Edexcel GCSE Biology Paper 1, Higher Tier (1BI0/1H)Paper 1 — every question, answered
We read the real Higher Tier papers Edexcel has published for Biology Paper 1 in June 2022 and June 2023, plus the mark schemes examiners actually used to grade them. Below is what real sub-questions on each topic have asked, what a full-mark answer looks like against that year's mark scheme, and what tripped candidates up. June 2019 is not currently hosted on Pearson's own filestore, so this page is built only from the two sittings we could verify directly from Pearson's own PDFs.
Questions © Pearson Education Ltd, quoted for analysis. Diagrams and photographs described in our own words, not reproduced. Mark scheme content translated into plain English, not copied. PrepWise is independent and not endorsed by Pearson or Edexcel.
The paper is a template
Same 12 question types, every sitting“Name the type of reproduction that produces genetically identical organisms, then weigh up an advantage and a disadvantage”
Both sittings we have use a real-world cloning example (grafted apple trees) to test whether you can name asexual reproduction and then argue both sides of producing genetically identical organisms.
1×asked“Name the type of reproduction that produces genetically identical organisms.”
“Name the type of reproduction that produces genetically identical organisms.”
What it’s really asking
It wants the single correct biological term for reproduction that makes offspring genetically identical to the parent, in the context of grafting apple tree shoots onto a rootstock.
What the sources actually showed — June 2023
A photograph of apple tree shoots grafted onto a rootstock, with the grafted shoots and the rootstock separately labelled.
The full worked answer — June 2023
Asexual reproduction.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise cloning questionsWhat the mark scheme rewarded
- The single word or phrase 'asexual reproduction'
- The mark scheme also accepted cloning or binary fission as alternative correct terms for this style of question, but not mitosis on its own, since mitosis is the cell division process rather than the name of the reproduction strategy
- Asexual reproduction involves only one parent and produces genetically identical offspring, called clones
- Grafting joins a shoot from one plant (the scion) onto the root system of another (the rootstock) so the new growth is genetically identical to the parent plant the shoot was cut from
- No fusion of gametes and no meiosis occurs in asexual reproduction, which is why there is no genetic variation between parent and offspring
Traps examiners saw
- Writing 'mitosis' when the question wants the name of the reproduction strategy, not the type of cell division involved
Full-mark self-check 0 of 1
1×asked“Grafting can be used to produce apple trees that are genetically identical. Give one advantage and one disadvantage of growing genetically identical apple trees.”
“Grafting can be used to produce apple trees that are genetically identical. Give one advantage and one disadvantage of growing genetically identical apple trees.”
What it’s really asking
It wants one distinct benefit of genetic identity in a crop (guaranteed characteristics, faster production) and one distinct cost of genetic identity (susceptibility to disease, inability to survive environmental change, reduced gene pool).
What the sources actually showed — June 2023
A photograph of apple tree shoots grafted onto a rootstock, with the grafted shoots and the rootstock separately labelled.
The full worked answer — June 2023
Advantage: every tree produced by grafting will have the same desired qualities as the parent plant, such as the same taste, size and yield of fruit, so the farmer knows exactly what they are growing and can produce it faster than waiting for new trees to grow from seed.
Disadvantage: because every tree is genetically identical, there is no genetic variation in the population, so if a new disease or a change in the environment appears that the parent tree cannot survive, all of the cloned trees are equally vulnerable and could be wiped out together, unlike a genetically varied population where some individuals might resist the disease.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise cloning questionsWhat the mark scheme rewarded
- Advantage: fruit will have desired qualities, or can be produced faster
- Disadvantage: susceptible to a disease, cannot survive an environmental change, or reduced gene pool
- The mark scheme explicitly told examiners to ignore a bare 'genetically identical, no variation' as the answer for either box, since that restates the question rather than giving a consequence
- Grafted trees share the parent's genotype, so all fruit-bearing characteristics are guaranteed rather than left to chance as they would be from seed-grown trees
- A population with no genetic variation cannot adapt through natural selection if the environment changes or a new pathogen appears, since no individual is likely to already carry resistance
Traps examiners saw
- Giving two versions of the same underlying point (for example, 'same taste' as the advantage and 'same taste is boring' as the disadvantage), the mark scheme wants two genuinely distinct consequences
Full-mark self-check 0 of 2
The method for every Q2/Q7 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Naming the correct process without hedging (asexual reproduction, sometimes tested as cloning or binary fission depending on context)
- Giving one genuine advantage AND one genuine disadvantage of genetic identity, not two of the same type
The steps
- Check whether the question is asking you to name the type of reproduction or to evaluate its consequences
- For genetic identity, keep advantage and disadvantage on separate, distinct points: desired traits guaranteed versus reduced gene pool or vulnerability to disease
- Do not repeat 'no variation' as both your advantage and disadvantage reasoning, the mark scheme wants two different consequences
What is the name of the first mammal to be cloned from an adult cell?
