What is IB Biology HL vs SL?

IB Biology HL (240 hours) covers significantly more content than SL (150 hours). Both cover the same four themes but HL adds deeper content including more detailed biochemistry, genetics (HL gene expression), immunology, and neuroscience. HL also has Paper 3 with additional HL-only content questions. HL is required for Medicine, Dentistry, Veterinary Science, and most Biological Sciences programmes at top universities.

What is the IB Biology Internal Assessment?

The IB Biology IA is an individual scientific investigation of approximately 10 pages worth 20% of the final grade. Students design an experiment using living organisms or biological data, collect and analyse results, and evaluate methodology. Marked on Exploration, Analysis, Evaluation, and Communication. Our examiners guide every stage — from research question and experimental design through to statistical analysis and evaluation.

Chemistry Physics Biology

🧬 IB Group 4 — Sciences

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Expert 1-on-1 online tutoring for IB Biology HL and SL. Full coverage of the new conceptual syllabus — Unity & Diversity, Form & Function, Interaction & Interdependence, Continuity & Change. IA guidance and Paper 1/2/3 coaching by IB Examiners.

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About IB Biology

What is IB Biology HL & SL?

IB Biology is a Group 4 science that explores life at every scale — from molecules to ecosystems. The new 2023 syllabus is organised around four conceptual themes — Unity & Diversity (cells and classification), Form & Function (biochemistry and physiology), Interaction & Interdependence (ecology and immunity), and Continuity & Change (genetics, DNA, and evolution).

IB Biology HL (240 hours) goes significantly deeper — additional content in gene expression, immunology, neuroscience, and biotechnology. HL is required for Medicine, Dentistry, Veterinary Science, and most Biological Sciences programmes at top universities. SL (150 hours) is appropriate for students who need biology for their programme at a non-specialist level.

Unlike Chemistry and Physics, Biology has a very high content load — there is simply a lot to know. The most effective approach is systematic coverage with regular recall practice, which is exactly how our IB Examiner tutors structure their sessions.

🧬 New 2023 conceptual syllabus

The revised IB Biology syllabus replaced the old topic-based structure with four integrated conceptual themes. All Sev7n Biology tutors teach the new 2023 syllabus.

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Required for Medicine & Biosciences

IB Biology HL is required by most universities for Medicine, Dentistry, Veterinary Science, Pharmacy, Nursing, and Biological Sciences programmes.

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Highest content load of the three sciences

Biology has more content to memorise and understand than Chemistry or Physics. Structured recall, spaced repetition, and concept mapping are essential — our tutors build these into every programme.

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IA — organism-based investigations

Biology IAs often use living organisms or biological datasets. Research question focus, ethical considerations, and statistical analysis are all critical. Our examiners guide design and analysis from the start.

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Genetics — the most dropped marks

Meiosis, gene expression (transcription/translation), HL epigenetics, and inheritance patterns (monohybrid, dihybrid, sex-linked) are consistently the most dropped marks in IB Biology exams.

IB Biology Syllabus

All 4 Conceptual Themes — HL & SL fully covered

The new 2023 IB Biology syllabus integrates content across four themes. HL additions clearly marked throughout.

Theme A

Unity & Diversity

Cell theoryCell structureCell membraneClassificationOrigin of lifeVirusesHL: Prokaryotic vs eukaryotic depthHL: Cladistics

Cell theory, prokaryotic and eukaryotic cells, organelles and their functions, cell membrane structure (fluid mosaic model), membrane transport, biological classification systems, cladistics and phylogeny. HL adds deeper content on membrane proteins, transport mechanisms, and evolutionary relationships.

Theme B — Highest content load

Form & Function

BiochemistryEnzymesPhotosynthesisRespirationHuman physiologyNervous systemHL: Metabolic pathwaysHL: Neuroscience depth

Biological molecules (carbohydrates, lipids, proteins, nucleic acids), enzyme kinetics, photosynthesis (light-dependent and light-independent reactions), cellular respiration (glycolysis, Krebs cycle, electron transport chain), human physiology (digestion, circulation, respiration, excretion, nervous and endocrine systems). HL adds detailed biochemical pathways, neurophysiology, and biotechnology applications.

Theme C

Interaction & Interdependence

EcologyFood websNutrient cyclesImmunityMicrobiomePlant biologyHL: ParasitismHL: Innate vs adaptive immunity

Ecosystems (populations, communities, trophic levels), food webs, energy flow, biogeochemical cycles (carbon, nitrogen), biodiversity and conservation, the immune system (innate and adaptive responses, antibodies, vaccination), microbiome and human health, plant structure and function. HL adds detailed immunology and parasitic interactions.

Theme D — Most exam questions here

Continuity & Change

DNA structure & replicationTranscription & translationMeiosisInheritance patternsEvolutionNatural selectionHL: Gene expressionHL: EpigeneticsHL: Biotechnology

DNA structure, semi-conservative replication, transcription, translation, genetic code, mutations, meiosis and variation, Mendelian genetics (monohybrid and dihybrid crosses), sex-linkage, natural selection and evolution, speciation. HL adds gene regulation, epigenetics, CRISPR and biotechnology. Theme D generates the most exam questions at both HL and SL — genetics diagrams and evolution essays are high-frequency.

Assessment

How IB Biology is assessed

The new 2023 syllabus changed the assessment structure. Our examiners coach every paper component.

