[UCSB] EEMB 2 - LATEST
MIDTERM 1
Does the logistic growth model account for intraspecific competition? -
ANSWERS-Yes
What does competition occur over? - ANSWERS-Resources
What are the possible outcomes when two species compete? -
ANSWERS-1. Both species coexist (stable/unstable equilibrium) but
must use resources differently
2. Species #1 goes extinct
3. Species #2 goes extinct
Where does competitive exclusion never occur? - ANSWERS-1.
Unstable environments (never reach equilibirum, low density of
organisms --> more resources --> less competition)
2. Unlimited resources or partitioning
3. Fluctuating environments --> reverse direction of competition before
exclusion occurs
What does the variable C stand for? - ANSWERS-Predator attack
efficiency
END OF
PAGE
1
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What does the Lotka-Volterra Predator-Prey model assume? -
ANSWERS-1. In the absence of predators, prey populations grow
exponentially
2. In the absence of food, predator populations decline exponentially
What are the oscillations in the Lotka-Volterra model due to? What is
the amplitude determined by? - ANSWERS-Due to time delays in the
response of predator density to that of prey density and vice versa (prey
comes in first); amplitude is determined by starting conditions
What are the 3 possible predicted outcomes out of the Lotka-Volterra
model? - ANSWERS-1. Coexistence
2. Oscillations
3. Extinctions (of either species, model does not predict extinction of
both, though this is a possible observed outcome)
Are there many good examples of clear predator-prey cycles in natural
populations? - ANSWERS-No
END OF
PAGE
2
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What 3 main ways do prey persist in the presence of predators? -
ANSWERS-1. Having a spatial or temporal refuge
2. Optimal foraging
3. Antipredator adaptations
Optimal foraging - ANSWERS-Predators switch to other prey as
original prey species fall to low abundance (prevents prey from being
driven to extinction)
What are examples of anti-predator adaptations? - ANSWERS-Chemical
defense, camouflage, agility, armor, masting, etc.
Masting - ANSWERS-Producing tremendous amounts of offspring at
once to overcome predators
Are species in a community closely linked? - ANSWERS-Yes
Ecosystem - ANSWERS-Communities of organisms embedded in their
physical/chemical environment (with the movement of energy and
materials)
END OF
PAGE
3
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What are some features of ecosystems? - ANSWERS-1. Open biological
systems (materials can freely move in and out of the system)
2. One way flow of energy
3. Cycling of nutrients
How are nutrients recycled? - ANSWERS-Fertilization
Trophic levels - ANSWERS-Groups of species, based on their
functional similarities
Which is the norm, food webs or food chains? - ANSWERS-Food webs
How many trophic levels do most communities have? - ANSWERS-3-5
trophic levels
Biomass - ANSWERS-Dry weight (measure of carbon)
Are most organisms very efficient? - ANSWERS-No
END OF
PAGE
4
MIDTERM 1
Does the logistic growth model account for intraspecific competition? -
ANSWERS-Yes
What does competition occur over? - ANSWERS-Resources
What are the possible outcomes when two species compete? -
ANSWERS-1. Both species coexist (stable/unstable equilibrium) but
must use resources differently
2. Species #1 goes extinct
3. Species #2 goes extinct
Where does competitive exclusion never occur? - ANSWERS-1.
Unstable environments (never reach equilibirum, low density of
organisms --> more resources --> less competition)
2. Unlimited resources or partitioning
3. Fluctuating environments --> reverse direction of competition before
exclusion occurs
What does the variable C stand for? - ANSWERS-Predator attack
efficiency
END OF
PAGE
1
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What does the Lotka-Volterra Predator-Prey model assume? -
ANSWERS-1. In the absence of predators, prey populations grow
exponentially
2. In the absence of food, predator populations decline exponentially
What are the oscillations in the Lotka-Volterra model due to? What is
the amplitude determined by? - ANSWERS-Due to time delays in the
response of predator density to that of prey density and vice versa (prey
comes in first); amplitude is determined by starting conditions
What are the 3 possible predicted outcomes out of the Lotka-Volterra
model? - ANSWERS-1. Coexistence
2. Oscillations
3. Extinctions (of either species, model does not predict extinction of
both, though this is a possible observed outcome)
Are there many good examples of clear predator-prey cycles in natural
populations? - ANSWERS-No
END OF
PAGE
2
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What 3 main ways do prey persist in the presence of predators? -
ANSWERS-1. Having a spatial or temporal refuge
2. Optimal foraging
3. Antipredator adaptations
Optimal foraging - ANSWERS-Predators switch to other prey as
original prey species fall to low abundance (prevents prey from being
driven to extinction)
What are examples of anti-predator adaptations? - ANSWERS-Chemical
defense, camouflage, agility, armor, masting, etc.
Masting - ANSWERS-Producing tremendous amounts of offspring at
once to overcome predators
Are species in a community closely linked? - ANSWERS-Yes
Ecosystem - ANSWERS-Communities of organisms embedded in their
physical/chemical environment (with the movement of energy and
materials)
END OF
PAGE
3
, [UCSB] EEMB 2 - LATEST
MIDTERM 1
What are some features of ecosystems? - ANSWERS-1. Open biological
systems (materials can freely move in and out of the system)
2. One way flow of energy
3. Cycling of nutrients
How are nutrients recycled? - ANSWERS-Fertilization
Trophic levels - ANSWERS-Groups of species, based on their
functional similarities
Which is the norm, food webs or food chains? - ANSWERS-Food webs
How many trophic levels do most communities have? - ANSWERS-3-5
trophic levels
Biomass - ANSWERS-Dry weight (measure of carbon)
Are most organisms very efficient? - ANSWERS-No
END OF
PAGE
4
