Chapter 4: Ecosystems and Energy

Chapter 4: Ecosystems and Energy Sazzy Gourley and Ariana Lutterman

1: What is Energy? • Energy: capacity or ability to do work • Six forms: 1. Chemical 2. Radiant/solar 3. Heat 4. Mechanical 5. Nuclear 6. Electrical • Can be potential or kinetic

2: Thermodynamics • Thermodynamics: the study of energy and its transformations • Three types of systems: • Closed: matter can’t move in and out, energy can • Open: matter and energy move in and out • Isolated: nothing in and out (not on earth)

Laws of Thermodynamics • 1st law: energy cannot be created or destroyed, but it can be transformed • Example: Light energy to heat energy • 2nd law: when energy is transformed, some energy is lost to the environment as heat • The amount of biologically usable energy decreases over time • Entropy: measure of disorder or randomness • Increases over time • Disorganized, unusable energy has high entropy

3: Photosynthesis and Cellular Respiration • Photosynthesis: biological process in which light energy from the sun is captured and transformed into chemical energy of carbohydrate molecules • 6CO2 + 12H2O + radiant energy  C6H12O6 + 6H2O + 6O2 • Cellular respiration: process in which the energy of organic molecules is released within cells of ALL organisms • C6H12O6 + 6H2O + 6O26CO2 + 12H2O + radiant energy

4: Chapter Vocabulary • Energy Flow: movement of energy in ONE direction • Arrow = flow, box = storage • Producer/Autotroph: uses sun directly for energy (plants) • Consumer/Heterotroph: depend on other organisms for energy • Decomposer/Saprotroph: break down dead organic material and absorb nutrients for energy

Detritus: currently decomposing organic matter • Detritivore: eats detritus • Trophiclevel: energy level in a food chain (e.g. primary, secondary, tertiary) • Primary consumer: eats producer • Secondary consumer: eats primary consumer • Tertiary consumer: eats secondary consumer

5: Ecological Pyramids • Pyramid of energy: total amount of energy stored at each trophic level • Law of 10%: only ten percent of energy in each trophic level moves to form new biomass • No exceptions

Pyramid of Biomass: dry weight of organic matter in each trophic level • Represents chemical energy stored in organic matter of a trophic level • Extrapolate to entire trophic level from quantitative samples (e.g. mark-recapture) • Exception: big whales, small krill, big algae whales krill algae

Pyramid of Numbers: total number of organisms at each trophic level • Decreases as you go up • Exception: one tree can feed multiple organisms birds insects tree

6: Productivity • Gross Primary Productivity (GPP): how productive are the plants • Net Primary Productivity: what’s available to primary consumers • Net Primary Productivity = Gross Primary Productivity – Plant Respiration • NPP = GPP - RP

Secondary Productivity: rate of biomass accumulation by heterotrophs (i.e. growth) • NPP = GPP – RP • GSP = NPP – Not Used – Fecal Waste (assimilated) • NSP = GSP – RC (energy gained at very end) • NEP = NPP – RC or GPP – RTOT • TLE (Trophic level efficiency) = Production/Consumption

7: Productivity Cleared Up GPP RP Not Used NPP Waste Ingested RC GSP (assimilated) NSP (growth and reproduction)

Chapter 4: Ecosystems and Energy