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MODULE 2
STUDY GUIDE
Lesson 1
ORGANISMS AND THEIR RELATIONSHIPS
• ecology
• biosphere
• biotic factor
• abiotic factor
• limiting factor
• tolerance
• population
• biological community
• ecosystem
• biome
• habitat
• niche
• predation
• symbiosis
• mutualism
• commensalism
• parasitism
• Ecology is the branch of biology in which interrelationships
between organisms and their environments are studied.
• Abiotic and biotic factors shape an ecosystem and determine the
communities that will be successful in it.
• Abiotic and biotic limiting factors restrict the growth of a popula-
tion within a community.
• Organisms have a range of tolerance for each limiting factor that
they encounter.
• Levels of organization in ecological studies include organism,
population, biological community, ecosystem, biome, and
biosphere.
• Symbiosis is the close relationship that exists when two or more
species live together. There are three types of symbiotic
relationships.
Lesson 2
FLOW OF ENERGY IN AN ECOSYSTEM
• autotroph
• heterotroph
• herbivore
• carnivore
• omnivore
• detritivore
• trophic level
• food chain
• food web
• biomass
• Autotrophs capture energy from the Sun or use energy from
certain chemical substances to make food.
• Heterotrophs include herbivores, carnivores, omnivores, and
detritivores.
• A trophic level is a step in a food chain or food web.
• Food chains, food webs, and ecological pyramids are models used
to show how energy moves through ecosystems.
Lesson 3
CYCLING OF MATTER
• matter
• nutrient
• biogeochemical cycle
• nitrogen fixation
• denitrification
• Biogeochemical cycles include the exchange of important nutri-
ents between the abiotic and biotic parts of an ecosystem.
• The carbon and oxygen cycles are closely intertwined.
• Nitrogen gas is limited in its ability to enter biotic portions of the
environment.
• Phosphorus and carbon have short-term and long-term cycles.
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Module 2 • Study Guide