Earth Systems Geology 1425 Chapter 15 A Planetary Perspective On Life: The Biosphere

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Earth Systems Geology 1425Chapter 15A
Planetary Perspective On LifeThe Biosphere
Department of Geology University of Texas at
Arlington
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(No Transcript)
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The BioSystem
http//www.euronet.nl/users/rkohm/biosphere/
? What is life? ? How is it organized? ?What
are the differences between life and non life?
Bacteria and Virus? ? Define the following
metabolism, growth, reproduction, evolution.
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The BioSystem
The four essential properties of living organisms
? Metabolism biological processing of chemicals
(food) to produce energy ? Growth changes in an
organism
? Reproduction The sexual or asexual process by
which organisms generate new individuals of the
same kind. ? Evolution Changes in populations
produced by changes in DNA modified by natural
selection.
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The BioSystem
? What are the differences between polymerization
and crystallization life forms and minerals? ?
What is a biological cell? What are the two types
of cells and how are they different? ? What can
multi-celled organisms do that single-celled ones
cannot?
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The BioSystem
Ordering of atoms and molecules occur in one of
two ways ? Polymerization by life forms growing
large chains of molecules by attaching other
molecules together. Requires energy ?
Crystallization of minerals Uses atomic forces
to attract and bond atoms and radicals together
producing a lattice of atoms. Releases energy.
Biopolymers
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The BioSystemStructure of life forms
? The cell is the basic unit of life. It has an
outer membrane, material that can metabolize food
and generate energy, and DNA that contains all
the information necessary to reproduce itself.
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The BioSystemStructure of life forms

• Two types of cells
• ? Prokaryotes have little internal structure and
  are the simplest of life forms. Most prokaryotes
  are single celled organisms like bacteria.

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The BioSystemStructure of life forms
Eukaryotes have a nucleus with a membrane housing
DNA as well as other structures that have
specific functions in the cell. Almost all
multicelled organisms (plants, animals) are
Eukaryotes.
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The BioSystemStructure of life forms
? Multi-celled organisms can have cellular
structures that specialize and perform different
functions i.e. they can form systems of cells
that single celled organisms cannot.
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The BioSystemStructure of life forms

• Cell growth follows specific plans
• Those growth plans are stored in DNA
  dioxyribonucleic acid
• Like barcodes, DNA stores genetic information

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The BioSystemClassification
? What is a species? ? How are species classified
and grouped? What are these groups named? ? What
is an ecological community? An ecosystem? A
biome, the biosphere? ? What are autotrophs,
heterotrophs and decomposers? How do they get
energy? How do they interact? ? What 4 elements
are necessary to support life?
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The BioSystemClassification
? Classification systems were initially based on
similarities in anatomy and energy source. ?
More recently, classifications are based on
evolutionary relatedness determined by DNA
similarities. ? DOMAINS are organisms with
similar cell types and similar origins.
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The BioSystemClassification
? Species a group of organisms that can
interbreed and exchange DNA ? Genus a group of
species with similar characteristics ? Family a
group of similar genus ? Order similar
families ? Class similar orders ? Phyla
similar classes ?Kingdom similar phyla ? Domain
similar cell structure evolutionary origin.
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The BioSystemHuman Classification
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The BioSystem

• ECO-HIERARCHY
• An ecological community is a group of species
  living together, interacting and competing for
  food and space.
• ? An ecosystem includes the ecological community
  as well as the physical and chemical environment.
• ? Biomes are groups of ecosystems that are
  similar. e.g. a tropical rainforest biome
  includes all the ecosystems of the world located
  in areas of high temperatures and rainfall.
• ? The biosphere is consists of all the biomes.

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The EcoSystem Life Support
Ecosystems (example below) are usually organized
into trophic levels i.e. who eats whom, better
known as the food chain.
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The EcoSystem Life Support
Ecosystems are also organized by species that get
their energy in different ways
Autotrophs vs. Heterotrophs Autotrophs fix their
own energy from inorganic sources -Autotrophs
are the producers in an ecosystem Heterotrophs
depend upon energy and carbon fixed by some other
organism -they are consumers, detritivores, or
decomposers (A mixotroph gets its energy from
inorganic sources, but relies on organic sources
of carbon).
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The EcoSystem Life Support

• An ecosystem must have a flow of energy (movement
  of energy through an ecosystem from the
  external environment (Sun) through a series of
  organisms and back to the external environment
  (space)).
• No single organism can make its own food from
  inorganic chemicals, producing organic compounds,
  and then decompose those compounds to be recycled
• There must be at least two types of organisms a
  producer of the organic compounds and a
  decomposer of organic compounds

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The EcoSystem Life Support

• ? Flow of energy in an ecosystem starts with the
  autotrophs
• ? Some autotrophs do not use light, but convert
  certain chemicals into energy, which is then used
  to convert nutrients into their organic
  structure. However, most autotrophs metabolize
  sunlight to produce CO2 and carbohydrates.

