1. Intro to Energy and Laws of thermodynamics
Ecosystem Energy Flow
Intro to Energy and Laws of thermodynamics

2. Thermodynamics
Thermodynamics are the principles that govern energy relationships
Describe constraints on the generation of heat
Transformations of energy
Energy transfer within a system or to the surroundings
If energy is added to a system from its surroundings; might return to surroundings in a different form
1st law thermodynamics
Energy is conserved when both a system and its surroundings are considered
It’s not created nor destroyed but transformed from one form to another

3. Thermodynamics 2nd law of thermodynamics (law of entropy)
In any energy transformation, some energy is lost as unusable energy in the sense that work cannot be performed
Energy in enviro sci class looks at these 2 ?s
Where does the energy needed for living organisms originate?
How is energy used by these organisms?

4. Where does ENERGY start?
Think of surface of earth as a system subject to the first 2 laws of thermodynamics
Electromagnetic radiation from the sun
~58% of radiation directed toward earth is reflected or absorbed as heat by out atmosphere
Less then 2% of remaining radiation is used by plants
The balance is transformed into heat
Energy released by geothermal and volcanic activity

5. Living things
Living organisms are temporary storage units for useful energy
One organism can be used by another as a source of energy
In transfer, energy is lost to environment as heat
We need to have continuous energy enter the system
Photosynthesizing organisms go thru oxidation-reduction reactions based on solar input to produce and store own carbohydrates; which then become energy for other organisms

6. Ecosystems and Energy
Food consumed undergoes chem reactions known as metabolism
Chemosynthesis – inorganic compounds (nitrites, hydrogen sulfide, hydrogen gas) provide the necessary energy for organisms to make own food
Photosynthesis
Green plants produce ATP (carrier for energy) and NADPH (carrier for e- used in synthesis of glucose) in their chloroplasts
Add CO2 and H2O
Now forma carbohydrate (glucose) in presence of sunlight and chlorophyll

7. Energy in Ecosystem Cellular Respiration Trophic Levels
CO2, H2O and energy are produced by the oxidation of glucose
Requires oxygen and occurs in mitochondria
Trophic Levels
Each step in the transfer of energy (autotroph to heterotroph and heterotroph to heterotroph) is a trophic level
Laws of thermodynamics apply to energy flow; less energy is available to organisms at each higher trophic level
Estimated that only 10% of energy at each trophic level is available to organisms at the next higher level

8. Energy in Ecosystem Food chains and webs Ecological Pyramids
Lowest level – autotrophs/producers
Primary consumers – herbivores
Secondary consumers – carnivores that eat the herbivores
Ecological Pyramids
Base = producers
Each trophic level above is some level of consumer
3 types: energy, numbers, and biomass

9. Ecological Pyramids Energy Biomass Levels
Shows decreasing amount of energy available to each successive trophic level
10% of energy at each level is available to organisms at next higher level
Biomass
Because only 10% of energy at a given trophic level is available to next higher level, food chains are short; number of organisms is lower than previous level
Levels
Need to determine which organisms on are the correct and appropriate level

10. Practice Question 1
How does the flow of energy through an ecosystem conform to the laws of thermodynamics? Be sure to discuss its origination, transformation, and utilization.

11. Answer 1
Ecosystems conform to the laws of thermodynamics. The first law of thermodynamics states that energy is conserved; that is, energy cannot be created or destroyed, but it may be converted from one form to another. An ecosystem is a closed system that receives energy from outside sources. The organisms making up the ecosystem transform this energy into useful forms for storage and later utilization. The second law of thermodynamics states that some energy is lost as “useless” energy. Therefore, energy enters the system; is converted to food, which is stored by organism; energy is used by metabolic processes and energy is dissipated to atmosphere

12. Question 2
Green plants produce most of the oxygen in our atmosphere through a series of complex reactions. Name and describe this generalized reaction.

13. Answer 2
Green plants produce most of the oxygen in our atmosphere by photosynthesis. The generalized reaction for this process is often referred to as “the light reaction.”
6CO H2O C6H12O O2

14. Question 3
What is the role of ATP and NADPH in metabolism? What effect does the amount of light have on the metabolism of green plants?

15. Answer 3
Green plants can make food by producing ATP (a carrier for energy) and HADPH (a carrier for electrons used in the synthesis of glucose) in their chloroplasts, which then reduce carbon dioxide and water to form a carbohydrate only in the presence of sunlight and chlorophyll

16. Question 4
ID the structure below and be specific. What factors limit the steepness of the sides of this structure?

17. Answer 4
The diagram shown may be biomass, energy, or numbers pyramid by trophic level. As one moves higher on pyramid, there is a decrease in biomass, energy, or numbers.

18. Question 5
A temperate deciduous forest contains the following organisms: oak tree, pine tree, grass, mouse, rabbit, cow, hawk, mushroom, dandelion, beetle, snake. Construct a food web using at least five of these organisms.