Species and communities 4.1

Ecology is the study of the interconnections between living organisms and their environment. There is such a complex network of links in any location that ecologists have to break down and classify these relationships whether they be feeding, competition or reproduction. This topic is an introduction to these divisions.

Key concepts

Learn and test your biological vocabulary for 4.1 Species and communities using these flashcards 


These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - good revision for all students.

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Summary list for topic 4.1 Species and communities

  • Species are "groups of organisms that can potentially interbreed to produce fertile offspring".
  • Members of a species may be reproductively isolated in separate populations.
  • Species can be autotrophic or heterotrophic in nutrition (a few species are both).
  • Consumers are heterotrophs that feed on living organisms by ingestion.
  • Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
  • Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.
  • A community is "populations of different species living together and interacting with each other."
  • An ecosystem is "a community and its interactions with the abiotic environment."
  • Autotrophs obtain inorganic nutrients from the abiotic environment.
  • The supply of inorganic nutrients is maintained by nutrient cycling.
  • Ecosystems have the potential to be sustainable over long periods of time

Skills (can you ....)

  • Classify species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.
  • Set up sealed mesocosms to try to establish sustainability. (Practical 5)
    Mesocosms in sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones.
  • Test for association between two species using the chi-squared test with data obtained by quadrat sampling.
    For example An ecosystem chosen where varying factors affect the distribution of the chosen species. Random quadrat sampling should be used to measure the presence or absence of the chosen species.


These diagram summaries cover the main sections of topic 4.1 Species and communities
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Exam style questions


Extra exam question

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Test yourself

This is a self marking quiz containing questions covering the topic outlined above.
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Just for fun

Everyone needs a bit of fun while they revise. Try this Species and communities wordshoot revision game.
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