IB Biology - Study Hub
A public revision hub for IB Biology (SL & HL) with a syllabus overview, exam structure, and the highest-priority topics to revise first — from molecules and cells to genetics, physiology, and ecology.
What is IB Biology?
IB Biology is a Group 4 experimental science that builds a connected understanding of life. The first-exams-2025 syllabus is organised into four themes — Unity and Diversity; Form and Function; Interaction and Interdependence; and Continuity and Change — taught around a shared set of concepts (structure and function, balance, transformation) and laboratory and data-analysis skills.
Assessment rewards precise biological language as much as recall: labelled diagrams, correct use of command terms, data interpretation, and well-structured extended responses. Aimnova covers Biology at Standard and Higher Level — HL extends each theme with extra depth — so you can understand the syllabus, prioritise revision, and move into the most repeated exam-style questions at your level.
Subject Group
Group 4 (Sciences)
Available on Aimnova
SL & HL
Teaching Hours
150 (SL) · 240 (HL)
Exam Papers
Paper 1 (A: MCQ · B: data) · Paper 2 · IA
IB Biology Assessment
Paper 1
36%1 h 30 (SL) · 2 h (HL)Two parts in one sitting: Section A is multiple-choice questions across the whole syllabus, and Section B is a set of data-based questions that assess your analysis of experimental data and graphs. No notes; no data booklet.
Paper 2
44%1 h 30 (SL) · 2 h 30 (HL)Short-answer and extended-response questions combining recall, explanation, data analysis, and diagram work across all four themes.
Internal Assessment
20%The Scientific Investigation: one individual investigation marked on research design, data analysis, conclusion, and evaluation. The same task and 20% weighting at SL and HL (about 10 hours of work at SL, 20 at HL), written up in a report of up to 3,000 words.
IB Biology Syllabus - All Themes and Topics
Unit 1: Unity and diversity
Unit 2: Form and function
Unit 3: Interaction and interdependence
Unit 4: Continuity and change
Unit 5: Experimental and data skills
Free IB Biology Study Resources
Start Studying
Jump into the live Biology study flow (SL & HL)
Exam Skills
Paper structures, command terms, and scoring strategy for Biology SL and HL
Flashcards
Spaced-repetition flashcards for definitions, processes, and command-term answers
Command Terms
Learn how IB wording (state, outline, explain, discuss) changes a high-scoring answer
Mock Exams
Full-length Biology mock papers under timed conditions
Frequently Asked Questions about IB Biology
What does IB Biology cover?
The first-exams-2025 syllabus is built from four themes: Unity and Diversity (molecules, cells, viruses, classification and evolution); Form and Function (how structure relates to function from molecules to whole organisms); Interaction and Interdependence (cell signalling, homeostasis, ecosystems and nutrient cycling); and Continuity and Change (DNA replication, inheritance, gene expression and natural selection). HL studies each theme in greater depth.
What is the difference between Biology SL and HL?
HL covers every SL theme plus additional higher-level content and extra depth, runs to 240 teaching hours versus 150, and sits longer Paper 1 and Paper 2 exams. Both levels do the same Scientific Investigation for the Internal Assessment (20%). The 2025 syllabus has no Paper 3 and no options.
How is IB Biology assessed?
Two external papers — Paper 1 (Section A multiple choice and Section B data analysis) counts 36%, and Paper 2 (short-answer and extended response) counts 44% — plus the Internal Assessment (20%), an individual Scientific Investigation. There is no data or formula booklet in Biology.
How should I revise IB Biology efficiently?
Learn the definitions and processes precisely, then practise drawing and labelling the key diagrams and reading data off graphs and tables. Answer to the command term — "outline", "explain", "discuss", and "evaluate" each demand a different depth — and use past-paper mark schemes to see exactly what examiners reward for each.
Start revising IB Biology with structure
Use the syllabus overview and live study path to focus on the cells, genetics, physiology, and ecology the exams test most — at SL and HL.
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