Energy Flow. ENERGY. Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion heat, electromagnetic radiation Potential energy – stored for possible use batteries, glucose molecules. Electromagnetic Spectrum.
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Energy is the ability to do work and transfer heat.
Kinetic energy – energy in motion
heat, electromagnetic radiation
Potential energy – stored for possible use
batteries, glucose molecules
Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content.
High energy, short
Wavelength in meters
(not to scale)
Low energy, long
Fig. 2-11, p. 43
Organisms vary in their ability to sense different parts of the spectrum.
Fig. 2-12, p. 43
The first law of thermodynamics: we cannot create or destroy energy.
We can change energy from one form to another.
The second law of thermodynamics: energy quality always decreases.
When energy changes from one form to another, it is always degraded to a more dispersed form.
Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.
Fig. 2-14, p. 45
Most producers capture sunlight to produce carbohydrates by photosynthesis:
Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H2S) gas .
Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy.
This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen.
in leaf cell
6CO2 + 6 H2O
C6H12O6 +6 O2
Fig. 3-A, p. 59
Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains.
Primary consumers that eat producers
Primary consumers eat primary consumers
Third and higher level consumers: carnivores that eat carnivores.
Feed on both plant and animals.
Decomposers: Recycle nutrients in ecosystems.
Detrivores: Insects or other scavengers that feed on wastes or dead bodies.
Bark beetle engraving
Carpenter ant galleries
Termite and carpenter ant work
Long-horned beetle holes
Dry rot fungus
Wood reduced to powder
Powder broken down by decomposers into plant nutrients in soil
Fig. 3-13, p. 61
Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need.
This is usually done through aerobic respiration.
The opposite of photosynthesis
Anaerobic respiration or fermentation:
Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen.
The end products vary based on the chemical reaction:
An ecosystem survives by a combination of energy flow and matter recycling.
Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem.
First Trophic Survival
(decomposers and detritus feeders)
Fig. 3-17, p. 64
Trophic levels are interconnected within a more complicated food web.
Fig. 3-18, p. 65
In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.
Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next.
Heat and Webs
Each tropic level
Fig. 3-19, p. 66
Gross primary production (GPP)
Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass.
Gross primary productivity and Webs
(grams of carbon per square meter)
Fig. 3-20, p. 66
NPP = GPP – R
Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R).
Sun and Webs
and unavailable to consumers
Gross primary production
Net primary production (energy available to consumers)
Growth and reproduction
Fig. 3-21, p. 66