Exam technique · Biology · 4 min read
IB Biology exams now: Paper 1A, 1B and 2 explained (2025 syllabus)
On this page
IB Biology changed completely for exams from May 2025. If you're using old past papers, notes from an older sibling, or a revision site that hasn't updated, you may be preparing for an exam that no longer exists. Here's what it looks like now, and how I'd prepare for each part.
The big changes
- No more Paper 3 and no more options. It's two papers plus the internal assessment.
- New structure. The course is organised into four themes: A Unity and diversity, B Form and function, C Interaction and interdependence, D Continuity and change. Sub-topics have codes like A1.1 (Water) or D4.3 (Climate change), not the old 1.1–11.5 numbering.
- Paper 1 now has two parts. 1A is multiple choice. 1B is data-based questions on experimental work.
- New IA. The "scientific investigation" is a report of up to 3,000 words, assessed on four criteria.
The papers
| Item | SL | HL |
|---|---|---|
| Paper 1 (1A + 1B, one sitting) | 1 h 30 min · 55 marks · 36% | 2 h · 75 marks · 36% |
| Paper 1A | Multiple choice (30 questions, 30 marks) | Multiple choice (40 questions, 40 marks) |
| Paper 1B | Data-based questions on experimental work (25 marks) | Data-based questions on experimental work (35 marks) |
| Paper 2 | 1 h 30 min · 50 marks · 44% | 2 h 30 min · 80 marks · 44% |
| Section A: data-based and short-answer. Section B: extended response, answer 1 of 2 | Section A: data-based and short-answer. Section B: extended response, answer 2 of 3 | |
| Internal assessment | 20% | 20% |
All of these figures are from the assessment section of the IB Biology guide (first assessment 2025). Calculators are allowed in both papers. There is no Biology data booklet for the 2026 and 2027 exams, whatever some revision sites say. A data booklet only arrives with the updated guide for first exams in May 2028, which keeps the same papers, marks and IA.
How I'd prepare for each part
Paper 1A: multiple choice
Multiple choice tests breadth across the whole syllabus, which is exactly where gaps hide. My rules for students:
- Read the stem first and try to answer before looking at the options.
- Eliminate the options that can't be right.
- Explain why. After every practice question, say in one sentence why the answer is right. "Sounds logical" isn't a reason, and it's the habit that makes students get the same question wrong twice.
Old Paper 1 MCQs from before 2025 are still useful practice for individual facts. Just skip questions on topics that were cut.
Paper 1B: data from experiments
This is the part students underestimate. You get data from an experiment you've probably never seen and need to read, describe and explain it. What helps:
- Practise describing trends with numbers from the graph, not just "it increases".
- Know the language of experimental design cold: independent, dependent and controlled variables, repeats, uncertainty, error bars, and what a correlation does and doesn't show.
- Do your own practicals properly. 1B is built around the kind of thinking a good IA needs.
The old Paper 3 Section A (data and practical questions) is the closest older practice material. I go through how to read and answer 1B questions in the Biology Paper 1B guide.
Paper 2: data, short answers and long answers
Section A rewards precise, short answers to the command term. Section B rewards structure. For the long answers I use a 9-step scaffold: define, where, what, how, when, why, example, diagram, limitations. That's explained in how to answer IB Biology Paper 2. Know your command terms (full list with traps) and be able to draw the key diagrams from memory.
What will come up?
Nobody outside the IB knows which questions will be on your paper, and you should be suspicious of anyone who claims to. What is reliable:
- Every sub-topic in your guide is fair game, and questions can combine themes. A question can start in B2.1 (membranes) and finish in C1.1 (enzymes).
- Unfamiliar contexts are guaranteed. Expect organisms, experiments and data you haven't studied. The question is testing whether you can apply the biology you know.
- Data handling appears in both papers. Don't treat it as a side skill.
Using older past papers safely
| Old material | Still useful? |
|---|---|
| Old Paper 1 (MCQ) | Yes, for topics still on the syllabus |
| Old Paper 2 | Yes for content and long-answer practice. Check that the topic still exists |
| Old Paper 3 Section A | Yes, closest thing to Paper 1B |
| Old Paper 3 options | Mostly no. Options were removed, though some content moved into the core |
The internal assessment
The scientific investigation is worth 20% at SL and HL. It's a report of up to 3,000 words. The IB states that half of the marks go to the conclusion and the evaluation, so your analysis and your evaluation matter as much as the experiment itself. You can collaborate in groups of up to three, but each student needs their own research question and data and writes their own report. Start with the research question guide, and if you're doing fieldwork, read the ecology IA guide.
Practice
Heptavo is built on the current Biology syllabus, every sub-topic from A1.1 to D4.3 at SL and HL. It has multiple-choice and data questions with mark schemes, so you can practise both papers' question styles daily.
Sources
- IB: Biology and Chemistry curriculum updates (shared science structure and IA, first assessment 2025).
- IB Biology guide, first assessment 2025 (papers, marks, weightings, calculators, IA), and the updated guide for first assessment 2028 (data booklet).