Paper 1A — MCQ

20%

SL: 45 min · HL: 1h — Multiple choice

30 questions (SL) / 40 questions (HL)
Tests breadth of knowledge across all four themes
Common traps: precise scientific terminology, negatively worded questions
Concept maps and diagram-based questions frequently appear

SL & HL

Paper 1B — Data-Based

20%

SL: 45 min · HL: 1h — Data interpretation

Questions based on experimental data, graphs, and biological research
Tests data analysis and scientific reasoning skills
Students interpret unfamiliar biological scenarios from data provided
Statistical analysis and graph interpretation skills essential

SL & HL

Paper 2 — Extended Response

SL 40% / HL 36%

SL: 1h15m · HL: 2h15m — Long answer

Short answer and extended response questions across all themes
Diagram drawing questions — annotated diagrams are heavily rewarded
Essay questions require organised, well-structured responses
HL questions require deeper analysis of mechanisms and systems

SL & HL

Internal Assessment (IA)

20%

SL & HL · ~10 pages · Individual investigation

Individual investigation using biological organisms or datasets
Marked on: Exploration, Analysis, Evaluation, Communication
Statistical analysis (t-test, chi-squared) is expected
Ethical considerations for research involving living organisms must be addressed

SL & HL

Why Sev7n

Why Sev7n for IB Biology tutoring

Examiners who mark the actual papers

Our IB Biology tutors are active IB Examiners. They know exactly which topics generate the most exam marks, how diagram questions are marked, and what level of detail is required in extended response answers.

Genetics — dedicated systematic coaching

Theme D genetics questions (meiosis diagrams, inheritance crosses, gene expression) are the most heavily tested in IB Biology. Our examiners dedicate specific sessions to building accurate, mark-earning genetics skills.

Diagram drawing coaching

Biology exams require accurately drawn, annotated diagrams of cells, organelles, synapses, chloroplasts, mitochondria, and more. Our tutors train diagram drawing to the exact standard examiners expect.

IA statistical analysis guidance

Biology IAs require statistical tests (t-test, chi-squared, Pearson's r). Many students don't know which test to use or how to interpret the results. Our examiners guide statistical analysis as a core IA skill.

New 2023 syllabus fully covered

The conceptual theme-based structure is a significant change from the old topic-based syllabus. All Sev7n Biology tutors teach the new 2023 syllabus with full coverage of HL AHL content.

Sessions recorded on Sev7n LMS

Every IB Biology session is saved to your dashboard. Replay complex biochemistry pathways, genetics worked examples, and physiology explanations as many times as needed before exams.

Student Stories

What IB Biology students say about Sev7n

★★★★★

"My daughter was losing marks on every genetics question — dihybrid crosses, sex-linkage, gene expression. Her Sev7n tutor built a systematic approach from scratch. By the end of term she was scoring full marks on every genetics question in mock papers."

★★★★★

"My IB Biology IA statistical analysis was completely wrong. My tutor showed me exactly which t-test to apply, how to interpret the p-value, and how to link the statistics back to my hypothesis. My IA grade improved from 15 to 22 out of 24."

★★★★★

"The photosynthesis and respiration pathways are a nightmare to memorise. My Sev7n tutor used visual diagrams and concept maps that made the connections between glycolysis, Krebs cycle and electron transport chain finally make sense. My Paper 2 biochemistry section score jumped significantly."

★★★★★

"IB Biology has so much content that my son was overwhelmed. His Sev7n tutor built a structured revision plan covering all four themes systematically. The examiner knew exactly which topics to prioritise. Final score was 7 — we couldn't be happier."

FAQs

IB Biology — frequently asked questions

What are the hardest topics in IB Biology? +

Most students find these hardest: Genetics — meiosis, monohybrid/dihybrid inheritance, sex-linkage, and gene expression/epigenetics (HL) in Theme D; Biochemistry — photosynthesis (light-dependent and Calvin cycle) and cellular respiration (Krebs cycle and ETC) in Theme B; Immunology — innate vs adaptive immunity, antibody production, and vaccines in Theme C. Our examiner tutors target these specifically in every IB Biology programme.

Is IB Biology HL required for Medicine? +

Yes — IB Biology HL is required by most medical schools globally. UK universities require Biology HL at a high grade. Indian medical colleges (via NEET) require strong biology knowledge. Most universities also require Chemistry HL alongside Biology HL for medicine. Some universities accept SL for non-medical bioscience programmes but always verify specific requirements.

How is the new IB Biology 2023 syllabus different? +

The revised 2023 IB Biology syllabus replaced the old topic-based structure (Topics 1-11 SL, 12-D HL) with four integrated conceptual themes: Unity & Diversity, Form & Function, Interaction & Interdependence, and Continuity & Change. The content is broadly similar but organised around biological concepts rather than discrete topics. All Sev7n tutors teach the new 2023 syllabus.

What makes a good IB Biology IA topic? +

A good Biology IA has a specific, focused research question with a clearly controllable independent variable and a measurable dependent variable. The best topics use accessible biological organisms or datasets and allow genuine statistical analysis. Common successful topics: effect of temperature on enzyme activity (catalase/amylase), effect of pH on plant growth, analysis of an ecological dataset, or investigation of a physiological variable. Avoid topics that require equipment not available at your school. Our examiners help students select topics with the right scope for a 20-page investigation.

IB Biology Tutoring by Active IB Examiners

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What is IB Biology HL & SL?

All 4 Conceptual Themes — HL & SL fully covered

How IB Biology is assessed

Why Sev7n for IB Biology tutoring

What IB Biology students say about Sev7n

IB Biology — frequently asked questions

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