1. Big Idea #2
Biological Systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis

2. Free Energy

3. Energy A very difficult to define quantity
The ability to do something (i.e. move)
2 general types:
Potential energy- stored energy
Kinetic energy – moving energy

4. Types of Potential Energy
Gravitational
Elastic
Nuclear
Electrical (separation of charges)
Chemical (energy stored in chemical bonds)

5. Chemical Potential Energy

6. Kinetic Energy Moving objects
Radiation (movement of light particles/waves)
Thermal (heat, movement of particles
Electrical (movement of electrons)

7. 1st Law of Thermodynamics
Energy is never created or destroyed
Energy is, however, transformed from one form to another
i.e. wind’s motion is converted to electricity, which is converted to heat and light energy in a light bulb

8. 2nd Law of Thermodynamics
The entropy of an isolated system is always increasing
Entropy is the amount of energy in an unusable form – usually heat
Systems are always losing usable forms of energy

9. What This Means
In every conversion of energy- a lot of energy is lost as heat
I.e. when you burn gas in your car- you lose a lot of energy as heat

10. Put Another Way
Energy will be spread from areas of high energy to low energy
I.e. heat will transfer from a hot pan to the air around it
A moving object will lose its kinetic energy to other objects and heat
Chemicals with a lot of potential energy tend to explode – releasing heat and movement of other objects

13. Why Do Biologists Care About This Physics Stuff?
Because living things obey these laws!
Living things are always losing energy to their surroundings

14. We Require an Energy Input
For living things to remain whole they must have an energy input
I.e. organisms must get energy from sun, deep thermal vents or eating

15. Order and Organization Require Energy
Things naturally break down – to keep them from breaking down or to put them together requires an input of energy

16. Energy Coupling
Processes that release energy are coupled to ones that require an input of energy
More energy must be released than is required for the next reaction due to entropy (energy loss)

17. Example Flexing a muscle requires an energy input
Breaking down food releases energy

18. Exergonic Reactions Release free energy
Used in living things to provide energy for other processes

19. The Most Significant Exergonic Reaction
ATP + H2O ADP + Pi + Energy
This is the main molecule the body uses to transfer energy to where it is needed

20. Making ATP is an Endergonic Reaction
It requires an input of energy
Made in cellular respiration (input of chemical energy in food)

21. Uses of Free Energy Maintain body temperature (some organisms)
Reproduction
Growth
Movement

22. Body Temperature Regulation
Endothermy
Ectothermy
Use heat released by metabolic reactions to keep a stable temp
I.e. humans
Use external sources to try to maintain body temperature
I.e. snakes/reptiles

23. Reproduction Requires a huge amount of energy!
Many species only reproduce when energy is available
I.e. most plants flower in the spring when sunlight energy is abundant

24. Growth
Extra free energy not needed for cellular processes like movement and reproduction can be put to growth
I.e. extra calories become stored fat

25. Energy Deprivation Mass is broken down to provide energy
Eventually death will occur if there is no energy input

26. Smaller Organisms Require More Food Per Body Mass
Smaller organisms have more surface area relative to volume, so they lose more heat
So they must replenish that energy loss by eating more (relative to their body size) than larger animals do

27. The Trophic Levels Energy works its way up the food chain
BUT at every level energy is being lost due to entropy
So there is less energy available for higher levels of the food chain

28. Energy on an Ecological Level
The more energy available for a population, the more it will grow
I.e. rain forests have the most abundant plant life – constant energy source

30. Loss of Energy
There is rarely enough energy to support more than 3-4 steps on a food chain
Very little energy left for top level carnivores- part of reason these animals so often are endangered

31. Energy Doesn’t Cycle!!!!!!