AQA GCSE Science BIOLOGY 2 Unit B2.4 Organisms and their environment

• Know that living organisms form communities, and we need to understand the relationships within and between these communities.

• Know that these relationships are affected by external influences.

• You should be able to use your skills, knowledge and understanding to:

  • suggest reasons for the distribution of living organisms in a particular habitat,

  • evaluate methods used to collect environmental data, and consider the validity of the method and the reproducibility of the data as evidence for environmental change,

    • at the end of an investigation and analysis, can you distinguish whether differences in distributions of an organism are due to one or more environmental factors?

    • is it possible to control, or allow for, different environmental factors?

  • and you should understand:

    • the terms mean (average of all of a data set), median (middle value in a data set) and mode (the most common value in a data set - could be more than one value)

    • that sample size is related to both validity and reproducibility,

      • the larger the sample, random sampling from many locations and the more times the experiment is repeated, the more reliable will be the final analysis and conclusions,

      • reproducibility is the key to a successful valid investigation,

AQA GCSE Science BIOLOGY Unit B2.4.1 Distribution of organisms

• a) Know and understand the physical factors that may affect an organism in its habitat:

  • temperature,

  • availability of nutrients,

  • amount of light,

  • availability of water,

  • availability of oxygen and carbon dioxide.

    • Organisms will be adapted by evolution to fill a niche in a particular area of the environment,

    • but if there is a change in any of the factors above, then organism populations will be affected, some will increase and some will decrease,

    • in extreme cases, one species might die out in an area and another species may take advantage and move in.

• b) Know and understand that quantitative data on the distribution of organisms can be obtained by:

  • random sampling with quadrats

  • sampling along a transect.

• Your practical work to develop your skills and understanding may have included the following:

  • investigative fieldwork involving sampling techniques and the use of quadrats and transects; which might include, on a local scale, the:

    • patterns of grass growth under trees,

    • distribution of daisy and dandelion plants in a field,

    • distribution of lichens or moss on trees, walls and other surfaces,

    • distribution of the alga Pleurococcus on trees, walls and other surfaces,

    • leaf size in plants growing on or climbing against walls, including height and effect of aspect.

  • analysing the measurement of specific abiotic factors in relation to the distribution of organisms

  • the study of hay infusions

  • the use of sensors to measure environmental conditions in a fieldwork context.