IB Biology

AP / IB · Science

IB Biology is organised around four themes — Unity and Diversity, Form and Function, Interaction and Interdependence, Continuity and Change — each examined at four levels of organisation: molecules, cells, organisms and ecosystems. Sessions work through that structure rather than a generic biology sequence, so a topic like water is met as a molecule (hydrogen bonding), then again as transport in xylem and as a habitat property. Work is tied to IB command terms and to the specific demands of Paper 1A, 1B, Paper 2 and the internal assessment, with HL-only content (such as detailed metabolic pathways and gene expression regulation) flagged separately from SL.

Start a session on IB Biology

What this covers

  • Answering to the command term: writing an 'outline' in two marks, an 'explain' with causal links, a 'distinguish' as paired contrasts, and a 'discuss' with both sides
  • Paper 1B data-based questions: reading unfamiliar graphs, error bars and tables, describing trends with quoted values and units, and separating description from explanation
  • Applying the required statistics — standard deviation, standard error and overlap of error bars, chi-squared for genetic crosses, t-test for comparing two means, and correlation versus causation
  • Internal assessment support: narrowing a research question, identifying and controlling variables, justifying method choice, processing raw data into a proper table with uncertainties, and structuring evaluation
  • Systems that recur across themes — membrane transport, gas exchange surfaces, water potential, nerve impulses, homeostasis and feedback — with the form-to-function argument made explicit
  • HL extension material including the light-dependent and light-independent reactions in detail, chemiosmosis, gene expression and epigenetics, and immunology

Where learners get stuck

Treating 'describe the trend' and 'explain the trend' as the same task in data questions
In earlier science courses both were rewarded with any relevant biology. IB examiners want description restricted to what the data show, with figures quoted, and explanation restricted to underlying mechanism — writing mechanism in a describe question earns nothing.
Saying water moves 'because of osmosis' or 'to where there is less water' instead of down a water potential gradient
Osmosis is first taught with concentration language, and solute concentration and water potential run in opposite directions. Students then invert the sign when handling plant cells, plasmolysis or kidney questions.
Confusing what the chi-squared and t-tests are actually testing, and stating a conclusion without reference to the critical value or p
Both are learned as procedures for getting a number. Chi-squared compares observed with expected frequencies (association or fit to a ratio), while the t-test compares two means; a conclusion has to name the null hypothesis and compare the calculated value with the critical value at the given degrees of freedom.
Building an internal assessment around a question that is too broad or has no measurable independent variable
Students choose a topic they find interesting before checking whether it produces continuous, repeatable numerical data within school constraints, so processing and evaluation have little to work with.

What a session looks like

A session usually starts with a short diagnostic question on the chosen topic to see how the idea is currently held, then moves through explanation with the tutor asking you to state relationships aloud rather than listening passively. Most sessions include at least one past-paper-style question answered under command-term rules, with the response marked point by point against what a markscheme would credit. Diagrams — a nephron, a synapse, a food web — are talked through step by step, and IA work is handled by discussing your data and draft sections rather than writing them for you.

Helpful to know first

  • MYP science, IGCSE Biology or equivalent, including cell structure, enzymes and basic genetics
  • Comfort with percentages, ratios, rearranging simple equations and reading line and bar graphs
  • For HL work, familiarity with basic organic chemistry: functional groups, condensation and hydrolysis reactions

Questions

Does this follow the new IB Biology syllabus with the four themes?
Yes. Sessions are organised by the current themes and levels of organisation, use the guiding questions as the framework for each unit, and distinguish SL content from HL extension material.
Can it help with my internal assessment?
It can help you refine a research question, plan variables and controls, choose the right statistical test, and review the structure of your analysis, evaluation and conclusion. It will not write the report or supply the data — that has to be your own work under IB academic integrity rules.
What is the difference between the IB Biology and AP Biology sessions?
AP Biology is built around the College Board's big ideas and free-response formats. IB Biology sessions use IB command terms, the four-theme structure, Paper 1A/1B and Paper 2 question styles, and the internal assessment criteria, and cover the HL-only content the IB specifies.
My child is strong on content but loses marks in exams. Can that be worked on?
That pattern usually comes from ignoring the command term, omitting units or data references, or answering more than the question asks. Sessions can focus on writing timed answers to past-paper-style prompts and comparing them against the marks a markscheme would award.

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