How to Design and Conduct a Scientific Investigation (Unit 1) (VCE SSCE Biology): Revision Notes

How to Design and Conduct a Scientific Investigation (Unit 1)

Overview of scientific investigations

As part of Unit 1 assessment, you will design and conduct your own scientific investigation related to cell function and/or regulation of biological systems. This investigation demonstrates your ability to plan experiments, generate data, and draw evidence-based conclusions.

A successful investigation requires:

• Generation of primary quantitative and/or qualitative data
• Thorough analysis and evaluation of collected data
• Identification of limitations in both data and methodology
• Discussion linking results to broader scientific concepts
• A clear conclusion addressing the research question

The three stages of investigation

The investigation process is divided into three interconnected stages:

Stage 1: Investigation design - Planning and preparing your experiment, including developing your research question, understanding relevant theory, and designing your methodology.

Stage 2: Scientific evidence - Conducting your experiment and collecting data using systematic approaches and maintaining proper documentation.

Stage 3: Scientific communication - Presenting your findings in a structured scientific report that clearly communicates your process, results, and conclusions.

Stage 1: Investigation design

Step 1: Developing a research question

Your research question forms the foundation of your entire investigation. It must relate to concepts from Unit 1, specifically the function and/or regulation of cells and systems.

Characteristics of good research questions:

• Testable - can be investigated through practical experimentation
• Achievable - realistic within available time, resources, and equipment
• Specific - clearly defined and focused on a particular aspect

Potential topic areas include:

• Homeostatic regulation mechanisms
• Apoptosis and cell death processes
• Cell cycle differences (prokaryotic versus eukaryotic)
• Semi-permeability of plasma membranes
• Structure and function of biological systems
• How cell size and shape contribute to function

Step 2: Understanding biological concepts

Before designing your experiment, you must clearly understand the biological theory underlying your research question. This serves two purposes:

For you: Clarifies what you're investigating and helps you design appropriate methods and analyse results effectively.

For your reader: Provides necessary background information to understand your investigation's significance and approach.

Your introduction should define key terms and explain the most important concepts. For instance, if investigating homeostasis, you would explain what homeostasis is, why it matters, how it normally functions, and what factors influence it.

Step 3: Selecting methodology and defining variables

Choosing your methodology

Select the most appropriate scientific approach for answering your research question. Options include:

• Controlled experiment
• Correlational study
• Fieldwork
• Modelling
• Process or system development
• Simulation

Defining your variables

Clear variable definition is essential for controlled experiments:

Independent variable (IV): The factor you deliberately change or manipulate. This is what you're testing.

Dependent variable (DV): The factor you measure or observe. This is what responds to changes in the independent variable.

Controlled variables: All other factors that must remain constant throughout the experiment to ensure fair testing.

Step 4: Stating your hypothesis

Hypothesis: A testable statement predicting how the independent variable will affect the dependent variable.

Your hypothesis should be based on your understanding of relevant biological theory and any background research you've conducted. After completing your experiment, your results will either support or refute this prediction.

A good hypothesis is:

• Specific and clear
• Testable through your methodology
• Based on scientific reasoning
• Written as a definite statement (not a question)

Step 5: Designing your experiment

Once you've selected your methodology, design the specific steps of your investigation. For controlled experiments, address these key components:

1. Measurement approach

• What will you measure and how?
• What instruments will you use?
• How long will the experiment run?
• What sample size will you use?

2. Experimental groups

• What different conditions will you test?
• How will you create these conditions?
• Will you include a control group?

3. Controlled variables

• What factors must remain constant?
• How will you ensure they don't vary?

4. Replication

• How many replicates will you have?
• Why is this number appropriate?

5. Error minimisation

• What potential errors might occur?
• How will you prevent or minimise them?

6. Sample selection

• How will you select your sample?
• Is your selection method appropriate and unbiased?

7. Safety and ethics

• What safety precautions are necessary?
• Are there ethical considerations?
• What personal protective equipment (PPE) is required?

Step 6: Considering internal measures

Before and after conducting your investigation, evaluate how well it satisfies important quality measures. Understanding these concepts helps you design better experiments and critically evaluate your results.

Accuracy: How close your results are to the true value of what you're measuring. For example, if the optimal photosynthesis temperature for a plant is known to be 35°C, accurate results would be close to this value.

Precision: How close your results are to each other across repeated measurements. High precision means replicate measurements give similar values, indicating a reliable method. Low precision shows wide variation between replicates.

Reproducibility: Whether other scientists could follow your method and obtain the same results. High reproducibility means your experiment is well-documented and your findings are reliable.

Repeatability: Whether you could personally repeat the experiment and get the same results. This indicates consistency in your experimental technique.

Validity: Whether your experiment actually measures what it claims to measure. A valid experiment directly addresses the research question without confounding factors.

Stage 2: Scientific evidence

Step 1: Establishing a logbook

A logbook is essential for recording all aspects of your investigation as it progresses. This reflects standard scientific practice and serves multiple purposes:

Documentation: Records all observations, measurements, and procedures as they occur.

Authentication: Provides evidence that you personally conducted the investigation.

Reflection: Allows you to track your thinking and decision-making process.

Assessment: Required for satisfactory completion of VCE Biology units.

Step 2: Collecting your data

Types of data

You must generate primary data - information you collect directly through your own investigation. This can be:

Quantitative data: Numerical measurements involving counts, units, and quantities. Examples include plant height in millimetres, temperature in degrees Celsius, or number of cells.

Qualitative data: Descriptive observations involving qualities and characteristics. Examples include colour changes, written descriptions of behaviour, or interview responses.