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The EcoSystem Life Support
? Photosynthesis by plants and some bacteria
converts light energy, C02 and H20 into sugars
(carbohydrates), which form the organic structure
and feeds the metabolic processes. This is a
polymerization process.
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The EcoSystem Life Support

• Energy flow in heterotrophs
• ? When many heterotrophs eat another organism,
  they oxidize the carbohydrates and proteins by
  respiration (breathing) producing C02 and H20.
  Oxidation produces energy, which is used by the
  organism to survive.

Energy flows one way through an ecosystem, while
chemical elements can recycle.
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The EcoSystem Life Support
? Respiration (breathing) is similar to an auto
engine
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The EcoSystem Life Support
Glucose
? Other heterotrophs (yeast) use a fermentation
process to decompose sugar into alcohol (or
lactic acid), C02 and H20, which also releases
energy for survival. ? "No species is an island".
Every species (including human) is dependent on
other species and the physical environment for
survival. The capacity to support life is the
characteristic of an ecosystem. "It takes an
ecosystem to raise offspring".
Pyruvic Acid
Lactic Acid
alcohol
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The EcoSystem Life Support
Phytoplankton (left), an autotroph

• Four elements necessary for life
• ? Recycling of chemical elements (nutrients)
• ? A flow of energy.
• ? Organisms that get their chemicals and energy
  from the physical environment without consuming
  other organisms (autotrophs bottom of the food
  chain)
• ? Organisms that get their chemicals and energy
  from other organisms (decomposers and
  heterotrophs).

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Food Chains Trophic Levels
? What is a food chain or food web? ? What is a
trophic level? ? What are three types of
heterotrophs? Which are most humans? ? How do
autotrophs, heterotrophs and decomposers recycle
nutrients?
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Food Chains Trophic Levels
? A trophic structure (Food chain, left) is a map
of who eats whom. ? Autotrophs are at the bottom
of the food web, and heterotrophs (including
people) cannot not survive without them.
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Food Chains Trophic Levels
? The heterotroph food web is complicated. Some
eat autotrophs (grazers), some eat other
heterotrophs (carnivores), and some eat both
(omnivores) ? Decomposers and detritivores eat
dead organisms and recycle their nutrients.
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Energy and Ecosystems
? Life involves growth, reproduction and
evolution, which requires "work", which changes
energy from an organized form to a less organized
form. ? Most of that energy comes from the sun,
but some autotrophs get that energy by oxidizing
inorganic ions.
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Energy and Ecosystems
The earth's biosphere is primarily supported by
the producers (autotrophs). Consumers
(heterotrophs and decomposers) provide the
nutrient pool for the producers in the form or
waste and dead bodies which are taken care of by
the decomposers.
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Energy and Ecosystems
The chemicals (nutrients) used for life are
constantly recycled. C, O, H and other nutrients
are converted to carbohydrates and other
molecules by the producers (autotrophs).
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Energy and Ecosystems
The heterotrophs oxidize or ferment the
autotrophs and other heterotrophs for energy and
nutrients. The decomposers use the dead
heterotrophs and autotrophs for energy and break
down the dead cells into nutrients that can be
recycled.
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• Energy flows from a lower trophic level to a
  higher one
• A small fraction of the energy available to each
  trophic level is converted to net production of
  new organic matter.
• A large fraction of the energy available to each
  trophic level is used in respiration.
• Respiration is the use of biomass to release
  energy that can be used to do work.
• Respiration returns carbon dioxide that has been
  removed by photosynthesis to the environment.

Transfer of energy through an ecosystem. At each
trophic level only a small proportion of energy
(approximately 10 percent) is transferred to the
next level.
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Population Dynamics
? What are the factors that affect the size of a
population (including humans) ? What is
exponential growth? What conditions cause it?
What stops it? ? The human population has been
growing exponentially for several hundred years.
What factors will limit this growth? ? What is
logistic growth? ? How does a species become
extinct?
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Population Dynamics
Some definitions ? A species is a population of
individuals who produce viable offspring. ?
Population dynamics the causes of growth, or
decline of a species.
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Population Dynamics

• Factors that control populations
• ? Nutrient and energy supply
• ? Competition (war) with other populations
• ? Predators, grazers
• ? Space, housing
• ? Disease
• ? Physical/Chemical Environment
• ? Temperature pressure
• ? Precipitation, humidity
• ? Chemical toxins and waste products
• ? In the case of humans, we can add
  cultural/religious space

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Population Dynamics
? Exponential growth (like compound interest)
will occur if all or most of the controlling
factors are favorable. ? Cannot continue
indefinitely because space, disease, competition
(war) and waste toxins will limit the population
if nutrient and energy supply does not.
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Population Dynamics

• ? Human population (left) has been in exponential
  growth for the past several hundred years at
  least.
• This cannot continue indefinitely. Necessary
  resources will eventually limit a population.
• The worlds population will be limited naturally
  by starvation, disease, war, waste toxins and
  lack of enough energy and nutrients to go around.

