1. Abiotic and biotic factors and
how they affect organisms
and their distribution

2. We have been learning about Niche and competition
What is a niche?
A niche is the role that an organism plays within a community.
What kind of resources will organisms be using in their
ecosystem?
Light, temperature and nutrient availability.
What types of interactions occur between organisms in
a community?
Competition and predation.

3. In this section we are learning more about specific
factors affecting organisms and ultimately biodiversity.
Biotic and abiotic factors affect organisms and the biodiversity in environments and ecosystems
Grazing, diseases, food availability and predation are biotic factors
Light intensity, moisture, pH, and temperature are abiotic factors
Human activities can have an impact on biodiversity
Natural hazards can have an impact on biodiversity
At the end of the section you should have an improved
understanding of these factors and how they affect
organisms, their distribution and biodiversity

4. Biotic factors
These are factors that are living including diseases,
predation, food availability, and grazing.
How would these affect organisms and their distribution?
(Remember you already discussed this in a previous lesson).
How might these factors affect biodiversity?

5. Grazing What is grazing?
Animals that eat plants to gain their energy are called grazers.
Commonly sheep, deer and rabbits are thought of as grazers.
How can these animals affect biodiversity by grazing?
It depends on the type of grazer.
Sheep are selective grazers. They select the more dominant
competitive grasses to eat.
How might this help the other plants growing in the area?
The other weaker species get the opportunity to grow more
so biodiversity is kept high.
However too many sheep would over graze the area and reduce biodiversity.

6. Rabbits are relatively unselective grazers.
What does this mean?
By eating almost all types of plants on grassland
they maintain a high diversity.
The more vigorous plants are kept in check.
Obviously a massive population of rabbits overgrazing
an area would decrease the biodiversity.

7. Temperature would affect the growth rate of organisms.
Abiotic factors
These are factors that are non living including light intensity, moisture, pH, temperature, O2 and CO2.
How might these factors affect organisms and their distribution?
How might these affect biodiversity?
Temperature would affect the growth rate of organisms.
Why would temperature affect growth rate?
All organisms rely on enzymes to control chemical reactions.
As the temperature increases reactions happen faster,
up to a certain point so growth could increase.
At lower temperatures there will be slower growth.

8. pH is another factor that can affect organisms especially
living in aquatic environments.
Why would pH affect organisms in aquatic environments?
Organisms work at their best in a small pH range.
If the pH changes then the biodiversity may
be affected as an organisms chances of survival may be
affected.
Examples of this include fish and corals growing in
aquatic environments.

9. The affect of human activities on the distribution of organisms and biodiversity
How are humans affecting the survival of plants and animals on the planet?
If animal and plant numbers decrease, biodiversity decreases.
If humans alter ecosystems the distribution of organisms will change.
Watch Episode 2 from State of the Planet DVD.
Make a note of the 5 ways humans are affecting biodiversity (with examples) as the DVD is playing.

10. Review Here are 2 short clips to recap
some of the work on distribution of organisms
vimeo.com/