Classification

• Biology


  The study of living organisms
• Characteristics of living organisms

  • Nutrition (feeding)
  • Respiration
  • Excretion
  • Movement
  • Irritability (sensitivity)
  • Growth
  • Reproduction
• Heterotrophs


  Animals that take in ready-made food
• Autotrophs


  Plants that make their own food
• Aerobic respiration


  Requires oxygen and takes place in most cells
• Anaerobic respiration


  Takes place without oxygen in certain cells
• Classification


  Grouping living organisms based on similarities and differences
• Levels of classification


  • Species
  • Genera
  • Families
  • Orders
  • Classes
  • Phyla
  • Kingdoms
• Species


  A group of organisms of common ancestry that closely resemble each other and are normally capable of interbreeding to produce fertile offspring
• Prokaryotae


  Kingdom with cells that lack true membrane-bound nuclei
• Eukaryotes


  Kingdoms with cells that contain true nuclei surrounded by membranes
• Viruses


  Particles made up of a piece of DNA or RNA surrounded by a protein coat, can only reproduce inside other living cells
• Ecology


  The study of the interrelationships of living organisms with each other and with their environment
• Environment


  The combination of factors that surround and act upon an organism
• Environmental factors


  • Biotic factors
  • Abiotic factors
• Habitat


  The place where a particular organism lives
• Population


  All the members of a particular species living together in a particular habitat
• Community


  All the populations of different species living together in a particular habitat
• Ecosystem


  A community of living organisms interacting with each other and with their abiotic environment
• Niche


  The position or role of an organism within an ecosystem
• Ecological study


  1. Identify different species

  2. Find out where they live

  3. Determine their numbers

  4. Find out about the relationships they have with each other and with the abiotic factors
• Ecosystems that could be studied

  • Pond
  • Piece of wasteland
  • Small area of woodland
  • Area of grassland
  • Sand dune
  • Rocky shore
• Organisms must never be collected or destroyed unnecessarily; as few as possible should be collected and returned to their original positions if possible, and their habitat should be left as undisturbed as possible
• Quadrat


  A square frame whose area is known, e.g. 0.25 m² or 1 m²
• Using quadrats


  1. Place quadrat at random several times within the ecosystem

  2. Count number of individuals of each species of plant and stationary or slow-moving animal found within the quadrat

  3. If not possible to distinguish individual plants, estimate percentage of quadrat area covered
• Quadrats


  • Used to study the distribution and abundance of plants and stationary or slow-moving animals in uniform ecosystems, e.g. an area of grassland
• Line transect


  A measuring tape or string that has marks at regular intervals, e.g. 10 cm or 25 cm, placed in a straight line across the ecosystem
• Using line transects


  Record species of plants and stationary or slow-moving animals touching the line, or touching the line at each mark
• Line transects


  • Useful where there is a transition of organisms across the ecosystem, e.g. down a rocky seashore
  • Give a quick idea of the species present and how they change across the ecosystem
• Belt transect


  A strip of fixed width, e.g. 0.5 m or 1 m, made by placing two parallel line transects across an ecosystem
• Using belt transects


  1. Record species found between the lines

  2. Alternatively, place a quadrat alongside one line transect and count number of individuals of each species found within its boundaries, repeating at regular intervals
• Species density


  The average number of individuals of a given species per m²
• Total population


  The total number of individuals of a given species in the area under study
• Estimating population sizes


  1. Using results from quadrats

  2. Using capture-recapture method
• Climatic factors affecting terrestrial organisms

  • Light
  • Temperature
  • Humidity
  • Water availability
  • Wind
  • Atmospheric gases
• Light


  • Essential for plants to make food by photosynthesis
  • Affects rate of photosynthesis
  • Synchronises activities of plants and animals with the seasons
• Temperature


  • Most organisms can only survive within a certain, narrow temperature range
  • Affects rate of photosynthesis and germination in plants, and activity of animals
• Humidity


  Affects rates of transpiration in plants and evaporation of water from some animals
• Water availability


  • Essential for life
  • Chemical reactions in cells and most life processes need water
  • Essential for photosynthesis in plants
• Wind


  • Essential for pollination and seed dispersal in many plants
  • Affects rate of transpiration in plants, rate of evaporation of water from animals, and growth of vegetation