IB Biology EE Examples — Annotated Exemplars

Five anonymised case studies from Cerebrum-supervised Biology EEs — 2 grade A, 2 grade B, 1 grade C — annotated with what scored and what slipped.

Effect of light wavelength on Chlorella O₂ production

Grade A

RQ: How does the wavelength of LED illumination affect the O₂ evolution rate of Chlorella vulgaris suspensions at a fixed optical density and irradiance?

What scored

✓Criterion A: RQ is specific, measurable, and testable in 4,000 words.
✓Criterion B: Accurate distinction between absorption spectrum and action spectrum, correctly cited.
✓Criterion C: 12/12 — each data point interpreted, anomalies discussed against the absorption-spectrum prediction.
✓Criterion E: RPPF captured a genuine pivot (from algal density to wavelength) with reasoning.

Where marks were lost

!Presentation criterion would have scored 4/4 with a more consistent figure-caption format.

Allelopathy of Lantana camara on native seedlings

Grade A

RQ: To what extent do aqueous extracts of Lantana camara leaves inhibit germination and early growth of two native grassland species in Delhi NCR?

What scored

✓Control for osmotic potential (parallel run with PEG 6000) handled Criterion A mark brilliantly.
✓Strong link in discussion to invasion biology and native-species conservation (C and B marks).
✓RPPF showed genuine engagement with failed pilot runs.

Where marks were lost

!Referencing was inconsistent — lost 1 mark on Presentation.

Mean March temperature vs tree flowering date in Delhi NCR

Grade B

RQ: To what extent does mean March temperature (2000–2024) correlate with the first-flowering date of Delonix regia, Jacaranda mimosifolia, and Cassia fistula in Delhi NCR, using citizen-science and herbarium records?

What scored

✓Data source documentation was rigorous — methodology transparent.
✓Strong Criterion D (Presentation) — clear figures with standardised captions.

Where marks were lost

!Critical Thinking (C) capped at 8/12: too much description of data, not enough mechanism-level discussion (phenological cueing, thermal units).
!Could have salvaged an A with one additional paragraph linking results to expected ecological consequences.

Hardy-Weinberg deviation in PTC tasting across three cities

Grade B

RQ: Do observed PTC-tasting allele frequencies in samples of 60 consenting Indian expatriate students in London, Dubai, and Singapore deviate significantly from Hardy-Weinberg equilibrium?

What scored

✓Ethics framing was excellent — consent, anonymisation, and parent/teacher oversight documented.
✓Chi-squared analysis correctly applied and interpreted.

Where marks were lost

!RPPF (Criterion E) was mechanical — reads like a log rather than reflection. Capped E at 3/6.
!Sampling was not random within each city cohort, and the student did not interrogate this enough in the discussion (Criterion C).

Caffeine dose vs Daphnia heart rate

Grade C

RQ: To what extent does caffeine concentration affect the heart rate of Daphnia magna?

What scored

✓Data collection was adequate; statistics were simple but correct.

Where marks were lost

!RQ is too broad — essentially identical to a standard IA. EE needs more scope.
!Criterion B: discussion stayed at textbook level — no engagement with relevant research beyond three references.
!Criterion C: only descriptive interpretation of the trend; no critical evaluation.

EE Exemplars — FAQ

Can I see a full Biology EE example?▾

Full exemplars are distributed only through schools and IB subscription services (Clastify, some subject platforms). We do not republish student work without consent. The annotations on this page show the pattern of reasoning that separates an A from a B, which is more transferable than reading a single essay end-to-end.

What mark is grade A in Biology EE?▾

Grade A = 27–34 out of 34. Grade B = 21–26. Grade C = 14–20. Grade D = 7–13. Grade E = 0–6 (failing condition for the Diploma when combined with a TOK grade E).

Do examiners read the RPPF reflection?▾

Yes, and it is explicitly assessed as Criterion E (Engagement) — 6 marks out of 34. It is the single most underrated part of the EE; students often write it mechanically the night before submission and lose 3 easy marks.

Get Criterion-Referenced EE Feedback

We mark your EE draft against all 5 criteria within 72 hours with examiner-style annotations — the same format you see above.

Book EE Review

EE Exemplars — FAQ

Can I see a full Biology EE example?▾

What mark is grade A in Biology EE?▾

Grade A = 27–34 out of 34. Grade B = 21–26. Grade C = 14–20. Grade D = 7–13. Grade E = 0–6 (failing condition for the Diploma when combined with a TOK grade E).