---

Apuntes

--- # 🧪 **BIOLOGY GUIDE (EXPLAINED + SHORT SUMMARY)** --- ## 🔹 **1. Macromolecules** ### 📖 Explanation: Macromolecules are large molecules that make up living organisms: * **Carbohydrates** → main source of quick energy * **Lipids** → store energy long-term and form membranes * **Proteins** → perform many functions (enzymes, structure, transport) * **Nucleic acids (DNA/RNA)** → store genetic information and control protein production ### ✏️ Summary: 👉 Carbs = quick energy | Lipids = long energy | Proteins = functions | DNA/RNA = info --- ## 🔹 **2. Water** ### 📖 Explanation: Water is essential because of its special properties: * **Cohesion** → water sticks to itself * **Adhesion** → water sticks to other surfaces * **Capillarity** → helps water move up plants * **Surface tension** → creates a strong surface layer * **Low density of ice** → ice floats * **Amphoteric** → can act as acid or base ### ✏️ Summary: 👉 Cohesion + adhesion + capillarity + surface tension + ice floats --- ## 🔹 **3. Protein Structure** ### 📖 Explanation: Proteins have 4 levels of structure: 1. **Primary** → amino acid sequence 2. **Secondary** → helix or sheet 3. **Tertiary** → 3D ...