IB Biology vocab: master terms for exam success
13 min readOliver Kidd (Co-founder)10 Jun 2026
IB Biology vocab is the set of precise scientific terms and command words that underpin every mark you earn in the IB Diploma Programme Biology course. Without exact terminology, even a well-understood concept can score poorly. The IB Biology curriculum organises content around four broad themes and multiple levels of biological organisation, which means your vocabulary study should follow the same structure. Platforms such as Quizlet and syllabus-aligned glossaries like those from Tutopiya offer ready-made biology vocab lists, but knowing how to use terms matters as much as knowing what they mean.
1. How IB Biology vocab is organised by syllabus themes
The IB Biology curriculum is built around four broad organising themes: Unity and Diversity, Form and Function, Interaction and Interdependence, and Continuity and Change. Every term you learn sits within at least one of these themes, and many terms connect across several. This structure is not just administrative. It reflects how biological knowledge actually works, with concepts linking across scales and contexts.
Alongside the four themes, the syllabus addresses multiple levels of biological organisation:
- Molecular (DNA, enzymes, ATP)
- Cellular (mitosis, membrane transport, cell signalling)
- Organismal (physiology, homeostasis, nervous system)
- Ecosystem (nutrient cycles, trophic levels, biodiversity)
Learning vocab by theme rather than in isolation builds the cross-linking that examiners reward. A student who understands “natural selection” only as a definition will struggle to apply it across ecology, genetics, and evolution questions. A student who has connected it across themes will not.
| Theme | Example vocabulary |
|---|---|
| Unity and Diversity | Homologous structures, phylogeny, cladistics |
| Form and Function | Enzyme active site, alveoli surface area, nephron |
| Interaction and Interdependence | Symbiosis, trophic cascade, hormone receptor |
| Continuity and Change | Meiosis, mutation, natural selection |
2. What are IB Biology command terms and why do they matter?
Command terms dictate the style and depth of every answer you write. Using the wrong vocabulary for the wrong command term loses marks even when your science is correct. The ten most tested command terms in IB Biology are:
- Define — state the precise meaning of a term, no examples needed
- Describe — state what happens or what something looks like, without explaining why
- Explain — give reasons or mechanisms; causes and effects are required
- Compare — state similarities and differences between two or more items
- Evaluate — weigh evidence and reach a reasoned judgement
- Discuss — present multiple perspectives or arguments with supporting evidence
- Outline — give a brief account covering the main points only
- Deduce — draw a conclusion from given information or data
- Draw — produce a labelled diagram to a biological standard
- Annotate — add brief notes or labels to a diagram or graph
High-scoring answers require pairing vocabulary with reasoning forms that match the command term. Writing a mechanism in response to “Describe” or giving only a definition in response to “Explain” are both mark-losing errors. The command term tells you the grammar of your answer; the vocabulary fills in the biology.
Pro Tip: Before you write any exam answer, underline the command term and ask yourself: does my response match its specific demand? This single habit can recover several marks per paper.
3. Essential IB Biology terminology across major topics
Precise IB syllabus terminology is what examiners scan for. Vague or everyday language costs marks, even when the underlying understanding is sound. The word “respiration,” for example, means the release of energy from glucose in IB Biology. Using it to mean “breathing” is a mark-losing error that appears more often than you might expect.
Below are high-priority terms across four core topic areas:
Molecules and cells
- Phospholipid bilayer, amphipathic, hydrophobic, active transport, facilitated diffusion, ATP synthase
Genetics and genomics
- Allele, locus, codominance, epigenetics, transcription factor, gene expression
Ecology and evolution
- Carrying capacity, niche, trophic level, allopatric speciation, genetic drift, founder effect
Physiology
- Negative feedback, osmoregulation, action potential, synaptic transmission, glomerular filtration
| Topic area | Common vague term | Precise IB term |
|---|---|---|
| Cell biology | “Cell wall breaks down” | “Plasma membrane becomes permeable” |
| Genetics | “Genes are passed on” | “Alleles are inherited via gametes” |
| Ecology | “Animals eat each other” | “Energy is transferred between trophic levels” |
| Physiology | “The body controls temperature” | “Negative feedback regulates core body temperature” |
Syllabus-aligned glossary resources organised by topic for both HL and SL are available and worth bookmarking as a regular reference.
4. How to learn and retain IB Biology terms effectively
Isolated memorisation of definitions is the least effective approach to vocabulary retention. Terms stick when you encounter them repeatedly in context, apply them in answers, and connect them to related concepts across themes.
These methods work:
- Spaced repetition flashcards — Quizlet sets organised by biology sub-topic use active recall and spaced repetition, which research in cognitive science consistently identifies as superior to passive re-reading
- Personal vocabulary bank — create a document tagging each term with its theme, level of organisation, and one exam-style sentence; this supports cross-topic revision and contextual recall
- Term substitution practice — take a mark-scheme answer and replace vague terms with precise syllabus equivalents; check that grammar and reasoning still hold
- Exam-style writing — practise writing short answers using command terms and target vocabulary together, not separately
Pro Tip: Build your vocabulary bank as you study each topic, not at the end of the course. Retrospective cramming of definitions rarely transfers to exam performance under timed conditions.
