Factors Affecting Populations (Edexcel IAL Biology)

Spec point — 5.12

Factors Affecting Populations

• The abundance and distribution of a species within a habitat are determined by a combination of biotic and abiotic factors

• Biotic factors are living factors that influence populations within their community; biotic factors come about as a result of the activity of other organisms e.g.

  • Predation
  • Food availability
  • Intraspecific competition, arising when individuals of the same species compete for resources
  • Interspecific competition, arising when individuals of different species compete for resources
  • Cooperation between organisms
  • Parasitism
  • Disease

The Impact of Biotic Factors on a Community Table

• Abiotic factors are non-living factors that influence populations within their community e.g.

  • Light intensity and wavelength
  • Temperature
  • Turbidity, or cloudiness, of water
  • Humidity
  • Soil or water pH
  • Soil or water salinity
  • Soil composition
  • Oxygen or Carbon dioxide concentration

The impact of Abiotic Factors on a Community Table