Principles of Ecology - Final Exam Prep (PCB 3044) 2026 – UCF
1. In the logistic growth equation, what does the term (K - N) / K represent?
A. The intrinsic rate of increase
B. The mortality rate of the population
C. The total number of individuals added to the population
D. The fraction of carrying capacity that is still available
Answer: D
Rationale: The term (K - N) / K modifies the growth rate based on how close the
population size (N) is to the carrying capacity (K), representing the unused portion of the
environment’s capacity.
2. Which type of survivorship curve is characterized by high mortality early in
life followed by high survival rates for the few individuals that reach adulthood?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C
Rationale: Type III curves are typical for species that produce many offspring with little
parental care, such as many fish and marine invertebrates.
,3. The ‘competitive exclusion principle’ states that:
A. Two species can coexist if they share the exact same niche
B. Predators prevent competition between prey species
C. Competition always leads to the extinction of both species
D. Two species with identical niches cannot coexist indefinitely
Answer: D
Rationale: Gause’s principle posits that if two species compete for the same limiting
resource, the more efficient one will eventually eliminate the other.
4. A keystone species is one that:
A. Has a disproportionately large effect on its community relative to its abundance
B. Occupies the lowest trophic level
C. Is the most abundant species in a community
D. Is the first to colonize a new habitat
Answer: A
Rationale: Keystone species, like sea otters or wolves, maintain community structure and
diversity despite not being the most numerous.
5. Which of the following describes primary succession?
A. Regrowth of a forest after a wildfire
B. Development of a community on newly exposed volcanic rock
C. Recovery of a field after it is no longer farmed
D. Changes in a pond after a flood
Answer: B
Rationale: Primary succession occurs in areas where no soil exists, such as lava flows or
retreating glaciers.
, 6. According to the 10% rule in ecology, if a primary producer level contains
10,000 J of energy, how much energy is available to secondary consumers?
A. 1,000 J
B. 100 J
C. 10 J
D. 1 J
Answer: B
Rationale: 10% of 10,000 is 1,000 (primary consumers), and 10% of 1,000 is 100
(secondary consumers).
7. Net Primary Productivity (NPP) is defined as:
A. Total solar energy captured by autotrophs
B. The amount of biomass consumed by herbivores
C. Gross primary productivity minus the energy used by autotrophs for respiration
D. The total carbon fixed by an entire ecosystem including decomposers
Answer: C
Rationale: NPP represents the actual biomass available to consumers after the plants have
met their own metabolic needs.
8. In the nitrogen cycle, the process of converting atmospheric nitrogen (N2)
into ammonia (NH3) is called:
A. Nitrification
B. Nitrogen fixation
C. Denitrification
D. Ammonification
Answer: B
Rationale: Nitrogen fixation is primarily performed by specialized bacteria, making
nitrogen available to the biotic community.
1. In the logistic growth equation, what does the term (K - N) / K represent?
A. The intrinsic rate of increase
B. The mortality rate of the population
C. The total number of individuals added to the population
D. The fraction of carrying capacity that is still available
Answer: D
Rationale: The term (K - N) / K modifies the growth rate based on how close the
population size (N) is to the carrying capacity (K), representing the unused portion of the
environment’s capacity.
2. Which type of survivorship curve is characterized by high mortality early in
life followed by high survival rates for the few individuals that reach adulthood?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C
Rationale: Type III curves are typical for species that produce many offspring with little
parental care, such as many fish and marine invertebrates.
,3. The ‘competitive exclusion principle’ states that:
A. Two species can coexist if they share the exact same niche
B. Predators prevent competition between prey species
C. Competition always leads to the extinction of both species
D. Two species with identical niches cannot coexist indefinitely
Answer: D
Rationale: Gause’s principle posits that if two species compete for the same limiting
resource, the more efficient one will eventually eliminate the other.
4. A keystone species is one that:
A. Has a disproportionately large effect on its community relative to its abundance
B. Occupies the lowest trophic level
C. Is the most abundant species in a community
D. Is the first to colonize a new habitat
Answer: A
Rationale: Keystone species, like sea otters or wolves, maintain community structure and
diversity despite not being the most numerous.
5. Which of the following describes primary succession?
A. Regrowth of a forest after a wildfire
B. Development of a community on newly exposed volcanic rock
C. Recovery of a field after it is no longer farmed
D. Changes in a pond after a flood
Answer: B
Rationale: Primary succession occurs in areas where no soil exists, such as lava flows or
retreating glaciers.
, 6. According to the 10% rule in ecology, if a primary producer level contains
10,000 J of energy, how much energy is available to secondary consumers?
A. 1,000 J
B. 100 J
C. 10 J
D. 1 J
Answer: B
Rationale: 10% of 10,000 is 1,000 (primary consumers), and 10% of 1,000 is 100
(secondary consumers).
7. Net Primary Productivity (NPP) is defined as:
A. Total solar energy captured by autotrophs
B. The amount of biomass consumed by herbivores
C. Gross primary productivity minus the energy used by autotrophs for respiration
D. The total carbon fixed by an entire ecosystem including decomposers
Answer: C
Rationale: NPP represents the actual biomass available to consumers after the plants have
met their own metabolic needs.
8. In the nitrogen cycle, the process of converting atmospheric nitrogen (N2)
into ammonia (NH3) is called:
A. Nitrification
B. Nitrogen fixation
C. Denitrification
D. Ammonification
Answer: B
Rationale: Nitrogen fixation is primarily performed by specialized bacteria, making
nitrogen available to the biotic community.
