1. 1.3 Energy & Equilibrium Kristin Page IB ESS 2015-2016
4/22/ :39 PM
1.3 Energy & Equilibrium
Kristin Page
IB ESS
© 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Significant Ideas
The laws of thermodynamics govern the flow of energy in a system and the ability to do work.
Systems can exist in alternative stable states or as equilibria between which there are tipping points.
Destabilizing positive feedback mechanisms will drive systems towards these tipping points, where as stabilizing negative feedback mechanisms will resist such changes.

3. Applications and Skills
Explain the implications of the laws of thermodynamics to ecological systems.
Discuss resilience in a variety of systems.
Evaluate the possible consequences of tipping points.

4. Knowledge and Understanding:
Know the first and second laws of thermodynamics
Give examples of the first and second laws of thermodynamics in ecological systems
Distinguish between stable equilibrium and steady state equilibrium
Distinguish between positive and negative feedback loops
Explain how positive and negative feedback loops lead to a system being stable or becoming unstable
Discuss factors that affect the resilience of a system.
Explain what is meant by tipping point and how the resilience of a system affects the tipping point

5. ECOSYSTEMS
Ecosystems involve interrelationships among climate, geology, soil, vegetation, and animals. These components are linked together transfers and transformations of energy and or matter.
Two basic processes occur in ecosystems
Cycling of matter: only a finite amount of nutrients on Earth so must be recycled
Flow of energy: all energy originates from the sun and is used by plants in photosynthesis and converted to a form usable by all other organisms

6. CYCLING MATTER
There are only finite amounts of nutrients available on the earth, therefore they must be recycled in order to ensure the continued existence of living organisms.

7. FLOW of ENERGY
Solar energy enters Earth's systems as radiant energy. This energy is used by plants for food production. As heat, it warms the planet and powers the weather system. Eventually, the energy is lost into space in the form of infrared radiation. Most of the energy needed to cycle matter through earth's systems comes from the sun.

8. ECOSYSTEMS & ENERGY
Thermodynamics is the study of the energy transformations that occur in a system.
2 Laws of thermodynamics:
1st Law of Thermodynamics: Principle of Conservation of Energy
Energy cannot be created or destroyed, it can only change forms
Therefore the total energy in an isolated system (universe) is constant

9. ECOSYSTEMS & ENERGY 2nd Law of Thermodynamics
In an isolated system, the total amount of entropy (disorder) will tend to increase.
More entropy = more disorder
Energy conversions are not 100% efficient
Energy is lost to the environment in the form of heat

10. SUN ENERGY

11. ECOSYSTEMS & ENERGY
Due to the 2nd Law of Thermodynamics, energy is not equally passed through a food chain
Plants only convert 1-2% of the energy they receive into stored sugars
In general only about 10% of the energy is passed from 1 trophic level to the next (the rest is used in metabolism, to do work, an as heat loss)
Less and less energy is available as you move up a food chain

12. ECOSYSTEMS & ENERGY
Pyramid of energy is always upright because at each transfer about % of the energy available at lower trophic level is used up to perform metabolic activities and as heat lost to the environment.
Only 10% of the energy is available to next trophic level (as per Lindemann's ten percent rule).

13. EFFICIENCY OF AN ECOSYSTEM
Efficiency is the comparison of the amount of work or energy done to the amount of energy that is consumed
𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦= 𝑈𝑠𝑒𝑓𝑢𝑙 𝑜𝑢𝑝𝑢𝑡𝑠 𝐼𝑛𝑝𝑢𝑡𝑠 (multiply by 100% to turn into %)
We use efficiency in ESS to discuss how efficient parts of the system are
For example: Is it more efficient to eat a plant or an animal?
Due to the loss of heat as you move up a food chain it is more efficient to eat a plant because there is less energy loss
In the example below, the carnivore is very inefficient as 1000J of sunlight started but only 0.1 joule is available to the lion

14. STEADY STATE EQUILIBRIUM
A state of balance between parts of a system
There are fluctuations in a system, however most systems return to a balanced state after a disturbance.
Steady-state equilibrium
allows an open system to go to back to balance after disturbance

15. NEGATIVE FEEDBACK Homeostasis
The property of a system to maintain a stable, constant condition.
Negative Feedback
The way living systems maintain homeostasis.
Involves a sequence of events that will cause an effect that is in the opposite direction to the original stimulus and thereby brings the system back to equilibrium.
Examples:
A population of insects may remain the same overall even though individuals are born or die.
Human body temperature; we get cold we shiver to warm up, we get hot we sweat to cool down

16. STATIC EQUILIBRIUM Static Equilibrium no changes over time
no inputs or outputs to system
non-living (cannot occur in living systems since there is always an exchange of energy and matter)
when a disturbance occurs a new equilibrium is reached
ex: rock formations over time, bottle sitting on table

17. Unstable or Stable Equilibrium
Stable Equilibrium: System returns to original state after disturbance
Unstable Equilibrium: System returns to new equilibrium after disturbance.

18. FEEDBACK LOOPS
Systems are constantly undergoing change and responding to change
There are 2 possible types of feedback mechanisms:
Positive Feedback Loops:
Changes bring about a new steady-state level
Destabilize a system

19. Positive Feedback Loop

20. FEEDBACK LOOPS Negative Feedback Loops:
Return system to original state
Stabilize a system

21. PREDATOR PREY RELATIONSHIPS
Predator Prey relationships are usually controlled by
negative feedback where:
Increase in Prey  Increase in Predator 
Decrease in Prey  Decrease in Predator 
Increase in Prey  and so on in a cyclical manner

22. Resilience & Tipping Points
Resilience: the ability of a system to “bounce back” after a disturbance
Low resilience: system does not return to original state
Generally high resilience is a good thing – ex a forest returns after a fire
However sometimes it is a bad thing – ex antibiotic resistant bacteria has high resilience
Tipping Point: when a system is pushed past the point of returning to it’s original state

23. Ecosystem Resilience
Many factors affect how resilient an ecosystem may be including;
Species Diversity: the more different species the more resilient it is
Habitat diversity: the more complex the interactions the more resilient
Genetic diversity: the more variety within a population the more resilient
Size of ecosystem: generally larger ecosystems are more resilient
Climate: arctic- harsh climate, little sunlight, cold vs rainforest – warm, lots of rainfall
Faster species reproductive rate (r-strategists recolonize faster than K-strategists)

24. Tipping Points Involve positive feedback loops
Once tipping point is reached there is a quick change to the system
Changes are long-lasting
Changes are difficult to reverse
There is a time lag between the events driving the change and the evidence of the impact

25. Tipping Point Examples
Eutrophication of a Lake (Gulshan)
Nutrients are added to lake (fertilizers)
Algal blooms occur due to increased nutrients
Sunlight is blocked from reaching lake floor
Oxygen levels in lake decrease
Living things die due to lack of oxygen
Decomposers thrive due to dead material
Decomposers release more carbon dioxide into lake as the decompose
Oxygen levels drop further

26. Tipping Point Examples
Species Extinction (Sunda Rhinoceros Bangladesh)
Poaching for horns & medicines
Habitat loss
Current population is between in a small region of Java

27. Tipping Point Examples

28. Tipping Point Examples

29. Tipping Point Examples

30. HOMEWORK
1.3 To Do Questions pp 36, 37, & 40