Cambridge IGCSE Biology 0610/42 is the May/June 2026 Paper 4 (Extended Theory), variant 2. It lasts 1 hour 15 minutes, is worth 80 marks and is sat by every Extended candidate. It had six compulsory questions, and one of them, on fish farming and conservation, carried 23 marks. This guide goes through the paper question by question 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 six 0610 papers from this series, see IGCSE Biology 0610 May/June 2026 past papers: what came up and how it was marked.

0610/42 at a glance

Question	Topic	Marks	Main command word
1	Transpiration: potometer and wind speed, water movement in the xylem	10	Describe, explain
2	Fish farming, sustainable resources, endangered species, AI and IVF	23	Explain, describe
3	The male reproductive system and meiosis	9	Complete, explain
4	Carbohydrates, glucagon, diabetes	13	Explain, describe
5	Osmosis in onion cells, mitosis, stem cells, mineral ion uptake	14	Explain
6	Heart-lung machine: heart structure and double circulation	11	State
	Total	80

Question-by-question walkthrough

Question 1: transpiration (10 marks)

A student used a potometer and a fan to measure how far an air bubble moved in 300 seconds at different wind speeds.

• Rate calculation (1 mark): 135 mm in 300 s gives 0.45 mm s⁻¹.
• Describe the effect of wind speed (2 marks): one mark for saying the rate increases as wind speed increases. The second mark is for spotting that the relationship is not linear: the rate rises far more steeply at the higher wind speeds. Most lost marks here come from stopping after the first point.
• Why the rate is only an estimate of water uptake (1 mark): not all the water taken up is lost by transpiration, because the plant uses some, for example in photosynthesis or to keep cells turgid. “Used in respiration” was rejected, because respiration releases water rather than using it.
• Two other factors (2 marks): temperature and humidity are the expected answers. Light intensity, soil moisture and carbon dioxide concentration were also accepted.
• How transpiration moves water up the xylem (4 marks): the scheme listed eight points. A full answer runs in order: water evaporates from the surfaces of mesophyll cells into the air spaces, the vapour diffuses out through the stomata, this lowers the water potential in the leaf, and that creates tension (the transpiration pull) on the column of water in the xylem, which stays unbroken because water molecules are attracted to each other (cohesion).

Question 2: fish farming and conservation (23 marks)

The context was tilapia, a fish farmed in outdoor ponds.

• Sustainable resource (2 marks): it is produced as fast as it is used, so it does not run out. “Renewable” was accepted for the first point. “Regrown”, “reused” or “recycled” scored nothing.
• Why sunlight helps the fish grow (3 marks): producers in the pond photosynthesise, light energy becomes chemical energy, so there is more food or biomass for the tilapia, which they use to make new cells and tissues. Extra oxygen for the fish’s aerobic respiration and less competition for food were also credited.
• Proteins (3 × 1 mark): the ion that supplies an element found in all proteins is nitrate (ammonium was also accepted). Protein is needed for growth and repair of tissues; “repair cells” was rejected. Too much waste organic matter leads to eutrophication, and “algal bloom” on its own was ignored.
• Why mesh size conserves fish (4 marks): the holes should be large, so small, young fish escape, grow to breeding age and reproduce, which keeps the wild population up. Saying “the nets are large” missed the point, because the mark is for the size of the holes.
• Why species become endangered (6 marks): a list of 18 marking points. The main groups were climate change (and species being unable to adapt fast enough), named examples of habitat destruction such as deforestation or urbanisation, hunting, overharvesting, named pollutants, invasive species and new predators, disrupted food chains, and disease. Two points rewarded linking cause to effect: the population size falls, and a smaller population has less genetic variation and fewer chances to find a mate. Greenhouse gases did not count as named pollutants, because they already sit under climate change. “Disruption of the ecosystem” without detail scored nothing.
• Artificial insemination and IVF (5 marks): for AI, sperm is collected and placed into the female’s reproductive tract at the time of ovulation. For IVF, eggs and sperm are collected, fertilisation happens outside the body in a dish, and the embryo is placed in the uterus. Extra credit was available for fertility hormones (FSH and LH), screening gametes or embryos, freezing sperm or using sperm banks, surrogate mothers, and choosing gametes from different populations to increase genetic variation. Screening eggs was rejected for AI, because AI uses no eggs.

