BIO 250 TEST 3 WITH ALL CORRECT & VERIFIED
ANSWERS (UPDATED TO PASS)
Succession Correct answer-Change in community structure over time typically following a
disturbance event
Disturbance Correct answer-An event that disrupts an ecosystem and kills a majority or all of the
organisms within
Autogenic Succession Correct answer-Changes in species composition are driven solely by internal
dynamics
Primary Succession Correct answer-An ecological succession that begins in an area where no biotic
community previously existed
Secondary Succession Correct answer-Succession following a disturbance that destroys a
community only partially, leaving few organisms alive
Facilitation Model of Succession Correct answer-Early species facilitate colonization by later, more
competitive species ; models mostly primary or severe secondary succession
Inhibition Model of Succession Correct answer-Assumes all species can inhabit a habitat from start
of colonization and once an organism is living in an area it inhibits the growth of all other individuals
in that area until death ; only models secondary succession
Tolerance Model of Succession Correct answer-Assumes all species can initially colonize the habitat
and specie do not inhibit but simply tolerate each other and share space ; the best competitors for
resources win in this model ; only models secondary succession
Allogenic Processes Correct answer-Outside influences that ensure communities are almost never
in equilibrium
Autogenic Processes Correct answer-Changes in a community as a result of the community itself
(internal)
Disturbance Regimes Correct answer-The general pattern or occurrence of a disturbance in a given
ecosystem
The Intermediate Disturbance Hypothesis Correct answer-Predicts that moderate scales of
disturbance, frequency, and magnitude lead to greatest community diversity
Trophic level Correct answer-Each step in a food chain or food web
Primary Producers Correct answer-First trophic level, bottom of the food chain, provide energy for
the rest of the chain usually through photosynthesis,
Herbivors Correct answer-Second trophic level, animals that eat plants/primary producers
Predators Correct answer-Third trophic level, animals that feed on herbivors
Tertiary Predators Correct answer-Fourth trophic level, predators that only feed on predators
, Top Predator Correct answer-Animal at the top of the food chain
Ecosystem engineers Correct answer-organisms that cause changes in the physical environment
sufficient to influence the structure of landscapes, ecosystems, or communities
Extirpated Correct answer-Locally extinct
Trophic Cascade Correct answer-When adding or removing higher trophic levels in a community
drastically alters other trophic level abundance, known as top-down control
Behavioral Cascade Correct answer-When adding or removing top predators effects herbivore
behavior patters affecting the abundance of primary producers.
Autogenic Engineers Correct answer-Alter environment by simply existing, i.e trees
Allogenic Engineers Correct answer-Alter environment by moving and building shit, i.e humans and
beavers
Climax Communities Correct answer-Late stage succession communities that are fully autogenic
until disturbance
If top-down interactions determine the structure of communities... Correct answer-Primary
producers in food chains with an odd number of trophic levels will be limited by resource
competition
Primary producers in food chains with an even number of trophic levels will be limited by consumers
Productivity Hypothesis of Food Chain Length Correct answer-Argues more productive ecosystems
will have longer food chains
Ecosystem Size Hypothesis of Food Chain Length Correct answer-Argues that food chain length
should increase with ecosystem size
Productive Space Hypothesis of Food Chain Length Correct answer-Argues both productivity and
ecosystem size are important in the possible length of food chains
Succession goes from... Correct answer-Bottom-up to top-down control over time
Resistance Correct answer-Describes how much a community changes due to a particular
disturbance, if the individuals do not die then community resistance is high
Return Time Correct answer-The amount of time it takes for a community to reach equilibrium
again after a disturbance event
Resilience Correct answer-Measure of how similar a post-disturbance community is to pre-
disturbance
Persistance Correct answer-The overall degree to which a community stays the same over time ;
long term resilience
ANSWERS (UPDATED TO PASS)
Succession Correct answer-Change in community structure over time typically following a
disturbance event
Disturbance Correct answer-An event that disrupts an ecosystem and kills a majority or all of the
organisms within
Autogenic Succession Correct answer-Changes in species composition are driven solely by internal
dynamics
Primary Succession Correct answer-An ecological succession that begins in an area where no biotic
community previously existed
Secondary Succession Correct answer-Succession following a disturbance that destroys a
community only partially, leaving few organisms alive
Facilitation Model of Succession Correct answer-Early species facilitate colonization by later, more
competitive species ; models mostly primary or severe secondary succession
Inhibition Model of Succession Correct answer-Assumes all species can inhabit a habitat from start
of colonization and once an organism is living in an area it inhibits the growth of all other individuals
in that area until death ; only models secondary succession
Tolerance Model of Succession Correct answer-Assumes all species can initially colonize the habitat
and specie do not inhibit but simply tolerate each other and share space ; the best competitors for
resources win in this model ; only models secondary succession
Allogenic Processes Correct answer-Outside influences that ensure communities are almost never
in equilibrium
Autogenic Processes Correct answer-Changes in a community as a result of the community itself
(internal)
Disturbance Regimes Correct answer-The general pattern or occurrence of a disturbance in a given
ecosystem
The Intermediate Disturbance Hypothesis Correct answer-Predicts that moderate scales of
disturbance, frequency, and magnitude lead to greatest community diversity
Trophic level Correct answer-Each step in a food chain or food web
Primary Producers Correct answer-First trophic level, bottom of the food chain, provide energy for
the rest of the chain usually through photosynthesis,
Herbivors Correct answer-Second trophic level, animals that eat plants/primary producers
Predators Correct answer-Third trophic level, animals that feed on herbivors
Tertiary Predators Correct answer-Fourth trophic level, predators that only feed on predators
, Top Predator Correct answer-Animal at the top of the food chain
Ecosystem engineers Correct answer-organisms that cause changes in the physical environment
sufficient to influence the structure of landscapes, ecosystems, or communities
Extirpated Correct answer-Locally extinct
Trophic Cascade Correct answer-When adding or removing higher trophic levels in a community
drastically alters other trophic level abundance, known as top-down control
Behavioral Cascade Correct answer-When adding or removing top predators effects herbivore
behavior patters affecting the abundance of primary producers.
Autogenic Engineers Correct answer-Alter environment by simply existing, i.e trees
Allogenic Engineers Correct answer-Alter environment by moving and building shit, i.e humans and
beavers
Climax Communities Correct answer-Late stage succession communities that are fully autogenic
until disturbance
If top-down interactions determine the structure of communities... Correct answer-Primary
producers in food chains with an odd number of trophic levels will be limited by resource
competition
Primary producers in food chains with an even number of trophic levels will be limited by consumers
Productivity Hypothesis of Food Chain Length Correct answer-Argues more productive ecosystems
will have longer food chains
Ecosystem Size Hypothesis of Food Chain Length Correct answer-Argues that food chain length
should increase with ecosystem size
Productive Space Hypothesis of Food Chain Length Correct answer-Argues both productivity and
ecosystem size are important in the possible length of food chains
Succession goes from... Correct answer-Bottom-up to top-down control over time
Resistance Correct answer-Describes how much a community changes due to a particular
disturbance, if the individuals do not die then community resistance is high
Return Time Correct answer-The amount of time it takes for a community to reach equilibrium
again after a disturbance event
Resilience Correct answer-Measure of how similar a post-disturbance community is to pre-
disturbance
Persistance Correct answer-The overall degree to which a community stays the same over time ;
long term resilience