Recording data

Record all results in your logbook as you collect them, even if they seem unusual or unexpected. Also note:

• Any deviations from planned procedure
• Unusual observations
• Equipment malfunctions
• Environmental conditions
• Anything that might affect results

This complete record helps you later identify potential sources of error and evaluate the reliability of your findings.

Stage 3: Scientific communication

Report structure overview

Your final presentation should follow standard scientific report conventions. The structure includes:

Section	Content
Title	The question under investigation
Introduction	Explanation of why the investigation matters, relevant biological concepts, clear aim, and hypothesis
Method	Summary of methodology and steps, authenticated by logbook entries. Identification of health, safety, and ethical guidelines followed
Results	Presentation of data in appropriate formats showing trends, patterns, and relationships
Discussion	Analysis of primary data, linking to biological concepts, identification of outliers and their treatment, limitations and improvements
Conclusion	Response to the research question based on analysis, with no new information introduced
References	Acknowledgement of all quoted and sourced content

Title

Your title should clearly state what you investigated. It can be your research question or a rewording of it. Keep it concise and informative.

Abstract (optional)

An abstract provides a brief summary of your entire investigation, typically 150-250 words. It helps readers quickly understand your work. Check with your teacher whether an abstract is required.

Structure your abstract by writing one sentence summarising each main section:

• Why the investigation matters (introduction)
• What you did (method)
• What you found (results)
• What it means (discussion/conclusion)

Introduction

The introduction sets up your investigation by explaining its importance and providing necessary background information.

Components of a good introduction:

1. Explanation for undertaking the investigation

Begin by justifying why your research matters. Why should anyone care about your findings? Link to broader implications or real-world applications.

Connect to previous research where appropriate. This demonstrates that you understand your investigation's place within biology as a whole.

2. Background biological concepts

Explain the key biological theory relevant to your investigation. Define important terms and describe the processes or systems involved.

Think about what knowledge you used when designing your experiment and forming your hypothesis. Present this information clearly so readers can understand your reasoning.

3. Aim and hypothesis

After providing context and background, clearly state your investigation's aim and your hypothesis.

The aim explains what you set out to discover. The hypothesis predicts the relationship you expect to find between your variables.

Method

The method section is like a recipe - it should allow another person to replicate your investigation exactly.

Materials

List everything needed to conduct your experiment. Be specific about equipment specifications (e.g., "tape measure with millimetre markings" rather than just "tape measure").

Methodology

Write step-by-step instructions describing exactly what you did. This can be formatted as numbered steps or paragraphs - check your teacher's preference.

Include any safety precautions or ethical considerations you addressed. Mention how you controlled variables and ensured consistent procedures.

Results

The results section presents your findings without interpretation or explanation. Save analysis for the discussion section.

Transform your data

Don't present raw data - transform it to highlight patterns and trends relevant to your research question.

Choose appropriate formats:

• Line graphs - best for showing how one variable changes in response to another over time or across a range
• Bar graphs - best for comparing categories or groups
• Scatter plots - best for showing relationships between two variables
• Tables - useful for precise values and when showing multiple data types

Discussion

The discussion is typically the longest section, where you analyse and interpret your findings.

1. Analysis and evaluation of primary data

Begin by restating your hypothesis and indicating whether your results support or refute it. Then analyse why you obtained these results.

Analysis involves examining your data in relation to your research question. What patterns emerge? What do the numbers tell you? How do these findings address your original question?

Consider the type and quality of data you collected. Primary quantitative data from controlled experiments generally provides strong evidence for cause-and-effect relationships.

2. Linking results to biological concepts

Explain your findings using the biological theory you introduced earlier. This demonstrates your understanding of how your results relate to broader scientific concepts.

3. Identifying outliers

Note any unusual results and explain possible causes. Decide whether to include or exclude outliers from your analysis, and justify this decision clearly.

4. Evaluation - identifying limitations and suggesting improvements

Critically examine your investigation's strengths and weaknesses. Consider potential sources of error and their impact on results.

Types of errors:

Personal errors - Mistakes made by the experimenter, such as miscounting, incorrect rounding, or mislabelling samples.

Systematic errors - Affect accuracy. Results consistently differ from the true value by the same amount, usually due to faulty equipment or poor calibration.

Random errors - Affect precision. Caused by unpredictable variations in measurement, leading to inconsistent results across replicates.

Types of bias:

Confirmation bias - Tendency to include only information supporting your hypothesis while ignoring contradictory evidence.

Selection bias - Non-random participant selection producing a sample that doesn't represent the wider population.

Publication bias - When only studies with positive findings get published, whilst those with negative results remain unreported.

Conclusion

Many students worry about conclusions, but they follow a straightforward structure:

1. Restate the research question

Remind readers what you investigated.

2. State whether your hypothesis was supported or refuted

Clearly indicate what your data showed.

3. Suggest future research directions

Based on your findings and limitations, what should be investigated next? How could future studies improve upon your work?

4. Explain broader implications

How do your findings matter to the real world? Why should people care about your results?

References and acknowledgements

Referencing

Cite all sources used in your investigation. Only include sources you actually referenced in your work, not everything you read.

Referencing includes two components:

In-text citations - Brief references in your report's body, used immediately after mentioning information from a source. Mainly appear in introductions and discussions.

Reference list - Complete list of all cited sources at your report's end.

Acknowledgements (optional)

You may include a brief acknowledgements section thanking people who helped with your investigation. Keep it concise and professional.

Key concepts summary

Remember!