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This lesson will increase your knowledge of conceptscovered in the following TEKS for biology:
3.a ± Analyze, review, and critique scientific explanations, includinghypotheses and theories, as to their strengths and weaknesses using scientificevidence and information
3.c ± Evaluate impact of research on scientific thought, society, and the
environment3.f ± Research and describe the history of biology and contributions of scientists
4.b ± Investigate and identify cellular processes
6.d ± Compare genetic variations observed in plants and animals7.b ± Illustrate the results of natural selection in the speciation, diversity,
phylogeny, adaptation, behavior and extinction
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This lesson will increase your knowledge of conceptscovered in the following TEKS for biology:
9.d ± Analyze the flow of matter and energy through different trophic levels and between organisms and the physical environment
11.b ± Investigate and identify how organisms respond to external stimulation
11.c ± Analyze the importance of nutrition, environmental conditions and physical exercise on health
11.d ± Summarize the role of microorganisms in maintaining and disruptingequilibrium including diseases in plants and animals and decay in an ecosystem
12.b ± Interpret interactions among organisms exhibiting predation, parasitism,commensalism, and mutualism
12.e ± Investigate and explain interactions in an ecosystem including foodchains, food webs, and food pyramids
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Previous Lesson
Agricultural Systems andTransgenic Organisms
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Q uestion: Manyof us take
agriculture for granted. Howhas it affected
human history?Photos courtesy of Texas Parks and Wildlife Department
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Development of agricultural systems made
advanced civilization possible
10,000 BC
Photo courtesy of TexasDepartment of Transportation
Today
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Q uestion: When did domesticationbegin and what was the first animaldomesticated?
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Dates (BC) and Places of FirstEvidence for Domestication
from Diamond, J., Guns, Germs and Steel, Random House, 1997
Dog 10,000 BC SW. Asia,China, North America
Sheep 8,000 BC SW. AsiaGoat 8,000 BC SW. AsiaPig 8,000 BC China, SW. AsiaCow 6,000 BC SW. Asia, India, North AfricaHorse 4,000 BC UkraineDonkey 4,000 BC Egypt
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Q uestion: Why is there a controversyover using grain to fatten cattle?
From: Time , November 8 , 1999
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Many more peoplecould be fed by thegrain used to feed thecattle than can be fedby the cattlethemselves
This is becauseproductive energy isdiminished with eachtrophic level
Based on: Scientific American , September 1976
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Q uestion: What is good and badabout genetically engineeredagricultural plants?
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Genetically Engineered PlantsThe Good: Crops can be engineeredto have important components of
diet, contain medically importantproteins, and to be pest resistantThe Bad: Plants could contain
pesticides that would harm humansand wildlife, or proteins that couldcause allergies in humans. Geneticscould escape to traditional crops.
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Today¶s LessonToday¶s Lesson
Pesticides andPesticides andOrganic FarmingOrganic Farming
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Pests, DDT and biomagnificationDDT, eagles and falconsEndangered Species ActOrganic farming
Overview of Lesson
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Domestic crops wereDomestic crops were
selected for maximumselected for maximumproductivity and had littleproductivity and had little
natural pest resistancenatural pest resistance
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Blight hitspotatoes, 1845
Based on: P op ulati o n Re po rts , May 1992
Potato famine of Ireland was caused bygenetically uniform crops and lack of
pesticides to protect them
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Pests attack andPests attack andeat our food cropseat our food crops
This problem isThis problem isdue, in part, to notdue, in part, to notselecting for pestselecting for pestresistance duringresistance duringdomesticationdomestication
Today¶s PestsToday¶s Pests
Based on: N ati o nal Ge o gra phic , February 1980
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DDT was invented in theDDT was invented in the
1940¶s and viewed as:1940¶s and viewed as:-- miracle for farmersmiracle for farmers-- and safeand safe
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³ The most discussed of the new insecticides is³ The most discussed of the new insecticides isdichlorodichloro- -diphenyldiphenyl- -trichloroethane, shortened totrichloroethane, shortened toDDT but also called Guesarol. This compound hasDDT but also called Guesarol. This compound hasremarkable power to kill insects, particularly bodyremarkable power to kill insects, particularly bodylicelice--the µcooties¶ of World War I. The prevalence of the µcooties¶ of World War I. The prevalence of typhus, carried by body lice, in the Mediterraneantyphus, carried by body lice, in the Mediterraneantheater of this war has emphasized its value.theater of this war has emphasized its value.DDT¶s effectiveness in war may well beDDT¶s effectiveness in war may well beovershadowed by its value in peace. Painstakingovershadowed by its value in peace. Painstakinginvestigations have shown it to be signallyinvestigations have shown it to be signallyeffective against many of the most destructiveeffective against many of the most destructiveinsects that feed upon crops.´insects that feed upon crops.´
Scientific AmericanScientific American , July 1944., July 1944.