Cloning questions always pair a real technique (grafting, tissue culture) with the advantage/disadvantage of genetic identity. Learn the standard pairs cold.
Practise cloning questions“Define pathogen, calculate real disease statistics, and explain why an infection is communicable”
Both sittings pair a straight definition question with a real numerical calculation using bacterial or population data, then ask why the disease can spread between people.
1×asked“State the meaning of the term pathogen.”
“State the meaning of the term pathogen.”
What it’s really asking
It wants the definition that links pathogens directly to causing disease, in the context of bacterial colonies on an agar plate (Q3(b)(i)).
What the sources actually showed — June 2023
A photograph of an agar plate showing several separate dark colonies of bacteria, with two colonies labelled.
The full worked answer — June 2023
A pathogen is an organism that causes disease.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise pathogens and disease transmissionWhat the mark scheme rewarded
- Any wording that links 'organism' to 'causes disease/illness/infection'
- Pathogens include bacteria, viruses, fungi and protists, but the definition itself is about the causal relationship to disease, not the type of organism
Traps examiners saw
- Naming a type of pathogen (bacteria, virus) instead of defining what a pathogen actually is
Full-mark self-check 0 of 1
1×asked“Each colony starts as one bacterium. Every time bacteria reproduce, the number of bacteria in each colony doubles. Calculate the number of bacteria in a colony after five hours, if each bacterium reproduces every 30 minutes.”
“Each colony starts as one bacterium. Every time bacteria reproduce, the number of bacteria in each colony doubles. Calculate the number of bacteria in a colony after five hours, if each bacterium reproduces every 30 minutes.”
What it’s really asking
It wants you to work out how many 30-minute doubling periods fit into 5 hours, then apply doubling that many times from a starting population of 1.
What the sources actually showed — June 2023
A photograph of an agar plate showing several separate dark colonies of bacteria, with two colonies labelled.
The full worked answer — June 2023
Five hours is 300 minutes. Dividing 300 minutes by the 30-minute reproduction time gives 300 divided by 30, which is 10 doubling periods.
Starting from one bacterium and doubling 10 times gives 1024 bacteria.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise pathogens and disease transmissionWhat the mark scheme rewarded
- Working showing 300 divided by 30, or equivalent recognition of 10 doubling periods (2 to the power 10)
- Final answer of 1024
- 512 was accepted for one mark only, since it represents 9 doublings rather than the full 10
- Bacteria reproduce by binary fission, splitting one cell into two genetically identical daughter cells
- Exponential growth means the population doubles at each reproduction interval rather than adding a fixed number of cells each time
Traps examiners saw
- Losing one doubling period by miscounting minutes-to-hours conversion, giving 512 instead of 1024
- Adding rather than doubling at each interval, which gives a linear rather than exponential result
Full-mark self-check 0 of 2
1×asked“Some bacteria are pathogens. State why chlamydia can be described as a communicable disease.”
“Some bacteria are pathogens. State why chlamydia can be described as a communicable disease.”
What it’s really asking
It wants the specific mechanism of spread (person to person, via sexual contact or body fluids) that makes chlamydia communicable rather than a non-communicable disease.
