Biology (0610) Biological Molecules Revision Note

This document provides an overview of biological molecules for CAIE IGCSE Biology. It introduces the three main classes of biomolecules: carbohydrates, fats and oils, and proteins. Carbohydrates and fats are made of carbon, hydrogen, and oxygen, while proteins also include nitrogen and sometimes sulfur. The guide explains how smaller molecules—such as simple sugars, fatty acids, glycerol, and amino acids—combine to form larger molecules like starch, glycogen, cellulose, fats, oils, and proteins. A detailed section on food tests outlines key experiments used to identify nutrients: Benedict’s test for reducing sugars (brick-red), iodine test for starch (blue-black), Biuret test for proteins (purple/violet), ethanol emulsion test for fats (cloudy), and DCPIP test for Vitamin C (colourless). The document also introduces the structure of DNA, describing it as a double helix of two coiled strands with base pairs (A–T and C–G) forming cross-links. While the exact names of bases are not required for the syllabus, understanding their pairing is essential. With concise explanations and practical examples, this resource equips students with fundamental knowledge of biomolecules, their roles, and how to test for them in laboratory experiments.