Topic 7 - Ecology

• Water cycle


  The cycle through which water moves between living organisms and the environment, involving evaporation, transpiration, condensation and precipitation.
• Trophic level


  The position of an organism in a food chain.
• Transect


  A line along an area used in sampling to determine the abundance and distribution of organisms in an ecosystem.
• Tertiary consumers


  Carnivores that consume other carnivores at trophic levels 4 and above of a food chain.
• Sustainable fisheries


  Methods of harvesting fish at a sustainable rate and increasing fish stocks, for example, by controlling net size or introducing fishing quotas.
• Sustainable


  The ability to maintain something for future generations.
• Secondary consumers


  Carnivores that consume herbivores at trophic level 3 of a food chain.
• Quadrat


  A square grid of known area used in sampling to determine the abundance and distribution of organisms in an ecosystem.
• Pyramid of biomass


  A table of the dry mass of living material at each trophic level of a food chain. This forms the shape of a pyramid.
• Producers

  Photosynthetic organisms (e.g. green plant or alga) at the start of the food chain that provide biomass for all living things.
• Primary consumers


  Herbivores that consume producers at trophic level 2 of a food chain.
• Prey


  Animals that are eaten by predators.
• Predators


  Consumers that prey on and eat other animals.
• Population


  All organisms of the same species living with one another in a habitat.
• Pollution


  Contamination or destruction of the natural environment due to human intervention.
• Peatlands


  Areas of peat soil in wetland habitats formed by the accumulation of partially decayed organic matter. Peat is commonly used as a garden compost.
• Mycoprotein


  A food high in protein (suitable for vegetarians) that is produced by the microorganism, Fusarium, in fermentation vats.
• Mode


  The number that occurs most commonly in a set of data values.
• Microorganisms


  Very small organisms involved in the recycling of materials in an ecosystem. They return mineral ions to the soil and convert carbon to carbon dioxide which is released into the atmosphere.
• Median


  The middle number in a list of values ordered from lowest to highest.
• Mean


  The average of a set of numbers calculated by dividing the sum of the values by the number of values.
• Interdependence


  The dependence of different organisms on each other for survival e.g. plants depend on pollinators, herbivores depend on plants.
• GM crops


  Crops that have had their genomes modified by the insertion of a desired gene from another organism.
• Global warming

  The gradual rise in the average temperature of the Earth due to increasing atmospheric levels of carbon dioxide and methane gas.
• Food security


  Ensuring that populations have access to adequate amounts of safe and nutritious food.
• Food chain


  Describes the feeding relationships between organisms and the resultant stages of biomass transfer. It takes the form: producer ⟶ primary consumer ⟶ secondary consumer ⟶ tertiary consumer
• Extremophiles


  Organisms that can live in extreme environments e.g. high temperatures, high salinity.
• The efficiency of biomass transfer between trophic levels is calculated using: efficiency = (biomass available after transfer / biomass available before transfer) x 100
• Ecosystem


  The community of organisms (biotic) and non-living (abiotic) components of an area and their interactions.
• Distribution


  The spread of living organisms in an ecosystem. It is affected by environmental changes which may be seasonal, geographic or man-made.
• Deforestation


  The removal of trees from land which is subsequently used to grow crops or provide space for cattle.
• Decomposition


  The breakdown of dead materials into simpler organic matter. The rate of decomposition is affected by temperature, water and oxygen availability.
• Decomposers


  Organisms that release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter.
• Compost


  Dead and decaying organic matter, commonly used as a fertiliser.
• Competition


  When different organisms compete for the same resources (e.g. light, water, mates, territory) in an ecosystem. This limits population sizes and stimulates evolutionary change.
• Community


  All of the populations of different species living together in a habitat.
• Carbon cycle


  The cycle through which carbon (in the form of carbon dioxide) moves between living organisms and the environment, involving respiration, photosynthesis and combustion.
• Biotic factors


  The living components of an ecosystem e.g. food availability, pathogens, predators and other species.
• Biogas


  A type of biofuel (methane gas) produced by anaerobic decay in biogas generators.
• Biodiversity


  The variety of living organisms in an ecosystem.