plants

plants的思维导图，分别有Plants are multicellular eukaryotes（真核细胞）、Plants are autotrophic（自制养料的）。

plants

• plants
  • Plants are multicellular eukaryotes（真核细胞）
  • Plants are autotrophic（自制养料的）
    • Plants produce their own food and energy from sunlight (photosynthesis)
• the structures of plants
  • cuticle
    • a waterproof layer of wax that coats the outside of leaves and stems
      • Wax, like all lipids, is hydrophobic
    • prevents plants from drying out
  • stomata
    • tiny holes in the leaves
    • allow CO2 to enter and allow H2O and O2 to exit
    • Two guard cells surround the opening of each stoma. They can open or close.
    • Transpiration is the loss of water through open stomata Transpiration draws water upwards from roots. If it is too dry or too hot, a plant may close its stomata to prevent dehydration .
  • The cell wall
    • a rigid layer outside the cell membrane that gives plant cells support and protection
    • are made of cellulose (a polysaccharide)
    • have pores (holes) that allow neighboring cells to share nutrients, water, and hormones.
  • Chloroplasts
    • organelles(细胞器） in plant cells where photosynthesis takes place
    • Chloroplasts contain chlorophyll（叶绿素）（ a photosynthetic pigment（色素）
    • Chlorophyll is located on discs called thylakoids（类囊体） that look like stacks of pancakes
      • Plant chlorophyll has a remarkably similar structure to animal hemoglobin.chlorophyll and hemoglobin proteins are homologous（同源的） structures.
• Photosynthesis
  • • Chlorophyll absorbs blue and red light from the sun and uses this energy to perform photosynthesis.
      • Reflection of green light causes plants to appear green.
    • Photosynthesis can be described by the chemical formula: 6 CO2 + 6 H2O + sunlight (energy)  C6H12O6 + 6 O2
      • Carbon dioxide enters through plant stoma
      • Water enters through plants roots
      • Sugars can be stored as starch or used in cellular respiration
      • Some O2 is used in cellular respiration and the rest is removed from the plant as waste.
      • Products of photosynthesis (sugar and oxygen) can be used in cellular respiration to generate energy (ATP)
      • • CO2 produced by cellular respiration can be recycled back into photosynthesis.
  • What happens to leaves in autumn?
    • Plants may change from green to red, orange, and yellow in autumn. Light and temperature changes signal some plants to stop photosynthesis. Green chlorophyll breaks down and other pigments that were hidden become visible. Eventually the leaf is no longer functional and drops off of the plant.
• Plant Reproduction
  • Alternation of Generations
    • Plants alternate between two different reproductive stages.
  • Sporophyte stage
    • plant produces spores
      • Spores grow and develop into a gametophyte
  • Gametophyte stage
    • plant produces gametes
      • Gametes are male and female sex cells that combine to create a sporophyte
• Plants respond to stimuli
  • Phototropism
    • Plants respond and grow towards light.
      • Cell growth at the tips of plants is uneven when light only falls on one side of the plant.
      • Indoor plants often exhibit phototropism.
  • Gravitropism
    • Plant roots grow in the same direction as the force of gravity and shoots grow opposite the force of gravity.
  • Thigmotropism
    • Plants grow in response to touching an object.
  • Nastic movements
    • are rapid responses to stimulation such as touch .
• Classification of Plants
  • The ancestors of plants likely resembled green algae (autotrophic protists)
    • Both plants and algae:
      • 1. perform photosynthesis using chlorophyll
      • 2. have cell walls
      • 3. store glucose as starch(淀粉）
      • 4. undergo alternation of generations
  • Plants are divided into four major phyla
    • Bryophytes:Non-vascular plants
      • characteristics
        • are small, simple plants.
        • Includes mosses, liverworts, and hornworts.
        • These plants must live in very moist environments because they have no vascular tissues to move water or nutrients through their bodies.
        • Instead water and nutrients move cell to cell.
      • moss
        • Bryophytes have root-like structures called rhizoids .
          • Rhizoids hold the plant in place and absorb water.
        • Bryophytes spend the majority of their life as gametophytes.
        • Sporophytes（孢子体） are small pods that produce spores.
    • vascular plants
      • Anatomy
        • Vascular plants have roots and shoots.
          • Shoots are above ground and include the stems and leaves.
            • Stems carry water and nutrients and hold up the leaves.
              • Stems holding plants upright may either be:
                • Herbaceous – soft, flexible, usually green .
                • Woody – hard, durable, usually brown (cell walls contain the biopolymer lignin).
            • Leaves are the site of photosynthesis.
          • Roots are plant organs found underground that hold a plant in place and draw water and nutrients up into the plant.
        • There are two types of vascular tubes in plants .
          • Xylem carries water and nutrients upwards from roots to shoots.
          • Phloem carries sugars made in leaves upwards and downwards to all parts of the plant .
          • Fluid in xylem and phloem is often called “sap” Maple syrup is made from maple tree sap.
