economic importance of plants
DESCRIPTION
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) - PowerPoint PPT PresentationTRANSCRIPT
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)– aspirin = synthetic version of
compound from willow– Table 30.1– 1/4 prescription medications--plant
produced (more efficient)
Artemisia produces antimalarial compound in glandular hairs
Science Jan 15, 2010
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)
ecological importance of plants
• ~290,000 sp. +• diverse habitats• nutrient cycling
• 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
carbon cycle
Fig 55.14
C from air stored in organisms, fossils, soils
respiration,decomposition, burning
return to air
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
Fig 55.14
water cycle
H20 evap (pl. stomata) & retention
shade
fallen leaves—>humus soil holds H20
habitat for detritivores (decomposers)
nitrogen cycle
Fig 55.14
prokaryotes convert N
plants absorb N, animals eat plants
plants retain N that would wash away
eutrophication:
increased nutrients in waterphytoplankton & plants grow abundantly
respire at night (use up O2)aerobic prok degrade (use up O2)obligate aerobes die (dead zones)
Fig 55.18
phosphorous cycle
Fig 55.14
P cycles between autotrophs (absorb it) & heterotrophs
or lost until geological processes return it
sticks to soil that is rich in organic matter
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
rates of nutrient cycling
dep. on temp, moisture, nutrients
faster at higher temps, enough H2O
slower if cold, too dry or too wet
example:
peatlands cool & wet anaerobic
organic matter accumulates
CO2 stored
sexual reproduction
• haploid: having 1 set of chromosomes
• diploid: having 2 sets of chromosomes
• polyploid: having >2 sets of chromosomes
sexual reproduction
• mitosis: division of nucleus to form
2 nuclei w/same no of chromosomes of original nucleus
• meiosis: division of nucleus to form4 nuclei w/half no. of chromosomes of original nucleus
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)
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
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
Life cycle terms
• heteromorphic (“other form”) generations look different
• isomorphic (“same form”) generations look the same
• alternation of heteromorphic or isomorphic generations
2n
nmeiosis syngamy
zygote
gametes
sporophyte
spores
gametophyte
kelps, plantsFig 28.16
3 Life Cycles Fig 13.6
n
2n
zygote
ChlamydomonasFig 28.22
n
2n
gametes
humans
mitosis mitosis
mitosis