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The Plant Kingdom Life cycle overview

Chapter 23. The Plant Kingdom Life cycle overview. Basic Concepts - asexual vs. sexual reproduction (most) asexual reproduction one individual, no diversity in offspring, less time and E asexual spores and structures s pores : small packets of DNA, protected by a tough outer coat

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The Plant Kingdom Life cycle overview

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  1. Chapter 23 The Plant Kingdom Life cycle overview

  2. Basic Concepts- asexual vs. sexual reproduction(most) • asexual reproduction • one individual, no diversity in offspring, less time and E • asexual spores and structures • spores: small packets of DNA, protected by a tough outer coat • mitosis  diploid (2n) structures

  3. two individuals, diversity in offspring, more time and E • involves reproductive structures: • sporangia, cones, flowers • monoecious vs. dioecious plants • monoecious: every ind. produces both egg and sperm • dioecious: separate male and female individuals Sexual reproduction

  4. Fig. 23.3 Alternation of generations

  5. sexual spores • haploid  produced through meiosis • sporophytephase of life cycle • plant itself is diploid (2n) • sexual gametes • egg and sperm cells • haploid, but produced through mitosis • gametophyte phase of life cycle • plant itself is haploid (n)

  6. Alternation of Generations-sporo. vs gametophyte • sporophyte generation • diploid (2n) stage • germ cells in reproductive structures undergo meiosis • produce 4 haploid spores each • spores will grow and develop  new gametophyte • most prominent generation in most plants

  7. haploid (n) stage • gametophyte develops from haploid spores • produces gametes (egg and sperm cells) • special cells in specialized structures • mitosis • why no need for meiosis here? • fertilization  zygote  new sporophyte • fertilization involves two different individuals of same species • not very prominent in most plants gametophyte generation

  8. Fig. 27.1 Alternation of generations in flowering plants

  9. Evolutionary Themes in Plants -plants developed from filamentous green algae -trend toward a completely terrestrial existence • rely less and less on water for reproduction • mechanisms to control water loss • vascular tissues for transport • xylem: transport of water • phloem: transport of food (sugars) --lightweight, resilient spores that can go dormant -protective packaging for gametes and embryos -prolonged sporophyte and reduced gametophyte generation

  10. Fig. 23.4 Reduction in the size of the gametophyte

  11. Angiosperms – Flowering Plants • reproductive structures are flowers • largest and most diverse group of plants on earth • divided into two broad classes: • monocotyledonae (monocots) • most herbaceous plants, grasses, weeds, agricultural plants • eudicotyledonae (eudicots) • all woody plants, some herbaceous plants

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