Introduction and The Biosphere

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Chapter1 and Chapter 34
Introduction and The Biosphere
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1.1-Levels of organization. Biosphere The
earth and everything on it (living and
nonliving), including the atmosphere. Ecosystem
All organisms living in a particular area, as
well as all the nonliving physical components of
the environment that affect the organisms, such
as air, soil, and sunlight. (Example Cascade
Mountain rain forest, Kentucky lake and its
watershed.) Community The organisms of an
ecosystem make up a community. Population The
members of a single species in a community make
up a population.
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Organism One member of a species. Organ
systems A group of organs that complete a
function within the individual. (Example
circulatory system or nervous system. Organ
One component of an organ system. (Example
heart, brain) Tissues An organ may be made up
of different tissues that perform a function.
Tissues are made up of groups of similar cells.
(Example muscle tissue, connective
tissue) Cell The smallest unit of life. A
cell is a membrane bound box that contains
molecules in a solution of water. Organelles
Subcellular membrane bound compartments that
partition special activities. (Example
chloroplasts for photosynthesis) Molecules
Combinations of atoms formed in cells and
organelles to perform a function such as
metabolism or storage of energy.
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1.2-The process of science. Observations are
made and from those a question is formulated.
A hypothesis is developed that is the expected
answer to the question. Experiments are
designed to test the hypothesis and predictions
are made as to what the results will be.
These predictions are testable using
mathematical equations (statistics). The
experimentation begins and the results are
evaluated by the statistical methods to determine
whether the hypothesis was valid.
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1.4- Biological diversity. Most biologists
arrange biological diversity into five
kingdoms. Monera- All prokaryotic organisms.
these are one-celled organisms that do not have
a nucleus. They have no organelles at all.
Protista- These are unicellular eukaryotic
organisms that include organisms that must eat
other organisms and photosynthetic species
that can make their own food from sunlight
and small molecules. Fungi- These are simple
organisms that are plant-like but are not
photosynthetic. They live on organic matter.
They include, yeast, molds, mushrooms and
toadstools. Plantae- Includes all plants and
multicellular algae. These organisms are
photosynthetic. Animalia- Includes all animals.
These organisms must get their food by
ingesting other organisms.
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Chapter 34. The Biosphere
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34.1- All organisms have been shaped by the world
we live on. The diversity of environments has
resulted in the evolution of diverse organisms.
Ecologists study how organisms interact with
each other and with their environment. Biotic
factors- other populations or organisms in the
community Abiotic factors- nonliving components
of the ecosystem. It should be noted that while
the environment has a very definite effect on
living things, the opposite is also true. From
the molecular level including the exchange of
gases with the atmosphere (use of O2 and
production of CO2 for animals) to physical
changes in the landscape, organisms effect the
environment in which they live.
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34.2- The biosphere can be considered to be the
sum of all the ecosystems (the global ecosystem.
For the last 5 years Murray State University
scientists have had a grant from the US
Department of Energy to study the contribution of
the Kentucky Lake Ecosystem to the cycling of
carbon into the global ecosystem. Note the
patchiness of the biosphere. It can easily be
seen from a airplane as you look out the window.
In some cases you are viewing borders of habitat
and in others you are actually viewing the
borders of ecosystems. Habitats are small
areas where individual organisms live such as a
downed tree or a pool within a stream.
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34.3- Environmental problems. Human activity has
had a devastating effect on the biosphere. From
the loss of habitat to damaging large ecosystems,
we have changed the earth. The book Silent
Spring by Rachel Carson in 1962 was one of the
first works that warned of the impending problems
that was being created by the used of chemical
pesticides including DDT. Today we see articles
written about global warming that is being
brought on by the production of greenhouse
gases such as CO2.
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34.4- Aboitic factors Physical and Chemical.
Among the most important abiotic factors that
affect organisms are light, water, temperature,
soil type, and oxygen. Two additional factors
are perhaps only slightly less important, those
are fire and wind.
