Sazzy Gourley and Ariana Lutterman

Chapter 4: Ecosystems and Energy

1: What is Energy?Energy: capacity or ability to do workSix forms:

1. Chemical2. Radiant/solar3. Heat4. Mechanical5. Nuclear6. Electrical

Can be potential or kinetic

2: ThermodynamicsThermodynamics: the study of energy

and its transformationsThree types of systems:

Closed: matter can’t move in and out, energy can

Open: matter and energy move in and outIsolated: nothing in and out (not on earth)

Laws of Thermodynamics1st law: energy cannot be created or

destroyed, but it can be transformedExample: Light energy to heat energy

2nd law: when energy is transformed, some energy is lost to the environment as heatThe amount of biologically usable energy

decreases over timeEntropy: measure of disorder or randomness

Increases over timeDisorganized, unusable energy has high entropy

3: Photosynthesis and Cellular RespirationPhotosynthesis: biological process in

which light energy from the sun is captured and transformed into chemical energy of carbohydrate molecules6CO2 + 12H2O + radiant energy C6H12O6 + 6H2O +

6O2

Cellular respiration: process in which the energy of organic molecules is released within cells of ALL organismsC6H12O6 + 6H2O + 6O26CO2 + 12H2O + radiant energy

4: Chapter VocabularyEnergy 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 detritusTrophic level: energy level in a food chain

(e.g. primary, secondary, tertiary)Primary consumer: eats producerSecondary consumer: eats primary

consumerTertiary consumer: eats secondary

consumer

5: Ecological PyramidsPyramid of energy: total amount of

energy stored at each trophic levelLaw 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

algae

krill

Pyramid of Numbers: total number of organisms at each trophic level

Decreases as you go upException: one tree can feed multiple

organisms

insects

tree

birds

6: ProductivityGross 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

GPPRP

NPP

Ingested

Not Used

GSP (assimilated

)NSP (growth

and reproduction)

Waste

RC