This lesson will increase your knowledge of concepts covered in the following TEKS for biology:

1
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
2
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
3
Previous LessonAgricultural Systems and
Transgenic Organisms
4
Question Many of us take agriculture for
granted. How has it affected human history?
Photos courtesy of Texas Parks and Wildlife
Department
5
Development of agricultural systems made advanced
civilization possible
Photo courtesy of Texas Department of
Transportation
10,000 BC
Today
6
Question When did domestication begin and what
was the first animal domesticated?
7
Dates (BC) and Places of First Evidence for
Domesticationfrom Diamond, J., Guns, Germs and
Steel, Random House, 1997
Dog 10,000 BC SW. Asia,China, North
America Sheep 8,000 BC SW. Asia Goat 8,000 BC SW.
Asia Pig 8,000 BC China, SW. Asia Cow 6,000 BC
SW. Asia, India, North Africa Horse 4,000 BC Ukra
ine Donkey 4,000 BC Egypt
8

• The dog was one
• of the first animals
• domesticated
• 10,000 years of
• domestication may
• explain why dogs
• are mans best
• friend

From Fort Worth Star-Telegram
9
Question Why is there a controversy over using
grain to fatten cattle?
From Time, November 8, 1999
10
Many more people could be fed by the grain used
to feed the cattle than can be fed by the cattle
themselvesThis is because productive energy is
diminished with each trophic level
Based on Scientific American, September 1976
11
Question What is good and bad about genetically
engineered agricultural plants?
12
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.

13
Todays LessonPesticides and Organic Farming
14
Overview of Lesson

• Pests, DDT and biomagnification
• DDT, eagles and falcons
• Endangered Species Act
• Organic farming

15
Domestic crops were selected for maximum
productivity and had little natural pest
resistance
16
Potato famine of Ireland was caused by
genetically uniform crops and lack of pesticides
to protect them
Blight hits potatoes, 1845
Based on Population Reports, May 1992
17
Todays Pests
Pests attack and eat our food crops This problem
is due, in part, to not selecting for pest
resistance during domestication
Based on National Geographic, February 1980
18
DDT was invented in the 1940s and viewed as-
miracle for farmers- and safe
19
The most discussed of the new insecticides is
dichloro-diphenyl-trichloroethane, shortened to
DDT but also called Guesarol. This compound has
remarkable power to kill insects, particularly
body lice-the cooties of World War I. The
prevalence of typhus, carried by body lice, in
the Mediterranean theater of this war has
emphasized its value. DDTs effectiveness in war
may well be overshadowed by its value in peace.
Painstaking investigations have shown it to be
signally effective against many of the most
destructive insects that feed upon
crops.Scientific American, July 1944.
20
Arial crop sprayers were used to spray tons of
DDT on crops across the U.S.
Photo courtesy of Texas Parks and Wildlife
Department
21
Pests became resistant to DDT
Based on National Geographic
22
Pesticide Resistance
In the beginning, most pests were sensitive to
DDT but a few were resistant The resistant forms
survived and reproduced In the end, most pests
were resistant to DDT
Based on National Geographic, February 1980
23
BiomagnificationThe concentration of pesticides
in higher levels of food chains
24
Trophic Levels
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
Most food chains consist of four trophic levels
25
Energy Available to Consumers at Next Trophic
Level
Energy Lost by Death and Decay
Energy Lost by Respiration
Energy Lost by Excretion
Energy Lost by Egestion of Feces
Energy Ingested
26
DDT in Food Chain
DDT is concentrated as it moved up food
chain This is because energy is lost (from
respiration) as go up food chain but DDT is not
Based on Campbell et al, Biology Concepts and
Connections, Benjamin Cummings
27
Overview of Lesson

• Pests, DDT and biomagnification
• DDT, eagles and falcons
• Endangered Species Act
• Organic foods

28
Bald Eagle

• Once was widely
• distributed over U.S.
• As a top carnivore it feeds on fish
• Swoops down and captures fish off the surface of
  the water

