Systems & Models
A system consists of inputs, __________, and outputs.
What are flows/processes?
What law states that energy cannot be created or destroyed?
What is the 1st law of thermodynamics?
Natural resources that produce natural income are called __________.
What is natural capital?
A group of individuals of the same species in the same area is a __________.
What is a population?
Organisms that make their own food are called __________.
Producers/autotrophs.
This type of system exchanges both energy and matter with its surroundings.
What is an open system?
This type of feedback loop increases change or deviation from equilibrium.
What is a positive feedback loop?
Name one sustainability indicator used to measure environmental health.
Ecological footprint, EPI, carbon footprint, air quality index, etc.
A niche includes the full range of __________ and interactions a species needs.
Biotic and abiotic conditions.
On average, only about ___% of energy is passed between trophic levels.
10%.
In ESS, arrows represent Flows and boxes represent _________.
What are Storages?
Define steady-state equilibrium.
A dynamic equilibrium with constant inputs and outputs fluctuating around a stable average.
What is the maximum sustainable yield?
The largest amount of a resource that can be harvested without reducing long-term availability.
What type of growth curve is seen when a population grows rapidly with no limits?
Exponential (J-curve).
Which biogeochemical cycle includes photosynthesis and combustion?
The carbon cycle.
Give one advantage and one limitation of using environmental models.
Advantage: simplify complex systems; predict outcomes.
Limitation: incomplete data or oversimplification.
Melting ice decreasing albedo is an example of what type of feedback?
Positive feedback.
Which two pollutant features make them especially harmful?
High concentration and high persistence.
Give two examples of density-dependent limiting factors.
Competition, predation, disease, parasitism.
Explain why biomass decreases as trophic levels increase.
Because energy is lost as heat at each transfer due to respiration.
Explain why feedback loops are important in dynamic environmental systems.
Because they control stability or change through positive or negative feedback, affecting system behavior over time.
Compare static equilibrium to steady-state equilibrium.
Static: no change (rare in nature).
Steady-state: constant but stable fluctuations.
Explain how environmental value systems (EVS) influence sustainability decisions.
EVS determine whether societies prioritize conservation, economics, technological solutions, or resource exploitation.
Explain the competitive exclusion principle.
No two species can occupy the same niche indefinitely; one will outcompete the other.
Describe the difference between a transfer and a transformation in a system.
Transfer = movement of matter/energy (e.g., ingestion, runoff)
Transformation = change in state/form (e.g., photosynthesis, respiration)