IB Biology Internal Assessment Exemplar
How does the concentration of immobilised lactase pills in sodium alginate beads affect the hydrolysis of lactase as measured by the concentration of glucose produced?
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Criteria A: Research Design
5/6
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3
6
Criteria Strands
Situates the research question within a specific, well-defined context of lactose intolerance and enzymology.
Explains key methodological considerations (variable selection, equipment limits, pilot trials) in terms of their impact on data validity.
Provides a detailed step-by-step procedure (volumes, timings, diagrams) that allows reproduction with only minor ambiguities.
Minor narrative digressions in the background reduce focus.
Bead diameter consistency and timing of photographic readings are not fully specified.
The protocol omits a bead-washing step to remove residual CaCl₂, which could affect pH control.
Criteria B: Data Analysis
4/6
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3
6
Criteria Strands
Raw and processed data are clearly communicated via photographs, tables, and a labeled scatter plot with error bars.
Statistical processing (means, standard deviations, Pearson and Spearman correlations) is carried out accurately with worked examples.
Axis titles include units and error bars illustrate variability effectively.
Uncertainties from glucose-strip calibration and reading error are omitted, underestimating total uncertainty.
Axis label formatting and decimal/comma usage lack polish.
Reliance on subjective colour assessment without numeric calibration reduces data precision.
Criteria C: Conclusion
4/6
0
3
6
Criteria Strands
Conclusion directly addresses the research question, linking LP concentration to glucose yield based on statistical results.
Fully consistent with the analysis and acknowledges anomalies (e.g., theoretical glucose limit).
Includes relevant comparison to accepted enzyme kinetics and some literature dosage information.
Over-interpretation of semi-quantitative strip values introduces slight overreach.
Comparison to scientific context is brief and could be deepened with additional published data.
Discussion of glucose-strip malfunction is valuable but not prominently integrated into the conclusion.
Criteria D: Evaluation
4/6
0
3
6
Criteria Strands
Explains specific methodological impacts (subjective strip reading, balance uncertainty, residual CaCl₂) on data validity.
Offers realistic, relevant improvements tied directly to identified limitations (glucometer use, precision balance, bead rinsing).
Evaluation explanations link each weakness to its relative impact on the investigation’s reliability.
Some suggested improvements (e.g., larger milk volume) are presented generically, without detailed connection to specific issues.
Does not quantify the potential pH change due to residual CaCl₂ to substantiate the impact on results.
Limited evaluation of sample size effects on statistical power.