      • classification
        • Pteridophytes:Vascular plants that do not form seeds
          • Include club moss, horsetails, and ferns .
          • Typically found in damp environments.
          • Fern
            • Anatomy of a Fern
              • Fronds – Leaves of a fern
              • Fiddlehead – tightly coiled new fronds
              • Rhizome – underground stem held to the soil by roots.
              • Roots – absorb water and nutrients.
            • Fern reproduction
              • The main body and fronds of a fern are the sporophyte .
              • Spores are produced on the underside of each frond.
              • Each spore forms a small heart-shaped gametophyte.
              • The gametophyte produces male gametes (sperm) and female gametes (eggs).
              • Fertilization – joining of two gametes resulting in the formation of a new sporophyte.
        • seed plants
          • Anatomy
            • Seeds are plant embryos surrounded by a food source (cotyledons) and a protective seed coat.
              • Advantages of seeds
                • Able to survive harsh seasonal conditions
                • Allows seeds to travel either by wind or animals.
            • Seeds grow into new plants(Sporophytes)
              • Cotyledons continue to feed the growing plant until it is able to make its own food via photosynthesis.
          • classification
            • Gymnosperms
              • Vascular plants that form seeds in cones
              • Includes conifers, ginkgos, cycads, and gnetophytes.
              • Other Gymnosperms
                • Cycads have palm-like leaves and live in tropical environments.
                • Ginkgos have unique fan shaped leaves
                  • Extracts of the Ginkgo biloba plant are used as a drug to enhance memory.
                • Gnetophytes are found in tropical or desert environments.
                  • Extracts of the gnetophyte Ephedra are used in: Traditional Chinese medicine The cold medicine Sudafed The illegal drug methamphetamine
            • Angiosperms
              • Vascular plants that form seeds in flowers
              • Flowers contain male and female gametophytes and become fruits.
                • Sometimes flowers do not always look the way you would expect. Grasses have very tiny flowers.
                • And there are some plants you may not realize have flowers!
              • Angiosperms are the largest and most diverse phyla in the Plant Kingdom.
                • Adapted to a wide variety of environments
                  • Tropics: Palm trees, rubber trees, and orchids
                  • Deserts: Cacti and succulents
                  • Temperate: Magnolia, elm, maple, and oak trees
                  • Marshes: Carnivorous plants and cattails.
                  • Tundra: Alder and birch trees.
              • Two Major Groups of Angiosperms:monocot&dicot
                • cotyledon
                • leaf veins
                • flower parts
                • vascular tissue
                • roots
              • Reproduction of Angiosperms
                • Flowers contain the male and female gametophytes.
                  • Male Parts of a Flower
                    • Stamen - a long thin filament topped by an anther.
                    • Anther - contains pollen grains
                      • Each pollen grain is a male gametophyte and contains plant sperm cells.
                  • Female Parts of a Flower
                    • Pistil – the entire female part of a flower
                    • Ovary – contains ovules and becomes a fruit
                    • Ovules – female gametophytes
                    • Stigma – sticky upper part of pistil where pollen lands
                    • Style – thin hollow structure sperm must travel down
                • Sexual Reproduction
                  • Pollination
                    • Pollination occurs when pollen grains are transferred to the stigma of the same or a different flower.
                      • Pollen grains may be carried by the wind or animals .
                      • Animals that carry pollen from flower to flower are called pollinators.
                  • Germination
                    • Pollen germination occurs when a pollen grain attached to the stigma of a flower is activated.
                    • The pollen grain produces a pollen tube that extends down through the style and into the flower ovary.
                  • Fertilization
                    • Fertilization occurs when the male gamete (sperm) joins with the female gamete (egg) forming a plant embryo .
                    • Each ovule containing a fertilized egg becomes a seed.
                    • The ovary becomes a fruit.
                • Asexual Reproduction in Plants
                  • Leaflets
                    • a small plant that forms on the leaf of a parent plant. .
                      • The leaflet may detach from the parent and become a new plant.
                  • Tubers
                    • Tubers are underground structures that store starches (such as potatoes and yams).
                    • Tubers can produce new plants asexually.
                  • Runners (a.k.a. stolons)
                    • horizontal stems that produce new plants nearby a parent plant.