Diversity of organisms — A/L Biology

A. Biological Classification Systems Definition: The systematic arrangement of organisms into hierarchical groups based on shared characteristics and evolutionary relationships. Explanation: Biological classification organizes living organisms into a structured hierarchy from broadest to most specific: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. This system helps scientists communicate about organisms consistently worldwide. The classification is based on morphological, anatomical, physiological, biochemical, and genetic characteristics. Modern classification increasingly uses molecular data like DNA sequences to determine evolutionary relationships. Think of it as: Like organizing a library where books are first grouped by major subjects (fiction/non-fiction), then by genre, then by author, and finally by individual titles. Real-world application: Used in conservation biology to identify endangered species, in agriculture to classify crop plants and pests, and in medicine to identify pathogens and develop targeted treatments. B.