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Home › IB Diploma Programme › IB Biology
IB BIOLOGY
IB Biology tutor online for HL and SL
IB Biology rewards students who read data closely and use exact scientific words. IB Learning Star offers online tutoring for the IB Diploma Biology course first examined in 2025, for HL and SL students alike. One-on-one lessons run live on Google Meet at times that suit your time zone, and your first class is a free trial.
HL and SL
One-on-one on Google Meet
Lessons in your time zone
Free trial class
WHERE THE MARKS GO
Why strong Biology students still lose marks
Students who know their Biology still drop marks in the same places, and none of them is a gap in revision.
SLIDE
1
Vague words.
“The enzyme dies” earns nothing where “the enzyme is denatured” earns the mark. Biology markschemes look for the exact term.
SLIDE
2
Answers that ignore the data.
In a data-based question the numbers are the evidence. An answer that explains the biology but never quotes the graph leaves marks behind.
SLIDE
3
Long answers with missing points.
A fluent paragraph can still make fewer separate points than the question has marks.
We work on these from the first lesson, with your own class notes and past work in front of us. For students who learn Biology in a second or third language, we build a word bank for each topic and practise the terms in full sentences. The IB accepts either the common name or the scientific name for an organism in an answer, which is one less thing to memorize.
Our tutors are certified IBDP tutors or have completed IBDP training, at least IB Category 2 workshops, and they teach in IB schools.
This page describes the course first examined in 2025. We will update it if the IB publishes a new Biology guide.
THE COURSE
The four themes of IB Biology, and what HL adds
The course is organized into four themes, A to D, and each topic is viewed at one of four levels of organization: molecules, cells, organisms and ecosystems. The IB recommends 150 teaching hours at Standard Level and 240 at Higher Level. Those hours include practical work, a collaborative sciences project and the scientific investigation, so the four themes share 110 hours at SL and 180 at HL.
molecules
cells
organisms
ecosystems
A.
THEME
Unity and diversity
SL hours
19
HL hours
33
WHAT IT COVERS
Water, nucleic acids, cell structure, diversity of organisms, evolution and speciation, conservation. HL adds origins of cells, viruses, and classification and cladistics.
B.
THEME
Form and function
SL hours
26
HL hours
39
WHAT IT COVERS
Carbohydrates, lipids and proteins, membranes, organelles, cell specialization, gas exchange, transport, adaptation and niches. HL adds muscle and motility.
C.
THEME
Interaction and interdependence
SL hours
31
HL hours
48
WHAT IT COVERS
Enzymes, cell respiration, photosynthesis, neural signalling, body systems, defence against disease, populations and energy flow. HL adds chemical signalling.
D.
THEME
Continuity and change
SL hours
34
HL hours
60
WHAT IT COVERS
DNA replication, protein synthesis, mutations and gene editing, cell division, water potential, reproduction, inheritance, homeostasis, natural selection, climate change. HL adds gene expression.
HL ONLY
HL students study every SL topic in more depth and take six topics that SL students do not: origins of cells, viruses, classification and cladistics, muscle and motility, chemical signalling and gene expression. Across the course HL adds 70 hours of material, with the most in theme D. If you are not sure which parts of a topic belong to your level, tell us at the trial class and we will map it for you.
THE EXAMS
How the Biology papers work
There are two papers at both levels. The course first examined in 2025 has no Paper 3 and no option topics, so older material built around options does not match it. Calculators are permitted. About half the marks on each paper go to analysing, evaluating and synthesizing, so recalling content is not enough on its own.
PAPER 1
36%
Paper 1: 1A and 1B
Paper 1 has two parts taken together. Paper 1A is multiple choice, and no marks are taken off for a wrong choice. Paper 1B has four data-based questions linked to experimental work and the syllabus, covering all four themes. At SL, Paper 1 lasts 1 hour 30 minutes and is out of 55 marks (30 for 1A, 25 for 1B). At HL it lasts 2 hours and is out of 75 marks (40 for 1A, 35 for 1B). Paper 1 is worth 36% of your grade at both levels.
MARKS
SL
1A · 30
1B · 25
HL
1A · 40
1B · 35
PAPER 2
44%
Paper 2
Paper 2 starts with a data-based question and short-answer questions in Section A, then extended-response questions in Section B. At SL it lasts 1 hour 30 minutes and is out of 50 marks: 34 in Section A and 16 in Section B, where you answer one of two questions. At HL it lasts 2 hours 30 minutes and is out of 80 marks: 48 in Section A and 32 in Section B, where you answer two of three. Paper 2 is worth 44% of your grade at both levels.
MARKS
SL
A · 34
B · 16
HL
A · 48
B · 32
Paper 1 · 36%
Paper 2 · 44%
Investigation · 20%
The remaining 20% comes from the scientific investigation, which your teacher marks and the IB moderates.
DATA QUESTIONS
Data-based questions in four reads
Paper 1B is built from data, and Paper 2 opens with a data question too. Students who do well read the data in the same order every time.
Read 1: axes and units.
What is measured, and in what unit?
›
Read 2: the trend, with numbers.
Say what happens and quote values from the graph or table.
›
Read 3: the comparison.
Compare one stretch with another, or one group with another, using the numbers.
›
Read 4: the biology.
Now explain, using the terms the markscheme looks for.
WORKED CASE
A worked case: an enzyme and temperature
A student measures the rate at which an enzyme releases oxygen at four temperatures: 2.1 cm³ min⁻¹ at 20 °C, 4.4 at 30 °C, 7.9 at 40 °C and 3.2 at 50 °C. The question says: explain the change in rate between 40 °C and 50 °C.
