organisms live in
different places because
environment varies
distribution of an organism
is where it is found many
factors affect where an
organism is found
- Temperature - Availability
of water - Availability of
oxygen and CO2 -
Availability of nutrients -
Amount of light
These may mean an organism may be
common in certain areas and less common
in other areas E.G daisies in middle of field
and none under the trees due to light levels
to study the distribution of organisms you
could use quadrats in two areas then compare
them or study how the oranisms' distribution
changes by placing quadrats along a transect.
Quadrats: study the
distribution of small
organisms
basically place a quadrat in a
random area (usually 1M
squared) and count the
organisms inside that
quadrat.
Transects: study
distribution of organisms
along a line
For example to see if a plant becomes
less common as you move from a
hedge to the middle of the field
to do this you can simply
measure a line using a tape
measure then count the
number of organisms which
touch that line( which
you're interested in) or use
quadrats which can be
placed next to each other
on the line or at intervals
work out population
size multiply mean
number of organisms
per quadrat by the
total area the
quadrats covered
when collecting environmental data
Reliability
Quadarts and
Transects are good
tools
but the results
must be reliable
and reproducible
larger sample size is
better in terms of
reliable results and
reproducible results
Validity
to be valid results
must be reliable
all variables need to
be controlled
the real question is
whether a
difference in
distribution is due
to only 1
environmental
factor