Cambridge AS & A Level Biology 9700/32 is the May/June 2026 Paper 3 (Advanced Practical Skills), variant 2. It is the AS Level practical paper, lasts 2 hours and is worth 40 marks. It had two compulsory questions: a 22-mark investigation into vitamin C and boiling, and an 18-mark microscopy question on a leaf. This guide goes through each task and shows what the official mark scheme gave marks for. The paper and its mark scheme are free on the Tutopiya Learning Portal.

For an overview of all five 9700 papers from this series, see A Level Biology 9700 May/June 2026 past papers: what came up and how it was marked.

9700/32 at a glance

Question	Task	Marks	Main skill
1(a)	Serial dilution of vitamin C, DCPIP titrations, vitamin C in a vegetable extract before and after boiling	13	Planning, recording, estimating
1(b)	Graph and conclusions: vitamin C tablets and blood vitamin C concentration	9	Graph, conclusions, reading a graph
2(a)	Plan diagram of a leaf section, drawing four outer cells, differences from a photomicrograph	13	Drawing and observation
2(b)	Calibrating an eyepiece graticule and measuring a resin duct	5	Calculation
	Total	40

Task-by-task walkthrough

Question 1: the effect of boiling on vitamin C (22 marks)

You had a 1.0% vitamin C solution (C), a vegetable extract with an unknown vitamin C concentration (U), DCPIP and distilled water (W). Vitamin C turns blue DCPIP yellow or orange, and the end-point is when the blue disappears. The more concentrated the vitamin C, the smaller the volume needed. You first practised finding the end-point by adding C drop by drop from a 1 cm³ syringe to 1.0 cm³ of DCPIP.

• Planning the serial dilution, 1(a)(i) (3 marks): four more concentrations, each half the one before, with 10 cm³ of each left over at the end. The first beaker in Figure 1.1 already held 20 cm³ of C. The marks were for the concentrations 0.5, 0.25, 0.125 and 0.0625, with % shown at least once (1); an arrow showing 10 cm³ transferred from the previous beaker into each new one (1); and an arrow showing 10 cm³ of water added to each beaker (1).
• Results table, 1(a)(ii) (5 marks): you made the dilutions, added each one drop by drop to 1.0 cm³ of DCPIP and recorded the volume needed to the nearest 0.01 cm³ (or “more than 1.0” if the DCPIP stayed blue). The five marks were:
  1. the independent variable heading (percentage concentration of vitamin C) in the first column, with no units in the body of the table;
  2. the dependent variable heading, volume of vitamin C / cm³, with no units in the body;
  3. a volume recorded for every concentration;
  4. a trend in the right direction: the volume for the highest concentration lower than for the lowest;
  5. volumes recorded to 0.01 cm³.
• Volumes of U and boiled U, 1(a)(iii) (1 mark): you titrated U against DCPIP, boiled the rest of U for 2 minutes, let it cool for at least 5 minutes and titrated it again. Recording both volumes earned the mark.
• Estimating vitamin C in U, 1(a)(iv) (1 mark): compare each volume with your own table to estimate a concentration before and after boiling. There is no fixed answer; the mark was for an estimate that matches your results.
• Explaining your results, 1(a)(v) (1 mark): any one explanation that fits your data: water evaporated during boiling; the vitamin C was broken down (bonds broken); or heating had no effect.
• Why find the end-point first, 1(a)(vi) (1 mark): so that the end-point is judged consistently in every test.
• Why counting drops is less accurate, 1(a)(vii) (1 mark): drop size varies.

Part (b) gave data on 250 volunteers who took tablets of different masses of vitamin C, with the average blood concentration 5 hours later. The blood concentration was 98 µmol dm⁻³ with no vitamin C and 202 µmol dm⁻³ with a 3.00 g tablet.

