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Chapter 22

Chapter 22. Plant Diversity. 22–1 Introduction to Plants. Objectives. Explain what a plant is Describe what plants need to survive Describe how plants first evolved. What Is a Plant?. Plants are members of the kingdom Plantae

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Chapter 22

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  1. Chapter 22 Plant Diversity

  2. 22–1 Introduction to Plants

  3. Objectives • Explain what a plant is • Describe what plants need to survive • Describe how plants first evolved

  4. What Is a Plant? • Plants are members of the kingdom Plantae • Plants are multicellular eukaryotes that have cell walls made of cellulose. They develop from multicellular embryos and carry out photosynthesis using the green pigments chlorophyll a and b

  5. The Plant Life Cycle • Plants have life cycles that are characterized by alternation of generations • the two generations are the haploid (N) gametophyte, or gamete-producing plant, and the diploid (2N) sporophyte, or spore-producing plant.

  6. What Plants Need to Survive • Sunlight • Water and Minerals • Gas Exchange • Movement of water and nutrients

  7. Early Plants • The first plants evolved from an organism much like the multicellular green algae living today.

  8. The First Plants  • The first true plants were still dependent on water to complete their life cycles, similar to today’s mosses in that they were simple in structure and grew close to the ground.

  9. From these plant pioneers, several major groups of plants evolved.

  10. Mosses

  11. Ferns

  12. Cone Bearing Plant

  13. Flowering plant

  14. Overview of the Plant Kingdom • Botanists divide the plant kingdom into four groups based on three important features: • Water conducting tissues • Seeds • Flowers

  15. 22 – 2 Bryophytes a.k.a (Non-vascular plants)

  16. Objectives • Describe the adaptations of Bryophytes

  17. bryophytes • Type of early plant with no vascular tissue that draw water in their cells by osmosis.

  18. Moss

  19. Liverwort

  20. Hornwort

  21. During at least one stage of their life cycle, bryophytes produce sperm that must swim through water to reach eggs of other individuals. • Therefore, they must live in places where there is rainfall or dew for at least part of the year

  22. Asexual Reproductive Part Sexual Reproductive/ Photosynthetic Part

  23. 22–3 Seedless Vascular Plants

  24. Objectives • Explain how vascular tissue is important to ferns and their relatives • Describe the three phyla of spore-bearing plants • Identify the stages in the cycle of ferns

  25. In just a few million years, plants grew to a whole new scale on the landscape. Q: What caused this increase in size? A: Vascular Tissue

  26. Vascular tissue • A type of tissue that is specialized to conduct water and nutrients through the body of the plant

  27. Evolution of Vascular Tissue • Both forms of vascular tissue—xylem and phloem—can move fluids throughout the plant body, even against the force of gravity.

  28. Xylem • Carry water upwards from the roots to every part of the plant

  29. Phloem • Transports nutrients and carbohydrates produced by photosynthesis from the leaves down to the roots

  30. Vascular plants also evolved the ability to produce lignin, a substance that makes cell walls rigid. • The presence of lignin allows vascular plants to grow upright and tall

  31. Ferns and Their Relatives • Seedless vascular plants include club mosses, horsetails, and ferns. • Like other vascular plants, ferns and their relatives have true roots, leaves, and stems.

  32. Roots • Absorb water and minerals

  33. Leaves • Collect light for photosynthesis

  34. Veins • Made of xylem and phloem

  35. Stems • Used for support, connect roots and leaves, carry water between them

  36. Club Mosses 

  37. Horsetails

  38. Ferns Underground Stem

  39. 22 – 4 Seed Plants

  40. Objectives • Describe the reproductive adaptations of seed plants • Describe the evolution of seed plants • Identify the four groups of gymnosperms

  41. Over millions of years, plants with a single trait—the ability to form seeds—became the most dominant group of photosynthetic organisms on land. • Seed plants are divided into two groups:

  42. Gymnosperms • Cone plants • Bear their seeds directly on the surfaces of cones Ex.) conifers, pines, spruces, cycads, ancient ginkgoes and gnetophytes

  43. Angiosperms • Flowering plants • Bear their seeds within a layer of tissue that protects the seed Ex.) grasses, flowering trees shrubs, wild flowers

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