The IB Biology exam is a challenging assessment that tests students’ understanding of biological concepts, practical skills, and scientific analysis within the International Baccalaureate curriculum. At The Princeton Review, we provide expert-led guidance, personalized study plans, and practice resources to help students master every topic — from cell biology to genetics — ensuring top performance in both Internal Assessments and final IB exams.
IB Biology is a two-year course for students aged 16 to 19 in the IB Diploma Programme. You can take it at Standard Level (SL) or Higher Level (HL). The course is all about understanding living things, from tiny cells and molecules to whole ecosystems, through experiments and hands-on learning.
It’s not just about memorizing facts. You’ll learn to think critically, solve problems, and connect ideas across biology. You’ll also see how biology affects the world around us.
Starting in May 2025, the course followed a new syllabus. It focused on big concepts instead of separate topics. Optional topics were removed, and exams were reduced from three papers to two. This made the course more focused and helped students see how everything connected.
The new 2025 IB Biology curriculum is organized around four overarching themes, each explored at four levels of biological organization (molecules, cells, organisms, and ecosystems). This matrix structure emphasizes that all biological concepts are interconnected and part of a larger understanding.
| Water and nucleic acids | Cell structure and function |
| Diversity of organisms and classification | Evolution and speciation |
| Conservation of biodiversity | Carbohydrates, lipids, and proteins |
| Membranes and transport | Enzymes and metabolism |
| Cell respiration and photosynthesis | Neural signalling and body system integration |
| Defence against disease | Populations and communities |
| DNA replication and protein synthesis | Mutations and gene editing |
| Cell and nuclear division | Reproduction and inheritance |
| Homeostasis and natural selection | Climate change and sustainability |
HL students study additional advanced topics, including muscle physiology and motility, chemical signalling, gene expression, viruses, classification and cladistics, and other specialized areas. HL courses cover approximately 60 additional hours of content beyond the core.
The two-year IB Biology program culminates in external examinations that test students' knowledge, understanding, and application skills. As of May 2025, the examination structure has been significantly revised.
Build strong fundamentals in cell biology, genetics, and evolution before moving to complex topics.
Use flashcards, teach others, and solve past papers to reinforce memory and understanding.
Balance speed and accuracy for Paper 1 and plan time based on marks for Paper 2.
Maintain sleep, hydration, and calmness through meditation and a balanced study routine.
Start by understanding the basic ideas like cell biology, genetics, and evolution. Biology builds up step by step, so if your basics aren’t clear, the tougher topics will feel even harder later on. Try to relate difficult concepts to simple, everyday examples, and keep revising the basics so they stay fresh in your mind.
Just reading your notes isn’t enough to do well in exams. It’s better to practice more questions, explain topics to your friends, and make flashcards for key terms. Try using spaced repetition — reviewing material multiple times over a few days or weeks — to improve retention.
Without previous exam papers, one cannot get ready properly for the real test. Practice completing papers under time pressure to simulate real exam conditions. Though the new syllabus has fewer papers, older ones still cover useful concepts.
Different question words require different types of answers. “Outline” needs a summary; “Explain” requires reasoning and detail; “Analyse” involves interpreting data. Understanding these avoids losing marks to format errors.
For Paper 1: Focus on speed and accuracy — eliminate wrong choices and underline keywords. For Paper 2: Allocate more time to higher-mark questions, starting with those you’re confident about.
The new curriculum encourages connecting topics. When studying one theme, think about how it links with others — this helps in extended-response questions and boosts understanding.
Ensure 7–9 hours of sleep, regular breaks, and hydration. Physical and mental balance often distinguishes top scorers from average performers.
Make short notes, diagrams, and tables summarizing processes and definitions. This improves recall and efficiency during revision.
Spend more time on complex areas like molecular biology, gene expression, and genetics. Identify weak points early and plan revisions accordingly.
The Internal Assessment is a 3,000-word maximum written report where you design and conduct your own scientific investigation. It's worth 20% of your final grade (both SL and HL use the same marking criteria).
Your IA is marked out of 24 points across four equally weighted criteria (6 points each):
Define your research question, justify your method, and plan effectively.
Reflect on strengths, weaknesses, and improvements.
For statistical validity, aim for about 25 data points from multiple trials and variations. Continuous data: 5 variations × 5 repeats. Discontinuous data: 2 variations × 10 repeats.
