IB
IB Diploma Biology SL
IB Diploma Biology SL is sat as two written papers of 1 hour 30 minutes each and an internal assessment worth 20%. Here are all 16 topics, with free revision notes, exam questions with mark schemes, flashcards and mind maps.
What do you want to do?
Topics
All papers
Any topic can come up on any paper · Paper 1: 1 hour 30 minutes · Paper 2: 1 hour 30 minutes · Internal assessment: About 10 hours, written up in at most 3,000 words- A1Molecules (Unity and diversity)Water · Nucleic acids2 subtopics
- A2Cells (Unity and diversity)Cell structure1 subtopic
- A3Organisms (Unity and diversity)Diversity of organisms1 subtopic
- A4Ecosystems (Unity and diversity)Evolution and speciation · Conservation of biodiversity2 subtopics
- B1Molecules (Form and function)Carbohydrates and lipids · Proteins2 subtopics
- B2Cells (Form and function)Membranes and membrane transport · Organelles and compartmentalization · Cell specialization3 subtopics
- B3Organisms (Form and function)Gas exchange · Transport2 subtopics
- B4Ecosystems (Form and function)Adaptation to environment · Ecological niches2 subtopics
- C1Molecules (Interaction and interdependence)Enzymes and metabolism · Cell respiration · Photosynthesis3 subtopics
- C2Cells (Interaction and interdependence)Neural signalling1 subtopic
- C3Organisms (Interaction and interdependence)Integration of body systems · Defence against disease2 subtopics
- C4Ecosystems (Interaction and interdependence)Populations and communities · Transfers of energy and matter2 subtopics
- D1Molecules (Continuity and change)DNA replication · Protein synthesis · Mutation and gene editing3 subtopics
- D2Cells (Continuity and change)Cell and nuclear division · Water potential2 subtopics
- D3Organisms (Continuity and change)Reproduction · Inheritance · Homeostasis3 subtopics
- D4Ecosystems (Continuity and change)Natural selection · Stability and change · Climate change3 subtopics
About IB Diploma Biology SL
IB Diploma Biology (first assessment 2025) has four themes (Unity and diversity, Form and function, Interaction and interdependence, Continuity and change), each studied at four levels: molecules, cells, organisms and ecosystems. That gives the 16 topics A1 to D4. This course shows the Standard Level content only: the additional higher level content is left out, so everything here is on your papers. Both papers can test any theme. Paper 1 has multiple-choice questions (1A) and data-based questions (1B). Paper 2 has data-based and short-answer questions (2A) and extended-response questions (2B). The internal assessment is a scientific investigation of your own.
Paper 1
- Time
- 1 hour 30 minutes
- Marks
- 36% of the grade: 55 marks
- Topics
- Paper 1A: 30 multiple-choice questions, with no marks taken off for wrong answers. Paper 1B: four data-based questions on experimental work and the syllabus. Any theme can come up.
Paper 2
- Time
- 1 hour 30 minutes
- Marks
- 44% of the grade: 50 marks
- Topics
- Section A: a data-based question and short-answer questions. Section B: one extended-response question from a choice of two. Any theme can come up.
Internal assessment
- Time
- About 10 hours, written up in at most 3,000 words
- Marks
- 20% of the grade: 24 marks
- Topics
- A scientific investigation of your own research question, marked by your teacher and moderated by the IB