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Arial crop sprayersArial crop sprayerswere used to spraywere used to spraytons of DDT ontons of DDT oncrops across thecrops across theU.S.U.S.
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
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Pests became resistant to DDTPests became resistant to DDT
Based on: N ati o nal Ge o gra phic
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Pesticide ResistancePesticide Resistance
In the beginning, mostIn the beginning, mostpests were sensitive topests were sensitive toDDT but a few wereDDT but a few wereresistantresistant
The resistant formsThe resistant forms
survived and reproducedsurvived and reproduced
In the end, most pestsIn the end, most pestswere resistant to DDTwere resistant to DDT
Based on: N ati o nal Ge o gra phic , February 1980
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BiomagnificationBiomagnification
The concentration of The concentration of pesticides in higher levels of pesticides in higher levels of
food chainsfood chains
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Most food chains consist of four trophic levels
Based on: Mader, S., I nquiry I nt o Life , McGraw-Hill
Trophic Levels
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Energy Availableto Consumers at
Next Trophic Level
Energy Lost byRespiration
Energy Lost byDeath and Decay
Energy Lost byExcretion
Energy Lost by
Egestion of Feces
Energy Ingested
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DDT is concentrated asDDT is concentrated asit moved up food chainit moved up food chain
This is because energyThis is because energyis lost (from respiration)is lost (from respiration)as go up food chain butas go up food chain butDDT is notDDT is not
Based on: Campbell et al, B i o l o gy: C o nce p ts
and C o nnecti o ns , Benjamin Cummings
DDT in Food Chain
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Pests, DDT and biomagnification
DDT, eagles and falconsEndangered Species ActOrganic foods
Overview of Lesson
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Bald EagleBald Eagle
Once was widelyOnce was widelydistributed over U.S.distributed over U.S.
As a top carnivore itAs a top carnivore itfeeds on fishfeeds on fish
Swoops down andSwoops down andcaptures fish off thecaptures fish off thesurface of the water surface of the water
Photo courtesy of Texas Parks and WildlifePhoto courtesy of Texas Parks and WildlifeDepartmentDepartment
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Scientists discovered that DDT wasScientists discovered that DDT wasconcentrated in the bald eagleconcentrated in the bald eagle
DDT affected the eagle¶s ability to reproduceDDT affected the eagle¶s ability to reproduce
Photos courtesy of Texas Parks and Wildlife DepartmentPhotos courtesy of Texas Parks and Wildlife Department
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Scientists foundScientists foundthat the eagle eggsthat the eagle eggshad thin egg shellshad thin egg shellsand broke easilyand broke easily
Nests containedNests containedbroken, rotten eggsbroken, rotten eggs
The number of The number of
young producedyoung producedper breedingper breedingpair was reducedpair was reduced
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Population of adultPopulation of adulteagles declined to 4,000eagles declined to 4,000
and the eagle was listedand the eagle was listedas ³ Endangered´as ³ Endangered´
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
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The Environmental Protection Agency (EPA)The Environmental Protection Agency (EPA)banned DDT in 1972banned DDT in 1972
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
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Eagle reproduction before and after DDT banEagle reproduction before and after DDT ban
Based on: Grier, J., Science, 1982
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Eagle populations increased rapidly andEagle populations increased rapidly andthe eagle is now listed as ³ Threatened´the eagle is now listed as ³ Threatened´
From: Time , July 11, 1994
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Peregrine FalconPeregrine Falcon Occurred naturallyOccurred naturallyover most of over most of
continental U.S.continental U.S.
Nests on cliffsNests on cliffs
Keen eyesightKeen eyesight(if human, could read(if human, could readnewspaper print at 110 yards)newspaper print at 110 yards)
Feeds on other birds,Feeds on other birds,knocking them out of knocking them out of the sky at 200 m.p.h.the sky at 200 m.p.h.