Important Note on Practice Materials:
The 2025 syllabus is new, so fewer past papers exist. However, many old syllabus questions still align with the current content — ask your teacher which are most relevant.
IB Biology is tough, but all you need is the right plan to manage all three papers with ease and confidence. Each paper requires different skills, so prepare smartly if you wish to score well.
This paper includes multiple-choice questions. To ace this paper, it is advised to revise key concepts and definitions from each topic. If you wish to improve speed and accuracy, you should practice more and more past papers and quizzes. Flashcards and quick recall tests can also help you a lot.
This paper has more analytical questions, which include data-based, short-answer, and extended-response questions. Practice putting biological processes in your own words and revise thoroughly multiple times. It is also useful for you to look at official IB mark schemes so you can familiarize yourself with the way that answers are assessed.
This tests your understanding of experimental work and optional topics. Review lab techniques, data interpretation, and the experiments, and summarize each option topic into mind maps to revise faster.
We can conclude that the key to effective prep for all the IB papers is consistency. So focus on revising small topics every day to avoid any stress before the real exam.
If you are a student thinking of taking IB Biology, one of your first decisions is to choose between Higher Level (HL) and Standard Level (SL). Both types will cover the same core syllabus, but there will be some differences in depth, assessment, and expectations.
In SL, students study the core topics (for example, cell biology, genetics, ecology, and human physiology) in a more condensed way. The purpose of this course is to help students understand basic biology.
The HL syllabus contains all of the topics in great detail, such as nucleic acids, metabolism, plants, and biotechnology. There will be more topics in HL as compared to SL, and they are more open-ended, data-based, and include critical thinking questions.
With assessment, HL students will be given longer papers and more challenging data-based and open-ended questions. HL students will have more time in the lab, creating their internal assessments and doing research.
The IB Biology Internal Assessment (IA) is a key component of your IB journey — a chance to explore biology beyond textbooks and apply what you’ve learned in a hands-on investigation. Whether you’re in Higher Level (HL) or Standard Level (SL), choosing the right IA topic is the first step toward an exciting and meaningful research experience.
As an HL student, you’re expected to go deeper into complex biological concepts. Your IA should reflect advanced understanding, precise data collection, and strong analytical skills. Here are some sample IB Biology HL IA ideas you can explore:
Your HL IA should challenge your critical thinking, involve controlled variables, and demonstrate a strong link to the IB Biology syllabus.
For SL students, the IA doesn’t need to be overly complex — it’s about demonstrating curiosity, accuracy, and understanding of biological methods. Here are a few IB Biology SL IA topics you can consider:
These topics are straightforward yet provide room for creativity and clear data analysis.
IB Biology may seem abundant in various complex terms and concepts; however, having a summary of essential definitions and formulas to refer to as you review your work can save you time and simplify the revision process! First, we will start with a few formulas you should memorize:
IB Biology involves more than memorizing ideas; it concerns understanding biological mechanisms present in the world. Practical experiments can support this! Working through experiments allows you to bridge theory vs actual data, and also prepares you for your Internal Assessment (IA) and final examination.
The experiments can not only contribute to making learning fun, but they will also help to build and evaluate key lab-based skills, such as data analysis and experimentation techniques that are necessary throughout the curriculum of IB curriculum.
At The Princeton Review Singapore, experienced tutors support you through the design and process of real and simulated lab sets, while helping to develop stronger internal assessments (IA), correctly report findings, and improve experimental evaluation methods.
IB Biology can feel overwhelming with endless notes, labs, IA deadlines, and revision! However, with some good time management techniques, you can manage everything with much ease.
When preparing for IB Biology, it is more than books alone; it is more about well-understood concepts, contexts for application, and practicing exam-style questions. So, where can you prepare effectively?
Most students start with school resources — your IB teacher, laboratory classes, and past papers are a great starting point! If you are seeking extra support, IB tuition centers or online coaching programs can help!
They provide students with a dedicated course that focuses on a deeper understanding of concepts, developing exam strategies, and obtaining individual feedback on assignments.
Following school resources, students can self-study independently using IB-approved textbooks and online resources, such as Pearson Biology for IB Diploma, Kognity, and IB resources. Each of these provides you with topic-based quizzes or revision notes to assess your knowledge from non-school-based support.
If you want to be prepared with other students and guided supervision, one of the best options is The Princeton Review Singapore, which helps students prepare for all three papers for IB Biology (1, 2, and 3).
