Biotic Factors Biosphere – life-supporting layer of Earth Biotic factors – all living organisms in a
biosphere
Abiotic Factors Nonliving factors in an environment Examples:
Air currents Temperature Moisture Light Soil
Trophic Relationships Autotrophs 1st level consumers (herbivores) 2nd level consumers 3rd level consumers 4th level consumers (top predators)
RULE OF 10 Only 10% of energy is transferred from
one trophic level to the next. Example:
It takes 100 kgs of plant materials (producers) to support 10 kgs of herbivores
It takes 10 kgs of herbivores to support 1 kg of 1st level predator
Symbiosis – “living together”Relationship
Type Species A Species B
Commensalism + 0
Mutualism + +
Parasitism + -
Nitrogen cycle Atmospheric nitrogen Runoff Fertilizers Decomposition Nitrogen fixing Synthesis of amino acids