For a broader view of exam preparation strategies that integrate vocabulary work with past paper practice, Tibertutor’s blog is a useful starting point.
5. Comparing IB Biology vocab resources: which suits you best?
Not all biology definitions resources are equally useful for IB students. The key question is whether a resource aligns with the IB syllabus structure, uses exam-style language, and organises terms in a way that matches how questions are asked.
| Resource type | Strengths | Limitations |
|---|---|---|
| Quizlet flashcard sets | Active recall, spaced repetition, mobile-friendly | Quality varies; not all sets are syllabus-aligned |
| Tutopiya DP Biology glossary | Syllabus-aligned, HL and SL separated, exam-style definitions | Less interactive than flashcard tools |
| Study guide websites | Broad coverage, often free | May use non-IB terminology or lack command term context |
| Tibertutor resources | Examiner-built, syllabus-monitored, integrated with analytics | Subscription required for full access |
The strongest approach combines two resource types: a structured, syllabus-aligned glossary for accurate definitions, and an active recall tool such as Quizlet for retention. A guide to IB science resources can help you evaluate which tools fit your study style and timeline.
Comprehensiveness matters less than exam alignment. A resource with 500 loosely defined terms is less useful than one with 150 terms written in the precise language that mark schemes reward.
Key takeaways
Mastering IB Biology vocab requires learning terms within their syllabus themes, pairing them with the correct command term response style, and practising their use in exam-style writing rather than memorising definitions in isolation.
| Point | Details |
|---|---|
| Theme-based learning | Organise vocabulary by the four IB themes to build cross-topic connections and contextual recall. |
| Command terms are non-negotiable | Each command term demands a specific response style; mismatching vocabulary and command terms loses marks. |
| Precision over paraphrase | Examiners scan for exact syllabus terms; vague everyday language costs marks even when the science is correct. |
| Active recall beats passive reading | Spaced repetition tools like Quizlet and term substitution exercises outperform re-reading definitions. |
| Build a personal vocab bank | Tag each term by theme, level of organisation, and exam sentence to support cross-topic revision. |
Why command terms and vocab must be studied together
Most students treat vocabulary and command terms as separate revision tasks. That is a mistake I have seen cost students several grade boundaries. The IB Biology exam does not test whether you know what “osmosis” means in isolation. It tests whether you can define it with precision, explain the mechanism behind it, or evaluate an experiment that uses it. Those are three completely different answers to the same word.
The students who score 6s and 7s are not necessarily the ones with the largest vocabulary. They are the ones who have practised matching their terminology to the specific demand of each question. A student who writes a beautifully detailed mechanism in response to “Outline” has wasted effort and lost marks. A student who writes “water moves from high to low water potential across a partially permeable membrane” in response to “Define osmosis” has done exactly what the mark scheme rewards.
My practical advice: take five past paper questions each week and, before writing anything, identify the command term and list the three or four vocabulary terms the answer must include. Then write. This single habit, done consistently, builds the instinct that separates good answers from great ones.
— Oliver
Strengthen your IB Biology preparation with Tibertutor
If you are working through your IB Biology course and want resources built specifically around the syllabus you are studying, Tibertutor is worth exploring. The platform is built by examiners and experienced educators, with flashcards, detailed notes, and exam-style questions all organised by syllabus theme and topic.
Every resource on Tibertutor is aligned to the current IB Biology syllabus, so the vocabulary and definitions you practise are the ones that appear in real mark schemes. Progress tracking and analytics help you identify which topic areas need more attention, so your revision time is spent where it counts most. Visit the Tibertutor student platform to explore the full range of IB Biology resources available to you.
FAQ
What is IB Biology vocab?
IB Biology vocab refers to the precise scientific terms and command words required by the IB Diploma Programme Biology syllabus. These terms are used in exam answers and must match the exact language that mark schemes reward.
How many command terms do I need to know for IB Biology?
The IB Biology course uses around ten core command terms, including Define, Describe, Explain, Compare, Evaluate, and Discuss. Each one requires a different response style and level of vocabulary precision.
Why does precise terminology matter in IB Biology exams?
Examiners scan answers for exact syllabus terms. Vague or everyday language, such as using “breathing” instead of “respiration,” can lose marks even when the underlying understanding is correct.
What is the best way to study IB Biology key terms?
Spaced repetition tools such as Quizlet flashcard sets organised by topic, combined with a personal vocabulary bank tagged by theme and level of organisation, are among the most effective methods for long-term retention.
How is IB Biology vocabulary organised in the syllabus?
The IB Biology syllabus organises content around four broad themes: Unity and Diversity, Form and Function, Interaction and Interdependence, and Continuity and Change. Learning vocabulary within these themes builds the contextual understanding that exam questions test.