IB Diploma

How to get a 7 in IB Biology

7 min read · updated 2026-10-13

IB Biology is organised around unity and diversity, form and function, interaction and interdependence, and continuity and change. A 7 needs secure knowledge across the whole course, accurate data handling for Paper 1B and an investigation that scores near the top of the 20% it carries.

How the course is assessed

The current Biology, Chemistry and Physics courses (first assessed in 2025) share one model. Paper 1 is worth 36%: Paper 1A is multiple choice and Paper 1B is data-based questions. Paper 2 is worth 44%, with short-answer and extended-response questions. The scientific investigation, an internally assessed project of about 10 hours, is worth the remaining 20%.

Paper 1 lasts 1 hour 30 minutes at SL and 2 hours at HL; Paper 2 lasts 1 hour 30 minutes at SL and 2 hours 30 minutes at HL. A calculator and the data booklet are allowed in both papers.

Topics that decide the grade

✓ Molecules and cells: the vocabulary every later topic depends on
✓ Genetics and inheritance, including problems with ratios
✓ Physiology: transport, gas exchange and homeostasis
✓ Ecology and evolution, with data from real studies
✓ Data-based questions in Paper 1B, often on unfamiliar experiments

Where marks are lost

Patterns we see in students' mocks:

✓ Answers that use everyday words instead of precise biological terms
✓ Describing a graph without quoting data from it
✓ Extended responses that list facts without linking them to the question
✓ Not using the marks available as a guide to how many points to make

The scientific investigation

The investigation is worth 20% and takes about 10 hours of class time. Choose a focused research question with a variable you can measure well, collect enough data to analyse properly, and evaluate the method honestly. It is the most reliable place to bank marks before the exams.

A 10-week plan to the exams

✓ Weeks 1-2: one topic a day with short questions; list the weakest from mocks
✓ Weeks 3-4: Paper 1B data questions every other day
✓ Weeks 5-6: Paper 2 extended responses, marked against markschemes
✓ Weeks 7-8: full timed papers, Paper 1 and Paper 2 on alternate days
✓ Weeks 9-10: redo lost questions and review key definitions and equations

How a 7 is decided

The IB sets grade boundaries for each subject after every session, and they are released to schools rather than published openly, so no fixed percentage guarantees a 7. In practice a 7 means near-complete command of the syllabus and very few lost marks on the investigation, so the plan is the same every year: secure the IA early, then make every paper-style question a habit.