Oxbridge biology interview questions: the real ones, and how to answer them
27 October 2026, for December 2026 interviews. Checked against Oxford's sample questions page in October 2026.
Most lists of Oxbridge biology interview questions are copies of each other. This one says where every question comes from, and shows you how to handle the five kinds that keep coming up.
Official published by Oxford, tutor named Reported described by a student who was interviewed Practice no traceable source
Jump to: The interview Official questions Reported questions How to answer Practice Myths FAQs
The interview at a glance
- 2 interviews, usually
- 25–30 minutes each
- 2–3 tutors in the room
- Oxford interviews online. Biochemistry applicants are normally seen at two colleges, and some send a short article to read first.
- Cambridge interviews in person or online, depending on the college. This year's main period is 7 to 18 December 2026.
- Both are testing how you think, not what you've memorised. One Oxford tutor says outright that getting the correct answer isn't important.
The official Oxford questions
From Oxford's sample interview questions page, which says they come straight from the tutors who interview. Tap a question to see what the tutor is looking for, in my words.
Biology
Official Why do some habitats support higher biodiversity than others?
Owen Lewis, Brasenose
Compare places like rainforests and reefs, and look for mechanisms. Do new species arise faster there, or do fewer go extinct? Then: how would you test your idea, and what data would you need?
Official Why do many animals have stripes?
Martin Speight, St Anne's
Sort the possibilities into categories, such as warning, camouflage and mimicry, then push on details: do stripes only appear in young animals? Does colour matter? The tutor says there are no right or wrong answers.
Official Here's a cactus. Tell me about it.
Martin Speight, St Anne's
A real cactus and a close-up photo of its surface. Observe at both scales and work out function from structure. See the walkthrough.
Official If you could save either the rainforests or the coral reefs, which would you choose?
Martin Speight, St Anne's
No detailed knowledge needed. Weigh biodiversity against what people get from each, and the threats each faces. The tutor says the final answer doesn't matter.
Official Is it easier for organisms to live in the sea or on land?
Martin Speight, St Anne's
Start by defining “easier”. Then compare the problems of each: salt, pressure and light in the sea; support, drying out and movement on land.
Official Why do lions have manes?
Owen Lewis, Brasenose
The follow-up is how you'd test your theory. See the walkthrough.
Official Ladybirds are red. So are strawberries. Why?
Owen Lewis, Brasenose
The same colour seems to say “don't eat me” on one and “eat me” on the other. See the walkthrough.
Official Would it matter if tigers became extinct?
Owen Lewis, Brasenose
The tutor is interested in the “because”. A possible follow-up: would it matter if fungi went extinct?
Biochemistry
Official Would you expect this compound to be more soluble in octanol or water?
Kathryn Scott, Christ Church
You're shown a structure with A-level functional groups. Think about the types of interaction and their strength, group by group, then the whole molecule. The extension is a graph of solubility against pH, which is really about which groups gain or lose a proton.
Official Here is a list of three compounds, A, B and C. Which one is most soluble?
Mark Wormald, Corpus Christi (an older version of the page)
Build a hypothesis from the bonding. The tutor may then say the real order is different, to see how you react and how you'd test it.
Official How many different molecules can be made from six carbon atoms and twelve hydrogen atoms?
Martin Galpin, University College (Chemistry)
Listed for Chemistry, but good practice for Biochemistry: draw the isomers, then think about rings, chirality and cis/trans.
Biomedical Sciences and Medicine
Official Why is sugar in your urine a good indicator that you might have diabetes?
Robert Wilkins, St Edmund Hall (Biomedical Sciences)
Filtration, then reabsorption by carrier proteins that behave like enzymes: there are only so many, so when blood glucose is high they're saturated and the excess spills into the urine.
Official Why do a cat's eyes appear to ‘glow’ in the dark?
Jan Schnupp, St Peter's (Biomedical Sciences)
Is the light made, or reflected? Then: why would reflecting it help a cat see in dim light?
Official Put these countries in order by crude mortality: Bangladesh, Japan, South Africa, the UK.
Andrew King, Exeter (Medicine)
Most people put Bangladesh or South Africa first. It's Japan, because it has an older population. Then: how would you compare countries fairly?
