1. 10/5/2011
Objective: Understand the significance of energy in biological systems
Warm-Up:
Why are autotrophs called “producers?”
Why might “producers” be a misleading term?

2. 10/10/2011
Objective: Be able to solve quantitative problems related to energy content
Warm-Up: What is the relationship between “calorie” as discussed in science textbooks and the calories listed on food labels?

3. Energy
10/3/2011

4. Energy
Energy can be defined as the capacity to do work or to cause change
Organisms store energy in organic molecules
Review: Which organic molecules are used for energy?
Energy stored in molecules is called chemical energy

5. Using Energy
During chemical reactions, some of the stored chemical energy is released
This “released” energy is called free energy
It’s called “free” because it is now available to do work; “free” here means usable
Free energy is used for chemical work
Making and breaking down complex molecules
Free energy is also used for transport and mechanical work
What are organisms transporting?
What’s an example of mechanical work?

6. Getting Energy
Organisms that obtain energy by consuming other organisms are called heterotrophs
Example?
Organisms that can get energy and nutrients from nonliving sources are called autotrophs
Vocab tip: “hetero” means other, “auto” means self, and “troph” means feed

7. Energy in Ecosystems Autotrophs supply energy to the whole biosphere
Can you explain why?
In an ecosystem, autotrophs are the producers
Why are they considered producers?
Heterotrophs are consumers in an ecosystem
Decomposers, organisms break down dead plants and animals, are vital to ecosystems
Why?

8. Energy Flow
1st Law of Thermodynamics: Energy cannot be created or destroyed, but it can change form
Total energy of the universe is constant
What does this mean for organisms?
2nd Law of Thermodynamics: systems tend towards disorder
Disorder of a system is called entropy
As free energy is released, the world becomes more disordered

9. When a large molecule is broken down into smaller molecules, free energy is released and there is more disorder (entropy).
Putting small molecules together to make bigger molecules decreases entropy, so it requires energy.

10. Energy Flow (cont.) Organisms have a high level of organization
Maintaining organization requires energy
“Lost as heat”
You’ll hear this quite a bit—I’ll even say it sometimes!—but it’s not quite right
Energy is never lost!
All organisms release some heat energy
This energy cannot be used for work—it is not free energy
Organisms are inefficient

11. Check Your Understanding
What’s the difference between chemical energy and free energy?
Why are autotrophs classified as producers?
Why are decomposers important?
What does the 1st Law of Thermodynamics have to do with biology?
Do organisms violate the 2nd Law of Thermodynamics? Why or why not?