1.2 Distribution of Organisms

• Give an example of a biotic factor that could affect biodiversity.

  - competition for resources

  - disease

  - food availability

  - grazing

  - predation
• Give an example of an Abiotic (remember A for Anti alive!!) factor that could affect biodiversity.

  - light intensity

  - moisture

  - pH

  - temperature
• Name a method that could be used to sample crawling insects in a woodland community.

  Pitfall trap
• Name a possible source of error associated with setting up a pitfall trap.

  - Traps left too long/not checked regularly

  - Trap not level with soil surface

  - Trap not camouflaged

  - the number and types of animals may not be representative of the ecosystem as a whole
• How could a researcher ensure that she got reliable results when using a pitfall trap?

  Set many traps (repeat the sampling procedure).
• Name a method that could be used to sample plants growing in a field.

  Quadrat
• How could a researcher eliminate bias when using a quadrat?

  Throw the quadrat randomly.
• Name an abiotic factor that could be measured and describe how to measure it.

  - Light -> using a light meter

  - Temperature -> using a thermometer

  - pH -> using a pH meter

  - soil moisture -> using a moisture meter
• Describe a possible source of error when using a moisture meter or pH meter.

  Contamination from a previous sample. You should wipe the probe between readings.
• Describe a possible source of error when using a light meter.

  Casting your own shadow over the meter.
• Describe a possible source of error when using a thermometer.

  -Not allowing enough time before taking a reading.
• What is an indicator species?

  Species that indicate environmental quality or levels of pollution by their presence, absence or abundance.