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
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After DDT was introducedAfter DDT was introducedin 1940s, DDT weakenedin 1940s, DDT weakenedthe birds¶ egg shells,the birds¶ egg shells,devastating the populationdevastating the population
By early 1970s, the entireBy early 1970s, the entire
U.S. population was downU.S. population was downto 12 breeding pairsto 12 breeding pairs
Peregrines were declaredPeregrines were declaredfederally endangered andfederally endangered andDDT bannedDDT banned
Peregrines were bred inPeregrines were bred incaptivity and reintroducedcaptivity and reintroduced
successfully in citiessuccessfully in cities
DDT & PeregrineDDT & Peregrine
Photos courtesy of Texas Parks and Wildlife DepartmentPhotos courtesy of Texas Parks and Wildlife Department
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³ In the United States at least 500³ In the United States at least 500species and subspecies of plantsspecies and subspecies of plantsand animals have become extinctand animals have become extinctsince the 1500s.´since the 1500s.´
Douglas Chadwick, H.,Douglas Chadwick, H., N ati o nal Ge o gra phic N ati o nal Ge o gra phic , March 1995, March 1995
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Endangered Species Act of 1973Endangered Species Act of 1973The Secretary of the Interior The Secretary of the Interior determines whether a species isdetermines whether a species isendangered or threatenedendangered or threatened
The Secretary develops andThe Secretary develops andimplements recovery plans for theimplements recovery plans for theconservation of endangered speciesconservation of endangered species
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DefinitionsDefinitions - - EndangeredEndangeredSpecies ActSpecies Act
Endangered SpeciesEndangered Species -- Any species that isAny species that is
in danger of extinction throughout all or ain danger of extinction throughout all or asignificant portion of its rangesignificant portion of its range
Threatened SpeciesThreatened Species -- Any species that isAny species that is
likely to become an endangered specieslikely to become an endangered specieswithin the foreseeable futurewithin the foreseeable future
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OTHER COMEBACKSESA is havingsomesuccess
2009 StatsAnimals 613Plants 747
endangeredspecies in theU.S.
Gray whale(Calif orn ia popu lation)
Aleutian Canadagoose
American alligator
Brown pelicanUtah prairie dot
Greenback cutthroattrout
1994
1985
1990
1987
1984
1978
date of change
Species removed fromendangered list or reclassified as threatened
Based on: Time , July 11, 1994
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Pests, DDT and biomagnification
DDT, eagles and falconsEndangered Species ActOrganic foods
Overview of Lesson
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Defining ³ Organic´Defining ³ Organic´
Foods produced withoutFoods produced withouthormones, antibiotics,hormones, antibiotics,herbicides, insecticides,herbicides, insecticides,
chemical fertilizers,chemical fertilizers,genetic modification or genetic modification or germgerm- -killing radiationkilling radiation
The USDA labels suchThe USDA labels suchfoods ³ certified organic´foods ³ certified organic´
From:From: N ewsweek N ewsweek , Sept. 30, 2002, Sept. 30, 2002
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Availability of Organic Products
Based on:Based on: N ewsweek N ewsweek , Sept. 30, 2002, Sept. 30, 2002
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Unanswered Q uestions aboutUnanswered Q uestions about
Certified Organic FoodsCertified Organic Foods
Are organic food safer than other foods?Are organic food safer than other foods?
Do organic foods taste better?Do organic foods taste better?
Are organic foods worth the extra costs?Are organic foods worth the extra costs?
Are people eating organic diets healthier thanAre people eating organic diets healthier thanpeople with conventional diets?people with conventional diets?
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Can organic farming helpCan organic farming help
the environment?the environment?
Pesticides now kill 67 million AmericanPesticides now kill 67 million American
birds per year birds per year
The Mississippi River dumps enoughThe Mississippi River dumps enoughfertilizer into the Gulf of Mexico to maintainfertilizer into the Gulf of Mexico to maintain
a 60 mile ³ dead zone´ devoid of fisha 60 mile ³ dead zone´ devoid of fish
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Pesticides and Human HealthPesticides and Human Health
India suffering from human healthIndia suffering from human healthconsequences of pesticide useconsequences of pesticide use
InfertilityInfertilityCancer related deaths increasingCancer related deaths increasingChildhood cancersChildhood cancersMental retardationMental retardation
Research shows pesticides and fertilizersResearch shows pesticides and fertilizersin the groundwater.in the groundwater.
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Next Lesson
The Water Cycle