IB Biology HL/SL Topic Prediction May 2026 | Sev7n
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🧬 Group 4 Sciences · New Syllabus 2025

IB Biology HL & SL
Topic Prediction Guide

Paper 1A (MCQ) · Paper 1B (Data) · Paper 2 (Extended Response) — subtopic frequency for IBDP May 2026. Based on May 2025 + 6 years of mapped old syllabus data.

⚠️ New syllabus from May 2025 · 4 Themes A–D · No Paper 3 · No options
6+Years Data
40+Subtopics
4Themes A–D
HL & SLBoth Levels
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Home› Resources› IB Biology HL & SL Topic Prediction May 2026
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How this analysis was built — please read New IB Biology syllabus first sat in May 2025. We have 1 real sitting (May 2025) + IBO Specimen papers (2023). To strengthen predictions, we mapped 6 years of old syllabus Paper 1 & Paper 2 data (2019–2024) onto the new 4 themes — core biology content is largely preserved. Old Topics 1–11 map cleanly onto Themes A–D. Old Paper 3 data excluded (tested options which no longer exist). Source labelled on each row: 🟢 New syllabus · 🟡 Mapped old syllabus.

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Viewing: IB Biology Higher Level (HL) Paper 1 (1A+1B, 2.5 hrs, 80 marks, 36%) + Paper 2 (2.5 hrs, 80 marks, 44%) + IA 20%. HL adds additional depth in all 4 themes — chemical signalling, cladistics, further genetics, homeostasis extensions.
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Paper 1A — Multiple Choice Questions
HL: 40 MCQs · 40 marks · 2.5 hrs combined with 1B | SL: 30 MCQs · 30 marks · 1.5 hrs combined | Calculator allowed · No penalty for wrong answers · All 4 themes tested
🟢 Biology MCQ insight: Biology MCQ tests factual recall, diagram interpretation, and application of concepts. In the old syllabus, Topic 1 (Cell biology) and Topic 3 (Genetics) historically dominated. In the new syllabus, Theme A (Unity & Diversity) and Theme D (Continuity & Change — DNA/Genetics) are expected to carry the most MCQ weight. Every theme appears in every paper — no topic is safe to skip.

Paper 1A MCQ frequency by theme — SL & HL

IB BIOLOGY — PAPER 1A MCQ TOPIC FREQUENCY | May 2025 + Mapped Old Syllabus 2019–2024 | SL & HL
Free preview: Theme A · Themes B–D locked below · 🟢 = new syllabus · 🟡 = mapped old data · HL-only rows greyed in SL view
RefThemeTopic / Subtopic M20M21M22M23M24M25★ HL only?May 2026
THEME A: UNITY & DIVERSITY — cells, classification, viruses, biodiversity (free preview)
A.1Unity/DivCell structure — prokaryotic vs eukaryotic, organelles, ultrastructure, scale & magnification 🟡✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
A.2Unity/DivClassification & diversity — binomial nomenclature, phylogenetic trees, kingdoms, domains 🟡✔—✔✔✔✔★SL&HL⭐⭐⭐⭐
A.3Unity/DivViruses — structure, lytic & lysogenic cycles, HIV, COVID, virus-host interactions 🟢—————✔★SL&HL⭐⭐⭐⭐ NEW
A.4Unity/DivConservation of biodiversity — species richness, ecosystem services, threats, conservation strategies 🟡✔✔—✔—✔★SL&HL⭐⭐⭐⭐
A.HLUnity/DivCladistics & gene pools — cladograms, shared derived characteristics, species concepts, speciation HL 🟢—————✔★HL⭐⭐⭐⭐ HL NEW

★ = confirmed appeared May 2025 · 🟢 new syllabus · 🟡 mapped old syllabus | HL-only rows greyed in SL view

