Study Guide for Test
Biosphere: layer of soil, water, and air that sustains life
Organism: most basic form of life, from bacterium to bears
Population: a group of individuals of the same species found in a given area or
location at a given time
Community: consists of the populations of living organisms that interact with one
another in an ecosystem
Habitat: place where a particular species lives and from which it obtains what it
needs for survival
Species: a group of organisms that are alike in several ways
Ecosystem: group of living organisms that interact with one another and the nonliving physical environment as one unit
Biotic Factors in an ecosystem include living parts: plants, animals, fungi,
microorganisms
Abiotic Factors in an ecosystem include non-living physical and chemical parts.
These include rocks, water, air, wind, soil nutrients, temperature, sun
*when resources are abundant, populations in an ecosystem tend to grow*
*population decrease when erosion removes nutrients from local soils*
*ecosystems are colder at higher elevations*
Oak-hickory is the most common type of forest ecosystem in PA covering 47% of
forested area in central and southern parts of state
Biomes: defined by their temperature and precipitation; Biomes located at high
latitudes tend to be extremely cold
Producers: use elements from the environment to make its own food
Trophic level: contains all organisms in a feeding level that are the same number
of steps away from the sun.
10% rule: only 10% of energy is passed along to the next level; 90% of the
energy from the producer is lost
Soil Horizons: layers of soil
Sedimentation – creates deep, fertile soils in flood plains and deltas
Carrying capacity: the number of individuals of a species that an ecosystem can
support
Homeostatis: balance in an ecosystem
- Natural disasters work against the ecosystem’s stability
Cycles
Evaporation, Condensation, Precipitation – 3 stages of water cycle
Carbon cycle – building block of life, essential for DNA, proteins, fats, and
carbohydrates
Nitrogen cycle –can use nitrogen only in nitrate form
Photosynthesis -
Respiration *Burning fossil fuels in cars and power plants has caused an increase in the
concentration of carbon dioxide in the atmosphere.*
*The zebra mussel was the invasive organism found in Lake St. Clair that spread as
far south as Louisiana and as far west as Oklahoma.*
Primary Succession: occurs in places where an ecosystem has never existed
Climax Community: formed in the last stages of succession
When something interrupts the process of succession it must start again at the
beginning stages.
The cause of succession can be something like the logging of a forest.
Stage 1: quick growing annual weeds cover the area
Stage 2: perennial weeds and grasses take hold among annual weeds
Stage 3: shrubs dominate
Stage 4: dominated by pine forest
Stage 5: pines crowded out and oak hickory forest dominates
Symbiosis: relationship between 2 organisms
Mutualism: both organisms benefit
Ex. Acacia ant and acacia tree
Ex. Honeybees and flowers
Commensalism: one organism benefits while the other neither benefits nor is
harmed
Ex. Orchids growing on the tops of trees
Ex. Barnacles on a whale
Parasitism: one benefits, the other is harmed
Ex. Predator vs. prey
Ex. Mosquito biting you