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C4.1 Species, Communities and Ecosystems
Definitions:
Key word Definition
Species a group of organisms that can interbreed and produce a fertile offspring
Population a group of organisms that of the same species that live in a particular area
Community a group of populations living and interacting together in a particular area
Ecosystem interaction between the community and its abiotic factors
Habitat environment in which a species is adapted to
Abiotic factors non-living factors (pH, temperature, type of soil)
Smallest to biggest: population --> community --> ecosystem
Autotrophs
● producers
● synthesise their own food/ organic compounds from other simple inorganic compounds.
● they gain organic nutrients from their abiotic environment
Phototrophs:
● produce organic compounds from inorganic by using light and chloroplasts (photosynthesis in plants)
Heterotrophs
● consumers
● obtain organic compounds through feeding on other organisms
Saprotrophs:
● decomposers
● obtain organic nutrients from dead organisms by external digestion
● they secrete digestive enzymes on dead organic matter and complex compounds are broken and
absorbed
, Detritivores:
● obtain organic nutrients from detritus (dead and particulate organic matter) by internal digestion
Communities
● Ecology: study of relationships between living organisms and their interactions with their environment
● organisms are highly dependent on their physical environment in their community
● communities are self-sustained because the essential nutrients are constantly recycled
● least to most inclusive: species --> population --> community --> ecosystem
Nutrient cycle:
● organisms depend on their environment to supply necessary nutrient for survival by recycling these
nutrients
1. plants absorb carbon dioxide and water from their abiotic environment to photosynthesise and make
carbohydrates
2. consumers eat plants and this transfers the nutrients from one organism to the other
3. when the organism dies and decomposes the nutrients are released back into the soil/abiotic
environment
4. the cycle continues
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