2. B2.4 Organisms and their environment
Living organisms form communities, and we need to
understand the relationships within and between these
communities. These relationships are affected by external
influences.
3. Candidates should use their skills, knowledge and
understanding to:
■ suggest reasons for the distribution of living
organisms in a particular habitat
■ evaluate methods used to collect environmental
data, and consider the validity of the method and the
reproducibility of the data as evidence for
environmental change.
5. B2.4.1 Distribution of organisms
a) Physical factors that may affect organisms are:
■ temperature
■ availability of nutrients
■ amount of light
■ availability of water
■ availability of oxygen and carbon dioxide.
These factors will affect where and how many
organisms will grow
7. We can study the distribution of an organism using a quadrat or a
transect.
b) Quantitative data on the distribution of organisms can be obtained
by:
■ random sampling with
quadrats
14. area of strips / length of transects /
number of transects
15. (ii) numbers of larders observed likely to be lower than
actual
do not accept squirrels share larders or squirrels have
more than one larder
since unlikely that all could be spotted if 5 m away or
old larders or
squirrels moved on / died
since squirrels are mobile and could be
missed / counted twice
16.
17. (no)
the bars show the range of the number of
squirrel larders in the different types of
woodland
although spruce woodlands have the larger
ranges, some spruce woodlands will have
very low numbers of larders
18. competition for light because potamogeton plants taller
competition for nutrients taller plants may have longer
roots
