IB Biology Tuition Online (SL and HL)
IB Biology at SL and HL, first assessed in 2025: four themes studied at four levels, from molecules to ecosystems, two papers and a scientific investigation.
Founder & Head of School, Afterkelas
Afterkelas teaches IB Biology online at SL and HL. University tutors run live classes, 1-to-1 or in small groups, on the four themes, the data questions the papers lean on, and the scientific investigation.
What IB Biology covers
The four themes and their subtopics as the guide lists them. Each theme runs through four levels of organisation, molecules, cells, organisms and ecosystems, and some subtopics are HL only.
A. Unity and diversity
9 topics- Water
- Nucleic acids
- Origins of cells
- Cell structure
- Viruses
- Diversity of organisms
- Classification and cladistics
- Evolution and speciation
- Conservation of biodiversity
B. Form and function
10 topics- Carbohydrates and lipids
- Proteins
- Membranes and membrane transport
- Organelles and compartmentalization
- Cell specialization
- Gas exchange
- Transport
- Muscle and motility
- Adaptation to environment
- Ecological niches
C. Interaction and interdependence
9 topics- Enzymes and metabolism
- Cell respiration
- Photosynthesis
- Chemical signalling
- Neural signalling
- Integration of body systems
- Defence against disease
- Populations and communities
- Transfers of energy and matter
D. Continuity and change
12 topics- DNA replication
- Protein synthesis
- Mutation and gene editing
- Cell and nuclear division
- Gene expression
- Water potential
- Reproduction
- Inheritance
- Homeostasis
- Natural selection
- Stability and change
- Climate change
Themes and levels
The course first examined in 2025 arranges biology on a grid: four themes, unity and diversity, form and function, interaction and interdependence, and continuity and change, each studied at four levels of organisation from molecules to ecosystems. The same idea can turn up in several places, and questions often link them.
Tutors teach each subtopic alongside the school and keep a map of the links, so a student can answer a question that joins, for example, enzymes, respiration and energy flow through an ecosystem.
Where marks are lost
Biology answers lose marks to vague wording where a precise term is expected, and to data questions answered without quoting the data. Paper 1B and the data questions of Paper 2 lean on analysis, and the guide lists skills such as the Lincoln index, the chi-squared test and the t-test, so students practise them with real numbers.
The scientific investigation
The internal assessment is a scientific investigation worth 20 percent, with about 10 hours of class time. Tutors can explain experimental design, statistics and data presentation, and what the criteria reward, but the investigation and the report are the student's own.
A question, worked through
A population ecology question from C4.1, Populations and communities, using the Lincoln index.
Question
In a capture-mark-release-recapture study, 40 beetles are caught, marked and released. A week later 50 beetles are caught, of which 10 are marked. Estimate the population size and state one assumption of the method.
- Lincoln index: population estimate = (number in the first sample × number in the second sample) ÷ number of marked individuals recaptured.
- Estimate = (40 × 50) ÷ 10 = 2000 ÷ 10 = 200 beetles.
- One assumption: the marked beetles mix evenly back into the population before the second sample is taken.
Answer About 200 beetles.
Frequently asked questions
Is IB Biology mostly memorisation?
Less than it looks. The terms must be exact, but the papers lean on data analysis and on linking ideas across themes, and the guide includes statistical skills such as the chi-squared test and the t-test.
What does HL add in IB Biology?
More depth across the themes, some HL-only subtopics and longer papers.
When should IB Biology tuition start?
Early in the first year, since the molecular and cell subtopics underpin most of the rest.
How much does IB Biology tuition cost?
The fee depends on the format (1-to-1 or a small group), how many classes a week and the tutor, so there is no single figure. Send an academic advisor the level, the school and the latest predicted grade on WhatsApp, and you will get the current packages and a quote, usually within one working day.