What the sources actually showed — June 2022
A table listing five sexually transmitted infections (chlamydia, gonorrhoea, genital herpes, genital warts, syphilis) with the number of people diagnosed with each per 1000 of the UK population in 2017.
| Sexually transmitted infection (STI) | Number of people diagnosed per 1000 of the population |
|---|---|
| Chlamydia | 3.7 |
| Gonorrhoea | 0.8 |
| Genital herpes | 0.6 |
| Genital warts | 1.1 |
| Syphilis | 0.1 |
The full worked answer — June 2022
Chlamydia is caused by bacteria which can be passed from person to person through sexual contact, so it is a communicable disease.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise pathogens and disease transmissionWhat the mark scheme rewarded
- It is passed or spread from person to person (via sexual contact or body fluids)
- OR caused by bacteria (as evidence it is an infectious rather than a lifestyle-caused disease)
- Communicable diseases are caused by a pathogen and can spread from an infected person to others
- Non-communicable diseases, such as heart disease or cancer, are not caused by pathogens and cannot spread between people in the same way
Traps examiners saw
- Describing symptoms of chlamydia instead of explaining why it counts as communicable
Full-mark self-check 0 of 1
1×asked“HIV is another sexually transmitted infection. Explain how HIV can lead to the onset of AIDS.”
“HIV is another sexually transmitted infection. Explain how HIV can lead to the onset of AIDS.”
What it’s really asking
It wants the mechanism linking HIV infection to AIDS: HIV destroys white blood cells, which weakens the immune system, making the person vulnerable to other infections.
The full worked answer — June 2022
HIV attacks and destroys the white blood cells of the immune system, which reduces the number of white blood cells available to fight infection. This compromises the immune system, making the infected person far more susceptible to other pathogens and infections, which is the stage described as AIDS.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise pathogens and disease transmissionWhat the mark scheme rewarded
- HIV destroys or reduces the number of white blood cells
- This compromises or weakens the immune system, making the person more susceptible to other pathogens/infections/diseases (not just 'more susceptible to AIDS')
- HIV specifically targets and destroys a type of white blood cell called T helper cells, which coordinate the immune response
- AIDS is diagnosed once the immune system is so weakened that the body can no longer fight off infections that a healthy immune system would clear easily
Traps examiners saw
- Writing 'more susceptible to AIDS' as the final consequence when AIDS is the very thing being explained, not a separate infection
Full-mark self-check 0 of 2
The method for every Q3/Q10 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Stating that pathogens are organisms that CAUSE disease, not just organisms linked to illness
- Correct substitution and evaluation in growth/population calculations, shown as working
- Linking communicable to the specific mechanism of spread between people (contact, body fluids)
The steps
- For a definition, name the causal relationship (causes disease) rather than an example organism
- For doubling-time calculations, work out how many doubling periods fit into the given time first, then apply the doubling
- For 'why is this communicable', link explicitly to person-to-person or body-fluid spread
What is a pathogen?
Pathogen and disease-transmission questions mix straight definitions with real percentage and doubling calculations. Practise both together.
Practise pathogens and disease transmission“Explain why antibiotics work on bacteria but not viruses, and how resistant strains evolve”
Both sittings test the mechanism of antibiotic action and the natural-selection explanation of resistance, sometimes in the same question, sometimes split across two.
1×asked“Explain why antibiotics can be used to treat bacterial infections.”
“Explain why antibiotics can be used to treat bacterial infections.”
What it’s really asking
It wants the mechanism: antibiotics inhibit specific bacterial processes, killing or stopping bacteria, while leaving the patient's own host cells undamaged.
What the sources actually showed — June 2023
A photograph of an agar plate showing several separate dark colonies of bacteria, with two colonies labelled.
The full worked answer — June 2023
Antibiotics inhibit specific processes inside bacteria, such as disrupting their cell walls, which destroys the bacteria or stops them growing and reproducing. Crucially, antibiotics do not affect or damage the patient's own host cells, because human cells do not have the same bacterial-specific structures the antibiotic targets.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise antibiotics and resistanceWhat the mark scheme rewarded
- They inhibit processes in bacteria (accept named processes, e.g. disrupt cell walls)
- So bacteria are destroyed/killed or growth/reproduction stops or slows
- But antibiotics do not affect or damage the host cell
- Bacteria are prokaryotic cells with a cell wall made of a different material to human cells, which some antibiotics specifically target
- Antibiotics have no effect on viruses, since viruses use the host's own cell machinery to reproduce rather than having their own bacterial-style processes to disrupt
Traps examiners saw
- Forgetting to state that host cells are unaffected, which is worth its own mark and is what makes antibiotics usable as a medicine at all
Full-mark self-check 0 of 3
1×asked“In 2017, a new strain of Klebsiella pneumoniae bacteria was discovered that was resistant to 26 different antibiotics. Explain how Klebsiella pneumoniae bacteria developed resistance to antibiotics.”
