N5 Biology Unit 3

• Ecosystem


  All of the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact
• Species


  A group of organisms which breed to produce fertile offspring
• Biodiversity


  The total variety that exists within a species and between species in an ecosystem
• Population


  The total number of individuals in 1 species
• Community


  The total number of living individuals in an ecosystem
• Producer


  A green plant which makes its own food (by the process of photosynthesis)
• Consumer


  An organism that consumes another organism for energy
• Herbivore


  An organism that eats only plants
• Carnivore


  An organism that eats only animals
• Omnivore


  An organism that eats both plants and animals
• Predator


  An organism which hunts, kills and eats other animals
• Prey


  An organism which is hunted, killed and eaten by other animals
• Niche


  The role an organism plays within a community. What it is, where it lives, what it needs, and how it interacts with other organisms
• Food chains and webs

  1. Always begin with a producer

  2. The arrows show the direction of energy flow or "is eaten by"

  
• When predicting what will happen if an organism is removed or reduced in a food web, you cannot assume that the predator will gain another food source
• Biotic factors


  Living factors which influence the ecosystem
• Examples of biotic factors

  • Competition for resources
  • Disease
  • Food Availability
  • Grazing
  • Predation
• Abiotic factors


  Non-living factors which influence the ecosystem
• Examples of abiotic factors

  • Light Intensity
  • Soil Moisture
  • pH
  • Temperature
• Sampling techniques


  1. Quadrats

  2. Pitfall Traps

  3. Line Transect
• Paired statement key


  A method used to identify organisms
• Interspecific competition


  Competition between two different species
• Intraspecific competition


  Competition between members of the same species
• What animals compete for

  • Food
  • Water
  • Shelter
  • Mates
• What plants compete for

  • Water
  • Light
  • Space to Grow
  • Nutrients
• Relationship between number of prey species and predator species

  As the number of prey species increases, the predator also increases, once the prey species declines, as does the predator as there is less to eat
• Indicator species


  Species that by their presence or absence indicate environmental quality or levels of pollution
• Photosynthesis


  Carbon dioxide + water -> oxygen + sugar

  
• Fate of sugar produced by photosynthesis


  • Used as a raw material of respiration
  • Used structurally as cellulose in cell walls
  • Stored as starch for use in the future
• Photosynthesis


  Light energy -> chlorophyll -> light reactions -> carbon fixation -> oxygen + sugar

  
• Limiting factors


  Factors which if they are in short supply, will slow down the rate of photosynthesis

  
• Limiting factors


  • Light INTENSITY
  • Carbon dioxide CONCENTRATION
  • Temperature

  
• The rate of photosynthesis can be measured by the dry mass of the plant over time, the number (or volume) of bubbles of oxygen gas given off over time

  
• Only a SMALL AMOUNT of energy is passed from one level of a food chain or web to the next
• Pyramid of energy


  Shows the total quantity of energy at each stage in a food chain, it will always resemble a true pyramid as the energy will always decrease as you go up the food chain
• Pyramid of numbers


  Shows the total number of organisms at each level in a food chain, these pyramids do not always look like a true pyramid
• An exponential growth in human population has meant that we have need to ensure higher crop yields in order to meet the food demands of the earth
• Fertilisers


  Give plants the nutrients they need to grow
• Pesticides


  Prevent pests attacking the crop
• Nitrates


  Used to build protein, plants obtain nitrates from the soil and animals obtain nitrates by eating plants or other animals