IB Biology - Introduction

When beginning to teach IB Biology it is important to do some long term planning. There would be nothing worse than arriving at the mock exams in year 2 finding 100 hours of IB Biology still to teach. There are some suggestions in the IB guide but everything depends on your teaching situation. In some schools HL and SL are taught together in the same class, in other school they are in separate classes. There may be other constraints regarding shared groups, laboratory space or special events.

This page contains some basic information which will help planning. There is also a page with four suggested Teaching Sequences for the topics which gives outline plans for the two years.

Overall Total Timings. There are 150 hours for SL and 240 hours for HL

The Practical Scheme of Work is also unchanged at: 40 hours for SL and 60 hours for HL

Teaching time for the core topics has increased to 95 hours (from 80 because there is one (15hr) option fewer)

The additional Higher level topics time allocation is 60 hours (from 55 adding 5 hours from the old second option)

Time allocation suggested for the option is now 15 hours for SL and 25 hours for HL (from 30/45 for 2 Options)

From these details above it is clear that there is roughly the same quantity of Biology to cover with both SL and HL students despite the reduction from one to two options.

Outline of the IB Biology topics on the new guide.


Core Topics95
1. Cell biology15
2. Molecular biology21
3. Genetics15
4. Ecology12
5. Evolution and biodiversity12
6. Human physiology20
Additional higher level (AHL)60
7. Nucleic acids9
8. Metabolism, cell respiration and photosynthesis14
9. Plant biology13
10. Genetics and evolution8
11. Animal physiology16
A. Neurobiology and behaviour1525
B. Biotechnology and bioinformatics1525
C. Ecology and conservation1525
D. Human physiology

Note: There are no specific SL options. SL students can study all four options. Each option has extra HL material.

One important area is the practical scheme of work. Section A of paper three will now contain short answer questions about the practical skills students will learn during the course. This ensures that IB Biology remains a practical science course but it will require some careful planning and it could take up a lot of time. To train the students to complete an investigation in just 20 hours of practical activities is quite a challenge.

PSOW - Practical Scheme of Work

Practical scheme of work4060
Practical activities2040
Individual investigation (internal assessment–IA)1010
Group 4 project1010

Six experiments in SL and one in the AHL are listed as practical activities which must be carried out. These skills will be assessed in paper 3 of the examination. There will only be three short questions or data analysis on these practical skills

TopicPrescribed labs
1Calculation of magnification of drawings, actual size of structures from drawings or micrographs
1Estimation of osmolarity in tissues
2Investigation of a factor affecting enzyme activity
2Separation of photosynthetic pigments by chromatography
4Attempting to create a sealed mesocosm

Monitoring of ventilation at rest and after mild and vigorous exercise

9Measurement of transpiration rates using potometers

The “Applications and skills” section of the syllabus lists 55 additional experiments that students should experience. It is clearly not possible to do each of these in 20 hours total, and so the strategic use of demonstrations and groupwork will be required.

Assessed Individual Investigation (10 hours)

This investigation is the only piece of assessed work required for the 20% internal assessment (IA)

The tasks can include:

  • Hands-on lab (Qualitative and quantitative data are valid)
  • Use of database for analysis and modeling
  • Extraction and graphical analysis from a database
  • Simulation (interactive/open-ended)
  • Hybrid hands-on + spreadsheet/database

There are 10 exemplar tasks in the Teacher Support material released on the OCC website

For further details about the PSOW please see the Practical Scheme of Work section of this website.
All materials on this website are for the exclusive use of teachers and students at subscribing schools for the period of their subscription. Any unauthorised copying or posting of materials on other websites is an infringement of our copyright and could result in your account being blocked and legal action being taken against you.