“In 2017, a new strain of Klebsiella pneumoniae bacteria was discovered that was resistant to 26 different antibiotics. Explain how Klebsiella pneumoniae bacteria developed resistance to antibiotics.”
What it’s really asking
It wants the full natural-selection explanation for how a resistant strain of bacteria arises and spreads through a population, not just the fact that resistance exists.
The full worked answer — June 2022
Resistance develops by natural selection. Within a population of Klebsiella pneumoniae, random mutation creates variation, so a small number of bacteria happen to carry a gene or allele that makes them resistant to a particular antibiotic.
When antibiotics are used to treat an infection, the non-resistant bacteria are killed, but the resistant bacteria survive the treatment, especially if a patient does not finish their full course of antibiotics and stops before all the bacteria, including the less-resistant ones, have been cleared.
The surviving resistant bacteria then reproduce, and because bacterial reproduction passes on genetic material to the offspring, the resistance is inherited by future generations. This process repeats every time antibiotics are used, so the proportion of resistant bacteria in the population increases over successive generations, eventually producing strains such as this one that are resistant to as many as 26 different antibiotics.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise antibiotics and resistanceWhat the mark scheme rewarded
- By natural selection/evolution
- Mutation in the bacterium/variation in the population (accept some bacteria have a gene/allele for antibiotic resistance)
- Only the resistant bacteria survive treatment by antibiotics (accept non-resistant bacteria killed by antibiotics)
- The resistant bacteria reproduce/divide
- Offspring inherit the resistance, or resistance passed onto future generations, or the process repeats increasing the level of resistance
- Klebsiella pneumoniae is a bacterium that can cause pneumonia and other infections, particularly dangerous in hospital settings
- Overuse of antibiotics and not completing a prescribed course both increase the selection pressure that allows resistant strains to spread
- Resistance genes can also spread between different bacteria through plasmid transfer, though this specific mark scheme rewarded the mutation/selection/inheritance chain rather than plasmid transfer for this question
Traps examiners saw
- Stopping the explanation at 'mutation causes resistance' without continuing through selection, survival, reproduction and inheritance, all four stages are needed for full marks
- Saying antibiotics 'cause' the resistance mutation directly, when the mutation already exists in the population by chance and antibiotics act as the selection pressure that favours it
Full-mark self-check 0 of 3
1×asked“New antibiotics are being developed to treat the disease caused by Klebsiella pneumoniae. Describe the stages of antibiotic development that would occur after the discovery of a new antibiotic.”
“New antibiotics are being developed to treat the disease caused by Klebsiella pneumoniae. Describe the stages of antibiotic development that would occur after the discovery of a new antibiotic.”
What it’s really asking
It wants the real named stages a new drug goes through: pre-clinical testing (in cells or animals), then clinical trials on humans, including the double-blind trial design.
The full worked answer — June 2022
The new antibiotic would first go through a pre-clinical testing stage, being tested on cells grown in a laboratory or on animals to check whether it is effective against the bacteria and whether it appears safe before any human is exposed to it.
If the pre-clinical results are promising, the antibiotic then moves into clinical trials, first on small numbers of healthy volunteers to check for safety and side effects, and then on patients who actually have the infection to check whether it is effective as a treatment.
