AP · session May 2027
Biology
Eight units, from molecules to ecosystems, written to the course and exam description effective fall 2025.
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Unit 1Chemistry of Life
Topic check · 5 questions- 1.1 Structure of Water and Hydrogen Bonding How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.2 Elements of Life How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.3 Introduction to Macromolecules How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.4 Carbohydrates How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.5 Lipids How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.6 Nucleic Acids How does the chemistry of a few kinds of atoms and molecules make life possible?
- 1.7 Proteins How does the chemistry of a few kinds of atoms and molecules make life possible?
Unit 2Cells
Topic check · 5 questions- 2.1 Cell Structure and Function How does the structure of each part of a cell let it do its job?
- 2.2 Cell Size Why are cells small, and why do small animals burn energy faster per kilogram than large ones?
- 2.3 Plasma Membrane How are the molecules of a plasma membrane arranged, and why that way?
- 2.4 Membrane Permeability Why do some substances cross a membrane easily while others cannot cross at all without help?
- 2.5 Membrane Transport How do cells move substances in and out, and when does it cost them energy?
- 2.6 Facilitated Diffusion How do substances the bilayer blocks get across without the cell paying for it?
- 2.7 Tonicity and Osmoregulation Which way will water move, and how do organisms keep their water balance?
- 2.8 Mechanisms of Transport How do cells use energy to move ions against their gradients, and why does it matter?
- 2.9 Cell Compartmentalization What does a eukaryotic cell gain by dividing itself into compartments, and what does it lose if a compartment fails?
- 2.10 Origins of Cell Compartmentalization How did eukaryotic cells come to have membrane-bound organelles, and how is compartmentalization different in prokaryotes?
Unit 3Cellular Energetics
Topic check · 5 questions- 3.1 Enzymes How do living things capture energy, and how do they spend it?
- 3.2 Environmental Impacts on Enzyme Function How do living things capture energy, and how do they spend it?
- 3.3 Cellular Energy How do living things capture energy, and how do they spend it?
- 3.4 Photosynthesis How do living things capture energy, and how do they spend it?
- 3.5 Cellular Respiration How do living things capture energy, and how do they spend it?
Unit 4Cell Communication and Cell Cycle
Topic check · 5 questions- 4.1 Cell Communication How do cells pass information to one another, near and far, so that a body or a colony acts as one?
- 4.2 Introduction to Signal Transduction What happens between a signal arriving at a cell and the cell responding?
- 4.3 Signal Transduction Pathways What can a signal make a cell do, and what happens when part of the pathway is broken, blocked or stuck on?
- 4.4 Feedback How does a body keep a condition near a target value, and why does it sometimes push a condition further from it on purpose?
- 4.5 Cell Cycle What happens, in order, between one cell division and the next, and how does mitosis give two cells with identical genomes?
- 4.6 Regulation of Cell Cycle How does a cell decide whether to move on to the next stage of the cycle, and what happens to the organism when that control fails?
Unit 5Heredity
Topic check · 5 questions- 5.1 Meiosis How does a diploid cell make haploid gametes, and how does that carry chromosomes from parents to offspring?
- 5.2 Meiosis and Genetic Diversity Why are brothers and sisters, from the same two parents, never genetically identical (unless they are identical twins)?
- 5.3 Mendelian Genetics If you know the parents' genotypes, how well can you predict the offspring, and how do you test whether real offspring fit the prediction?
- 5.4 Non-Mendelian Genetics When offspring do not come out in Mendel's ratios, what is going on, and how can the data tell you which explanation fits?
- 5.5 Environmental Effects on Phenotype If two organisms have exactly the same genes, why can they still look different?
Unit 6Gene Expression and Regulation
Topic check · 5 questions- 6.1 DNA and RNA Structure What is it about DNA and RNA that lets them carry instructions from one generation to the next?
- 6.2 DNA Replication How does a cell make an exact copy of its DNA before it divides?
- 6.3 Transcription and RNA Processing How is the information in a gene copied into a message the cell can use, and how is that message prepared?
- 6.4 Translation How does a sequence of bases become a working protein?
- 6.5 Regulation of Gene Expression How does a cell switch its genes on and off, and turn them up and down?
- 6.6 Gene Expression and Cell Specialization How do cells with identical DNA end up doing completely different jobs?
- 6.7 Mutations How do changes in DNA change organisms, and why do those changes matter for evolution?
- 6.8 Biotechnology How do scientists copy, separate, read and transfer DNA, and what can the results tell them?
Unit 7Natural Selection
Topic check · 5 questions- 7.1 Introduction to Natural Selection Why do some traits become more common in a population over time, while others fade out?
- 7.2 Natural Selection Why does a population need variation to survive a changing environment, and why can the same trait help in one place and harm in another?
- 7.3 Artificial Selection How do people change the variation in the species they breed, and what does that do to the diversity inside a population?
- 7.4 Population Genetics How can a population evolve when nothing is selecting anything, simply by chance?
- 7.5 Hardy–Weinberg Equilibrium What would a population's allele and genotype frequencies look like if nothing were changing them, and how do we use that to tell whether it is evolving?
- 7.6 Evidence of Evolution How do we know that organisms have changed over time and share common ancestors?
- 7.7 Common Ancestry What features inside cells show that every eukaryote, from fungi to plants to animals, shares a single common ancestor?
