Principles of Ecology - Exam 2 Review 2026 – UCF
1. What is the primary difference between Net Primary Production (NPP) and
Gross Primary Production (GPP)?
A. NPP includes the energy used by autotrophs for respiration.
B. NPP is GPP minus the energy used by autotrophs for respiration.
C. GPP represents the energy available to secondary consumers.
D. NPP represents the total energy captured by photosynthesis.
Answer: B
Rationale: NPP represents the energy remaining after plants have met their own metabolic
needs through respiration (NPP = GPP - R).
2. According to Shelford’s Law of Tolerance, an organism is most likely to be
found in environments where:
A. Abiotic factors are at their absolute maximum limits.
B. Abiotic factors fall within the range of the organism’s physiological optimum.
C. Abiotic factors are at their absolute minimum limits.
D. There is the highest level of competition for resources.
Answer: B
Rationale: Shelford’s Law states that the distribution of a species is controlled by the
environmental factor for which the organism has the narrowest range of adaptability.
,3. Which type of survivorship curve is characteristic of species that produce
many offspring but provide little to no parental care?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C
Rationale: Type III curves show high mortality rates early in life, typical of species like fish
or insects that release many eggs.
4. What does the ‘K’ represent in the logistic growth equation dN/dt = rN(1 -
N/K)?
A. The intrinsic rate of increase
B. The carrying capacity of the environment
C. The population density at time zero
D. The number of individuals added to the population
Answer: B
Rationale: K stands for carrying capacity, which is the maximum population size that a
particular environment can sustain.
5. Which of the following is an example of a density-independent factor
regulating population growth?
A. Competition for food
B. A catastrophic wildfire
C. Spread of a contagious disease
D. Predation pressure
Answer: B
Rationale: Density-independent factors, like natural disasters or weather, affect
populations regardless of their size or density.
, 6. Character displacement is most likely to occur between two species that are:
A. In a mutualistic relationship
B. Competing for the same limiting resource in sympatry
C. Occupying different trophic levels
D. Living in completely different geographical regions
Answer: B
Rationale: Character displacement is the tendency for characteristics to be more divergent
in sympatric populations of two species than in allopatric populations, reducing
competition.
7. What is a ‘keystone species’?
A. The most abundant species in a community
B. A species that has a disproportionately large effect on its environment relative to its biomass
C. The first species to colonize a new habitat
D. A species that is at the bottom of the food chain
Answer: B
Rationale: Keystone species maintain the structure of a community; their removal often
leads to significant changes or collapse of the ecosystem.
8. In the process of nitrogen fixation, atmospheric nitrogen (N2) is converted
into:
A. Ammonia (NH3)
B. Nitrite (NO2-)
C. Nitrate (NO3-)
D. Nitrous oxide (N2O)
Answer: A
Rationale: Nitrogen fixation by bacteria converts gaseous N2 into ammonia (NH3), which
can then be used by plants.
1. What is the primary difference between Net Primary Production (NPP) and
Gross Primary Production (GPP)?
A. NPP includes the energy used by autotrophs for respiration.
B. NPP is GPP minus the energy used by autotrophs for respiration.
C. GPP represents the energy available to secondary consumers.
D. NPP represents the total energy captured by photosynthesis.
Answer: B
Rationale: NPP represents the energy remaining after plants have met their own metabolic
needs through respiration (NPP = GPP - R).
2. According to Shelford’s Law of Tolerance, an organism is most likely to be
found in environments where:
A. Abiotic factors are at their absolute maximum limits.
B. Abiotic factors fall within the range of the organism’s physiological optimum.
C. Abiotic factors are at their absolute minimum limits.
D. There is the highest level of competition for resources.
Answer: B
Rationale: Shelford’s Law states that the distribution of a species is controlled by the
environmental factor for which the organism has the narrowest range of adaptability.
,3. Which type of survivorship curve is characteristic of species that produce
many offspring but provide little to no parental care?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C
Rationale: Type III curves show high mortality rates early in life, typical of species like fish
or insects that release many eggs.
4. What does the ‘K’ represent in the logistic growth equation dN/dt = rN(1 -
N/K)?
A. The intrinsic rate of increase
B. The carrying capacity of the environment
C. The population density at time zero
D. The number of individuals added to the population
Answer: B
Rationale: K stands for carrying capacity, which is the maximum population size that a
particular environment can sustain.
5. Which of the following is an example of a density-independent factor
regulating population growth?
A. Competition for food
B. A catastrophic wildfire
C. Spread of a contagious disease
D. Predation pressure
Answer: B
Rationale: Density-independent factors, like natural disasters or weather, affect
populations regardless of their size or density.
, 6. Character displacement is most likely to occur between two species that are:
A. In a mutualistic relationship
B. Competing for the same limiting resource in sympatry
C. Occupying different trophic levels
D. Living in completely different geographical regions
Answer: B
Rationale: Character displacement is the tendency for characteristics to be more divergent
in sympatric populations of two species than in allopatric populations, reducing
competition.
7. What is a ‘keystone species’?
A. The most abundant species in a community
B. A species that has a disproportionately large effect on its environment relative to its biomass
C. The first species to colonize a new habitat
D. A species that is at the bottom of the food chain
Answer: B
Rationale: Keystone species maintain the structure of a community; their removal often
leads to significant changes or collapse of the ecosystem.
8. In the process of nitrogen fixation, atmospheric nitrogen (N2) is converted
into:
A. Ammonia (NH3)
B. Nitrite (NO2-)
C. Nitrate (NO3-)
D. Nitrous oxide (N2O)
Answer: A
Rationale: Nitrogen fixation by bacteria converts gaseous N2 into ammonia (NH3), which
can then be used by plants.
