IB Biology Syllabus (Latest Core + Optional Topics)

International Baccalaureate (IB) Biology Syllabus and Study Link

Image Credit: International Baccalaureate Organization.

Core Topics (95 Hours)

Topic 1. Cell biology (15 Hours)

1.1 Introduction to Cells

1.2 Ultrastructure of Cells

1.3 Membrane Structure

1.4 Membrane Transport

1.5 The Origin of Cells

1.6 Cell Division

Topic 2. Molecular biology (21 Hours)

2.1 Molecules to Metabolism

2.2 Water

2.3 Carbohydrates and Lipids

2.4 Proteins

2.5 Enzymes

2.6 Structure of DNA and RNA

2.7 DNA Replications, Transcription, and Translation

2.8 Cell Respiration

2.9 Photosynthesis

Topic 3. Genetics (15 Hours)

3.1 Genes

3.2 Chromosomes

3.3 Meiosis

3.4 Inheritance

3.5 Genetic Modification and Biotechnology

Topic 4. Ecology (12 Hours)

4.1 Species, Communities, and Ecosystems

4.2 Energy Flow

4.3 Carbon Cycling

4.4 Climate Change

Topic 5. Evolution and biodiversity (12 Hours)

5.1 Evidence for Evolution

5.2 Natural Selection

5.3 Classification and Biodiversity

5.4 Cladistics

Topic 6. Human physiology (20 Hours)

6.1 Digestion and Absorption

6.2 The Blood System

6.3 Defense Against Infectious Disease

6.4 Gas Exchange

6.5 Neurons and Synapses

6.6 Hormones, Homeostasis, and Reproduction

Additional Higher Level (HL) Topics (60 Hours)

Topic 7. Nucleic Acids (9 Hours)

7.1 DNA Structure and Replication

7.2 Transcription and Gene Expression

7.3 Translation

Topic 8. Metabolism, Cell Respiration, and Photosynthesis (14 Hours)

8.1 Metabolism

8.2 Cell Respiration

8.3 Photosynthesis

Topic 9. Plant Biology (13 Hours)

9.1 Transport in the Xylem of Plants

9.2 Transport in the Phloem of Plants

9.3 Growth in Plants

9.4 Reproduction in Plants

Topic 10. Genetics and Evolution (8 Hours)

10.1 Meiosis

10.2 Inheritance

10.3 Gene Pools and Speciation

Topic 11. Animal Physiology (16 Hours)

11.1 Antibody Production and Vaccination

11.2 Movement

11.3 Kidney and Osmoregulation

11.4 Sexual Reproduction

Optional Topics

Option A. Neurobiology and Behaviour (15 Hours for SL and 25 hours for HL)

A.1 Neural development

A.2 The human brain

A.3 Perception of stimuli

A.4 Innate and learned behavior (Higher Level Only)

A.5 Neuropharmacology (Higher Level Only)

A.6 Ethology (Higher Level Only)

Option B. Biotechnology and Bioinformatics (15 Hours for SL and 25 hours for HL)

B.1 Microbiology: organisms in industry

B.2 Biotechnology in agriculture

B.3 Environmental protection

B.4 Medicine (Higher Level Only)

B.5 Bioinformatics (Higher Level Only)

Option C. Ecology and Conservation (15 Hours for SL and 25 hours for HL)

C.1 Species and communities

C.2 Communities and ecosystems

C.3 Impacts of humans on ecosystems

C.4 Conservation of biodiversity

C.5 Population ecology (Higher Level Only)

C.6 Nitrogen and phosphorus cycles (Higher Level Only)

Option D. Human Physiology (15 Hours for SL and 25 hours for HL)

D.1 Human Nutrition

D.2 Digestion

D.3 Functions of the Liver

D.4 The Heart

D.5 Hormones and Metabolism (Higher Level Only)

D.6 Transport of Respiratory Gases (Higher Level Only)

Practical scheme of work (40 Hours for SL and 60 Hours for HL)

Practical activities (20 Hours for SL and 40 Hours for HL)

Individual Investigation (10 Hours for SL and HL)

Group 4 project (10 Hours for SL and HL)

Disclaimer: Syllabus and contents on this page are only used for educational purposes. If there are any copyright issues regarding the content, please email us at microbenotes@gmail.com.

References and Sources

  1. https://www.ibo.org/programmes/diploma-programme/curriculum/sciences/biology/
  2. https://blog.prepscholar.com/the-complete-ib-biology-syllabus-standard-level-sl-and-higher-level-hl
  3. https://www.sdgj.com/ckfinder/userfiles/files/9a6ff27578e18e3f1023a4dc046beef1.pdf

About Author

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Sagar Aryal, PhD

Dr. Sagar Aryal is a microbiologist, researcher, and science communicator from Nepal. He is also co-founder and Research Head of the Department of Natural Products at the Kathmandu Research Institute for Biological Sciences (KRIBS), where he leads research on natural product discovery and microbial biodiversity. Dr. Aryal earned his Ph.D. in Microbiology from Tribhuvan University, Kathmandu, Nepal, in 2025, supported by a DAAD Research Grant and a University Grants Commission (UGC) Nepal Ph.D. Fellowship. His research interests include Actinomycetes, Myxobacteria, microbial taxonomy, and natural products, particularly the discovery of bioactive compounds with potential pharmaceutical applications. He isolated and identified Nocardia nepalensis, a novel bacterial species from Nepal, contributing to understanding microbial diversity in the region. Dr. Aryal has published more than 16 research articles in international journals and contributed three book chapters to established academic publications. He has presented scientific research findings and developed international research collaborations through visits to more than 18 countries across Asia, Europe, North America, and Oceania. From 2023 to 2025, he served as the American Society for Microbiology (ASM) Young Ambassador to Nepal. Since December 2025, he has served as an Editorial Board Member of Scientific Reports, a Nature Portfolio journal. In recognition of his scientific contributions, Dr. Aryal received the NAST Science and Technology Youth Award 2025 from the Nepal Academy of Science and Technology. He previously received the Frs. Locke and Stiller Research Award (LSRA) for the 2017-2018 cycle from St. Xavier's College, Kathmandu, and a Nepal Academy of Science and Technology (NAST) Research Grant for 2017-2018. Alongside his scientific career, Dr. Aryal has more than 15 years of experience in blogging, content writing, and search engine optimization (SEO).