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Plants

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Plants

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  1. Unit 6 Plants

  2. Botany-study of plants

  3. Plant Evolution • Plants share a common ancestor with algae: • Cell walls of cellulose • Same type of chlorophyll used in photosynthesis • Food stored as starch

  4. Plant Evolution • Scientist hypothesize that plants originally lived under water • Over time, plants adapted to live on land: • Cuticle • Stomata • Vascular Tissue • Reproductive Strategies

  5. Plant Adaptations • Cuticles • Fatty or waxy coating covering the cell • Helps prevents water from evaporating • Acts as a barrier to invading microorganisms

  6. Plant Adaptations • Stomata • Enable the exchange of gases • Opening in outer layer of leaves • Openings are controlled by guard cells

  7. Plant Adaptations • Vascular Tissue • Specialized transport tissue • Enables faster movement of substance over greater distances • Provide structure and support • Two types: Xylem and phloem • Xylem-carries water • Phloem-carries sugar or organic compounds (food)

  8. Plant Adaptations • Reproductive Strategies • Some plants use spores to reproduce • Some plants use seeds • Alternation of generations • Gametophyte • Sporophyte

  9. Alternation of Generations • Gametophyte stage-gametes (sperm and egg) • Sporophyte stage- results from the fertilization of egg by sperm

  10. Plant Classifications

  11. Plant Classification • Nonvascular Plants • No vascular tissue • Transport water/nutrients via diffusion and osmosis • Small, short • Collectively called bryophytes • Grow in moist climates • Mosses, hornworts, and liverworts

  12. Plant Classification • Vascular plants • Contain xylem and phloem • Xylem-carries minerals and water through the plant • Phloem-carries sugars through the plant • Vascular plants can be seedless or seed plants

  13. Plant Classification • Seedless Vascular Plants • Club mosses, horsetails, ferns • Reproduce via spores • Spores are found on the underside of leaves in clusters called sori (sorus)

  14. Plant Classification • Seed Vascular Plants • Highly diverse (5 divisions) • Do not require water for fertilization • Seeds have cotyledons (store/absorb food for young sporophyte) • Sporophyte generation is dominant

  15. 5 Divisions of Vascular Seed Plants • Coniferophyta: • Wide range of shapes/sizes, climates • Produce seeds in cones for reproduction • Can be deciduous or evergreen • Often referred to as conifers or gymnosperms

  16. 5 Divisions of Vascular Seed Plants • Anthophyta: • Flowering seed plants • Most widely distributed (75% of plant kingdom) • Often referred to as angiosperms, which can produce seeds in fruits or flowers • Can further be divided into monocots or dicots (eudicots)

  17. Monocots and Dicots

  18. Monocots and Dicots

  19. Venation

  20. Checkpoint Review

  21. Nonvascular or Vascular?

  22. Nonvascular or Vascular?

  23. Nonvascular or Vascular?

  24. Nonvascular or Vascular?

  25. Which is seedless vascular?

  26. Gymnosperm or Angiosperm?

  27. Gymnosperm or Angiosperm?

  28. Plant Tissues

  29. Plant Cells • Cell walls, chloroplasts, and a large central vacuole set plant cells apart from animal cells • Plant cells undergo photosynthesis mainly in the leaves where chloroplasts are numerous

  30. Plant Tissues • Meristematic tissue • Dermal tissue • Vascular tissue • Ground tissue

  31. Plant Tissues • Meristematic tissue: • Regions of rapidly dividing cells • Figure 22.3 (pg. 635) • Apical meristems- tips of roots and stems, make the plant grow longer (primary growth) • Intercalary meristems- located throughout the stem, their growth increases plant length, e.g. mowing the grass (primary growth) • Lateral meristems- increases root and stem diameter (secondary growth)

  32. Plant Tissues • Dermal cells: Epidermis • Outer covering of the plant • Can secrete lipids to form the cuticle • Stomata- small openings in leaves and stems for gas exchange; guard cells control the opening/closing of stomata • Root hairs- increase surface area, material uptake

  33. Plant Tissues • Vascular Tissue: • Xylem- water-carrying vascular tissue, transports materials one way (away from roots) • Phloem- food-carrying vascular tissue, transports materials both directions,

  34. Plant Tissues • Ground Tissue: • Functions include photosynthesis,storage, support • Basically any tissue that isn’t meristematic, dermal, or vascular

  35. Roots • Absorb materials, provide support, anchor the plant to the ground • Root cap- protects the root’s apical meristem • Types of roots • Table 22.2 (pg. 641)- taproot, fibrous root, modified root (pneumatophores, adventitious roots)

  36. Stems • Support, transportation of materials • Types of stems • Table 22.3 (pg. 643)- tuber, rhizome, runner, bulb, corm

  37. Leaves • Primary function: photosynthesis, transpiration • Transpiration-process in which water evaporates from the inside of the leaves to the outside through stomata • Petiole: attaches blade to stem • Palisade mesophyll: column-shaped, contain many chloroplasts • Spongy mesophyll: loosely packed cells, allows for movement of gases such as oxygen

  38. Cross section of a leaf

  39. Leaf Modifications • Modifications help plants survive in different environments (e.g., cactus spines)

  40. Plant Responses • Tropic Responses- tropism, a plant’s growth response to an external stimulus • Table 22.4 (pg. 651) • Phototropism- response to light • Gravitotropism- response to gravity • Thigmotropism- response to touching an object, e.g., vines on a tree

  41. Plant Reproduction

  42. Parts of a Flower • Sepals: protect the flower bud; look like small leaves surrounding the bud or petals • Petals: colorful structures; attract pollinators (e.g., bees); surround the reproductive organs

  43. Parts of a Flower • Stamen: male reproductive structure; composed of two parts • Filament- stalk that supports the anther • Anther- contains the pollen grains • Pollen grain: contain plant’s sperm that will be used to fertilize the plant’s egg • The stamen is the structure with black tips in the picture!

  44. Parts of a Flower • Pistil: female reproductive structure; composed of three parts • Stigma- tip of the pistil; where pollination occurs • Style- connects stigma to ovary • Ovary- contains ovules (where eggs form) • The pistil is the big red thing in the picture!

  45. Pollination • Self pollination vs Cross pollination • Animal pollination: animals collect pollen on their bodies and move it from one flower to the next • Wind pollination: the wind blows the pollen to the plant ovary for fertilization; these flowers normally aren’t very colorful (i.e., they don’t need to attract animals to pollinate)

  46. Photoperiodism • The factor that affects the opening/closing of flowers; based on the number of hours of uninterrupted darkness • Short-day (Long night) • Long-day (Short night)

  47. Seed Germination • Germination: when the seed begins to grow • Seedling-refers to a young plant

  48. Fruit • Endosperm- a tissue that surrounds the embryo and provides nutrients to the developing plant