Biology: Overview
Your essay must focus on the science of living organisms. If your topic touches on other areas (like medicine, sports science, or ethics), you must keep the focus firmly on biology.
Avoid Unethical or Dangerous Topics
Simple, safe experiments using school equipment are encouraged and can score very highly!
Pick a Topic You Can Actually Research
How to Research Your Topic
You have two main paths:
Path 1: Primary Research (Doing an Experiment)
Examples: Testing plant growth with different fertilizers, surveying insect diversity in two areas, studying the behavior of fish in response to light.
Path 2: Secondary Research (Using Existing Data)
Example: Taking a public data set on climate change and a specific bird population, and performing your own statistical analysis to find a correlation.
Writing the Essay
Start with a Clear Plan
The "So What?" Factor (Analysis)
Examples: "My sample size was small," "My measuring tool was not very precise," "It's hard to control every variable when working with living plants."
Show Your Own Work
In short: Pick a safe, biological topic you love, do a careful investigation, and then focus on explaining and criticizing your own results like a true scientist.
Requirements for a Biology EE
Ensure your paper meets the requirements: Print, highlight, and annotate this page and pin it above your desk!
Use Command Terms in your essay to indicate a strong background in your subject
Read what EXAMINERS have said to know what the examiners are looking for.
Read about a BROAD topic to gradually narrow to a FOCUSED topic.
Once you have a focused topic, read more to generate a Research Question that you KNOW you can answer in a thesis statement.
Think of your Extended Essay as a scientific detective story. You're investigating a question, gathering clues (data), and reaching an evidence-based conclusion.
Do Your Homework First: Before you do anything else, you need to become an expert on the basic science behind your topic. This is true for everyone, whether you're doing an experiment or a literature-based essay.
Understand the Concepts: Use textbooks and reliable websites to fully grasp the theories and concepts. You can't analyze advanced research if you don't understand the basics.
Choose Good Sources: When you move to scientific journals and articles, make sure they are credible. Explain in your essay why you chose these specific sources.
A Sharp Question is Key: Your entire essay is built around your research question. It must be focused and clear.
What Makes a Good Question?
It sets the structure for your entire essay.
It leads to a specific methodology (an experiment or a way to analyze data).
It uses the correct scientific terminology.
All the variables in your question must be things you can clearly define and measure.
Remember: You must use metric units (The International System of Units - SI)!
Write a Recipe: Your method should be so clear and detailed that another student could read it and repeat your investigation exactly.
Be Scientific: Your plan must show that you are controlling variables and measuring things in a standardized, fair way.
Be Clear and Organized: Present your data in tables, graphs, or diagrams. Everything must be clearly labeled with titles, units, and numbers so it's easy to understand.
For Secondary Research: It's okay to use graphs from other sources, but you must do your own analysis of that data. You can't just copy their conclusions.
What Does It All Mean? This is where you explain the significance of your results. Do they answer your research question?
"Negative" Results are Still Results! If your data does NOT support your original hypothesis, that is perfectly fine! A honest analysis of unexpected results often makes for a more interesting and sophisticated essay.
Support Your Claims: Your conclusions must be directly backed up by the data you presented.
Be Your Own Biggest Critic: This is where you show you're a true scientist. You must critically evaluate your own work.
Ask Yourself:
How did my methodology affect my results? Was it a good way to answer my question?
What were the limitations? (e.g., small sample size, imperfect equipment, time constraints)
How could this investigation be improved in the future?
What new questions did my research uncover?
Your EE is a journey of scientific inquiry. It's not about proving you were right from the start. It's about showing you can ask a meaningful question, follow a rigorous process, and think critically about your findings, whatever they may be.
Sample Research Questions
Review the topics & questions below
Topic: KNO3 concentrations and growth rate
Research question: What is the effect of increasing KNO3 concentrations (0.1 mM, 0.2 mM, 0.3 mM, 0.4 mM, 0.5 mM) on the growth rate of onion roots (Allium cepa)?
Outline of Approach: Independent variables, such as increasing nitrate concentrations, may have to be fine-tuned. Some concentrations may lead to the death of the plants. A pilot experiment is recommendable, as well as comparing with published (scientific) concentrations.
Topic: Parity as a measurable variable in the development of breast cancer
Research question: To what extent is parity a measurable variable in the development of breast cancer?
Outline of Approach: Studies from different countries reporting rates of breast cancer and associated risk factors are accessed using PubMed, Directory of Open Access Journals (DOAJ), JSTOR, Google Scholar and Science Direct. Studies are selected using a set of predetermined criteria that are clearly explained.
The data from the selected journal articles is analysed and evaluated in a way that allows valid comparisons to be made. It must then be made clear how the data has been interpreted and manipulated.
Biology Questions, scoring A or B
(from the OLD GUIDE - use for ideas only)
How do different concentrations of aspartame etc etc affect differently on the human gut microbiota etc etc?
How does the effectiveness of cotrimoxazole on Escherichia coli differ from different drug dispensaries in the Pakkret region?
How do different concentrations of βTamarindus indicaβ pulp solution extracted by using 50% aqueous ethanol and 70 ΜC deionized water affect differently on βEscherichia coliβ as measuredβ by the zone of inhibition?
How do different doses of the antioxidants Vitamin C and Vitamin E affect the human immune system in the short-term?
To what extent do adding different concentrations of Plant Growth Promoting Rhizobacteria (PGPR), affect the growth of seeds of non-legumes of agricultural plant, Jasmine rice (Oryza Stiva L.), measured by the length of roots and shoots?
Past Papers: Why Read Them?
Biology Papers
Examples from the OLD GUIDE, to be used for ideas only
Assessment of a Science Essay
Review the general assessment criteria in the Assessment Tab first.
Then review these descriptors, specific to SCIENCE courses, to see what to focus on.
Five Criterion: Full marks = 30 points
A: Framework for the Essay
The research question will decide the research methods, which then need to yield appropriately scientific data that supports a logical response to it. A focused question encourages strong data analysis and critical evaluation of findings.
For sciences extended essays where the research is conducted in universities or other external organizations, ensure that the methods used are your own and not just those established by the organization.
Structural conventions: essays in the sciences often include more data than other subjects, so make sure that data tables, diagrams and graphs can be clearly understood and are appropriately labelled, and that all data is clearly processed. Examples of calculations should include mathematical uncertainties on the measurements collected.
B: Knowledge and Understanding
Knowledge and understanding must be demonstrated by exploring and discussing the underlying processes and theories, using clear and well-explained terminology. This is especially critical in essays based on secondary data. For example, when investigating the turnover rate of an enzyme, it is essential to discuss enzyme kinetics.
C: Analysis and Line of Argument
Analysis must follow standard processes, including qualitative and quantitative approaches and statistical methods where appropriate, and may include mathematical transformation. The analysis should be done in such a way as to address the research question directly.
Analysis of secondary data must be your own.
A clear line of argument should be maintained throughout and all elements of your sciences extended essay should be linked; only then is it effective in communicating your message. For example, if the topic is about the kinetics of photosynthesis, then discussion of the morphology of plant leaves is not relevant.
If the research question is not fully answered, you should state unresolved issues, account for these and suggest improvements.
D: Discussion and Evaluation
The discussion should be critical, have a scientific context and must always be linked to the research question. Ensure that discussions use the sources to support conclusions.
The conclusion should not be a repetition of results but a supported, well-explained synthesis of them.
The evaluation of your essay should indicate any unresolved issues, accounting for these and suggesting improvements, and should be linked to the findings and the research question.