Energy Energy is defined as the ability to do work.

Forms of Energy Chemical Thermal (Heat) Sound Light Kinetic Potential Electric Nuclear

Chemical Reactions Exothermic (Energy Releasing) Endothermic (Energy Absorbing) Both types often need some energy input to get the chemical reaction started = Activation Energy.

Reactants Products Activation energy Activation energy

Enzymes Lower Activation Energy Reactants Reaction pathway with enzyme Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Products

Terminology for Chemical Formulas Reactant + Reactant  Product In a reaction that uses an enzyme: Substrate Product Enzyme

Conservation of Matter and Energy Matter and energy can neither be created or destroyed. Only the form can be changed. Matter is recycled in an ecosystem. Energy flows through an ecosystem. Autotrophs transform light energy into chemical energy by the process of photosynthesis. Heterotrophs acquire chemical energy by consuming other living organisms. (Food Chain) Nutrient molecules are recycled in an ecosystem as organisms acquire them and then release them when consumed or when they die and decay.