1. Ecosystems: How they work
Chapter 3

2. Chapter Introduction: Serengeti
Herbivores of Serengeti migrate.
Why do they do that?
The vegetation in the plains is high in phosphorus that they need for growth and lactation
The presence of predators in the woodlands may force the herds to migrate to the grasslands where they are less vulnerable.

3. Appendix C Matter Atoms Elements Molecules Compounds Bonding
Check it out, read it over!

4. Cycle of Growth
The process of growth, reproduction, death and decay of organisms is a continuous process.
Taking various atoms from the environment (food), assembling them into living organisms (growth), disassembling them (decay), and repeating the process.
Driving the cycle is the genetic program living things have to grow and reproduce.

5. Characterizing life Six main elements N-CHOPS Nitrogen Carbon Hydrogen
Oxygen
Phosphorus
Sulfur
Where do they occur?
Atmosphere
Lithosphere
Hydrosphere
O, N, C (as CO2)
P, S H

6. N-CHOPS: what they form
In living organisms the six key elements make up:
Proteins
Carbohydrates (sugars and starches)
Lipids (fats)
Nucleic acids (DNA and RNA)
The common denominators that make up tissues of living things are:
C-C, C-H, C-O bonds.

7. Definitions: Minerals- any hard, crystalline, inorgainc material.
Organic- Chemical compounds making up the tissues of life.
Inorganic- All other compounds, not containing Carbon based bonds.

8. Energy Two forms: Measured in calories Kinetic Potential
Light, heat, movement, electricity
Potential
Chemical potential=battery, gas, firewood, explosives
Measured in calories
Small unit so most of the time it is measured in kilocalories (Calories).

9. Law of conservation of energy
First Law of Thermodynamics
Energy is neither created nor destroyed, but may be converted from one form to another.
Joule and von Helmholtz

10. Second Law of Thermodynamics
F=ma
In any energy conversion, some of the usable energy is always lost.
General Statement:
Systems will go spontaneously in one direction-toward increasing entropy.
Clausius

11. Example of Entropy:
It is possible to pump water up hill, where energy is being put in to the system. In contrast, flow in the opposite direction, which releases energy, occurs spontaneously.

12. The energy of molecules
Organic=High potential energy
Inorganic=Low potential energy

13. (An energy demanding process) 6CO2 + 12H2O  C6H12O6 + 6O2 + 6H2O
Photosynthesis
(An energy demanding process) 6CO2 + 12H2O  C6H12O6 + 6O2 + 6H2O
Light energy input
Chlorophyll in the cells of the plant absorbs the kinetic energy of light and uses it to remove hydrogen atoms from water molecules

14. The purpose of Glucose
Alone or combined with N, P, S or other minerals, Glucose is the raw material used for making all other organic molecules.
Gives the plant energy when it is broke down through cell respiration.
Can be stored for future energy use.
Each step of photosynthesis is aided by enzymes (proteins that promote the synthesis or breaking of chemical bonds).

15. Cellular Respiration Basically the reverse of Photosynthesis:
C6H12O6 + 6O2  6CO2 + 6H2O + energy
(high potential energy) (low potential energy)
The purpose of cellular respiration is to release the potential energy contained in organic molecules to perform the activities of the organism.

16. Organic materials Three pathways to take:
More than 60% of what is digested and absorbed is oxidized to provide energy, waste products are released back into the environment.
Remainder of what is digested and absorbed goes into body growth, maintenance and repair, and storage (fat).
Part not absorbed passes out as fecal waste.

17. Definitions
Fermentation- decomposers can meet their energy needs through the partial breakdown of glucose that can occur in the absence of oxygen.
Forms alcohol, methane, acetic acid
Anaerobic- absence of oxygen
Aerobic- presence of oxygen

18. Trophic levels
As energy flows from one trophic level to the next, only about 10% of the energy is passed on because:
Much of the preceding trophic level is standing biomass and is not consumed.
Much of what is consumed is used for energy.
Some of what is consumed is undigested and passes through the organism.

19. Carbon Cycle

20. Human impacts on Carbon Cycle
Burning fossil fuels
More in chapter 20.

21. Phosphorus Cycle

22. Human impacts on Phosphorus Cycle
Use of phosphorus containing fertilizers.
Leads to severe water pollution.
Affects ocean ecosystems.

23. Nitrogen Cycle

24. Human impacts on Nitrogen Cycle
Fertilizers.
Affects fresh water systems
Fossil fuel combustion also fixes nitrogen from the air.