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Chapter 22: Plants

Chapter 22: Plants. What is a Plant?. Plant  mostly multicellular organisms of eukaryotic cells with think cell walls and that mostly get energy through photosynthesis Autotrophs  produce their own energy (chlorophyll a and b in chloroplasts)

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Chapter 22: Plants

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  1. Chapter 22: Plants

  2. What is a Plant? • Plant mostly multicellular organisms of eukaryotic cells with think cell walls and that mostly get energy through photosynthesis • Autotrophs produce their own energy (chlorophyll a and b in chloroplasts) • Heterotrophs plants gain energy from decomposing organic material

  3. What do Plants need to survive? • Reactants of photosynthesis: • Sunlight, CO2, Water • Gas Exchange: • Take in CO2 but also release O2 (byproduct that can limit photosynthesis) • Minerals/Nutrients: • Absorbed from the soil through the roots • Space: • Crowding limits sunlight which lowers photosynthesis rate • Photosynthesis is a very inefficient reaction, so a high rate is needed to survive

  4. The Plant Kingdom • 5 Groups based on Adaptations: • Green Algae simplest plants; seedless • Bryophytes complex plants but lack main plant structures; seedless • Seedless Vascular Plants typical plants but seedless • Cone-Bearing typical plants that produce seeds • Flowering seed producing plants with flower adaptations

  5. The Plant Life Cycle • All plant groups follow alternation of generation life cycles • Diploid (2N) Phase: • Sporophyte multicellular phase that produces spores • Spores grow into gametophytes • Haploid (N) Phase: • Gametophyte multicellular phase that produces gametes (sperm and eggs) • Gametes fuse (fertilization) to make sporophyte

  6. Green Algae • Can be unicellular or multicellular (volvox) • Haploid cells most of the time and reproduce by mitosis • Haploid gametes can fuse to make diploid zygote that can be dormant for long periods of time • Survive unfavorable environment • Must live in water or on moist land; nutrient rich soil

  7. Bryophytes • Multicellular plants but lack leaves, stems, and roots • Lack of vascular tubes means moss can only be 1 meter high • Most common type is moss • Rhizoids simple root-like tubes that help absorb water and nutrients • Most of its life is the gametophyte form and requires water to mix gametes • Must live on moist ground

  8. Seedless Vascular Plants • Club Moss, Horsetails, and Ferns • Vascular tissue hollow tubs inside the plant that allow the movement of water and nutrients • Xylem moves water • Phloem nutrients • Rhizomes underground root system • Sporophyte releases spores which grow into heart-shaped gametophytes; sperm and eggs need water to mix

  9. Cone-Bearing Plants • Seed plant embryo, energy supply, and protective coating (seed coat) • Allows spreading of plants away from water sources • Gymnosperms “naked seed”; sporophyte release pollen grains (male-gametophyte) from Pollen Cones • travel by wind to fertilize ovules (eggs) in Seed Cones (pollination)

  10. Flowering Plants • Must abundant plant forms • Angiosperms “enclosed seed”; flower contains ovaries and pollen (sperm) • After fertilization ovaries develop into fruit (contain seeds); animals eat fruit and spread seeds in droppings • Flowers allow pollination by animals; much more efficient than wind • Categorize plants by: • Soft or hard stems(wood) • Annual or biennial life cycles • # of cotyledons (seed leaves); monocots (one) or dicots (two) • Flower petals in multiples of 3, 4, or 5 • Vascular buddle formations • Types of leaves

  11. Type of Flowering Plants • 5 Classifications: • Amborella oldest known angiosperms; only 1 species still exists • Water Lily large, showy flowers • Magnoliids wide range of flowers in both size and complexity • Monocots 20% of flowering plant species; includes rice, corn, wheat, orchids, lilies, and irises • Eudicots 75% of flowering plant species; very diverse class

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