AQA A2 Biology
Learning Objectives
Introduction to Ecology
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Define species, population, habitat and community
Define ecological niche
Give examples of biotic and abiotic conditions
Spec link: Module 3.4.1 Populations and ecosystems
 A population is all the organisms of one species in a habitat. Populations of different species
form a community.
 Within a habitat a species occupies a niche governed by adaptation to both biotic and abiotic
conditions
Sheltered Rocky Shore Investigation
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Collect reliable quantitative ecological data
Use percentage cover and frequency as measures of abundance
Spec link: Module 3.4.1 Investigating populations
 The use of percentage cover and frequency as measures of abundance.
Spec link: Module 3.6.2 Implementing
 collection of reliable quantitative ecological data involving a specific abiotic factor,
frequency, population density and percentage cover.
Gastropod Microhabitat Investigation
Fieldwork
 Use random sampling (frame quadrats) to obtain quantitative data
 Explain why random sampling is used
 Construct an appropriate hypothesis
Follow up
 Construct a null hypothesis
 Calculate the chi squared test statistic
 Interpret the test statistic, at the 5% significance level
 Accept or reject the null hypothesis
Spec link: Module 3.4.1 Investigating populations
 Random sampling with quadrats and counting along transects to obtain quantitative data.
Spec link: Biological principles
 Random sampling results in the collection of data which is unbiased and suitable for
statistical analysis
Spec link: Investigative and practical skills
 Fieldwork involving the use of frame quadrats and line transects
Spec link: Module 3.6.3 Data analysis
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χ2 Chi Squared
construct an appropriate null hypothesis
calculate the test statistic given a standard scientific calculator
interpret the calculated test statistic in terms of the appropriate critical value at the 5%
significance level, making reference to chance, probability and acceptance or rejection of the
null hypothesis
Effect of Exposure Investigation
Fieldwork
 Identify the independent and dependent variables
 Identify other variables that may affect the data
 Random sampling along a line transect
 Explain why random sampling is used
Follow up
 Construct a null hypothesis
 Calculate the standard error
 Interpret the results in terms of 95% confidence limits
 Identify and assess limitations
Spec link: Module 3.6.1 Investigating biological problems
 identify the independent variable and describe an appropriate method of varying it in such
detail that a student starting an A2 course could carry out the suggested procedure without
further assistance.
 identify the dependent variable and describe how they would collect a full range of useful
quantitative data that could be analysed statistically, measured to an appropriate level of
accuracy and precision.
 identify other variables that might be expected to exert a significant influence on the results,
use knowledge from relevant parts of the A Level specification to explain why, and describe
how they would be kept constant or monitored.
Spec link: Investigative and practical skills
 fieldwork involving the use of line transects
Spec link: Biological principles
 Random sampling results in the collection of data which is unbiased and suitable for
statistical analysis
Spec link: Module 3.6.3 Data analysis
 standard error and 95% confidence limits
 construct an appropriate null hypothesis
 calculate the test statistic given a standard scientific calculator
 interpret the calculated test statistic in terms of the appropriate critical value at the 5%
significance level, making reference to chance, probability and acceptance or rejection of the
null hypothesis
Saltmarsh Investigation
Fieldwork
 Describe succession
 Explain how certain species change the environment
 Describe how changes in the abiotic environments affect the diversity
Follow up
 Identify limitations in equipment and methods
 Discuss the affects of the limitations on the reliability of the data
 Suggest realistic ways to reduce the effect of the limitations
Spec link: Module 3.4.7 Ecosystems are dynamic environments
 Succession from pioneer species to climax community
 At each stage in succession, certain species may be recognised which change the
environment so that it becomes more suitable for other species.
 The changes in the abiotic environment result in a less hostile environment and changing
diversity.
 Conservation of habitats frequently involves management of succession
Spec links: Module 3.6.4 Limitations are inherent in the material and apparatus used
 identify the limitations inherent in the apparatus and techniques used
 discuss and assess the relative effects of these limitations on the reliability and precision of
the data and on the conclusions that may be drawn, resolving conflicting evidence
 suggest realistic ways in which the effect of these limitations may be reduced
Quadrat Comparison
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Construct an appropriate hypothesis and a null hypothesis
Calculate the Spearman’s Rank test statistic
Interpret the test statistic, at 5% significant level
Accept or reject the null hypothesis
Spec links: Module 3.6.3 Data analysis
 Spearman rank correlation
 construct an appropriate null hypothesis
 calculate the test statistic given a standard scientific calculator
 interpret the calculated test statistic in terms of the appropriate critical value at the 5%
significance level, making reference to chance, probability and acceptance or rejection of the
null hypothesis
Energy Flow Investigation (Freshwater/Rocky Shore)
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Explain the main route through which energy enters an ecosystem
Explain what happens to energy as it is transferred through a food chain
Draw pyramids of number, biomass and energy
Explain the relationship of the pyramids to the corresponding food chains and webs
Spec links: Module 3.4.5 Energy transfer
 Photosynthesis is the main route by which energy enters an ecosystem
 Energy is transferred through the trophic levels in food chains and food webs and is
dissipated.
 Quantitative consideration of the efficiency of energy transfer between trophic levels.
 Pyramids of numbers, biomass and energy and their relationship to their corresponding food
chains and webs.
Mark-Release-Recapture Population Investigation
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Explain what causes variations in population size
Use the mark-release-recapture methods for mobile species
Spec link: Module 3.4.1 Variations in population size
 Population size may vary as a result of: the effect of abiotic factors and the interactions
between organisms: interspecific and intraspecific competition and predation.
Spec link: Module 3.4.1 Investigating populations
 The use of mark–release–recapture for more mobile species.
Conservation Study
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Conservation of habitats involves management of succession
Use knowledge and understanding to present scientific arguments and ideas relating
to species and habitat conservation
Evaluate issues related to conservation
Explain how conservation relies on science
Spec links: Module 3.4.7 Ecosystems are dynamic systems
 Conservation of habitats frequently involves management of succession
 use their knowledge and understanding to present scientific arguments and ideas relating to
the conservation of species and habitats
 evaluate evidence and data concerning issues relating to the conservation of species and
habitats and consider conflicting evidence
 explain how conservation relies on science to inform decision-making