At a glance
- Current guide
- First taught 2023, first assessed May 2025
- Paper 1
- 1A multiple choice + 1B data-based, 36%
- Paper 2
- Short and extended response, 44%
- Internal assessment
- Scientific investigation, 20%, 10 hours
- Teaching hours
- SL 150, HL 240
IB Biology assessment, SL and HL
| Component | SL | HL | Weighting |
|---|---|---|---|
| Paper 1A: multiple choice | 30 questions | 40 questions | 36% with Paper 1B |
| Paper 1B: data-based questions | 25 marks | 35 marks | 36% with Paper 1A |
| Paper 1 total time | 1 h 30 min (55 marks) | 2 h (75 marks) | |
| Paper 2: data-based, short answer, extended response | 1 h 30 min, 50 marks | 2 h 30 min, 80 marks | 44% |
| Scientific investigation (IA) | 10 hours, 24 marks | 10 hours, 24 marks | 20% |
Papers 1A and 1B are sat together in one sitting. At HL, Paper 2 Section B asks for two of three extended responses.
What changed in 2025, and why it matters
The old course had numbered topics and an option paper (Paper 3). The current guide drops the options and asks students to connect ideas across the four themes and levels of organisation: a question can start with enzyme structure and end with an ecosystem consequence. Most of the classic content is still there (cells, genetics, evolution, physiology, ecology), but it is arranged around concepts rather than chapters.
That shift matters for revision. Past papers from before 2025 are still useful for practice on individual ideas, but their structure and many of their questions do not match the current exams. A tutor will choose old questions selectively and lean on the specimen and post-2025 papers for full practice.
Where IB Biology marks are lost
- Paper 1B and Paper 2 data questions. Students describe a graph without quoting values, or explain a trend without linking it to the biology. Data handling is now a large share of the marks.
- Imprecise vocabulary. "The enzyme dies" instead of "the active site is denatured" costs marks at every level.
- Extended responses without structure. The markscheme rewards distinct, correct points; long paragraphs that repeat one idea score low.
- Command terms. "Outline", "explain" and "evaluate" ask for different depths of answer.
- A scientific investigation with an unmeasurable question. A narrow, quantitative research question with a clear independent variable is what makes the report work.
How one-to-one Biology lessons work
A tutor who teaches IB Biology follows the school's order of themes and uses each lesson for three things: making sure the concept is understood (often by drawing processes on the shared whiteboard), practising the matching data-based question, and building precise written answers that match markscheme language. HL students also get regular practice linking ideas across themes, which the new papers reward.
For the scientific investigation, the tutor helps the student turn an interest into a focused research question, plan a method with controlled variables, and understand how to process and evaluate data. The investigation itself must be the student's own work, as the IB requires.
When to start
The best time is DP1, before the investigation is due and while the foundational ideas of cells, molecules and genetics are being taught. Students starting in DP2 should begin at least one term before mocks.
Common questions
Is IB Biology HL much harder than SL?
HL adds 90 teaching hours of extra content and longer papers (Paper 2 is 2 hours 30 minutes against 1 hour 30 minutes). Many students find HL manageable if they keep up with content weekly; the volume is the main challenge.
Is there still a Paper 3 in IB Biology?
No. From May 2025, IB Biology has two papers and the scientific investigation. The options and Paper 3 were removed.
What is the scientific investigation?
An individual investigation of about 10 hours, written up as a report and marked by the teacher against four criteria (research design, data analysis, conclusion and evaluation), then moderated by the IB. It is worth 20% at both levels.
Are old past papers still useful?
For practising individual ideas, yes. For full exam practice, use specimen papers and papers from May 2025 onwards, which match the current format.
How much do IB Biology lessons cost?
$15 a lesson, the same flat rate for every subject and level, on a weekly plan billed monthly. Lessons are 60 minutes, one to one and online, and the first lesson is a free trial.
Sources
Dates and figures on this page come from these official and published sources. Always confirm deadlines on the official page before acting on them.