Ecosystem Energy Worksheet
Ecology & Environmental Science
Ecosystem Energy & Trophic Dynamics
Name:
Date: Period:
1 Part 1: The 10% Rule & Energy Pyramids
Lindeman's Efficiency Law
Apex (Tertiary)
▲ 10%
Secondary Consumers
▲ 10%
Primary Consumers (Herbivores)
▲ 10%
Primary Producers (10,000 kcal)
Producers generate 10,000 kcal of chemical energy. Calculate the usable energy available at each subsequent trophic tier:
Primary Cons.
kcal
Secondary Cons.
kcal
Apex Predator
kcal
Where does the remaining 90% go? State two primary causes:
2 Part 2: Food Web Energy Flow & Cascade
Network Pathway Analysis
Marsh Grass / Algae
Autotrophs
Ribbed Mussels / Snails
Primary Consumers
Blue Crabs / Terrapins
Secondary Consumers
Osprey / Bald Eagles
Apex Predators
───► (energy transfer) ───► ───► (energy transfer) ───► ───► (energy transfer) ───►
A. What biological phenomenon does the arrow direction signify?
B. If a parasite reduces Blue Crabs by 75%, predict the effect on Ribbed Mussels:
3 Part 3: Keystone Species Investigation
Evidence-Based Reasoning
Yellowstone Wolf Reintroduction: In 1995, gray wolves returned to Yellowstone. Elk herds were forced to move more frequently, reducing grazing on riverbank willow trees. Thriving willows stabilized stream banks, cut water erosion by half, and allowed beaver and songbird populations to surge.
Explain why the gray wolf is classified as a keystone species and how its presence indirectly transformed the physical river landscape:
4 Part 4: Terminology Check
Match term to definition
1. Biomass Match: [ ___ ]
A. Breaks down dead organic matter and recycles nutrients.
2. Autotroph Match: [ ___ ]
B. Species exerting strong control on community structure.
3. Decomposer Match: [ ___ ]
C. Total mass of living organisms within a trophic level.
4. Keystone Species Match: [ ___ ]
D. Organism synthesizing energy from solar/inorganic inputs.
