Current syllabus · first assessment 2025

IB · Biology · SL

IB Biology SL Study Hub

Study the current IB Biology SL course through its four themes, official assessment model and live syllabus knowledge tree.

Question Bank Practice

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Subject overview

IB Biology SL at a glance

Explore the current first-assessment-2025 knowledge tree: four organising themes viewed across molecules, cells, organisms and ecosystems.

4
syllabus units
34
mapped topics
7
study tools

What you study in IB Biology SL

IB Biology SL explains living systems through four connected themes: unity and diversity, form and function, interaction and interdependence, and continuity and change.

The current course recommends 110 hours of syllabus content and a 40-hour experimental programme. Use the live syllabus map below to move from each theme into its official SL topics and learning objectives.

IB Biology SL syllabus

Explore the current first-assessment-2025 knowledge tree: four organising themes viewed across molecules, cells, organisms and ecosystems.

IB Biology SL exam skills

Build the knowledge, data, inquiry and scientific-communication skills assessed across the current IB Biology course.

  • Recall and apply preciselyUse biological terminology and concepts accurately, then apply them in unfamiliar contexts.
  • Read biological dataExtract patterns from graphs, tables, images and primary or secondary data before drawing a supported conclusion.
  • Design and evaluate investigationsIdentify variables, plan reproducible methods, process data, address uncertainty and evaluate limitations and improvements.
  • Build evidence-led responsesCombine biological knowledge with supplied evidence, explain mechanisms and sustain an extended response.
  • Use quantitative toolsSelect suitable mathematical and technological tools, show appropriate processing and interpret the biological meaning of results.
  • Communicate an investigationFrame a focused research question and present a coherent, ethical and evidence-based scientific report.

SourceOfficial course publication

Know the exam

IB Biology SL assessment format

The current course has three hours of external assessment worth 80% and one internal assessment (IA) worth 20%. Paper 1A and Paper 1B are separate booklets completed together in one shared 90-minute sitting.

Paper / componentQuestionsTime% of grade
Paper 1A30 multiple-choice questions30 marksMultiple-choice questions on SL syllabus content.Shared 1 hour 30 minutes with Paper 1B36% combined with Paper 1B
Paper 1B4 data-based questions25 marksCompulsory data-based questions addressing all four organising themes.Shared 1 hour 30 minutes with Paper 1A36% combined with Paper 1A
Paper 2Answer all of Section A · answer 1 question in Section B in the May 2025 structure50 marksData-based and short-answer questions followed by extended-response questions.1 hour 30 minutes44%
Internal assessment (IA)1 scientific investigation24 marksA scientific investigation: an individual open-ended investigation using data to answer the student's own research question, reported in no more than 3,000 words.10 recommended course hours20%

SourceOfficial assessment publication

Historical performance

IB Biology SL May 2025 results baseline

May 2025 was the first assessment of the current Biology course. This official global distribution is a baseline, not yet a multi-year trend; N means no grade was awarded.

May 2025 mean grade
4.2
mean score
Grade 7
5.7%
of candidates
Grade 6
13.8%
of candidates
Grade 5
20.7%
of candidates
Grade 4
26.2%
of candidates
Grade 3
21.7%
of candidates
Grade 2
8.7%
of candidates
Grade 1
0.8%
of candidates
SessionCandidatesMean7654321N
May 202521,9214.25.7%13.8%20.7%26.2%21.7%8.7%0.8%2.4%

SourceOfficial results publication

IB Biology SL questions

This Hub follows the current IB Biology course first assessed in 2025. The live syllabus map is filtered to SL content.

Paper 1A and Paper 1B are separate booklets completed in one shared 90-minute sitting and contribute 36% together. Paper 2 contributes 44%, and the internal assessment (IA)—a scientific investigation—contributes 20%.

The course connects four organising themes across molecules, cells, organisms and ecosystems, with 110 recommended content hours and a 40-hour experimental programme.

IB sets boundaries for each examination session. A complete official public Biology SL boundary table for the current course was not available, so EduNinja does not publish estimated ranges as official.