Importance of Classification * All organisms used to be classified as plants and animals * Old system was simplistic, was not specific, caused a lot of confusion and disagreement * 1930’s electron microscope developed, internal structural features could be used for classification, smaller organisms such as bacteria could be studied in detail * The 5 kingdom classification system is more accurate because: * It reflects our understanding of how different groups are related through evolution * There are now arguments to create a 6 kingdom system
Major features of the Animal Kingdom (Animalia) * Most animals are usually mobile (some exceptions e.g. sea anemone) * Heterotrophic (can’t manufacture their own food) * Have very organised and specialised cells and body systems * Most reproduce sexually, this gives rise to genetic variation * Some animals reproduce asexually (fast reproduction e.g. aphids all clones i.e. genetically identical) * Multicellular, chemically complex and highly organised * Do not have a cell wall
Major features of the Plant Kingdom (Plantae) * Most plants are usually immobile (i.e. can’t move) * Autotrophic (can make their own food via photosynthesis) * Some plants are organised and have specialised cells and body systems * Most reproduce asexually (fast reproduction, but all genetically identical) * Cell wall made of cellulose * Plants contain chlorophyll; a green pigment necessary for photosynthesis * Majority of plants grow with the same structure i.e. they all rely on roots and have a stem * Surface of most plants is covered by a wax-like layer known as the cuticle

Major features of the Bacteria Kingdom (Monera) * Single celled organisms * Reproduce by splitting into two * Absorb nutrients from outside their body * Have no membrane around their nucleus * Found in almost every imaginable habitat e.g. air, soil and water * Extremely small * These organisms are prokaryotic * Some do not possess a definite nucleus and lack cell organelles
Major features