The Extinction of Life on Earth - Contemporary Issues in Biology

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14 Δεκ 2012 (πριν από 4 χρόνια και 10 μήνες)

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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




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


Previous Lesson


Origin and Evolution
of Life

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

13.7 billion




Origin of the universe

4.5 billion


Formation of Earth

3.5 billion


Earliest known fossil bacteria

3.5 billion to present

Evolution of all forms of life

3
-
4 million


Lucy present

0.13 million



Homo sapiens

arise

Years Before Present

Evolutionary Times

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?

Original population:
10% dark
-
colored
phenotype

After pollution:
80% dark
-
colored
phenotype

Based on: Campbell, et al.,
Biology: Concepts & Connections
, Benjamin Cummings

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



Today’s Lesson


Agricultural Systems and
Transgenic Organisms


Humans before agriculture


Domestication and agriculture


Energy flow in agricultural systems


Productivity and technology


Genetic engineering

Overview of Lesson

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
.

12,000 years ago, humans

(
Homo sapiens
) were widely
distributed

Based on:
Smithsonian
, October 1986

12,000 years ago, agricultural systems
did not exist and humans

(
Homo sapiens
) were hunter
-
gatherers

Based on:
Smithsonian
, October 1986

Humans used tools such as needles,
spears and clothes, and lived

in small groups


Based on:
Smithsonian
, October 1986

What made it possible to change from
small groups to the large cities of today?

10,000 BC

Today

Photo courtesy of Texas Department of
Transportation

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


Prehistoric humans


Domestication and agriculture


Energy flow in agricultural systems


Productivity and technology


Genetic engineering

Overview of Lesson

Domestication process began about
12,000 years ago


A domesticated plant or animal is
modified from its wild ancestors for use
by humans

Domestication

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


Changes in wheat through domestication

Wild

form

Based on:
Scientific American
, September 13, 1976

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 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

Ukraine

Donkey

4,000

BC

Egypt




Dates (BC) and Places of First

Evidence for Domestication

from 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

Corn, Beans, Squash

3,500

BC

Mesoamerica

Potato



3,500

BC

Andes

Sunflower



2,500

BC

Eastern U.S.


Movement of agricultural crops

from the Fertile Crescent

From:
New York Times
, November 18, 1997

Highly advanced civilizations were
present by 2,000
-

4,000 BC

Based on:
National Geographic
, September, 1998


Prehistoric humans


Domestication and agriculture


Energy flow in agricultural systems


Productivity and technology


Genetic engineering

Overview of Lesson

There are two types of agricultural systems
that make the energy of the sun available as
food to humans

Sun

Grass

Herbivore

Man

Sun

Grain Crop

Man

Photos courtesy of Texas Department of Transportation

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

Electromagnetic Spectrum

Based on: Campbell, et al.,
Biology: Concepts & Connections
, Benjamin Cummings

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

Relationship between
photosynthesis and
cellular respiration

Photosynthesis

Respiration

Based on: Campbell et al.,
Biology: Concepts
and Connections
, Benjamin Cummings

Energy flow in two
types of agricultural
systems

Based on:
Scientific American
, September 1976


Prehistoric humans


Domestication and agriculture


Energy flow in agricultural systems


Productivity and technology


Genetic engineering

Overview of Lesson

Growth in Agricultural Productivity

From: :
Scientific American
, February, 1983

Harvesting Technology

Photos courtesy of Texas Department of Transportation

Irrigation Technology

Photos courtesy of Texas Department of
Transportation

Based on:
Scientific American
, February 1983


Domestication

Technology

Pesticide

Technology

Photo courtesy of Texas Parks and Wildlife Department

Photo courtesy of Texas Department of Transportation

Fertilizer Technology

Despite Technology, Chronic
Under
-
nutrition is Still a
Worldwide Problem


Prehistoric humans


Domestication and agriculture


Energy flow in agricultural systems


Productivity and technology


Genetic engineering

Overview of Lesson

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

Agricultural plants have been modified to
contain human genes to produce human
proteins to fight human disease

From:
Time
, May 26, 2003

Many agricultural plants are undergoing
genetic engineering to fight pests

From:
Time
, May 26, 2003

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

This corn contained a protein that
provides resistance to pests and was
only approved for animal foods



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






Next Lesson


Pesticides and Organic
Farming