1
Read 1: temperature in °C, rate in cm³ of oxygen per minute.
2
Read 2: the rate rises from 2.1 to 7.9 between 20 °C and 40 °C, about 3.8 times, then falls to 3.2 at 50 °C, a drop of about 59% from the peak.
3
Read 3: the fall over the last 10 °C (4.7 cm³ min⁻¹) is bigger than the rise over either earlier 10 °C step (2.3 and 3.5), so something besides simple speeding up has happened.
4
Read 4: below the peak, warmer molecules move faster, so substrate and active site collide more often. Above it, the extra energy breaks the bonds that hold the enzyme in its three-dimensional shape.
FULL ANSWER
A full answer reads: “Between 40 °C and 50 °C the rate falls from 7.9 to 3.2 cm³ min⁻¹. The higher temperature breaks bonds that hold the enzyme’s shape, so the active site changes shape and the substrate no longer fits. The enzyme is denatured, fewer enzyme-substrate complexes form, and less oxygen is released each minute.”
One more habit: the graph has no reading between 40 °C and 50 °C, so it cannot show that 40 °C is the optimum. A careful answer says so.
LONG ANSWERS
Long answers: one marking point per sentence
Section B asks for extended responses, so a single answer carries a lot of marks. We plan these before writing: list the points the question needs, then write one point per sentence so that each one can earn a mark.
INSTEAD OF
WRITE
The enzyme dies.
The enzyme is denatured.
Oxygen goes into the blood.
Oxygen diffuses across the alveolar wall into the capillaries, down a concentration gradient.
The bacteria became resistant.
Bacteria with an allele for resistance survived the antibiotic and reproduced, so more of the next generation carried that allele.
Explain
Compare
Evaluate
Discuss
The command term in the question decides what each point must do. Explain asks for reasons or causes. Compare asks you to refer to both items throughout. Evaluate asks for strengths and limitations, and discuss asks for a balanced range of arguments. We practise reading the command term first, every time.
THE INVESTIGATION
Choosing an investigation you can finish
The scientific investigation is worth 20% of your grade at both levels. You answer a research question of your own by collecting and analysing quantitative data, and you report it in up to 3,000 words. The report is marked out of 24 on four criteria worth 6 marks each: research design, data analysis, conclusion and evaluation.
4 × 6 = 24
School lab
Fieldwork
Spreadsheet or model
Database
Simulation
A school lab experiment is one route. The guide also allows fieldwork, a spreadsheet analysis or model, data taken from a database, and a simulation. A student whose school lab is limited therefore still has choices. Whatever the route, the question needs a dependent variable that can be measured well.
In lessons we help you choose a question you can measure with what you have, plan the range and number of readings, work out the uncertainty, read your draft against the four criteria and sharpen the evaluation.
LESSONS
What a Biology lesson looks like
01
The first lesson is a diagnostic. You show us a recent test or paper and we find where the marks went: a vague term, a data question answered without numbers, or a long answer with points missing. After it we agree a plan around your weakest topics and your exam session.
02
Each lesson takes one topic and ends with a full answer in the form the IB markscheme rewards. You get a short set of questions to try before the next lesson. Closer to the exams we add timed Paper 1B and Paper 2 questions, with written feedback on your wording.
Lessons are one-on-one on Google Meet, in your time zone.
FAQ
What Biology students and parents ask us
Q
My child knows the content but still gets a 4. What changes in lessons?
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We look at where the marks are going before we teach anything new. Usually it is exact wording, answers that skip the numbers in the data, or long answers with too few separate points. Lessons practise those three things on real exam-style questions, and we show the corrections in writing.
Q
Can the investigation use a database or a simulation instead of a lab?
⌄
Yes. The IB allows lab work, fieldwork, spreadsheet analysis and modelling, data from a database, and simulations. The investigation must still collect and analyse quantitative data and answer your own research question. Ask your teacher what your school accepts.
Q
How is HL Biology different from SL?
⌄
HL has 70 more teaching hours, longer papers and extra content, including six topics SL students do not take: origins of cells, viruses, classification and cladistics, muscle and motility, chemical signalling and gene expression. The skills of reading data and writing exact answers are the same at both levels.
Q
Which past papers still fit the new course?
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Q
Can lessons help with Biology vocabulary if English is not my first language?
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Yes. We build a word bank for each topic and practise the terms in full answers. For organisms, the IB accepts the common name or the scientific name.
Q
Can I use a calculator in the Biology papers?
⌄
Yes, calculators are permitted in Paper 1 and Paper 2. Your school will tell you which models the IB allows.
Q
Who teaches the lessons?
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Your tutor is a certified IBDP tutor or has completed IBDP training, at least IB Category 2 workshops, and teaches in an IB school. We match the tutor to your course and level.
Q
Will lessons fit my time zone?
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Yes. Lessons are one-on-one on Google Meet and we plan them around your school day, wherever you are.
Q
How do I start?
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Book a free trial class. We use it to see where you are, then suggest a plan and a lesson schedule.
Use papers written for the course first examined in 2025. Older papers include Paper 3 and option topics, which this course no longer has, so they match only the topics that remain. Your tutor will tell you which older questions are still useful.
Start with a trial class for Biology
Tell us your level (SL or HL), your exam year and the topics that worry you most. We will plan the first lesson around them.