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Light is required for photosynthesis, which
essentially powers the ecosystem as we will
discuss later. All life requires water. Its
availability effects the organisms that can live
in an ecosystem and has had significant influence
on the evolution of many species including
terrestrial species (example, the camel).
Aquatic ecosystems are affected by the quality of
the water and can be devastated by pollution,
which includes the addition of nutrients as well
as poisons.
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Most organisms live where temperatures are
between 0oC and 50oC. However, there are those
that live in extreme environments of the artic
and in hot springs. It should also be noted that
there are environments where large temperature
fluctuations occur which also influences
evolution and life in those ecosystems. Soils
types are quite diverse from the rich soils of
the midwestern U.S. to the sands of desserts that
have little in the way of nutrients.
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Oxygen availablity is obviously critical to the
life forms that can inhabit an ecosystem.
Aquatic systems have oxygen in solution, but may
become anoxic during certain times. For example,
water near the sediment in Kentucky Lake becomes
anoxic in the middle of summer when the
temperatures are up and microbial metabolism in
the sediments is high. Where do the fish go?
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34.6- Regional Climate affects the distribution
of communities. Climate obviously is a major
abiotic factor in ecosystems. Climate
basically includes temperature and rainfall.
Additionally, wind and water currents are
important factors and influence temperature and
rainfall as is described in this section. Note
that not only are the eastern or western
directions important, but the up and down
directions affect climate and weather (figure C,
page 670).
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34.7 Oceans. Oceans cover 75 of the earths
surface and are saltwater. The rainfall on
terrestrial ecosystems comes from the evaporation
of ocean water. The climates of some land masses
are affected by ocean currents from the equator.
Photosynthesis by marine algae provide a large
portion of the oxygen in the atmosphere.
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Oceans have several different ecosystems. Estuari
es. Areas where freshwater and seawater mix.
There is a gradient of salt concentration.
Estuaries are among the most productive
ecosystems on earth and contain such animals as
oysters, crabs, and many fish species. The
intertidal zone is where water meets the land.
It is flooded at high tide and dry at low tide.
These range from salt marshes to sandy beaches.
These are types of wetlands, which are ecosystems
that are intermediate between aquatic ecosystems
and terrestrial ones.
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The intertidal zone is part of the pelagic zone
(see figure c., page 673). The pelagic zone is
the water itself. The pelagic zone contains
phytoplankton (algae and cyanobacteria) and
zooplankton tiny animals that drift in the water.
Also included is the benthic zone, which is
the sediment at the bottom. Organic material
from the excretions of animals and from dead
things that sink make the benthic zone relatively
rich for microbial activity.
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The photic zone is the portion of the water that
is penetrated by sunlight allowing photosynthsis
to occur. The aphotic zone depends on material
sinking from the photic zone above. Recently,
however, life was discovered in the aphotic zone
that does not depend upon the photic zone.
Bacteria are able to use chemical energy from
hydrothermal vents in the ocean floor to start
the food chain.
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34.8- Freshwater. Lakes, rivers, and streams
contain freshwater communities and are influenced
by the water shed. Both ground water (often
anoxic) and surface water (usually oxic) feed
them providing a source of organic material that
adds to material produced by algal and bacterial
photosynthesis. Temperature plays a major role
in freshwater ecosystems, as does pH, and oxygen
concentrations. As important as anything is
the availability of nitrogen and phosphorus, two
very important nutrients for living things.
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34.9-34.18. Terrestrial Ecosystems. The major
terrestrial ecosystems are called biomes. Types
of Biomes include tropical rain forrests,
savannas, deserts, chaparral, temperate
grasslands, deciduous temperate forests,
coniferous forests, and tundra. I am not going
to lecture on these, but you should know the
basic characteristics of each from the text.
Know what permafrost is, what the taiga is, etc.
In which would you expect to find scrub oaks?
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