• Activation energy is the energy needed for reactions to proceed
• Enzymes lower activation energy and can be affected by pH, temperature, and substrate concentration
• Enzyme activity can be regulated through various means
• Laws of thermodynamics dictate energy transfer and ATP structure
• Metabolism involves anabolic and catabolic pathways, while photosynthesis involves carbon fixation and the Calvin cycle

For further study and review, the AP Biology Unit 3 study guide PDF and the AP Biology Unit 3: Cellular Energetics practice test are valuable resources. Additionally, the Enzyme regulation and substrate concentration notes, and the Gibbs free energy and activation energy examples can provide in-depth knowledge and understanding. Mastering the difference between enzyme regulation and substrate concentration, understanding the types of enzyme regulation, and the Gibbs free energy and activation energy formula is crucial for success in the AP Biology Unit 3: Cellular Energetics Test Answer Key.