves produce food for plants
Food produced for plants eaten by animals Releases energy for animal to use
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Plants for food Animals that eat plants food source for animals that eat other animals
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Uses of leaves Leaves used for food Used as medicine
Animals, humans, insects etc. Cattle, sheep, etc. eat leaves of grass Examples: Cabbage Lettuce Spinach Onions Leaves used for spices: sage, bay, parsley, etc Tea Peppermint Spearmint Used as medicine Foxglove contains chemical digitalis Used in treating heart disease
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Changes in leaves Colored pigment Green =chlorophyll
Forms only when light is present Yellow & red also present Chlorophyll covers up the effects of other pigments Some plants are always colors other than green Example: Coleus Plant Some plants change color in the fall Flow of sap slows Temp drops Less sunlight Chlorophyll breaks down Other colors show through
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http://www. bio. umass. edu/biology/conn. river/liverwts
liver warts slide 4 Moss slide 4 life cycle of moss slide9 slide 12 fern spores 2 slide 12 fern life cycle slide 14 peanut slide 15 pine cone slide 17 Spruce Cones slide 17 Fir Cone slide 17 Male & female pine cones slide 19 life cycle of a conifer squash slide 22 leaf structure slide 24 leaves slide 25 leaf layers slide 26 photosynthesis slide 31 insects eating leaves slide 34 monarch caterpillar slide 34 coleus plant slide 37
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