Question 3: the male reproductive system (9 marks)

• Table of name, letter and function (5 marks, one per row): the rows covered the sperm duct, prostate gland, scrotum, urethra and penis. Common slips: saying the sperm duct carries urine (rejected), saying the prostate “produces semen” (ignored; it secretes the fluid that semen contains), and saying the scrotum “regulates temperature” (ignored). Keeping the testes cooler than body temperature was accepted.
• Why meiosis in the testes matters (4 marks): it makes sperm, halves the chromosome number (46 to 23) so the cells are haploid, so that after fertilisation the zygote is diploid again. Genetic variation between sperm and the fact that each sperm carries an X or a Y chromosome (which decides the sex of the offspring) also scored.

Question 4: carbohydrates and blood glucose (13 marks)

• Elements in carbohydrates (1 mark): carbon, hydrogen and oxygen.
• Organs on a diagram (2 marks): the letter of the organ that makes urea (the liver) and of the one that makes pepsin (the stomach).
• The hormone that raises blood glucose (3 marks): name glucagon, then explain that it causes glycogen to be broken down to glucose in the liver. Naming insulin or adrenaline here scored nothing for the name, and “muscle” was ignored as the location. This is the pair the mark scheme singles out for spelling: if you write a word that could be read as either glucagon or glycogen, you risk the mark.
• One other hormone that raises blood glucose (1 mark): adrenaline.
• Comparing two glucose curves (3 marks): for the person without diabetes, the concentration is always lower, rises less, and falls back to the starting level sooner (about 2.5 hours, against 5 to 6 hours with diabetes). The fourth point was a comparative data quote, and units had to appear at least once for both axes (mg per 100 cm³ and hours).
• Treating type 1 diabetes (3 marks): insulin by injection, pump or patch (“insulin” alone was not enough), monitoring blood glucose, counting carbohydrates, matching food to activity, keeping a healthy weight, and pancreas or islet cell transplants.

Question 5: osmosis, mitosis and roots (14 marks)

• Onion cells in two salt solutions (6 marks): cells in solution A were turgid and cells in B were plasmolysed. The marking points: osmosis; water crosses a partially permeable membrane; solution A has a lower salt concentration (higher water potential) than the cells, B the reverse; water moves into the cells in A and out of those in B; the vacuole gets bigger in A and smaller in B; in A the contents push on the cell wall, which stops the cell bursting; in B the membrane pulls away from the wall. Answers in terms of “water concentration” were ignored for the water-potential point, so use water potential or salt concentration. The scheme also had a full set of points for students who read the A cells as unchanged (an isotonic solution).
• Roles of mitosis in a root (3 marks): making new cells, growth in length, repair of damaged tissues, replacing cells and asexual reproduction. “Cell elongation” and “repair cells” scored nothing.
• Stem cells in a root (1 mark): they divide to produce unspecialised cells that can become specialised, such as root hair cells, xylem or phloem.
• Magnesium in a palisade cell (1 mark): chlorophyll. “Chloroplast” was ignored.
• How roots absorb mineral ions (3 marks): by active transport across the cell membrane of root hair cells, against the concentration gradient, using energy from respiration and carrier proteins in the membrane.

Question 6: the heart-lung machine (11 marks)

• Naming heart structures (6 marks across four parts): an atrioventricular valve, a semilunar valve and the left ventricle; the septum as the structure that keeps oxygenated and deoxygenated blood apart; the vena cava as the vessel the drainage tubes connect to; and the lungs as the organ the oxygenator replaces.
• Arteries supplying heart muscle (1 mark): the coronary arteries.
• Double circulation sentences (4 marks): blood passes through the heart twice per circuit, this is a double circulation, blood can be pumped at higher pressure, and that supplies oxygen to cells more efficiently for aerobic respiration.