• Graph, 1(b)(i) (4 marks): axes labelled with the variable and unit, mass of vitamin C in tablet / g on x and average concentration of vitamin C in blood / µmol dm⁻³ on y (1); scales of 0.5 g to 2 cm and 20 µmol dm⁻³ to 2 cm, labelled at least every 2 cm (1); all points plotted correctly (1); and the points joined with a thin line through every point (1). A line of best fit does not earn this mark.
• Two conclusions, 1(b)(ii) (2 marks): any two of: the more vitamin C taken, the higher the blood concentration; vitamin C is already in the blood before any is taken; at higher masses the curve levels off, so the relationship is not linear.
• Mass needed for a 50% rise, 1(b)(iii) (2 marks): one mark for the working, 98 × 1.5 = 147 µmol dm⁻³ (98 multiplied by 1.5, or half of 98 added to 98), and one for reading the mass at 147 correctly from your graph. Because 147 is between the values for 0.00 g and 1.00 g, the answer lies between those two masses.
• Why use 250 people, 1(b)(iv) (1 mark): to identify anomalous results or to avoid bias.

Question 2: microscopy of a leaf (18 marks)

Slide K1 was a stained transverse section of a leaf.

• Plan diagram, 2(a)(i) (5 marks): a large drawing of the whole section in sharp pencil, with one ruled label line to the palisade mesophyll. The marks were for: an appropriate size and no shading (1); drawing the correct section of the leaf (1); the vascular bundle in the correct proportion to the whole leaf, with no cells drawn (1); three lines for the epidermis and two lines around the vascular bundle (1); and a label line and label to the palisade mesophyll layer (1).
• Drawing four cells, 2(a)(ii) (5 marks): two adjacent epidermal cells and two adjacent hypodermal cells, each touching at least two others, with the cuticle. The marks: appropriate size with sharp, continuous lines (1); only four cells, each touching at least two others, with a cuticle drawn (1); two lines around each cell and three lines where two cells touch (1); the correct shape of the cells (1); and a label line and label to the cuticle (1).
• Three differences from Figure 2.1, 2(a)(iii) (3 marks): one mark per correct observable difference, not colour. The mark scheme’s examples: the overall shape (K1 square, Figure 2.1 semicircular), the shape of the vascular bundle (circular against oval), the number of resin ducts (fewer in K1) and the palisade cells (thinner in K1, thicker in Figure 2.1). Put each feature in its own row with a comparison in both columns.

Part (b) used two photomicrographs taken with the same microscope and lenses.

• Calibrating the eyepiece graticule, 2(b)(i) (2 marks): one stage micrometer division is 0.25 mm. Read from Figure 2.2 how many eyepiece units line up with one stage division (1). One eyepiece unit is then 0.25 mm divided by that number of units, multiplied by 1000 to give micrometres; the second mark was for working that shows the division and the conversion to micrometres (1).
• Length of the resin duct lumen, 2(b)(ii) (3 marks): measure the lumen in Figure 2.3 in eyepiece units (1), multiply by your answer to 2(b)(i) (1) and give the answer to two significant figures (1). Give the unit, because the answer line does not print one.

Where the marks are on 9700/32

• Biological drawing carried 10 marks: the plan diagram (5) and the four-cell drawing (5). Most of these marks are for following rules (size, line quality, no shading, no cells in a plan, label lines), so they are the most reliable marks on the paper.
• Recording and planning carried 9 marks: the serial dilution diagram (3), the results table (5) and recording the volumes of U (1).
• Calculations and estimates carried 8 marks: 1(a)(iv) (1), 1(b)(iii) (2) and the graticule questions in 2(b) (5).
• Explaining, concluding and evaluating carried 6 marks: 1(a)(v), 1(a)(vi), 1(a)(vii), the two conclusions in 1(b)(ii) and 1(b)(iv).
• The graph carried 4 marks, and observing differences carried 3.

