Characteristics of living organisms

• Characteristics of Living Organisms

  • Movement: an action by an organism or part of an organism causing a change of position or place
  • Respiration: the chemical reactions that break down nutrient molecules in living cells to release energy for metabolism
  • Sensitivity: the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses
  • Growth: a permanent increase in size and dry mass by an increase in cell number or cell size or both
  • Reproduction: the processes that make more of the same kind of organism
  • Excretion: the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements
  • Nutrition: the taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds, ions and usually need water
• Species


  A group of organisms that can reproduce to produce fertile offspring
• Classification of organisms


  • Features that organisms share
  • More features in common the more subdivided the groups get
• Binomial system


  • Organisms named in Latin using two parts: genus (capital letter) and species (lowercase letter)
  • Binomial names are in italics
• Sequence of classification


  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Dichotomous key


  • Used to identify organisms based on a series of questions about their features
  • Branching into two descriptions at a time
• Using a dichotomous key


  1. Pick a single organism to start

  2. Follow the statements from the beginning

  3. Answer each statement/question using the information provided

  4. Eventually reach the name of the organism

  5. Repeat for another organism
• Classifying organisms based on evolutionary relationships

  • Traditional methods grouped organisms based on shared physical features
  • Limitations in determining evolutionary relationships
  • Using DNA sequences to determine how closely related species are
• The first division of living things is into five kingdoms: Animals, Plants, Fungi, Protoctists, Prokaryotes
• Main features of animals

  • Multicellular
  • Cells contain a nucleus
• DNA sequences can show how closely related different species are
• As DNA base sequences are used to code for amino acid sequences in proteins, the similarities in amino acid sequences can also be used to determine how closely related organisms are
• The Five Kingdoms


  • Animals
  • Plants
  • Fungi
  • Protoctists
  • Prokaryotes
• Animals


  • Multicellular
  • Cells contain a nucleus but no cell walls or chloroplasts
  • Feed on organic substances made by other living things
• Plants


  • Multicellular
  • Cells contain a nucleus, chloroplasts and cellulose cell walls
  • Feed by photosynthesis
• Vertebrate classes


  • Fish
  • Amphibians
  • Reptiles
  • Birds
  • Mammals
• Invertebrates


  • Do not possess a backbone
  • Classified based on whether they have legs or not
• Arthropod classes


  • Insects
  • Arachnids
  • Crustaceans
  • Myriapods
• Main features of a group are shared between the groups, while defining features set a group apart from the others