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Plants

Plants. Chapter 21. Plant Evolution. Plant : multicellular , photosynthetic eukaryotic organism that contains tissues and organs with specialized structures and functions. Plants share a common ancestor with green algae.

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Plants

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  1. Plants Chapter 21

  2. Plant Evolution • Plant: multicellular, photosyntheticeukaryotic organism that contains tissues and organs with specialized structures and functions • Plants share a common ancestor with green algae. • Plants developed derived traits (adaptations) to be able to live on land. • Cuticle • Stomata • Vascular tissue • Reproductive strategies • Seeds

  3. PLANT LEAFperformsphotosynthesis • Not pictured • Vascular tissues: specialized transport tissues that move water and nutrients from the roots to the rest of the plant; provides support • Reproductive strategies: adaptations of gametes and mutually beneficial relationships with other living things • Seeds:Seed coats protect embryo of new plants as they scatter on land CUTICLEreduces waterloss; STOMATAallow gas exchange (photosynthesis and cellular respiration) STEMsupports plant(and may performphotosynthesis) ALGAE Surrounding watersupports the algae WHOLE ALGAEperformsphotosynthesis;absorbs water,CO2, andminerals fromthe water ROOTSanchor plant;absorb water andminerals from the soil (aidedby mycorrhizalfungi) HOLDFASTanchors the algae

  4. Plant Classification • Two main categories: • Nonvascular Plants (earliest to diverge) • Called Bryophytes • Common examples: mosses, hornworts, and liverworts • Small plants • Lack true leaves; use root-like rhizoids to anchor them into to a surface • Live in damp, shady areas to assist in providing water to tissues • Vascular Plants (evolved later) • Seedless Plants (ferns) and Seed Plants • Contain a xylem and phloem • Have well-developed root system • Rigid stem

  5. Vascular Seedless Plants - Ferns • Tend to live in damp, shady areas • Water is need for flagellated sperm to reach the egg to reproduce new generations of the plants.

  6. Vascular Seed Plants • The appearance of seeds is a major evolutionary step. • Pollen grains transport sperm rather than water. • Seed Structure – protects embryo: • Seed coat: protective coating • Embryo: growing, developing new plant • Cotyledons: store food or help absorb food for the growing embryo • Monocotyledons – have one cotyledon • Dicotyledons – have two cotyledons • Location of Seeds • Angiosperms – seeds are found in a fruit • Gymnosperms – seeds are NOT part of a fruit; naked seeds

  7. Gymnosperms – Naked Seed Plants • Gymnosperms diverged before angiosperms. Fruits are a more recent adaptation. • Division Coniferophyta: • Male cones produce pollen, which carries sperm. • Female cones are larger and more open to allow the sperm to collect. • Female cones remain on the plant until seeds are mature. • When the cone drops from the tree, seeds are spread.

  8. Angiosperms – Fruit-bearing, Flowering Plants • Flowers are reproductive structures in plants. • Sepal: protects flower buds • Petal: attracts pollinators and provides landing pad • Stamen – MALE reproductive organ; filament supports the anther; anther produces pollen (sperm) • Pistil or Carpel – FEMALE reproductive organ; pollination occurs at stigma; embryo (SEEDS) develop in the ovary; fruits form from the ovary

  9. Fruits – Seed Dispersal • Fruits are seed dispersal adaptations.

  10. Categories of Angiosperms

  11. Categories of Angiosperms

  12. Categories of Angiosperms • Monocot is on the left • Oat plant • Dicot is on the right • Bean plant • Notice the differences in the two plants.

  13. Categories of Angiosperms In monocots, the vascular bundles in the stem cross section are usually scattered or more complex of an arrangement as compared to dicots. The vascular bundles in the stem cross section of dicots are arranged in a circle, or ring.

  14. Types of Monocots and Dicots

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