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The IB regularly reviews and updates its curricula to ensure they align with current scientific knowledge and teaching practices. While the updated curriculum brings with it a range of topics and assessment formats to explore, it is important to take a closer look at the changes between the 2014 and 2023 syllabus in order to understand the full impact of the updates.

In this article, we will compare the topics and assessment format of the 2014 and 2023 IB Biology syllabi. We will be highlighting the changes and improvements made.

IB Biology Syllabus Topics

Core Topics

The core topics in IB Biology provide a foundation for understanding biological concepts and processes. In the 2014 curriculum, the core topics included cell biology, molecular biology, genetics, ecology, evolution, and biodiversity.

In the updated 2023 curriculum, one major change is how the content is organised. Although the syllabus may look different and have revised topic titles, don’t worry because a lot of the biology content is still the same as 2014’s syllabus. In fact, the 2023 syllabus contains approximately 5% less content than the 2014 syllabus. There are 4 main themes:

  • Unity and diversity
  • Form and function
  • Interaction and interdependence
  • and Continuity and change.

In addition, the syllabus structure now includes four levels of organisation:

  • Molecules
  • Cells
  • Organisms
  • and Ecosystems.

See syllabus breakdown here.


The options component of the IB Biology syllabus allows students to explore specific areas of interest in greater depth. The 2014 curriculum featured 4 options, including human physiology, neurobiology and behaviour, biotechnology and bioinformatics, and ecology and conservation.

It is important to note that the options have been removed from the 2023 curriculum. However, a few of the options have been included in the SL and HL courses. However, this incorporation of option material into the SL and HL courses does not increase the total content.

For instance, there are points about the cardiac cycle from human physiology, gene knockout approaches to research from biotechnology and bioinformatics, and details of the brain and spinal cord from neurobiology and behaviour. Ecological succession, population growth curves, and pollution from ecology and conservation.

IB Biology Assessments

External Assessment

For IB Biology 2023 syllabus (first assessments 2025), there are only two examination papers, Paper 1 and Paper 2, for each level and the weightage of SL exam papers is now equal to HL papers. See format here.

Other changes include the removal of option topics (neurobiology and behaviour, biotechnology and informatics, ecology and conservation and human physiology).

From the current four options some of the content was incorporated into the course at either standard level or higher level.

Internal Assessment

The individual investigation in IB Biology has been updated and is now called the “scientific investigation”, with the opportunity for students to collaborate and support each other within small groups. Where appropriate, students can share similar methodologies, provided that the independent or dependent variables differ, and the data collected is unique to each student. Students will continue to submit an individual report, with a maximum word count of 3,000 words.

This component still counts for 20% of the overall assessment, with the external assessment accounting for the remaining 80%. The allocated time of 10 hours has not changed. However, the criteria has been revised and will place a greater emphasis on higher-order thinking skills with 50% of the marks allocated for conclusion and evaluation.


The IB Biology syllabus update for 2023 brings several notable changes that enhance the learning experience for students. The inclusion of new core topics reflects the dynamic nature of biology and provides a more comprehensive understanding of the subject. The revised assessment format emphasises inquiry, application, and critical thinking skills, better preparing students for further studies and careers in the biological sciences. With these updates, the IB Biology curriculum continues to offer a challenging and engaging educational experience, equipping students with the knowledge and skills necessary for success in the field of biology.

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