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economic importance of plants

economic importance of plants. food— 80% human calories (stored starch) from 6 crops wheat, rice, maize potatoes, casava, sweet potatoes fiber, wood (lignified cell walls) fabric, paper, building material, fuel. economic importance of plants. medicine (2ndary chemical compounds)

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economic importance of plants

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  1. economic importance of plants • food— 80% human calories (stored starch) from 6 crops • wheat, rice, maize • potatoes, casava, sweet potatoes • fiber, wood (lignified cell walls) • fabric, paper, building material, fuel

  2. economic importance of plants • medicine (2ndary chemical compounds) • aspirin = synthetic version of compound from willow • Table 30.1 • 1/4 prescription medications--plant produced (more efficient)

  3. Science Jan 15, 2010 Artemisia produces antimalarial compound in glandular hairs

  4. Plant nutrition • autotrophs w/ chlplsts--PS pigments • chla & accessory pigments: chlb, carotenoids • light energy from sun, C from CO2 • minerals N, P, K, Ca, Mg, S • (and 7 micronutrients) • make sugar; store as starch • energy from breakdown of food • mitochondria--cellular respiration (requires O2)

  5. ecological importance of plants • ~290,000 sp. + • diverse habitats • nutrient cycling

  6. base of terrestrial food chain (Fig 54.11) • primary producers • energy transfer ~10% efficient • (Figs 55.9 & 10) • most goes to cellular respiration, waste--> heat

  7. carbon cycle C from air stored in organisms, fossils, soils respiration, decomposition, burning return to air Fig 55.14

  8. CO2 and plants w/extra CO2, plant growth increases but limited by other nutrients growth affected by temp & precip plants may not be able to migrate fast enough, esp. w/ habitat fragmentation

  9. water cycle H20 evap (pl. stomata) & retention shade fallen leaves —>humus soil holds H20 habitat for detritivores (decomposers) Fig 55.14

  10. nitrogen cycle prokaryotes convert N plants absorb N, animals eat plants plants retain N that would wash away Fig 55.14

  11. eutrophication: increased nutrients in water phytoplankton & plants grow abundantly respire at night (use up O2) aerobic prok degrade (use up O2) obligate aerobes die (dead zones) Fig 55.18

  12. phosphorous cycle P cycles between autotrophs (absorb it) & heterotrophs or lost until geological processes return it sticks to soil that is rich in organic matter Fig 55.14

  13. Hubbard Brook Expts: studies of nutrient cycling • isolated valleys, bedrock, drain indply • 60% H2O leaves, 40% evap through plants • internal cycling conserves nutrients • remove plants from one valley • 30-40% increase water loss • minerals lost: Ca2+, K+, NO3- • conclusion: plants control nutrient cycling • acid rain dissolves Ca2+, affects biomass • added Ca2+ improves plant health

  14. rates of nutrient cycling dep. on temp, moisture, nutrients faster at higher temps, enough H2O slower if cold, too dry or too wet

  15. example: peatlands cool & wet anaerobic organic matter accumulates CO2 stored

  16. sexual reproduction • haploid: having 1 set of chromosomes • diploid: having 2 sets of chromosomes • polyploid: having >2 sets of chromosomes

  17. sexual reproduction • mitosis: division of nucleus to form 2 nuclei w/same no of chromosomes of original nucleus • meiosis: division of nucleus to form 4 nuclei w/half no. of chromosomes of original nucleus

  18. sexual reproduction • fertilization (syngamy): fusion of 2 gametes to form 1 zygote • isogamy: gametes same form and size • anisogamy: gametes same form, different size • oogamy: large non-motile gamete (egg) & small motile gamete (sperm)

  19. Life cycle terms • alternation of generations: life cycle with at least 2 multicellular phases that can be distinguished by reproductive cells and sometimes by morphology • spore: a reproductive cell capable of growing into a new organism w/out fusing with another cell

  20. Life cycle terms • sporophyte: multicellular spore-producing phase of organism with an alternation of generations • gametophyte: multicellular gamete producing phase of organism with an alternation of generations

  21. Life cycle terms • heteromorphic (“other form”) generations look different • isomorphic (“same form”) generations look the same • alternation of heteromorphic or isomorphic generations

  22. gametes n n 2n 2n zygote humans Chlamydomonas Fig 28.22 3 Life Cycles Fig 13.6 gametophyte mitosis mitosis spores gametes n meiosis syngamy 2n zygote sporophyte mitosis kelps, plants Fig 28.16

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