What the investigation does
A controlled experiment compares plant appearance, chlorophyll content and photosynthetic electron transport across three horticultural insecticides.
What the examiner response highlights
The design connects a concentration series and control directly to observable and spectrophotometric outcomes.
Using whole-plant observations, chlorophyll measurements and a DCPIP assay allows the findings to be compared across biological levels.
The discussion links experimental trends to photosystem II and considers their wider agricultural meaning.
What to examine critically
The evaluation identifies issues such as stray light and unmeasured pH but does not prioritize or quantify their likely effects.
A current version should explain why the different measures form one coherent argument rather than two loosely connected investigations.
How to use this example
Study the decisions behind the work: how the question is narrowed, what counts as evidence in this subject, how the line of argument develops, and where the evaluation becomes specific. Do not copy its wording, structure or method as a template.
Assessment changes for first examination in May 2027 redesign the criteria around the essay framework, knowledge and understanding, analysis and argument, discussion and evaluation, and reflection. Always check the requirements for your own session.
Read the evidence behind this breakdown
Open the available archived material, then return to the guide to compare the examiner's comments with the choices made in the essay.
Find the official source
The underlying essay belongs to an IB-published legacy collection. Access it through the IB Store or the Programme Resource Centre if your school provides access.
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