How to answer Paper 2: data analysis and short answers in Section A, and choosing, planning and writing extended responses in Section B.
Paper 2 is a single booklet in two sections. Section A has data-based and short-answer questions across the whole course. Section B has extended-response questions, from which you choose: SL candidates answer one of two, HL candidates two of three. Section A rewards precise, short answers tied to data; Section B rewards planned, well-organised answers that cover every part of the question.
At SL, Paper 2 lasts 1 hour 30 minutes and is worth 50 marks: 34 in Section A and 16 in Section B. At HL it lasts 2 hours 30 minutes and is worth 80 marks: 48 in Section A and 32 in Section B, from two questions of 16 marks each. Paper 2 carries 44% of the final grade at both levels.
Both sections draw on the same knowledge as Paper 1. None of the questions is multiple choice, so every mark depends on what you write, draw or calculate.
Section A usually opens with a longer data-based question, built on several linked data sets from published research or experiments, followed by structured questions on different parts of the course. Each structured question is split into short parts, each with its own command term and a small number of marks.
The data-based question gives two to five related figures or tables and asks a series of questions that move from reading the data to explaining and evaluating it. Later parts often ask you to combine information from two figures, so it pays to read every figure and its caption before writing.
Read the introduction: what organism, what was measured, and what each figure shows.
For each figure, read the title, axes, units and key, and note the main trend in the margin.
Answer each part in order, with values and units from the data.
Where a part says "using the data" or "with reference to figure 2", quote from that figure.
Use your biology to explain trends, but keep the explanation tied to the context given.
A student counted stomata on the upper and lower surfaces of ten leaves of one species of broad-leaved plant, using nail-varnish impressions viewed under a light microscope. The results, a practice data set, are shown in the table.
Leaf surface | Mean stomatal density / mm⁻² | Standard deviation / mm⁻² | Number of leaves |
|---|---|---|---|
Upper (adaxial) | 38 | 9 | 10 |
Lower (abaxial) | 210 | 18 | 10 |
The short-answer questions test recall and understanding across all four themes. Typical stems are "label the diagram", "outline the role of", "explain how", "compare and contrast", "draw a molecular diagram of" and "annotate the graph to show". Answers should be as long as the marks require and no longer: one precise point per mark.
Stem | Marks | What a full-mark answer contains |
|---|---|---|
State the name of the bond formed between two amino acids. | 1 | Peptide bond. |
Outline the role of ATP synthase in the mitochondrion. | 2 | Enzyme in the inner membrane; uses the flow of H⁺ through it to make ATP from ADP and phosphate. |
Explain how the structure of the alveolus is adapted to gas exchange. | 3 | Three features, each with its function: one cell thick (short diffusion distance); large total surface area; dense capillary network maintaining a concentration gradient. |
Compare and contrast the structure of DNA and RNA. | 3 | One similarity and two paired differences: both are polymers of nucleotides; deoxyribose versus ribose; thymine versus uracil; double-stranded versus single-stranded. |
Section A often asks for a drawing: a molecular diagram (glucose, an amino acid, a dipeptide, a phospholipid), a diagram from a micrograph, a pedigree chart, a Punnett grid, a cladogram or an energy pyramid. Marks go to named features drawn correctly and labelled clearly.
Molecular diagrams: every atom and bond shown, OH and H groups on the correct carbons, the correct ring form (α- or β-glucose), the bond that joins two units labelled.
Diagrams of structures: the features the question names, in the right positions and proportions, with ruled label lines that touch the structure.
Sketch graphs: labelled axes with variables (units if known), the correct shape and the key features labelled.
Sketching a graph from memory is a common Section A task. The oxygen dissociation curve for adult haemoglobin is a typical example, with its HL extension, the Bohr shift.
Each Section B question is worth 16 marks. Fifteen are for the content, split between labelled parts, typically three, such as 4 + 4 + 7 or 3 + 5 + 7; the sixteenth is for the quality of the answer as a whole. The parts usually move from describe or outline to explain or discuss, and they often draw on more than one theme. A question might start with protein structure and end with a gene mutation, or start with the structure of a leaf and end with the global carbon cycle.
The choice is one of the few decisions that can change your Paper 2 mark by several marks at once. Spend a few minutes on it.
Read every part of every Section B question, not just the first part.
For each question, ask whether you can answer the part with the most marks well, because that part decides most of the score.
Check the command terms: an "explain" or "discuss" part needs reasons and balance, not just facts you remember.
Choose the question where you can write the most distinct, correct points across all its parts.
Section B markschemes are lists of acceptable points for each part, with a maximum for the part. There are usually more points listed than marks available, so an answer can reach full marks without making every point. Each point is credited once: repeating an idea in different words does not add marks. Points written in the wrong part may not be credited, so answer each part under its own label.
One mark of the 16 is awarded for the quality of the whole answer. It is given when the answer is clear enough to be followed without rereading, is concise, and has little or no repetition or irrelevant material. Writing one idea per sentence, with the correct terms throughout, earns this mark and also makes each content point easier to credit.
A plan of one or two minutes for each part prevents both padding and missing points. Write it as a list of key words in the margin or on the planning space, and tick each item off as you use it.
Underline the command term and the scope of each part ("in humans", "with reference to one example").
List the points you can make for the part, then order them logically: structure before function, cause before effect, steps in sequence.
Write one point per sentence, using technical terms.
Include a labelled diagram where it carries marks more quickly than words (a membrane, a nephron, a cladogram), and refer to it in the text.
For "discuss" and "evaluate", plan points on both sides and a final judgement.
Leave a few minutes at the end to reread for missing words and contradictions.
The question links three subtopics: DNA structure (A1.2 Nucleic acids), DNA replication (D1.1) and the effect of a mutation on a protein and on the phenotype (D1.2 Protein synthesis, D1.3 Mutation and gene editing, B1.2 Proteins). It is set at SL; an HL paper might replace part (b) with the roles of the specific replication enzymes.
Problem | What it looks like | What to do instead |
|---|---|---|
Describing instead of explaining | "The rate increases and then levels off." | Add the cause of each change: "because light is no longer the limiting factor". |
Unpaired comparisons | A paragraph on mitosis and a paragraph on meiosis. | Pair every point, or use a table. |
Vague data description | "It goes up." | Quote the values, units and range: "from 4.2 to 14.3 cm³ between 10 and 40 °C". |
Imprecise terms | "Energy is produced"; "the enzyme dies"; "water moves down a concentration gradient". | "ATP is produced"; "the enzyme is denatured"; "water moves from higher to lower water potential". |
Teleology | "Bacteria become resistant in order to survive." | "Resistant bacteria survive and reproduce, so the allele for resistance becomes more common." |
Skipping part of a question | One side of "discuss", or no judgement in "evaluate". | Plan both sides and a conclusion before writing. |
With a free account, Augment remembers where you stopped in the notes and which questions you have marked.