this lesson will increase your knowledge of concepts covered in the following teks for biology: 3.a...
TRANSCRIPT
This lesson will increase your knowledge of concepts covered in the following TEKS for biology:
3.a – Analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information
3.c – Evaluate impact of research on scientific thought, society, and the environment
3.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 animals
7.b – Illustrate the results of natural selection in the speciation, diversity, phylogeny, adaptation, behavior and extinction
This lesson will increase your knowledge of concepts covered 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 disrupting equilibrium 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 food chains, food webs, and food pyramids
Previous Lesson
Agricultural Systems and Transgenic Organisms
Question: Many of us take agriculture for granted. How has it affected human history?Photos courtesy of Texas Parks and Wildlife Department
Development of agricultural systems made advanced civilization possible
10,000 BC
Photo courtesy of Texas Department of Transportation
Today
Question: When did domestication begin and what was the first animal domesticated?
Dates (BC) and Places of First Evidence for Domestication
from Diamond, J., Guns, Germs and Steel, Random House, 1997
Dog 10,000 BC SW. Asia,China, North AmericaSheep8,000 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
From: Fort Worth Star-Telegram
•The dog was one of the first animals domesticated
•10,000 years of domestication may explain why dogs are man’s best friend
Question: Why is there a controversy over using grain to fatten cattle?
From: Time, November 8, 1999
Many more people could be fed by the grain used to feed the cattle than can be fed by the cattle themselves
This is because productive energy is diminished with each trophic level
Based on: Scientific American, September 1976
Question: What is good and bad about genetically engineered agricultural plants?
Genetically Engineered Plants• The Good: Crops can be engineered to
have important components of diet, contain medically important proteins, and to be pest resistant
• The Bad: Plants could contain pesticides that would harm humans and wildlife, or proteins that could cause allergies in humans. Genetics could escape to traditional crops.
Today’s LessonToday’s Lesson
Pesticides and Pesticides and Organic FarmingOrganic Farming
•Pests, DDT and biomagnification•DDT, eagles and falcons•Endangered Species Act•Organic farming
Overview of Lesson
Domestic crops were Domestic crops were selected for maximum selected for maximum
productivity and had little productivity and had little natural pest resistancenatural pest resistance
Blight hits potatoes, 1845
Based on: Population Reports, May 1992
Potato famine of Ireland was caused by genetically uniform crops and lack of
pesticides to protect them
Pests attack and Pests attack and eat our food cropseat our food crops
This problem is This problem is due, in part, to not due, in part, to not selecting for pest selecting for pest resistance during resistance during domesticationdomestication
Today’s PestsToday’s Pests
Based on: National Geographic, February 1980
DDT was invented in the DDT was invented in the 1940’s and viewed as:1940’s and viewed as:- miracle for farmers- miracle for farmers- and safe- and safe
““The most discussed of the new insecticides is The most discussed of the new insecticides is dichloro-diphenyl-trichloroethane, shortened to dichloro-diphenyl-trichloroethane, shortened to DDT but also called Guesarol. This compound has DDT but also called Guesarol. This compound has remarkable power to kill insects, particularly body remarkable power to kill insects, particularly body lice-the ‘cooties’ of World War I. The prevalence of lice-the ‘cooties’ of World War I. The prevalence of typhus, carried by body lice, in the Mediterranean typhus, carried by body lice, in the Mediterranean theater of this war has emphasized its value. theater of this war has emphasized its value. DDT’s effectiveness in war may well be DDT’s effectiveness in war may well be overshadowed by its value in peace. Painstaking overshadowed by its value in peace. Painstaking investigations have shown it to be signally investigations have shown it to be signally effective against many of the most destructive effective against many of the most destructive insects that feed upon crops.”insects that feed upon crops.”
Scientific AmericanScientific American, July 1944., July 1944.
Arial crop sprayers Arial crop sprayers were used to spray were used to spray tons of DDT on tons of DDT on crops across the crops across the U.S.U.S.
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
Pests became resistant to DDTPests became resistant to DDT
Based on: National Geographic
Pesticide ResistancePesticide Resistance
In the beginning, most In the beginning, most pests were sensitive to pests were sensitive to DDT but a few were DDT but a few were resistantresistant
The resistant forms The resistant forms survived and reproducedsurvived and reproduced
In the end, most pests In the end, most pests were resistant to DDTwere resistant to DDT
Based on: National Geographic, February 1980
BiomagnificationBiomagnification
The concentration of The concentration of pesticides in higher levels of pesticides in higher levels of
food chainsfood chains
Most food chains consist of four trophic levels
Based on: Mader, S., Inquiry Into Life, McGraw-Hill
Trophic Levels
Energy Available to Consumers at
Next Trophic Level
Energy Lost by Respiration
Energy Lost by Death and Decay
Energy Lost by Excretion
Energy Lost by Egestion of Feces
Energy Ingested
DDT is concentrated as DDT is concentrated as it moved up food chainit moved up food chain
This is because energy This is because energy is lost (from respiration) is lost (from respiration) as go up food chain but as go up food chain but DDT is notDDT is not
Based on: Campbell et al, Biology: Concepts and Connections, Benjamin Cummings
DDT in Food Chain
•Pests, DDT and biomagnification•DDT, eagles and falcons•Endangered Species Act•Organic foods
Overview of Lesson
Bald EagleBald Eagle
•Once was widelyOnce was widely distributed over U.S.distributed over U.S.