- 7.8 Continuing Evolution How do we know evolution is still happening, and why does it matter for medicine and farming?
- 7.9 Phylogeny How do biologists work out, and draw, how closely related different species are?
- 7.10 Speciation How does one species split into two, and why does that sometimes happen fast and sometimes very slowly?
- 7.11 Variations in Populations Why are genetically diverse populations more likely to survive a disease, a drought or a new predator, and why are small, uniform populations at risk?
- 7.12 Origins of Life on Earth What evidence tells us when life on Earth began, and why might RNA have come before DNA and proteins?
Unit 8Ecology
Topic check · 5 questions- 8.1 Responses to the Environment How do organisms respond to changes around them, and why do those responses decide who survives and reproduces?
- 8.2 Energy Flow Through Ecosystems How does energy flow and matter cycle through an ecosystem, and what happens when the energy supply changes?
- 8.3 Population Ecology What decides how fast a population grows, and what does growth look like when nothing holds it back?
- 8.4 Effect of Density on Populations Why does a growing population slow down and level off, and how do we calculate its growth when it does?
- 8.5 Community Ecology How do we describe a community, and how do the interactions between its species change it over time?
- 8.6 Biodiversity Why do diverse ecosystems cope better with change, and what happens when one part is added or removed?
- 8.7 Disruptions in Ecosystems How do new species, human activity and natural events disrupt ecosystems, and how do populations respond?
The course in one page
The course in one page. Eight units, from molecules to ecosystems, written to the course and exam description effective fall 2025. The May 2027 exam is on Monday 3 May 2027, in the afternoon.
The exam
| Section | What | Time | Share of the score |
|---|---|---|---|
| I | 60 multiple-choice questions, four options each | 90 min | 50% |
| II | 6 free-response questions | 90 min | 50% |
The exam is hybrid: you answer Section I on screen in the College Board's Bluebook app, and you write Section II by hand in a paper booklet. A calculator is allowed in both sections (four-function, scientific or graphing; Bluebook has one built in), and you get the AP Biology Equations and Formulas sheet in both.
Section I is not a memory test. Most questions start from something to read: a data table, a graph, an experiment, a model of a pathway, a pedigree. Some come in sets of four or five on one shared stimulus.
Section II, question by question
| Question | Type | Points | Time to spend |
|---|---|---|---|
| 1 | Interpreting and evaluating experimental results | 9 | about 25 min |
| 2 | Interpreting and evaluating experimental results, with graphing | 9 | about 25 min |
| 3 | Scientific investigation | 4 | about 10 min |
| 4 | Conceptual analysis | 4 | about 10 min |
| 5 | Analyse a model or visual representation | 4 | about 10 min |
| 6 | Analyse data | 4 | about 10 min |
34 points in all. Each point is one idea a reader looks for: an identified variable, a justified prediction, a correctly plotted graph with labelled axes and error bars, a claim backed by evidence and reasoning. A long answer that never commits to a claim scores nothing for that point.
The eight units
| Unit | What it covers | Share of Section I |
|---|---|---|
| 1 Chemistry of Life | water, the elements of life, and the four kinds of large molecule | 8–11% |
| 2 Cells | cell structure, size, membranes and transport, compartments, how cells arose | 10–13% |
| 3 Cellular Energetics | enzymes, energy, photosynthesis, respiration | 12–16% |
| 4 Cell Communication and Cell Cycle | signalling, feedback, the cell cycle and its control | 10–15% |
| 5 Heredity | meiosis, Mendel and beyond, the environment's part | 8–11% |
| 6 Gene Expression and Regulation | DNA and RNA, replication, transcription, translation, regulation, mutation, biotechnology | 12–16% |
| 7 Natural Selection | selection, population genetics, evidence for evolution, phylogeny, speciation, the origin of life | 13–20% |
| 8 Ecology | responses to the environment, energy flow, populations, communities, biodiversity, disruption | 10–15% |
Units 3, 6 and 7 together are up to half of Section I. Unit 7 alone can be a fifth.
The skills it marks
The course and exam description names six science practices, and every question tests one of them on top of the biology:
- Concept explanation: explain a process or a structure and what it does.
- Visual representations: read a diagram or model, and say what it shows or leaves out.
- Questions and methods: hypotheses, independent and dependent variables, controls, what an experiment can and cannot show.
- Representing and describing data: draw the right graph, describe a trend.
- Statistical tests and data analysis: calculations from the formula sheet (chi-square, standard error, Hardy–Weinberg, water potential, rates, Simpson's index), and what error bars say.
- Argumentation: make a claim, back it with evidence, give the reasoning that links them.
How it is scored
Your Section I and Section II scores are combined and converted to a score from 1 to 5. A 3 is "qualified", and many colleges give credit for a 3 or 4 and above. College Board does not publish the cut-off for each score, and it changes from year to year. In May 2026, 71% of students scored 3 or higher and 15% scored 5. When Educerie gives you a likely score, it is a range from our own questions, never a College Board score.
These notes
One page for every topic in the course and exam description, in its order: what you must be able to do, the biology, where marks are lost, and questions to try with model answers. Every explanation and question is Educerie's own, written from the published description. AP is a trademark of College Board, which does not endorse Educerie.