Photo courtesy of Texas Parks and Wildlife
Department
29

• Scientists discovered that DDT was
• concentrated in the bald eagle
• DDT affected the eagles ability to reproduce

Photos courtesy of Texas Parks and Wildlife
Department
30
Scientists found that the eagle eggs had thin egg
shells and broke easily Nests contained broken,
rotten eggs The number of young produced per
breeding pair was reduced
31
Population of adult eagles declined to 4,000 and
the eagle was listed as Endangered
Photo courtesy of Texas Parks and Wildlife
Department
32
The Environmental Protection Agency (EPA) banned
DDT in 1972
Photo courtesy of Texas Parks and Wildlife
Department
33
Eagle reproduction before and after DDT ban
Based on Grier, J., Science, 1982
34
Eagle populations increased rapidly and the eagle
is now listed as Threatened
From Time, July 11, 1994
35
Peregrine Falcon

• Occurred naturally
• over most of continental U.S.
• Nests on cliffs
• Keen eyesight
• (if human, could read newspaper print at 110
  yards)
• Feeds on other birds, knocking them out of the
  sky at 200 m.p.h.

Photo courtesy of Texas Parks and Wildlife
Department
36
DDT Peregrine

• After DDT was introduced
• in 1940s, DDT weakened
• the birds egg shells,
• devastating the population
• By early 1970s, the entire
• U.S. population was down
• to 12 breeding pairs
• Peregrines were declared
• federally endangered and
• DDT banned
• Peregrines were bred in
• captivity and reintroduced
• successfully in cities

Photos courtesy of Texas Parks and Wildlife
Department
37
Overview of Lesson

• Pests, DDT and biomagnification
• DDT, eagles and falcons
• Endangered Species Act
• Organic foods

38
In the United States at least 500 species and
subspecies of plants and animals have become
extinct since the 1500s. Douglas Chadwick, H.,
National Geographic, March 1995
39
Endangered Species Act of 1973

• The Secretary of the Interior determines whether
  a species is endangered or threatened
• The Secretary develops and implements recovery
  plans for the conservation of endangered species

40
Definitions - Endangered Species Act

• Endangered Species - Any species that is in
  danger of extinction throughout all or a
  significant portion of its range
• Threatened Species - Any species that is likely
  to become an endangered species within the
  foreseeable future

41

• OTHER COMEBACKS

• ESA is having some success
• 2009 Stats
• Animals 613
• Plants 747 endangered species in the U.S.

Species removed from endangered list or
reclassified as threatened
date of change
1994
Gray whale (California population) Aleutian
Canada goose American alligator Brown
pelican Utah prairie dot Greenback cutthroat trout
1990
1987
1985
1984
1978
Based on Time, July 11, 1994
42
Overview of Lesson

• Pests, DDT and biomagnification
• DDT, eagles and falcons
• Endangered Species Act
• Organic foods

43
Defining Organic
Foods produced without hormones, antibiotics,
herbicides, insecticides, chemical fertilizers,
genetic modification or germ-killing
radiation The USDA labels such foods certified
organic
From Newsweek, Sept. 30, 2002
44
Availability of Organic Products
Based on Newsweek, Sept. 30, 2002
45
Unanswered Questions about Certified Organic Foods
Are organic food safer than other foods? Do
organic foods taste better? Are organic foods
worth the extra costs? Are people eating organic
diets healthier than people with conventional
diets?
46
Can organic farming help the environment?
Pesticides now kill 67 million American birds per
year The Mississippi River dumps enough
fertilizer into the Gulf of Mexico to maintain a
60 mile dead zone devoid of fish
47
Pesticides and Human Health

• India suffering from human health consequences of
  pesticide use
• Infertility
• Cancer related deaths increasing
• Childhood cancers
• Mental retardation
• Research shows pesticides and fertilizers in the
  groundwater.

48
Next Lesson The Water Cycle