3.2: Distribution of Organisms Flashcards
Biotic factor definition + 5 examples
A living factor that influences an ecosystem
* Competition
* Disease
* Food availability
* Grazing
* Predation
Abiotic factor definition + 4 examples
A non living factor that influences an ecosystem
* Light intensity
* Moisture
* pH
* Temperature
Factors that increase biodiversity
3
- Increased moisture levels
- Warm temperatures
- Good food availability
Factors that decrease biodiversity
3
- Extremes of temperature
- Over grazing
- Too many predators
How can abiotic factors be measured?
3
- Light intensity: light meter
- Soil moisture: moisture meter
- Soil pH: pH meter
Errors with light meter
User casting shadow over meter: should stand to one side to prevent casting shadow
Errors with moisture meter
Moisture/soil left on probe from previous reading: make sure probe is wiped dry between readings
Errors with pH meter
Moisture/soil left on probe from previous reading: make sure probe is wiped dry between readings
How can plant an animal populations be estimated?
Representative sampling
How are plants sampled with quadrats?
3 points
- Quadrat is placed at a random area to be studied for it to be representative
- Number of organisms being investigated within quadrat are counted
- Repeated to make estimate more reliable
How are animals sampled with pitfall traps?
6 points
- Dig a hole and place a cup in it so it is level with the ground
- Make sure there is drainage holes in the bottom of the cup
- Cover the top with leaves
- Repeat at least 5 times
- Check regularly
- Identify species using a key
Error of quadrat
Human judgement may falsely judge if something is in the quadrat or not: use basic rules to prevent this
Error of pitfall trap
Animals may escape / be eaten: cover trap and keep it hidden from predators
What is a paired statement key?
A set of paired questions that allow living things to be identified
What is an indicator species?
Species that by their presence, abudance or absence indicate levels of pollution in the environment