Official Viruses depend on human cells to reproduce. Is it surprising that they cause disease?
Chris Norbury, Queen's (Medicine)
Think about how symptoms like sneezing help a virus spread, and why killing the host is risky for it. Then: could there be viruses that cause no disease, and how would we find them?
Oxford also publishes demonstration interviews. The links are here, with three Cambridge Natural Sciences examples. Watch at least one all the way through.
Questions students say they were asked
Mostly from the Oxford Student Union's Alternative Prospectus. The detailed accounts are older, but they match what students describe now. One 2023 Oxford applicant counted 11 or 12 graphs in 30 minutes.
Reported Why are ladybirds red and black? Why do birds sing?
Oxford Biology, Queen's, 2015
The ladybird question is one of the official ones, so this confirms it was really used.
Reported Here are some fossils. You can ask three questions to find out about them.
Oxford Biology, Queen's, 2015
An information-gathering exercise: choose questions that tell you the most.
Reported A skull, a video of lemmings, data on blue tits, and a fossil.
Oxford Biology, Balliol, 2014
For each: what's interesting about it, what is it, and why did it evolve that way?
Reported Lichen, a pine cone and some moss. How does each one get its food?
Oxford Biology, St Hilda's, 2015
The tutor explained that lichen is a partnership between a fungus and an alga, then asked how that partnership might work.
Reported A graph of how much DNA different organisms have. What strikes you most?
Oxford Biology, St Hilda's, 2015
Reported Wild and domesticated maize, then a series of genetic crosses.
Oxford Biology, St Hilda's, 2015
Reported Invent any technology to help biological discovery. Would it really work?
Oxford Biology, St Hilda's, 2015
The tutor challenged the answer with “Do you really think that would lead to new discoveries?”
Reported Interpret a brain scan. Why do death rates differ between two countries?
Oxford Biomedical Sciences
The country comparison echoes the official mortality question.
Reported Suggest a mechanism for joining two proteins together. How is pH regulated?
Cambridge Biological Natural Sciences, anonymous review
Expect chemistry and biochemistry if one of your interviewers is a chemist.
Reported If I mix lithium ions into water, what happens?
Cambridge Physical Natural Sciences, 2015
This led on to charge density and hydrogen bonding.
Expect a question about your personal statement too. One Balliol applicant was asked which book on it was their favourite, and why.
The five kinds of question, and how to answer them
Nearly every question above is one of these five. Practise the type, not the answer, and always think out loud: tutors can only reward reasoning they can hear.
1“What does this graph show?”Example: how much DNA different organisms have
- Read the axes before the data. What's measured, in what units? Is the scale logarithmic? On a log scale, a small gap can be a thousandfold difference.
- Say the main pattern in one sentence. Here: the amount of DNA doesn't follow complexity. An amoeba has far more than a human.
- Offer more than one explanation. Maybe much of the DNA doesn't code for anything. Maybe some organisms carry many copies of their genome.
- Say how you'd tell them apart. What would you measure, and what would each idea predict?
Follow-ups will push: why do bacteria have so little DNA? (Copying it takes time, and bacteria compete by dividing fast.) Are bacteria always smaller? (No: some have more DNA than yeast.)
2“Tell me about this”Example: a cactus
- Describe before you explain. Shape, size, colour, texture, at the large scale and then the small one.
- Link each feature to a function. No leaves, so less surface to lose water from. The spines are modified leaves, so the green stem must do the photosynthesis. The ribs let it swell when it stores water.
- Ask what problem it's solving. Here, almost everything comes back to keeping water in a dry place.
- Follow the chain. Spines protect against being eaten: by what sort of animals? Offshoots at the base: how is it reproducing?
3“How would you test that?”Example: why do lions have manes?
- Give a few hypotheses, not one. Protection in fights. A signal of strength to females. A warning to rival males.
- Make each one predict something different. If it's protection, males with fuller manes should be injured less. If it's a signal, females should prefer them and rivals avoid them.
- Design the simplest fair test. Change one thing only. Put out life-size model lions with different manes and watch who approaches which. Researchers in the Serengeti did exactly that.
- Say what could go wrong. Sample size, how you'd measure the result, and what else could explain it.
