An ecosystem refers to any system of living (biotic) organisms that functions with non-living (abiotic) chemical or physical factors in the environment. Essentially, biotic organisms are continually engaged in a relationship with other biotic and ab
- An ecosystem refers to any system of living (biotic) organisms that functions with non-living (abiotic) chemical or physical factors in the environment. Essentially, biotic organisms are continually engaged in a relationship with other biotic and abiotic components. Ecosystems recycle matter (both macro and micronutrients) through a variety of pathways and processes (biogeochemical cycles) that involve both biotic and abiotic components. Humans can influence these cycles, especially in agriculture, by using fertilisers. Induced cycles also occur for pollutants. Ecosystems are highly sensitive to change; altering biogeochemical cycles or introducing new elements can have dramatic effects on both the biotic and abiotic organisms present
- In Part A: you will propose an experiment to investigate the movement of one biogeochemical or pollutant in a model ecosystem.
- In Part B: you will implement and write up a practical investigation into the movement of a biogeochemical or pollutant in a model ecosystem.
- In small groups (3-4), you will propose an investigation into one of the following questions:
- How do biogeochemicals cycle through an ecosystem?
- How does pollution affect an ecosystem?
- How well do soils retain fertilisers?
- To do this you will devise a hypothesis and propose conditions for testing. A full method is not required for this stage; however, the proposal should briefly (dot points and no more than 1 A4 page in total) cover the following:
- The hypothesis to be tested.
- Biogeochemical processes relevant to the experiment.
- Justification of the significance of the investigation.
- Relevant variables (dependent, independent, controls) identified and used to clearly outline conditions for testing.
- Ethical and safety considerations.
- Apparatus to be requested from the laboratory technician. This proposal must be submitted prior to conducting the experiment.
- In small groups (3-4), you will design and conduct an experiment to test the hypothesis proposed in Part A.
- Individually you will complete a full scientific report on the experiment. The report is to have a fully researched and referenced introduction that includes cited diagrams and pictures; this may draw heavily on the background information presented in your proposal. The introduction should also include a falsifiable hypothesis for testing from
- Conduct background research.
- Choose one variable or factor that may affect your chosen investigation and manipulate this factor in your experiment this will be the experimental variable.
- Design your experiment and ensure that you have a control.
- Plan your experiment so that you reduce the effects of all identified extraneous variables.
- Obtain necessary apparatus, chemicals, substrates, and specimens and construct model ecosystems.
- Conduct the experiment, collecting quantitative data; it is recommended to use a datalogger or other apparatus to achieve precise and accurate measurements.
- Analyse your data.
- Communicate your findings as a practical report (2000 words) (see How to write a practical report and Improving your lab report in the Term 3 class GoogleDrive).
- Include a bibliography that contains all resources directly referenced in the essay and other resources used in your research. You must correctly format your bibliography in Harvard Format. Information on how this is done can be found at Writing a Bibliography and at UNSW Harvard Referencing. For more guidance on writing a practical report .
- The assignment focuses on investigating ecosystem functions through biogeochemical cycles or pollutant movement. It is divided into two parts:
- Part A Proposal
- Formulate a hypothesis.
- Identify relevant biogeochemical processes.
- Provide justification of the study’s significance.
- Define variables (independent, dependent, control).
- Mention ethical and safety considerations.
- List the apparatus required.
- Submit the proposal before conducting the experiment.
- Part B Experiment & Report
- Use the Part A hypothesis to design and conduct an experiment.
- Carry out background research with citations.
- Manipulate one experimental variable while maintaining controls.
- Collect quantitative data using accurate tools (e.g., dataloggers).
- Analyse data, present findings, and compile a structured scientific report.
- Include an introduction, methodology, results, discussion, and conclusion.
- Provide a Harvard-formatted bibliography.
- Understanding the Task
The mentor began by breaking down the requirements into manageable steps, ensuring students understood the difference between Part A (proposal) and Part B (practical report). - Formulating the Hypothesis (Part A)
Students were guided to pick one research question (e.g., How well do soils retain fertilisers?) and frame a falsifiable hypothesis. The mentor explained how to link the hypothesis with biogeochemical processes like nitrogen or phosphorus cycling. - Identifying Variables & Safety
The mentor stressed the importance of distinguishing between independent, dependent, and controlled variables. Ethical and safety considerations (e.g., chemical handling, disposal of pollutants) were highlighted to ensure compliance with lab standards. - Planning the Apparatus & Proposal Submission
Students listed apparatus needed (soil trays, fertilisers, sensors, beakers, dataloggers). The mentor checked feasibility and ensured alignment with learning outcomes. - Conducting the Experiment (Part B)
The mentor guided students to build a model ecosystem, manipulate one factor (e.g., fertiliser type), and collect quantitative data. Students were encouraged to minimize extraneous variables by maintaining consistent light, temperature, and water conditions. - Writing the Report
Each student was mentored to:- Write a strong introduction with research and diagrams.
- Present methods clearly, ensuring replicability.
- Analyse results using graphs and tables.
- Critically discuss findings, linking back to hypothesis and theory.
- Conclude with significance and limitations of the study.
- Compile a properly formatted Harvard-style bibliography.
- Students learned how ecosystems recycle nutrients and how pollutants alter natural processes.
- They developed skills in hypothesis formulation, experimental design, and variable control.
- They applied critical thinking and analytical skills to evaluate results.
- They gained experience in academic writing, referencing, and presenting scientific arguments.
