Collecting Data in Biology (DP IB Biology): Revision Note

Concluding in Biology

• The conclusion is a brief, focused summary of the findings of your investigation

• Your goal is to provide a clear and concise answer to your research question, based only on the evidence from your data analysis

• A strong conclusion relates your specific findings back to broader biological principles and compares them to established patterns or published data

Principles of concluding

Interpret processed data and analysis to draw and justify conclusions

• Your conclusion must be justified by your data

  • This is the most important rule

• Start your conclusion with a direct answer to your research question

• Use the trend you identified in your interpretation to make a definitive statement

• Include key processed data as evidence to support your statement, such as:

  • the final calculated value (e.g. the isotonic point of a tissue)

  • the optimal value from your graph (e.g. the optimal temperature for an enzyme)

  • key values that demonstrate the trend (e.g. the mean percentage change in mass at the lowest and highest concentrations)

• Never introduce new ideas or explanations in the conclusion

  • It should only be a summary of what you have already analysed

Relate the outcomes to the stated research question or hypothesis

• You must explicitly state whether your results support or refute your initial hypothesis

  • For example: "The data shows that the enzyme's activity peaked at pH 8 and decreased at higher and lower pH values, which supports the hypothesis."

• If your results do not support your hypothesis, that is perfectly fine and does not mean your experiment has "failed"

  • It is a valid scientific finding, and you should state it clearly

  • You can then suggest reasons for the discrepancy in your evaluation

Compare the outcomes to the accepted scientific context

• A high-level conclusion compares your experimental results to accepted literature values from the IB data booklet, textbooks, or other reliable sources

• This comparison allows you to comment on the accuracy of your outcome

• When making a comparison, you should:

  • State the expected pattern or published value

  • Cite your source (e.g. "Campbell Biology, 12th Edition")

  • If comparing to a specific value, you can quantify the difference by calculating the percentage error

Discuss the impact of uncertainties on the conclusions

• The spread of your data, represented by standard deviation and error bars, determines the confidence you have in your conclusion

  • If error bars are small and do not overlap between different conditions, you can be more confident that the difference you have observed is significant

  • For example:

    • The small standard deviations for all measurements, as shown by the error bars on the graph, indicate that the data is precise and the identified trends are reliable

    • The non-overlapping error bars between the pH 7 and pH 8 conditions suggest that the increase in enzyme activity is statistically significant

  • If error bars are large or overlap between different conditions, you can be less confident that the differences you observe are significant

  • The variation in the data means the apparent trend might be due to random error rather than a true effect

  • For example:

    • The large standard deviations shown by the error bars on the graph suggest that the data are less precise, and there may have been inconsistency between trials

    • The overlapping error bars between the pH 7 and pH 8 conditions indicate that the difference in enzyme activity may not be statistically significant, and additional repeats would help confirm whether the observed pattern is reliable

  • Note that these examples are for illustrative purposes and are not representative of the data presented above