Principles of Ecology - Exam 3 Prep 2026 – UCF
1. What is the primary difference between Gross Primary Production (GPP) and
Net Primary Production (NPP)?
A. GPP includes energy used for respiration, while NPP does not.
B. NPP includes energy lost as heat, while GPP does not.
C. GPP is measured only in aquatic systems, while NPP is terrestrial.
D. NPP is the total energy fixed by photosynthesis before any use.
Answer: A
Rationale: NPP is GPP minus the energy used by primary producers for autotrophic
respiration.
2. Which process converts atmospheric nitrogen (N2) into a form usable by
plants?
A. Denitrification
B. Nitrification
C. Ammonification
D. Nitrogen Fixation
Answer: D
Rationale: Nitrogen fixation is the conversion of N2 into ammonia or other nitrogenous
compounds by bacteria or lightning.
,3. According to the Competitive Exclusion Principle, what happens when two
species compete for the exact same limiting resource?
A. They will both evolve to share the resource equally.
B. Both species will increase in population size.
C. One species will be eliminated from the community.
D. Predation on both species will decrease.
Answer: C
Rationale: Gause’s principle states that two species competing for the same limiting
resource cannot coexist at constant population values.
4. What type of survivorship curve is characterized by high mortality early in
life?
A. Type I
B. Type II
C. Type IV
D. Type III
Answer: D
Rationale: Type III curves show high death rates for the young, often seen in organisms
that produce many offspring but provide little care.
5. In the context of island biogeography, which island would likely have the
highest species richness?
A. A small island far from the mainland.
B. A small island near the mainland.
C. A large island far from the mainland.
D. A large island near the mainland.
Answer: D
Rationale: MacArthur and Wilson’s theory predicts that large islands near the mainland
have higher colonization rates and lower extinction rates.
, 6. Which of the following is an example of a density-independent factor
regulating population growth?
A. Disease
B. Competition for food
C. Predation
D. A catastrophic flood
Answer: D
Rationale: Density-independent factors, like natural disasters or weather, affect
populations regardless of their size.
7. The specific role or ‘way of life’ an organism plays within its ecosystem is
known as its:
A. Niche
B. Habitat
C. Trophic level
D. Biotype
Answer: A
Rationale: An ecological niche includes all the physical and biological conditions in which a
species lives and the way the species uses those conditions.
8. What is the term for a species that has a disproportionately large effect on its
community relative to its abundance?
A. Keystone species
B. Indicator species
C. Dominant species
D. Endemic species
Answer: A
Rationale: Keystone species maintain the structure of a community, and their removal
often leads to a collapse in diversity.
1. What is the primary difference between Gross Primary Production (GPP) and
Net Primary Production (NPP)?
A. GPP includes energy used for respiration, while NPP does not.
B. NPP includes energy lost as heat, while GPP does not.
C. GPP is measured only in aquatic systems, while NPP is terrestrial.
D. NPP is the total energy fixed by photosynthesis before any use.
Answer: A
Rationale: NPP is GPP minus the energy used by primary producers for autotrophic
respiration.
2. Which process converts atmospheric nitrogen (N2) into a form usable by
plants?
A. Denitrification
B. Nitrification
C. Ammonification
D. Nitrogen Fixation
Answer: D
Rationale: Nitrogen fixation is the conversion of N2 into ammonia or other nitrogenous
compounds by bacteria or lightning.
,3. According to the Competitive Exclusion Principle, what happens when two
species compete for the exact same limiting resource?
A. They will both evolve to share the resource equally.
B. Both species will increase in population size.
C. One species will be eliminated from the community.
D. Predation on both species will decrease.
Answer: C
Rationale: Gause’s principle states that two species competing for the same limiting
resource cannot coexist at constant population values.
4. What type of survivorship curve is characterized by high mortality early in
life?
A. Type I
B. Type II
C. Type IV
D. Type III
Answer: D
Rationale: Type III curves show high death rates for the young, often seen in organisms
that produce many offspring but provide little care.
5. In the context of island biogeography, which island would likely have the
highest species richness?
A. A small island far from the mainland.
B. A small island near the mainland.
C. A large island far from the mainland.
D. A large island near the mainland.
Answer: D
Rationale: MacArthur and Wilson’s theory predicts that large islands near the mainland
have higher colonization rates and lower extinction rates.
, 6. Which of the following is an example of a density-independent factor
regulating population growth?
A. Disease
B. Competition for food
C. Predation
D. A catastrophic flood
Answer: D
Rationale: Density-independent factors, like natural disasters or weather, affect
populations regardless of their size.
7. The specific role or ‘way of life’ an organism plays within its ecosystem is
known as its:
A. Niche
B. Habitat
C. Trophic level
D. Biotype
Answer: A
Rationale: An ecological niche includes all the physical and biological conditions in which a
species lives and the way the species uses those conditions.
8. What is the term for a species that has a disproportionately large effect on its
community relative to its abundance?
A. Keystone species
B. Indicator species
C. Dominant species
D. Endemic species
Answer: A
Rationale: Keystone species maintain the structure of a community, and their removal
often leads to a collapse in diversity.