Where the marks are on 0610/42

• “Explain” questions carried 30 of the 80 marks: 1(b), 2(d), 2(e), 3(b), 4(b)(ii), 5(a) and 5(b)(iv). These are where Extended grades are decided.
• Recall carried 26 marks: the “state”, “name”, “list” and “complete” parts. These should be close to full marks with secure knowledge.
• The two 6-mark answers, 2(e) and 5(a), are 12 marks together. Both are points-based, so six short, separate, specific points beat one long paragraph.
• Describe questions carried 15 marks, including the graph comparison in 4(c), which needed data with units.
• Question 2 alone is worth 23 marks. If ecology and conservation is a weak area, it costs more on this paper than any other topic.

How to self-mark 0610/42 with the mark scheme

1. Learn the abbreviations first. A semicolon separates marking points, a slash shows alternatives for the same point, A means accept, R means reject, I means ignore, ecf means error carried forward and AVP means any other valid point. An underlined word must appear in your answer.
2. Mark point by point, not by impression. For each “any four from” or “any six from” list, tick the numbered points your answer actually contains and stop at the maximum.
3. Read the guidance column. That is where the R and I notes sit, for example “repair cells” being rejected in 2(c)(ii). An answer that sounds right can still be on the reject list.
4. Apply the list rule. For a “state two” question, mark only your first two answers. A wrong answer still uses one of the places, and two answers that contradict each other cancel out.
5. Check spelling where two terms could be confused, especially glucagon and glycogen.
6. Log each lost mark as missing knowledge, a misread command word or a careless slip, and revise in that order.

Sit 0610/42 as a timed mock

The paper allows 75 minutes for 80 marks, a little under one minute per mark. A workable plan:

Block	Marks	Time
Question 1	10	9 minutes
Question 2	23	21 minutes
Question 3	9	8 minutes
Question 4	13	12 minutes
Question 5	14	13 minutes
Question 6	11	9 minutes
Check, especially calculations and spelling	–	3 minutes

Plan the two 6-mark answers before you write: jot six separate points in the margin, then turn each into one sentence.

Other May/June 2026 0610 papers

• 0610 Paper 12 (Core Multiple Choice)
• 0610 Paper 22 (Extended Multiple Choice)
• 0610 Paper 32 (Core Theory)
• 0610 Paper 52 (Practical Test)
• 0610 Paper 62 (Alternative to Practical)

Practise and download

• Download 0610/42 and its mark scheme on the Learning Portal →
• All 0610 May/June 2026 papers: overview and marking patterns
• Try a free IGCSE Biology quiz

Need help with a 0610 topic? Book a free trial lesson with an IGCSE Biology tutor →

Frequently asked questions

What topics were on 0610 Paper 42 May/June 2026? +

Six questions: transpiration and water movement in the xylem; fish farming, conservation and captive breeding; the male reproductive system and meiosis; blood glucose control and diabetes; osmosis in onion cells, mitosis and mineral uptake in roots; and a heart-lung machine question on heart structure and double circulation.

How many marks is 0610/42 and how long is it? +

It is out of 80 marks and lasts 1 hour 15 minutes. Question 2, on fish farming and conservation, is the biggest at 23 marks.

Which questions on 0610/42 2026 were worth 6 marks? +

Two: Question 2(e), explaining why species become endangered, and Question 5(a), explaining the appearance of onion cells in two salt solutions. Both are marked as a list of separate points, one mark each, up to six.

What was the answer to the transpiration rate calculation in 0610/42? +

The bubble moved 135 mm in 300 seconds, so the rate is 135 ÷ 300 = 0.45 mm per second. It was worth one mark.

Is 0610/42 the Core or Extended paper? +

Extended. Paper 4 is the Extended theory paper, sat alongside Paper 2 (Extended multiple choice) and either Paper 5 or Paper 6. Core candidates sit Paper 3 instead.

Where can I download 0610/42 May/June 2026 and its mark scheme? +

Both are free to download and print on the Tutopiya Learning Portal, on the Cambridge IGCSE Biology 0610 past papers page.

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