PCB 3044
PCB3044 Final Exam 2026
20.1 Key Concept
Energy in ecosystems originates with primary production by autotrophs.
-In most ecosystems, primary production occurs through the process of
photosynthesis, however, ecosystems without light use chemosynthesis for
primary production.
20.2 Key Concept
Net primary production is constrained by both physical and biotic environmental
factors.
-Net primary production represents the amount of energy created and stored as
biomass. The rate of production is influenced by climate variables, nutrient
availability, and species interactions within a system (top-down control).
20.3 Key Concept
Global patterns of net primary production reflect climate constraints and biome
types.
-The latitudinal gradient in NPP is correlated with variation in climate variables
precipitation and temperature and associated effects on the diversity and
abundance of autotrophs.
20.4 Key Concept
Secondary production is generated through the consumption of organic matter
by heterotrophs.
-Energy produced by autotrophs is passed to higher trophic levels through
feeding interactions. Heterotrophs use some energy for their own processes,
lost some to the environmenta, and store the remainder in their biomass as
energy sources for other organisms.
Gross primary production
Amount of carbon fixed by autotrophic organisms in an ecosystem
Net Primary Production
Energy produced by autotrophs and stored as biomass
Primary Productivity
PCB 3044
, PCB 3044
the rate of primary production
Autotrophs
Organisms creating energy, also known as producers
Carbon Source
Gross primary production less than respiration
Carbon Sink
Gross primary production more than respiration
21.1 Key Concept
Trophic levels describe the feeding positions of groups of organisms in
ecosystems.
-Most ecosystems have 3-4 trophic levels, including primary producers, primary
consumers, secondary consumers, and tertiary consumers.
21.2 Key Concept
The amount of energy transferred from one trophic level to the next depends on
food quality and on consumer abundance and physiology.
-Energy is lost at each level as it is used by the organism or lost to the
environment as waste products.
21.3 Key Concept
Changes in the abundances of organisms at one trophic level can influence
energy flow at multiple trophic levels.
-The addition or loss of species in an ecosystem influences species interactions
and energy flow through the trophic structure, due to changes in top-down or
bottom-up controls on the community.
21.4 Key Concept
Food webs are conceptual models of the trophic interactions of organisms in an
ecosystem.
-Food webs represent the complexity of the trophic interactions in an
ecosystems and better capture organisms utilizing food sources at multuple
trophic levels.
Secondary Production
PCB 3044
PCB3044 Final Exam 2026
20.1 Key Concept
Energy in ecosystems originates with primary production by autotrophs.
-In most ecosystems, primary production occurs through the process of
photosynthesis, however, ecosystems without light use chemosynthesis for
primary production.
20.2 Key Concept
Net primary production is constrained by both physical and biotic environmental
factors.
-Net primary production represents the amount of energy created and stored as
biomass. The rate of production is influenced by climate variables, nutrient
availability, and species interactions within a system (top-down control).
20.3 Key Concept
Global patterns of net primary production reflect climate constraints and biome
types.
-The latitudinal gradient in NPP is correlated with variation in climate variables
precipitation and temperature and associated effects on the diversity and
abundance of autotrophs.
20.4 Key Concept
Secondary production is generated through the consumption of organic matter
by heterotrophs.
-Energy produced by autotrophs is passed to higher trophic levels through
feeding interactions. Heterotrophs use some energy for their own processes,
lost some to the environmenta, and store the remainder in their biomass as
energy sources for other organisms.
Gross primary production
Amount of carbon fixed by autotrophic organisms in an ecosystem
Net Primary Production
Energy produced by autotrophs and stored as biomass
Primary Productivity
PCB 3044
, PCB 3044
the rate of primary production
Autotrophs
Organisms creating energy, also known as producers
Carbon Source
Gross primary production less than respiration
Carbon Sink
Gross primary production more than respiration
21.1 Key Concept
Trophic levels describe the feeding positions of groups of organisms in
ecosystems.
-Most ecosystems have 3-4 trophic levels, including primary producers, primary
consumers, secondary consumers, and tertiary consumers.
21.2 Key Concept
The amount of energy transferred from one trophic level to the next depends on
food quality and on consumer abundance and physiology.
-Energy is lost at each level as it is used by the organism or lost to the
environment as waste products.
21.3 Key Concept
Changes in the abundances of organisms at one trophic level can influence
energy flow at multiple trophic levels.
-The addition or loss of species in an ecosystem influences species interactions
and energy flow through the trophic structure, due to changes in top-down or
bottom-up controls on the community.
21.4 Key Concept
Food webs are conceptual models of the trophic interactions of organisms in an
ecosystem.
-Food webs represent the complexity of the trophic interactions in an
ecosystems and better capture organisms utilizing food sources at multuple
trophic levels.
Secondary Production
PCB 3044