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Population Dynamics
?Logistic Growth occurs if all the factors remain
constant. Population grows exponentially for a
while, and then levels off at a stable number
determined by a controlling factor. ? Logistic
growth is the ideal, but all the factors
fluctuate in time so populations also fluctuate
in response.
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Population Dynamics
Logistic growth is ideal, but not likely

• Environmental change
• Interactions with other species
• Random events (???)
• Effects of individuals on one another
• Random time lags

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Populations become extinct when any one of the
controlling factors changes to an extent that
more die than are born.
The population was decimated by egg harvesting,
hunting of nesting females and by the accidental
drowning of thousands of turtles in shrimp trawl
nets in the Gulf of Mexico. The nesting
population of female Kemps ridleys was down to a
few hundred nesting females laying approximately
700 nests in 1985. The Kemp's ridley population
is slowly recovering and now approximately 10,000
nests are laid at Rancho Nuevo each year.
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Gaia Hypothesis
? How does the biosphere affect the geosphere,
atmosphere and hydrosphere? ? What is the Gaia
Hypothesis?
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Bio-geo-hydro-atmosphere interactions
? The biosphere interacts with the others
spheres in a number of ways ? Water, humidity,
temperature, oxygen, CO2 and mineral nutrients
all affect the biosphere. ? The biosphere also
affects the atmospheric composition and
temperature by controlling CO2 and O2. ? The
biosphere puts C into plants and animals,
removing it from the atmosphere, and some organic
material is buried in the geosphere in the form
of coal and petroleum. ? The biosphere also
affects humidity and the hydrosphere by
transpiring H2O moving groundwater into the
atmosphere. ? The biosphere affects seawater
composition by removing CaCO3 ? Humans (part of
the biosphere) remove coal and petroleum, burn
it, and put CO2 back into the atmosphere.
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Gaia Hypothesis
The Earth, James Lovelock proposes, behaves as if
it were a super organism, consisting of all the
living things (biosphere) and of their material
environment (geo-hydro-atmosphere).
He argues that such things as the level of
oxygen, the formation of clouds, and the
saltiness of the oceans are controlled by
interacting physical, chemical and biological
processes. The self-regulation of climate and
chemical composition is a process that emerges
from the tightly coupled evolution of the
geosphere, atmosphere, hydrosphere and biosphere.
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Gaia Hypothesis
Gaia, known as Earth or Mother Earth, was an
early earth goddess born from Chaos, the great
void of emptiness within the universe, and with
her came Eros. She gave birth to Pontus (the Sea)
and Uranus (the Sky) parthenogenetically (without
male intervention).
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Gaia Hypothesis

• The Gaia hypothesis is an updated version of the
  ancient myth.
• ? Life alters the physical/chemical environment
  (True)
• ? Life tends to stabilize the environment and
  preserve the conditions for life to exist (it
  provides negative feedback). (True)

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Liquid Water
Earth is just the right distance from the sun for
water to be liquid if the Earth were closer to
the Sun, like Venus, the water would be
vaporized if farther, like Mars, it would turn
to ice. Living tissue, of course, is mostly
water. Without liquid water, no life. Without
liquid water, no geological erosion, transport
and deposition on Earths surface no minerals
available to build bodies.
Gases Balance
Earth's atmosphere has a mix of gases that
maintains a temperature range "just right" for
life the gases maintain a remarkable balance.
Oxygen
Oxygen, essential to almost all life, is an
example. If oxygen were increased by 4 percent,
virtually everything on Earth would go up in
flames at the first lightning flash. Lower
concentrations of oxygen would slow down or
eliminate the chemical processes needed for
living things to function.
Carbon Dioxide
Carbon dioxide provides another example of fine
balance. At less than one-half of 1 percent of
atmospheric volume, it is still essential to
keeping temperatures warm enough for life through
its role in trapping some solar radiation. When
carbon dioxide levels reach just one percent,
however, a runaway greenhouse effect can take
hold, eventually leading to a climate like that
of Venus.
Earth's Mass
Earths mass is large enough so that its gravity
can hold an atmosphere (gravity holds the air
close to the planet). An atmosphere allows the
fluid cycling of elements, as in the water cycle.
If Earth were much larger, its gravity would hold
an atmosphere too dense to admit light from the
sun the surface would be too dark for
photosynthesis.
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Gaia Hypothesis

• These alterations benefit life and tend to
  preserve it, so on a global scale the Earth can
  be viewed as a super organism whose purpose is
  self-preservation (a philosophical question, not
  a scientific one).