Definitions (Edexcel GCSE Biology Combined Science): Revision Notes

Definitions

Term	Definition
Individual	Single organism
Population	All organisms of one species in a habitat
Community	All organisms of different species living in a habitat
Ecosystem	Community of organisms along with all the non-living conditions
Biomass	Store of energy
Producers	Green plants • they make food by photosynthesis
Primary Consumers	Usually eat plant material • they are herbivores (e.g., rabbits, caterpillars, cows, sheep)
Secondary Consumers	Usually eat animal material • they are carnivores (e.g., cats, dogs, lions)
Predators	Kill for food; they are either secondary or tertiary consumers
Prey	The animals that predators feed on
Scavengers	Feed on dead animals (e.g., crows, vultures, hyenas)
Decomposers	Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces
Species	Organisms that have similar characteristics
Trophic Level	Position of an organism in a food chain
Xerophytic	Plants adapted to dry conditions
Biomes	Divide the earth's surface into distinct regions
Parasitism	Parasites live on/in host species and only they benefit
Mutualism	Relationship where both organisms benefit
Interdependence	Organisms depend on each other for shelter/food to survive and reproduce
Biotic	Living factors
Abiotic	Non-living factors
Biodiversity	Variety of living organisms in an ecosystem, affected by human interactions
Non-indigenous Species	Species that don't naturally occur in an area
Indigenous Species	Occur naturally in an area
Reforestation	When land where a forest previously stood is replanted to form a new forest
Drought	When there isn't enough precipitation
Precipitation	Rain, snow, sleet that falls and condenses on the ground
Condensation	Change of state from vapour/gas to liquid
Transpiration	Evaporative loss of water vapour from stomata
Evaporative	Change in state from liquid into water vapour/gas
Respiration	Exothermic chemical reaction carried out by cells
Intra-specific Competition	When members of the same species compete for the same resources in an ecosystem
Conservation	Protecting animals and ecosystems