Definition of terms:
a self-contained community
of interacting organisms and their physical
Habitat: the place where an organism
Ecological Niche: the role of a species in
a community including it’s position in the
food chain and interactions with other
species and the physical environment.
Food Chain: A diagram that shows flow of energy in
an ecosystem between named organisms at 2 or
more trophic levels.
Trophic Level: the feeding level in a food chain.
-Producer: autotrophic organism that uses either light
energy or energy from simple chemical reactions to
produce biological molecules.
-Consumer: a heterotrophic organism that feeds on
producers and/or consumers.
Web: A diagram that shows many
interrelated food chains in an ecosystem.
Pyramids of Biomass
Pyramids of Energy
Ecological Deficiency = energy available to a tropic level
energy consumed by previous tropic level
This shows what percentage of the energy consumed by one trophic
level is available to the next.
The Nitrogen Cycle
Facts about nitrogen:
N2 is an unreactive molecule due to the
presence of a strong triple bond which
also makes it not readily available to
Nitrogen is an important component of
Main processes in the Nitrogen
Amination: Autotrophs use
nitrate ions to make amino
acid. Nitrates(NO3) in the soil
are reduced to
nitrites(NO2)which are then
further reduced to
ammonia(NH4). Ammonia then
attaches itself to the products
of the Calvin Cycle to form
break down excreted and
egested materials in the soil as
well break down the dead
remains of plants and animals
into ammonium compounds.
Nitrification: Conversion of
ammonia to nitrates. Some
bacteria use ammonia in their
energy transfer reactions and
oxidize it to nitrite ions. Other
bacteria then use these nitrite
ions (in similar reactions) and
excrete nitrate ions
Denitrifiction: conversion of
nitrite ions to atmospheric
nitrogen. Usually carried out by
bacteria which provide
themselves with energy by
reversing nitrogen fixation