•As a top carnivore it As a top carnivore it feeds on fishfeeds on fish
•Swoops down and Swoops down and captures fish off the captures fish off the surface of the watersurface of the water
Photo courtesy of Texas Parks and Wildlife Photo courtesy of Texas Parks and Wildlife DepartmentDepartment
•Scientists discovered that DDT wasScientists discovered that DDT was concentrated in the bald eagle concentrated 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
Scientists found Scientists found that the eagle eggs that the eagle eggs had thin egg shells had thin egg shells and broke easilyand broke easily
Nests contained Nests contained broken, rotten eggsbroken, rotten eggs
The number of The number of young produced per young produced per breedingbreedingpair was reducedpair was reduced
Population of adult Population of adult eagles declined to 4,000 eagles declined to 4,000 and the eagle was listed and the eagle was listed as “Endangered”as “Endangered”
Photo courtesy of Texas Parks and Wildlife DepartmentPhoto courtesy of Texas Parks and Wildlife Department
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
Eagle reproduction before and after DDT ban Eagle reproduction before and after DDT ban
Based on: Grier, J., Science, 1982
Eagle populations increased rapidly and Eagle populations increased rapidly and the eagle is now listed as “Threatened”the eagle is now listed as “Threatened”
From: Time, July 11, 1994
Peregrine FalconPeregrine Falcon •Occurred naturallyOccurred naturally over most of over most of continental U.S.continental U.S.
•Nests on cliffsNests on cliffs
•Keen eyesight Keen eyesight (if human, could read (if human, could read newspaper 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
•After DDT was introducedAfter DDT was introduced in 1940s, DDT weakenedin 1940s, DDT weakened the 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 down to 12 breeding pairsto 12 breeding pairs
•Peregrines were declaredPeregrines were declared federally endangered andfederally endangered and DDT bannedDDT banned
•Peregrines were bred inPeregrines were bred in captivity 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
•Pests, DDT and biomagnification•DDT, eagles and falcons•Endangered Species Act•Organic foods
Overview of Lesson
““In the United States at least 500In 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., National GeographicNational Geographic, March 1995, March 1995
Endangered Species Act of 1973Endangered Species Act of 1973
• The Secretary of the Interior The Secretary of the Interior determines whether a species is determines whether a species is endangered or threatened endangered or threatened
• The Secretary develops and The Secretary develops and implements recovery plans for the implements recovery plans for the conservation of endangered speciesconservation of endangered species
Definitions - Endangered Definitions - Endangered Species ActSpecies Act
• Endangered SpeciesEndangered Species - Any species that is - Any species that is in danger of extinction throughout all or a in danger of extinction throughout all or a significant portion of its rangesignificant portion of its range
• Threatened SpeciesThreatened Species - Any species that is - Any species that is likely to become an endangered species likely to become an endangered species within the foreseeable futurewithin the foreseeable future
OTHER COMEBACKS ESA is having
some success
2009 StatsAnimals 613Plants 747
endangered species in the U.S.
Gray whale (California population)
Aleutian Canada goose
American alligator
Brown pelican
Utah prairie dot
Greenback cutthroat trout
1994
1985
1990
1987
1984
1978
date of change
Species removed from endangered list or reclassified as threatened
Based on: Time, July 11, 1994
•Pests, DDT and biomagnification•DDT, eagles and falcons•Endangered Species Act•Organic foods
Overview of Lesson
Defining “Organic”Defining “Organic”
Foods produced without Foods produced without hormones, antibiotics, hormones, antibiotics, herbicides, insecticides, herbicides, insecticides, chemical fertilizers, chemical fertilizers, genetic modification or genetic modification or germ-killing radiationgerm-killing radiation
The USDA labels such The USDA labels such foods “certified organic”foods “certified organic”
From: From: NewsweekNewsweek, Sept. 30, 2002, Sept. 30, 2002
Availability of Organic Products
Based on: Based on: NewsweekNewsweek, Sept. 30, 2002, Sept. 30, 2002
Unanswered Questions about Unanswered Questions 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 than Are people eating organic diets healthier than people with conventional diets?people with conventional diets?
Can organic farming help Can organic farming help the environment?the environment?
Pesticides now kill 67 million American Pesticides now kill 67 million American birds per yearbirds per year
The Mississippi River dumps enough The Mississippi River dumps enough fertilizer into the Gulf of Mexico to maintain fertilizer into the Gulf of Mexico to maintain a 60 mile “dead zone” devoid of fisha 60 mile “dead zone” devoid of fish
Pesticides and Human HealthPesticides and Human Health
India suffering from human health India suffering from human health consequences of pesticide useconsequences of pesticide use
•InfertilityInfertility•Cancer related deaths increasingCancer related deaths increasing•Childhood cancersChildhood cancers•Mental retardationMental retardation
Research shows pesticides and fertilizers Research shows pesticides and fertilizers in the groundwater.in the groundwater.
Next Lesson
The Water Cycle