How to self-mark 9700/32 with the mark scheme

1. Learn the abbreviations first. A semicolon separates marking points, a slash shows alternatives, A means accept, R means reject, I means ignore, AW means alternative wording, ecf means error carried forward and AVP means alternative valid point.
2. Accept that your readings are your own. The volumes in 1(a)(ii) and 1(a)(iii) and the estimates in 1(a)(iv) have no fixed answer. Check the table against the rules (headings, units only in headings, 0.01 cm³) and check that the trend runs the right way.
3. Check the dilution figures exactly: 0.5, 0.25, 0.125, 0.0625, 10 cm³ transferred and 10 cm³ of water each time.
4. Mark the graph point by point. Check the scale against 0.5 g and 20 µmol dm⁻³ per 2 cm, then check every point and that your line is thin and passes through all of them.
5. Mark the drawings strictly. Any shading, any cells inside the plan, more than four cells, or sketchy lines each lose a mark.
6. Check 2(b) for working and figures. No working can cost the method marks, and the duct length must be to two significant figures.

Sit 9700/32 as a timed mock

The paper allows 120 minutes for 40 marks, but Question 1 includes boiling for 2 minutes and cooling for at least 5, so plan the practical first. You can only sit the full paper with the lab materials; without them, practise the planning, table, graph and Question 2 parts. A workable plan:

Block	Marks	Time
Question 1(a): dilutions, titrations, boiling U	13	50 minutes
Question 1(b): graph and data questions	9	17 minutes
Question 2(a): plan diagram, cell drawing, differences	13	33 minutes
Question 2(b): graticule calculations	5	12 minutes
Check the table, graph and significant figures	–	8 minutes

While boiled U cools, draw the results table and start the graph in 1(b).

Other May/June 2026 9700 papers

• 9700 Paper 12 (Multiple Choice)
• 9700 Paper 22 (AS Level Structured Questions)
• 9700 Paper 42 (A Level Structured Questions)
• 9700 Paper 52 (Planning, Analysis and Evaluation)

Practise and download

• Download 9700/32 and its mark scheme on the Learning Portal →
• All 9700 May/June 2026 papers: overview and marking patterns
• Try a free A Level Biology quiz

Need help with a 9700 topic? Book a free trial lesson with an A Level Biology tutor →

Frequently asked questions

What was on 9700 Paper 32 May/June 2026? +

Two questions. Question 1 (22 marks) was a DCPIP practical on whether boiling reduces the vitamin C in a vegetable extract, plus a graph of blood vitamin C against the mass of vitamin C in a tablet. Question 2 (18 marks) was microscopy: a plan diagram of a leaf section, a drawing of four outer cells, three differences from a photomicrograph and an eyepiece graticule calibration.

How many marks is 9700/32 and how long is it? +

It is out of 40 marks and lasts 2 hours. It is the AS Level practical paper and both questions are compulsory.

What concentrations did the 9700/32 serial dilution need? +

Starting from the 1.0% vitamin C solution, each step halves the concentration: 0.5%, 0.25%, 0.125% and 0.0625%. The mark scheme gave one mark for these concentrations with the % unit, one for transferring 10 cm³ from the previous beaker each time and one for adding 10 cm³ of distilled water each time.

How was the graph on 9700/32 marked? +

Four marks: axis labels with units, a scale of 0.5 g to 2 cm on the x-axis and 20 µmol dm⁻³ to 2 cm on the y-axis, correctly plotted points, and the points joined with a thin line through every point. A line of best fit does not earn the fourth mark.

What was the eyepiece graticule calibration on 9700/32? +

Count how many eyepiece graticule units line up with one 0.25 mm stage micrometer division in Figure 2.2, then divide 0.25 mm by that number and multiply by 1000 to get micrometres per eyepiece unit. The working had to show the division and the conversion to micrometres.

Where can I download 9700/32 May/June 2026 and its mark scheme? +

Both are free to download and print on the Tutopiya Learning Portal, on the Cambridge AS & A Level Biology 9700 past papers page.

Ready to Excel in Your Studies?

Get personalised help from Tutopiya's expert tutors. Whether it's IGCSE, IB, A-Levels, or any other curriculum — we match you with the perfect tutor and your first session is free.

Book Your Free Trial