The Extinction of Life on Earth: Is the End Near?

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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 6.c
Identify and illustrate how changes in DNA cause
mutations and evaluate the significance of these
changes 6.d Compare genetic variations observed
in plants and animals 9.b Compare the energy
flow in photosynthesis to the energy flow in
cellular respiration
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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 12.a
Analyze the flow of energy through various cycles
including the carbon, oxygen, nitrogen and water
cycles 12.d Identify and illustrate that
long-term survival of species is dependent on
resource space and may be limited 12.e
Investigate and explain interactions in an
ecosystem including food chains, food webs, and
food pyramids 13.a Evaluate the significance of
structural and physiological adaptations of
plants to their environment
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Previous Lesson Origin and Evolution of Life
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• Question According to scientists, what are the
  ages of the following events?
• Homo sapiens arise
• Lucy
• Evolution of life on earth
• Life first appears on earth
• Earth formed
• Universe formed

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Evolutionary Times
Years Before Present
0.13 million Homo sapiens arise
3-4 million Lucy present
3.5 billion to present Evolution of all forms of
life
3.5 billion Earliest known fossil bacteria
4.5 billion Formation of Earth
13.7 billion Origin of the universe
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Question After the Industrial Revolution in
England, the tree bark changed from light to dark
and the moth populations changed from
predominantly light to dark. How would
evolutionary theory explain this?
After pollution 80 dark-colored phenotype
Original population 10 dark-colored phenotype
Based on Campbell, et al., Biology Concepts
Connections, Benjamin Cummings
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Evolution

• Change in the genetic makeup of a population
  through time, sometimes leading to formation of
  new species
• Natural selection by the environment determines
  which organisms will survive and reproduce
• Natural selection (bird predation) favored dark
  moths after the trees became dark

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Todays Lesson Agricultural Systems and
Transgenic Organisms
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Overview of Lesson

• Humans before agriculture
• Domestication and agriculture
• Energy flow in agricultural systems
• Productivity and technology
• Genetic engineering

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Out of Africa Theory Our human ancestors
evolved in Africa and then spread around the world
Based on Diamond, J., Guns, Germs and Steel,
Random House, 1997.
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12,000 years ago, humans (Homo sapiens) were
widely distributed
Based on Smithsonian, October 1986
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12,000 years ago, agricultural systems did not
exist and humans (Homo sapiens) were
hunter-gatherers
Based on Smithsonian, October 1986
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Humans used tools such as needles, spears and
clothes, and livedin small groups
Based on Smithsonian, October 1986
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What made it possible to change from small groups
to the large cities of today?
Photo courtesy of Texas Department of
Transportation
10,000 BC
Today
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Large cities and highly advanced civilizations
were only possible after we domesticated wild
plants and animals and developed agricultural
systems
Photo courtesy of Texas Department of
Transportation
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Overview of Lesson

• Prehistoric humans
• Domestication and agriculture
• Energy flow in agricultural systems
• Productivity and technology
• Genetic engineering

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Domestication
Domestication process began about 12,000 years
ago A domesticated plant or animal is modified
from its wild ancestors for use by humans
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Early domestication was unintentional seeds
brought back by hunter-gatherers foraging in the
wild grew by accident in latrines and garbage
dumps
Later domestication was conscious scientists
planted many different seeds, selected the best
progeny and planted their seeds
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Changes in wheat through domestication
Wild form
Based on Scientific American, September 13, 1976
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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
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Dates (BC) and Places of First Evidence for
Domesticationfrom Diamond, J., Guns, Germs and
Steel, Random House, 1997
Wheat, Pea, Olive 8,500 BC SW. Asia Rice,
Millet 7,500 BC China Sorghum 5,000 BC Sahel C
orn, Beans, Squash 3,500 BC Mesoamerica Potato 3
,500 BC Andes Sunflower 2,500 BC Eastern U.S.
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Movement of agricultural cropsfrom the Fertile
Crescent
From New York Times, November 18, 1997
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Highly advanced civilizations were present by
2,000 - 4,000 BC
Based on National Geographic, September, 1998
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Overview of Lesson

• Prehistoric humans
• Domestication and agriculture
• Energy flow in agricultural systems
• Productivity and technology
• Genetic engineering

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There are two types of agricultural systems that
make the energy of the sun available as food to
humans
Photos courtesy of Texas Department of
Transportation
Sun Grass Herbivore Man
Sun Grain Crop Man
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All agricultural systems are based on plants
converting the energy of the sun to the energy of
sugar through the process of photosynthesis
energy of the sun carbon dioxide water
energy of sugar oxygen
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Electromagnetic Spectrum
Based on Campbell, et al., Biology Concepts
Connections, Benjamin Cummings
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Energy is lost due to respiration of plants and
animals
energy of sugar oxygen energy of ATP carbon
dioxide water
Energy of ATP is then used to stay alive
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Relationship between photosynthesis and cellular
respiration
Photosynthesis
Respiration
Based on Campbell et al., Biology Concepts
and Connections, Benjamin Cummings
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Energy flow in two types of agricultural systems
Based on Scientific American, September 1976
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Overview of Lesson

• Prehistoric humans
• Domestication and agriculture
• Energy flow in agricultural systems
• Productivity and technology
• Genetic engineering

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Growth in Agricultural Productivity
From Scientific American, February, 1983
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Harvesting Technology
Photos courtesy of Texas Department of
Transportation
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Irrigation Technology
Based on Scientific American, February 1983
Photos courtesy of Texas Department of
Transportation
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DomesticationTechnology
PesticideTechnology
Photo courtesy of Texas Parks and Wildlife
Department
Photo courtesy of Texas Department of
Transportation
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Fertilizer Technology
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Despite Technology, Chronic Under-nutrition is
Still a Worldwide Problem
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Overview of Lesson

• Prehistoric humans
• Domestication and agriculture
• Energy flow in agricultural systems
• Productivity and technology
• Genetic engineering

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Genetic Engineering
Take a gene (directing synthesis of a desired
protein) from an animal or plant and insert it
into an agricultural plant The engineered
agricultural plant makes the protein specified by
the inserted gene. Large quantities of the
protein can be produced by growing large crops of
the engineered plant
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From Time, May 26, 2003
Agricultural plants have been modified to contain
human genes to produce human proteins to fight
human disease
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From Time, May 26, 2003
Many agricultural plants are undergoing genetic
engineering to fight pests
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Critics have named crops with human genes
Pharmageddon. Environmentalists are worried
that unnaturally combined genes may spread like
genetic kudzu.Foods with unnatural proteins
are called Frankenfood. People are worried
about buying foods in the grocery store that are
genetically engineered to produce their own
pesticides.
From Time, November 29, 1999
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This corn contained a protein that provides
resistance to pests and was only approved for
animal foods
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• 2005 GM strain contaminating traditional canola
  Canada, Australia
• 2009 GM genes escape to wild corn Mexico
• 2009 crops tested for GM cross contamination in
  Australia
• 2009 Mass GM corn crop failure in South Africa

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Next LessonPesticides and Organic Farming