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Paper 1A — Themes B, C, D (Full Analysis)
Now showing the remaining themes locked behind the gate. Theme A free preview is shown above.
RefThemeTopic / Subtopic M20M21M22M23M24M25★ HL only?May 2026
THEME B: FORM & FUNCTION — membranes, proteins, enzymes, cell specialisation
B.1Form/FuncMembranes & transport — fluid mosaic model, osmosis, active/passive transport, endocytosis✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
B.2Form/FuncProteins — structure (primary to quaternary), enzymes, induced fit, inhibition, denaturation✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
B.3Form/FuncOrganelles & specialisation — mitochondria, chloroplasts, cell differentiation, stem cells✔✔—✔✔✔★SL&HL⭐⭐⭐⭐⭐
B.4Form/FuncGas exchange & transport — lung structure, haemoglobin, heart, blood vessels, stomata, transpiration✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐
B.HLForm/FuncChemical signalling — hormones, receptor proteins, signal transduction cascades, gene expression HL—————✔★HL⭐⭐⭐⭐ HL NEW
THEME C: INTERACTION & INTERDEPENDENCE — ecosystems, homeostasis, immunity
C.1InteractEcosystems — food chains/webs, energy flow, trophic levels, ecological pyramids, succession✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
C.2InteractCycling of matter — carbon cycle, nitrogen cycle, water cycle, decomposition, global warming✔✔✔—✔✔★SL&HL⭐⭐⭐⭐
C.3InteractDefence & immunity — innate vs adaptive immunity, antibodies, vaccinations, autoimmunity, allergens✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐
C.4InteractHomeostasis — thermoregulation, blood glucose (insulin/glucagon), osmoregulation, kidney structure✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
C.HLInteractNervous system & muscle — neurones, synapses, action potential, reflex arcs, muscle contraction HL—————✔★HL⭐⭐⭐⭐ HL
THEME D: CONTINUITY & CHANGE — DNA, genes, cell division, evolution (most tested overall)
D.1ContinuityDNA & RNA — structure, complementary base pairing, replication, transcription, translation✔✔✔✔✔✔★★SL&HL⭐⭐⭐⭐⭐ CERTAIN
D.2ContinuityCell division — mitosis stages, meiosis, crossing over, non-disjunction, cancer✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐ CERTAIN
D.3ContinuityInheritance — Mendelian genetics, dihybrid crosses, sex linkage, codominance, ABO blood groups✔✔✔✔✔✔★★SL&HL⭐⭐⭐⭐⭐ CERTAIN
D.4ContinuityNatural selection & evolution — Darwin, variation, adaptation, speciation, evidence for evolution✔✔✔✔✔✔★SL&HL⭐⭐⭐⭐⭐
D.HLContinuityEpigenetics & gene regulation — methylation, histone modification, lac operon, gene expression control HL—————✔★HL⭐⭐⭐⭐ HL NEW

★★ = heavily tested M25 · ★ = confirmed · 🟡 mapped old · 🟢 new syllabus | HL rows greyed in SL view

🟡 M25 Biology findings: DNA/RNA (D.1), Inheritance genetics (D.3), Membranes/Transport (B.1) and Immunity (C.3) were reported as heavily tested in May 2025. New topics A.3 (Viruses) appeared prominently — as expected for a new syllabus. HL-only additions (Cladistics, Chemical signalling, Epigenetics) all featured in Paper 1A and Paper 2.

🔴 Top 5 Biology MCQ topics — every year

  • D.1 DNA & RNA — structure, replication, transcription, translation. Appears in every paper without fail. Know all steps deeply.
  • D.3 Inheritance — Mendelian crosses, sex linkage, codominance. Always 3–5 MCQ questions. Know how to draw Punnett squares fast.
  • B.1 Membranes — fluid mosaic model, osmosis, transport types. Every year, every level.
  • C.4 Homeostasis — blood glucose, thermoregulation, kidney. Always appears with diagrams.
  • C.1 Ecosystems — food webs, energy flow, trophic levels. Consistent across all sittings.

🟢 Biology MCQ technique

  • No penalty — attempt every question
  • Many questions include diagrams — read labels carefully before the text
  • For genetics crosses: draw the Punnett square even in MCQ — it’s faster than mental calculation
  • HL: cladogram questions — identify the most recent common ancestor from the diagram
  • Eliminate clearly wrong answers first — usually 2 can be ruled out immediately
  • Key command words in MCQ: “which”, “most likely”, “explains” — watch the qualifier
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Paper 1B — Data-Based Questions
Both SL & HL: 20 marks · sat together with 1A (no break) | 4 data-based questions on experimental work, lab skills, and scientific methods | Calculator allowed
🟡 What Paper 1B tests in Biology: This paper replaced old Paper 3 Section A. It presents real biological data — graphs, tables, electron micrographs, experimental results — and asks you to read, calculate, interpret and evaluate. The biology content can come from any theme, but the skills are always the same: reading graphs, identifying anomalies, calculating percentage change, evaluating experimental design, and suggesting improvements.

🟡 Skills always tested in Paper 1B

  • Graph reading — extract values, describe trends, identify anomalies
  • Statistical analysis — mean, standard deviation, error bars, t-test interpretation
  • Percentage change calculations — very common, easy marks
  • Evaluating experimental design — identify variables, suggest controls
  • Interpreting micrographs — identify organelles, measure scale
  • Suggesting improvements — larger sample size, repeat trials, blind study