4Genetics on paperExample: wild and domesticated maize
- Set it up properly. Choose letters for the alleles, say which is dominant, and write out the parents' genotypes first.
- Know the standard moves. To check a plant is homozygous, cross it with itself or with a homozygous recessive. Two heterozygotes give a 3:1 ratio.
- When a result doesn't fit, use it. One trait appeared in 1 in 1,024 plants. That's (1/4)5, which suggests five genes, each needing two recessive copies.
Practise working crosses quickly and neatly. Under pressure it's easy to lose track of which plant is which.
5“Why is it like that?”Example: ladybirds and strawberries
- Notice the puzzle. The same colour is a warning on one and an invitation on the other.
- Think about who the signal is for. A ladybird tastes foul, and being easy to spot means birds learn to leave it alone. A strawberry wants its seeds spread, and red stands out against green once it's ripe.
- Go one step further. Why doesn't a bird confuse the two? Does “red” even look the same to a bird as it does to us?
For any “why” question: what advantage does it give, to whom, and at what cost? Then, how would you find out if you're right?
More questions to practise with
Practice From tutoring-company lists. None has a traceable source, but they're the right style. Say your answers out loud, ideally to someone who'll push back.
- Why do leaves have their stomata on the lower surface?
- Why don't animals have wheels?
- How would you test whether a rat can tell red from blue?
- If a carrot can grow from one carrot cell, why can't a human?
- Why are big, fierce animals so rare?
- Why is it easier for oxygen to bind to haemoglobin once one molecule has bound?
- Why do we need ATP, rather than releasing energy from glucose directly?
- Why are there only twenty amino acids?
- What evidence is there that humans are still evolving?
- Why does a cat have tortoiseshell fur?
- For which disease is it an advantage to carry one copy of the cystic fibrosis allele?
- About 1 in 4 deaths in the UK are from cancer, but about 1 in 10 in the Philippines. Why?
- Why do living things need hormones?
- How does the structure of DNA relate to its function?
Famous questions that probably weren't asked
These appear in every round-up of “weird Oxbridge questions”, but none has a college, a year or a first-hand account behind it:
- “What would you do if I were a magpie?”
- “Describe a potato, then compare it with an onion.”
- “How would you poison someone without the police finding out?”
- The tutor who throws a pen and asks you to draw what you saw.
- “Roses are red, violets are blue. Why?” Probably a garbled version of the real ladybird question.
The real questions are less strange, and more useful to prepare for: biology you can reason through, not tricks.
Questions I get asked
Will I be asked one of these questions?
Probably not the exact one. Tutors change their questions, and Oxford publishes these partly so you know the style. You'll almost certainly get the same kinds: graphs, specimens, experiment design and reasoning about why living things are the way they are.
What if I don't know the answer?
Say what you do know, make a sensible guess, and explain your reasoning. Tutors give hints, and how you use them is part of what they're watching. Saying “I don't know” and stopping is the only real mistake.
Do I need to know things beyond A-level?
No. The questions are built so that A-level knowledge is enough to make a start. What they test is whether you can apply it to something new.
Will they ask about my personal statement?
Often, especially at the start. Be ready to talk about anything you mentioned, particularly books, for several minutes.
Are Oxford interviews online?
Yes. Oxford's colleges voted in 2023 to keep interviews online for the next few years. Cambridge varies by college, so check the page for yours.
Want to practise for real?
My interview diagnostic is a 45-minute mock on material you haven't seen, with feedback straight afterwards. Or start free with my guide to what happens in the interview. There's also a free webinar on Saturday 14 November.
Sources
Checked 27 October 2026. Quoted questions are as published; tutors' explanations are summarised in my own words.
- University of Oxford: sample interview questions
- University of Oxford: Biochemistry course page
- Oxford Department of Biochemistry: undergraduate admissions
- University of Cambridge: what to expect at your interview
- Downing College, Cambridge: Natural Sciences
- Oxford SU Alternative Prospectus: Biology interviews
- That Oxford Girl: Q&A with an Oxford Biology interviewee (2023)
- Times Higher Education: Oxford reveals the method in the madness of its interview questions (2010)
- Student.com: which Oxbridge interview questions are fake?
Written by Flora, who teaches this. More about me, or email me a question.