AP Biology

What This Unit Covers This unit explores the chemical foundation of biological systems, emphasizing how the molecular structure of water and organic compounds dictates their functions. You will examine how elements combine into macromolecules—carbohydrates, lipids, proteins, and nucleic acids—and how their specific chemical properties allow life to exist at the cellular level.

Why It Matters on the Exam Unit 1 accounts for approximately 8–11% of the AP exam score. You should expect questions that require you to analyze molecular diagrams, predict the effects of changing chemical structures (like denaturing a protein), and explain how hydrogen bonding influences the emergent properties of water.

How to Study It

• Master the Functional Groups: Don’t just memorize the names of macromolecules; learn which chemical functional groups define them and how those groups dictate their behavior in water.
• Visualize the Bonds: Practice drawing dehydration synthesis and hydrolysis reactions to understand how polymers are assembled and broken down.
• Connect Structure to Function: For every macromolecule, create a "Why it works" chart; for example, explain why the hydrophobic nature of lipid tails makes them ideal for forming cell membranes.
• Use Active Recall for Water: Be prepared to explain how hydrogen bonding leads to properties like cohesion, adhesion, and high heat capacity, and how these specific traits support life in diverse environments.