1 - Characteristics and Classification of Living Organisms

• Characteristics of living organisms


  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Excretion
  • Nutrition
  • Reproduction
• Movement


  An action by an organism or part of an organism causing a change of position or place
• Respiration


  The chemical reactions in cells that break down nutrient molecules and 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
• Excretion


  Removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials and substances in excess of requirements
• Nutrition


  Taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds and ions and usually need water
• Biologists use 7 characteristics to proof whether the things found is alive or not
• Growth


  • All organisms begin small and get larger, by the growth of their cells and by adding new cells to their bodies
• Movement


  • All organisms are able to move to some extent. Most animals can move their whole body from place to place, and plants can slowly move parts of themselves
• Sensitivity


  • All organisms pick up information about changes in their environment, and react to the changes
• Excretion


  • All organisms produce unwanted or toxic waste products as a result of their metabolic reactions, and these must be removed from the body
• Reproduction


  • Organisms are able to make new organisms of the same species as themselves
• Nutrition


  • Organisms take substances from their environment and use them to provide energy or materials to make new cells
• Respiration


  • All organisms break down glucose and other substances inside their cells, to release energy that they can use
• Traditional classification method


  Based on morphology (external bodies, such as whether they had legs or wings) and anatomy (internal body structure, by dissection)
• Modern classification method


  Based on DNA sequence and protein sequence

  
• The more similar base sequences they have, the more closely related they are. Closely related means they share a more recent common ancestor than organisms with very different base sequences that have a very distant ancestor
• The more similar the amino acid sequences, the more closely related the species are to one another. They have a more recent common ancestor than species that have protein sequences that are less similar
• DNA barcoding is useful in the conservation of animals because it allows accurate identification of animals, is cheap, easy, quick and efficient, can distinguish characteristics, identify previously unknown species, and help identify threatened/endangered species

  
• It is better to use DNA sequences/protein sequences/modern method because it is more accurate than traditional classification systems, easier/cheaper/quicker/more efficient to use than other identification methods, and only a trace sample is needed
• Species


  A group of organisms that can reproduce to produce fertile offspring
• Binomial (two-name) system


  Each species had a scientific name made up of its genus and species, e.g. Canis lupus
• Five kingdoms of living organisms


  • Animal
  • Plant
  • Fungus
  • Protoctist
  • Prokaryote
• Animals


  • Multicellular, have a nucleus but no cell walls or chloroplasts, feed on organic substances made by other living organisms
• Plants


  • Multicellular, have a nucleus, cell walls made of cellulose and contain chloroplasts, feed by photosynthesis, may have roots, stems and leaves
• Fungi


  • Multicellular, have nucleus, have cell walls not made of cellulose, do not have chlorophyll, feed by saprophytic or parasitic nutrition
• Protoctists


  • Multicellular or unicellular, cells have a nucleus, cells may or may not have a cell wall and chloroplasts, some feed by photosynthesis and others feed on organic substances made by other organisms
• Prokaryotes


  • Unicellular, no nucleus, have cell walls not made of cellulose, have no mitochondria, have DNA
• Main groups of vertebrates


  • Mammals
  • Birds
  • Reptiles
  • Amphibians
  • Fish
• Main groups of arthropods


  • Myriapods
  • Insects
  • Arachnids
  • Crustaceans
• Fish


  • Vertebrates with scaly skin, have gills, have fins, live in water
• Amphibians


  • Vertebrates with moist, scale-less skin, eggs laid in water, larva (tadpole), lives in water, adult often lives on land, larva has gills, adult has lungs
• Reptiles


  • Vertebrates with scaly skin, lay eggs with rubbery shells
• Birds


  • Vertebrates with feathers, forelimbs have become wing, lay eggs with hard shell, have a beak
• Mammals


  • Vertebrates with hair, have a placenta, feed on milk by mammary glands
• Insects


  • Arthropods with 3 pairs of jointed legs, 2 pairs of wings, breathe through tracheae, body divided into head, thorax and abdomen, live on the land
• Crustaceans


  • Arthropods with more than 4 pairs of jointed legs, breathe through gills, live in wet places, aquatic
• Arachnids


  • Arthropods with 4 pairs of jointed legs, breathe through gills called book lungs, live on the land
• Myriapods


  • Arthropods consisting of many segments, each segment has jointed legs