🧬 Experimental contexts from Specimen + M25

  • Enzyme activity experiment — rate vs temperature/pH graph, Vmax
  • Osmosis investigation — potato/onion cells in different concentrations
  • Ecology fieldwork data — quadrat sampling, species richness, Simpson’s index
  • Population genetics data — allele frequency, Hardy-Weinberg context
  • Photosynthesis experiment — light intensity vs rate, absorption spectra
  • Practice old Paper 3 Section A questions (2019–2024) — identical skill set
⚠ Key revision tip for Paper 1B: Every mark in Paper 1B is a skill mark. You do not need to memorise content to do well here — you need to practise reading biological data carefully. Practise writing answers in this structure: State the value → Describe the trend → Suggest a biological explanation → Evaluate the method. Command words are everything: “identify” needs 1 mark, “explain” needs 2–3 marks.
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Paper 2 — Extended Response (Highest mark value)
HL: 80 marks · 2.5 hrs · 44% | SL: 50 marks · 1.25 hrs · 44% | Data-based questions (Section A) + short answer + extended response (Section B) | Covers all 4 themes
🔴 Paper 2 is where Biology exams are won. At 44% for both levels, this is the most important paper. Section A has a mandatory data-based question (must answer all). Section B has short and extended response questions. Extended response questions (6–15 marks each) require knowledge across themes — e.g. “Explain how DNA structure relates to protein synthesis” links Theme D.1 and D.2.

Paper 2 extended response priorities — May 2026

IB BIOLOGY — PAPER 2 EXTENDED RESPONSE TOPIC FREQUENCY | May 2025 + Mapped 2019–2024
Extended questions demand multi-theme synthesis | Command words: explain, evaluate, discuss, compare | HL-only rows greyed in SL view
ThemeTopic AreaM21M22M23M24M25★Avg MarksMay 2026
THEME D — Most extended Paper 2 marks (DNA/Genetics always tested deeply)
D.1+D.2Molecular biology extended — DNA structure, replication, transcription + translation as one linked question✔✔✔✔✔★★12–18⭐⭐⭐⭐⭐ CERTAIN
D.3Genetics problems — dihybrid cross, linkage, sex-linked traits, pedigree analysis with explanation✔✔✔✔✔★★10–16⭐⭐⭐⭐⭐ CERTAIN
D.4Evolution extended — natural selection mechanism, evidence, Hardy-Weinberg, speciation✔✔—✔✔★8–12⭐⭐⭐⭐
THEME B — Proteins, enzymes and cell function
B.2Protein structure + enzyme function extended — lock-and-key vs induced fit, inhibition types, denaturation✔✔✔✔✔★10–14⭐⭐⭐⭐⭐
B.3+B.4Cell specialisation + physiology — stem cells, differentiation, gas exchange systems, haemoglobin dissociation✔—✔✔✔★8–12⭐⭐⭐⭐
THEME C — Ecosystems, homeostasis, immunity
C.1+C.2Ecology + biogeochemical cycles — energy loss in trophic levels, carbon cycle analysis, human impact✔✔✔✔✔★10–16⭐⭐⭐⭐⭐
C.3Immunity extended — antibody production, B and T cells, vaccination, clonal selection, HIV mechanism✔✔✔—✔★8–12⭐⭐⭐⭐⭐
C.4Homeostasis extended — negative feedback, insulin/glucagon pathway, kidney structure + function✔✔✔✔✔★10–14⭐⭐⭐⭐⭐
HL topicsChemical signalling, nervous system, epigenetics, cladistics — HL extended questions always include these HL————✔★10–16⭐⭐⭐⭐⭐ HL

🔴 Paper 2 top priorities

  • D.1+D.2 Molecular biology — DNA structure → replication → transcription → translation as one long question. Every year, 12–18 marks.
  • D.3 Genetics problems — always a genetics cross question. Know dihybrid, sex-linked, codominance thoroughly.
  • C.1 Ecosystems — food chain/web analysis with data. Energy loss calculations always required.
  • B.2 Enzymes — graph interpretation + mechanism explanation. Consistent across all sittings.
  • C.4 Homeostasis — negative feedback, kidney, glucose regulation. Every year without fail.

✍️ Paper 2 extended response technique

  • Use the mark allocation to gauge answer length — 1 mark = 1 distinct point
  • For “explain” questions: mechanism + reason + outcome (3-part structure)
  • For “evaluate”: state advantage, state limitation, reach a conclusion
  • Use correct biological terminology — “phospholipid bilayer” not “fat layer”
  • Annotate diagrams — label all parts, add arrows to show direction/process
  • For HL: link across themes — examiners reward cross-theme connections

About the new IB Biology syllabus

IB Biology was restructured for first assessment in May 2025. The old 11-topic syllabus has been replaced by 4 conceptual themes (Unity & Diversity, Form & Function, Interaction & Interdependence, Continuity & Change) with 40+ subtopics. Paper 3 is gone. Options (Neurobiology, Biotechnology, Ecology, Human Physiology) are removed, with some content integrated into HL core.

HL vs SL key differences

  • Paper 1: SL = 30 MCQ / HL = 40 MCQ
  • Paper 2: SL = 50 marks / HL = 80 marks
  • HL additions: Cladistics · Chemical signalling · Nervous system & muscle · Epigenetics · Advanced genetics
  • Hours: 150 SL vs 240 HL
IB Physics → IB Chemistry →

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