IB Biology HL Internal Assessment Example

The student frames a focused, biologically specific investigation with clearly defined variables, organism, unit, and time frame.

The student's rationale for the topic is well grounded in biological context, especially the link between radicle length, seed vigour, and caffeine as a potential allelochemical.

The design contains enough procedural detail for most of the method to be followed, and the student justifies several key decisions rather than merely listing them.

The procedure still contains meaningful ambiguities, including the mismatch between five groups and six concentrations, the undefined volume of “five drops,” and the imprecise temperature control.

The design does not fully address the problem of independence, since each treatment appears to rely on a single Petri dish and therefore risks pseudoreplication.

Some methodological choices are explained only partly, so the investigation is not yet reproduced with complete clarity.

The raw and processed data are communicated clearly through tables, graphs, and summary statistics, making the overall treatment pattern easy to follow.

The student shows appropriate awareness of variability by including standard deviations, coefficients of variation, and error bars.

The data processing is relevant to the research question and the main downward trend in radicle length is presented clearly.

The communication is not consistently precise, with unit inconsistencies and a numerical error in the discussion of the graph range.

The analysis treats seeds within a single dish as independent observations, which inflates the strength of the statistical inference and creates a serious pseudoreplication issue.

Uncertainty is considered, but important sources such as solution preparation and drop volume are not quantified, and some statistical interpretation goes beyond what the test actually supports.