1. 3.4 Energy & Metabolism I. Energy
A. Def- the ability to move or change matter
B. Forms
1. Light, heat, chemical, mechanical, electrical, etc.
II. Changing Matter
A. Physical Change
1. occurs when only the form or shape of the matter changes

2. 2. The substances do not change into different substances
3. ex- adding sugar to iced tea
B. Chemical Change
1. Occurs when a substance changes into a new substance
2. ex– wood burning
C. Conservation of Mass
1. Matter is neither created nor destroyed in any change

3. D. Conservation of Energy
1. Energy is neither created nor destroyed, it changes forms
III. Chemical Reactions
A. Reactant
1. the substance that is changed in a chemical reaction
B. Product
1. the new substance that is formed

4. C. Activation Energy
1. The minimum kinetic energy that colliding particles need to start a chemical reaction
D. Alignment
1. Chemical reactions can only occur when the activation energy is available and the correct atoms are aligned.

5. IV. Biological Reactions
A. Enzymes
1. is a molecule that increases the speed of a reaction
B. Enzyme Activity
1. Active site
a. the region where the reaction takes place
2. Substrates
a. reactant in a chemical reaction

6. 3. Enzymes and substrates work like a lock & key or puzzle pieces.
C. Metabolism
1. Breaking down of your food into useful energy (ATP)
2. Use enzymes to reduce the activation energy
3. Carried out in a step by step process
4. Very little heat is produced