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Biology TodayThird Edition
Chapter 11
Plants to Feed the World
Copyright © 2004 by Garland Science
Eli Minkoff • Pam Baker
Plants to Feed the World
A. PlantsUses (food, etc)nutrition (photosynthesis; know equation)
B. EconomicsPlants are producersAnimals (and others) are consumersFungi and bacteria are decomposersEnergy flows through the economyChemicals are recycled within the economy
e.g., the nitrogen cycle
Plants to Feed the World
C. Plant anatomyparts and functionsvascular tissuewater movement
(osmosis, transport, transpiration)
D. Increasing crop yieldFertilizer (benefits and dangers)Soil makeup and conservationWater distribution (hydroponics)Monocultures (benefits and dangers)Pests and controlling themFood pyramid and biomagnificationGMO’s advantages / disadvantages ?
(genetically modified organisms -= GMO)
Plants
Over 250,000 species 80,000 are edible by humans 30 major crops in the world 4 feed more than all
others wheatricecornpotatoes
Food
Plants
Food (Drinks, spices)FragrancesDyesPoisonsDecorationsBuilding materialMedicinesFuelPaper
Plant Nutrition
autotrophic
photosynthesis
(energy)
sunlight CO2 H2O glucose O2+ + +
Sun supplies all of our energyPlants capture and store energy
(autotrophic)
Energy flow
We eat plant material to get energy(heterotrophic)
producers
consumersprimary, secondary, …
Some organisms are absorptive heterotrophs
decomposers
Fig. 11-1
Fig. 11-2
Fig. 11-3
Fig. 11-4
Fig. 11-5
Chemicals cycle
Energy flow
usplants
C6H12O6 O2
H2OCO2
Chemicals cycle
Other chemical cycle tooe.g., nitrogen
amino acid, DNA, RNA
Chemicals cycle
Plants need nitrogen too
absorb nitrates and nitrites
nitrogen-fixationconvert N2 from air to NH3
nitrificationconvert NH3 to NO3-,NO2-
Fig. 11-6
Fig. 11-8
Plant Anatomy
Specialized plant parts:leavesrootsstemsflowers
photosynthesisabsorptiontransportreproduction
vascular tissue
xylemphloem
water and mineralsnutrients (sap)
Fig. 11-9
hypotonic
Fig. 11-10
Increasing crop yields
Fertilizeradds nutrients needed by plants to the soil
Animal waste (manure)CompostingChemical fertilizer
disease&
run-off
Fig. 11-13
What do plants need to grow ?
watersoil
Soil
Loose material
weathered rockorganic material
Soil types
parent rockclimategroundwateractivity of living organisms
topsoil
made slowly(1 inch/200-1000 years)
lost to erosion
“non-renewable”
don’t poison it or loose it
Plants to Feed the World
A. PlantsUses (food, etc)nutrition (photosynthesis; know equation)
B. EconomicsPlants are producersAnimals (and others) are consumersFungi and bacteria are decomposersEnergy flows through the economyChemicals are recycled within the economy
e.g., the nitrogen cycle
Plants to Feed the World
C. Plant anatomyparts and functionsvascular tissuewater movement
(osmosis, transport, transpiration)
D. Increasing crop yieldFertilizer (benefits and dangers)Soil makeup and conservationWater distribution (hydroponics)Monocultures (benefits and dangers)Pests and controlling themFood pyramid and biomagnificationGMO’s advantages / disadvantages ?
(genetically modified organisms -= GMO)
Water
90% lost to transpiration
plants need it:photosynthesistransportturgor pressure
Irrigation
supplying water to crops
expensive ?
Increasing crop yields
What do plants need to grow ?
water yessoil no
Hydroponics
growing crops without soil
expensiveconstructionmaintenance
monoculture
“inside”
controlled climateprotectedno tillingmore control Fig. 11-15
Monocultures
single species
rapid spread of disease
damage by pests
depletion of soil
Figure 11.16 (1)
Figure 11.16 (2)
Controlling pests
30% of many crops are destroyed
insects (adult and/or larvae)rodentsfungi
protect with pesticides
(kills pests)
Increasing crop yields
Controlling pests
ideal pesticide
kill only target pestno effect on non-targetsavoid devel. of resistance strainsbreakdown to harmless substances
ideal pesticide does not exist
Increasing crop yields
DDT
kills lots of insectssprayed on soldiers to kill liceused on crops to kill pests
(more food)sprayed on water to kill mosquitoes
(less disease)
Increasing crop yields
Controlling pests
DDT
expensivekills non-target speciesDDT-resistancepollute drinking waterbiomagnification
food pyramid
Controlling pests
Width shows biomass
p r o d u c e r smust be on bottom
they can’t pass on all their energy to next level
primary
consumer
secondary
consumer
Figure 11.17
Controlling pests
biomagnification
some chemicals get concentrated in tissues of the body
Figure 11.18
many pesticides interfere with the nervous system of the pest
Controlling pests
may damage our nervous system as well
Controlling pests
Integrated pest control
monitor pest levels
Increasing crop yields
Figure 11.19a
Controlling pests
Integrated pest control
monitor pest levels
pheremones
Increasing crop yields
Figure 11.19b
Controlling pests
Integrated pest control
monitor pest levels
pheremones
predator species
Increasing crop yields
Figure 11.19d
? safe
Figure 11.19d
exotic species
Controlling pests
Integrated pest control
monitor pest levels
pheremones
predator species
economic impact . . .
Increasing crop yields
cost/benefit
Increasing crop yields
Artificial selection
“These breeders chose individuals of the species that best exemplified the trait they desired. They allowed these individuals to mate, while preventing mating between individuals that did not have the desired trait.” BT3 pg. 397
Figure 11.20
Increasing crop yields
Green Revolution
Export better strains to poor countriesBetter yields…
… we are no better off
population growthsustainability
See quote page 398, BT3
Increasing crop yields
Genetic engineering (GMO’s)
transgenic plants
nutritional value(protein, starch)
pest resistanceherbicide resistanceshelf life
Increasing crop yields
Genetic engineering (GMO’s)
transgenic plants
molecular farmingtobaccohave plant make “products”
“blue genes”blue pigment gene into cottons plants
Increasing crop yields
Genetic engineering (GMO’s)
transgenic plants
risks biological ?concerns ethical ?
