Biosphere
The biosphere is part of the earth in which life exists. It is 20 km
thick from
the bottom of the ocean to the lower atmosphere. It consists of
three layers:
the lithosphere, which is the land on the surface of the earth;
the hydrosphere,
which comprises of the water on the earth as well as water
vapor in the air; and
the atmosphere, which is made up of the air that
surrounds the earth. The living
organisms in the biosphere interact and
affect each other in many ways. This is
called a biotic factor. Similarly,
there are non-living elements that have an
effect on living organisms, these
are considered abiotic factors. Examples of
abiotic factors are air,
temperature, water, soil, light, and minerals. In a
biosphere, organisms live
in special groupings. For instance, a population
consists of all individuals
of a species living in a general area. A community
is a population located in
a certain area living among different species. An
ecosystem is yet a larger
conglomeration of a population, a community, and
abiotic factors. Ecosystems
can be aquatic or terrestrial. The earth's aquatic
ecosystem makes up about
75% of the earth's surface. This aquatic environment is
divided into marine
and freshwater environments. The earth's terrestrial
ecosystem is mainly made
up of forests and deserts, which make up for 25% of the
earth's surface. The
role or function of an organism in a community is that
organism's niche. An
organism's niche is an area picked by that organism based
on physical factors
such as temperature, light, oxygen and carbon dioxide
content and biological
factors such as food, competition for resources and
predators. This niche
provides the organism a place to live in. A habitat
remains consistent with
an organism's niche as well as provides the organism
with a place to
reproduce. In this case, organisms may have the same habitat,
but different
niches. There are three types of relationships involving the
interactions
between organisms. They are mutualism, commensalism, and
parasitism.
Mutualism is a relationship where both organisms benefit from
their
interaction with each other. An example is the honey bee and a
flowering plant.
Commensalism only benefits one organism, but the other
organism is not affected.
Parasitism only benefits one organism and harms
the other organism, which most
of the time is the host. In the ecosystem,
matter and nutrients are cycled via
biogeochemical cycles such as water,
carbon dioxide, nitrogen, and phosphorous.
The burning of fossil fuels
contributes to the industrial cycle of carbon
dioxide in the atmosphere. This
contributes to the greenhouse effect, which has
been a reason for global
warming. Nitrogen is found in the atmosphere and makes
up about 78% of the
earth's air mixture. Oxygen makes up about 22% of the
earth's air mixture,
and pollutants make up about 1% of the earth's air mixture.
Nitrogen is
important in the development of organisms on earth, as the make
compounds
such as proteins and amino acid. These compounds are important because
they
make up DNA and other compounds crucial to the formation and sustenance
of
life. Changes in an ecosystem are brought about by different factors.
For
example, ecological succession brings about the replacement of one
community by
another in an ecosystem. In other instances, organisms that
colonize an area
with no community present are considered pioneer organisms.
A climax community
is the final stage of development of organisms and can be
disrupted by a major
catastrophe like a volcanic eruption.