These clinical trials are often run as double-blind trials, where neither the patient nor the doctor giving the treatment knows whether the patient is receiving the new antibiotic or a placebo, which prevents bias from affecting the results.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise antibiotics and resistanceWhat the mark scheme rewarded
- The antibiotic goes through a development phase
- Pre-clinical stage/trials
- Testing on animals or testing in-vitro/on cells (accept named animals)
- Clinical stage/trials
- Testing on healthy volunteers/testing on patients
- Double-blind trials (or a description of double-blind trials, e.g. placebo and drug groups)
- Pre-clinical testing checks toxicity and effectiveness before any human trial begins
- Phase 1 clinical trials use small numbers of healthy volunteers primarily to check safety, before larger trials on actual patients test effectiveness
- A placebo is a substance with no active drug in it, used so that patient responses can be compared fairly against those given the real antibiotic
Traps examiners saw
- Jumping straight from 'discovered' to 'given to patients', skipping the pre-clinical animal/cell testing stage entirely
- Describing a placebo trial without mentioning that it is specifically double-blind, which is the detail the mark scheme wanted named
Full-mark self-check 0 of 3
The method for every Q3/Q5 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Explaining that antibiotics disrupt bacterial processes without harming the host's own cells
- Building the FULL resistance chain: mutation/variation, survival of resistant bacteria under antibiotic selection pressure, reproduction, and inheritance of resistance
The steps
- For 'why antibiotics work', always state they target bacterial-specific processes and do not damage human host cells
- For 'how resistance develops', walk through the full chain: mutation creates variation, antibiotics act as a selection pressure, resistant bacteria survive and reproduce, resistance is inherited
- For antibiotic development questions, name the real stages in order: pre-clinical testing (cells/animals), then clinical trials on humans including double-blind design
What do antibiotics kill or stop growing?
Resistance questions want the full chain from mutation to inheritance, not just 'bacteria evolve'. Practise building the whole argument.
Practise antibiotics and resistance“Identify eye and brain structures, explain vision defects, and calculate nerve impulse speed”
Both sittings build a full Q4 around the eye and brain, mixing multiple choice structure identification with explain-type questions on cataracts, short-sightedness, and nerve impulse timing.
1×asked“An optician can use the chart to diagnose short-sightedness. Give one reason why people are short-sighted. Which diagram shows how short-sightedness can be corrected?”
“An optician can use the chart to diagnose short-sightedness. Give one reason why people are short-sighted. Which diagram shows how short-sightedness can be corrected?”
What it’s really asking
It wants the physical cause of short-sightedness (eyeball too long, cornea/lens too curved, light focusing in front of the retina) and recognition that a concave lens is needed to correct it.
What the sources actually showed — June 2023
An optician's eye chart showing rows of letters decreasing in size, with the top row labelled 'legally blind', a middle row labelled 'below average vision' and a lower row labelled 'normal vision'.
Four labelled diagrams (A to D) of a simplified eye each showing a different lens shape (convex or concave) placed in front of the eye, with light rays passing through to the retina.
The full worked answer — June 2023
People are short-sighted because the eyeball is too long, or because the cornea or lens is too curved, which causes light rays to be refracted too strongly and focus in front of the retina rather than directly on it.
The correct diagram is C, which shows a concave lens placed in front of the eye. A concave lens spreads out the light rays slightly before they reach the eye's own lens, which moves the focal point back so it lands correctly on the retina instead of in front of it.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise the nervous systemWhat the mark scheme rewarded
- The eyeball is too long, OR the cornea is too curved, OR the lens is too thick/too curved, OR the cornea/lens refracts light too much, OR light rays focus in front of the retina
- The correct diagram showing a concave lens correcting the light path onto the retina
- Short-sightedness (myopia) means distant objects appear blurred because light from them focuses before it reaches the retina
- A concave (diverging) lens spreads light rays apart slightly before they enter the eye, moving the focal point backward onto the retina
- Long-sightedness, by contrast, is corrected using a convex lens, since in that condition light focuses behind the retina
Traps examiners saw
- Saying the image forms 'in front of the retina' when it should be inside the eye but before reaching the retina, precise wording (focuses in front of the retina) is what earns the mark
- Selecting a diagram with a convex lens, which corrects long-sightedness rather than short-sightedness
Full-mark self-check 0 of 2
1×asked“Describe why a person with cataracts would see the image shown in Figure 6.”
“Describe why a person with cataracts would see the image shown in Figure 6.”
What it’s really asking
It wants the mechanism: protein builds up in the lens, clouding it, so light is dispersed or scattered rather than passing through cleanly to the retina.
What the sources actually showed — June 2023
Two images of the same letter, one shown sharp and clear labelled 'person with normal vision', and one shown blurred and hazy labelled 'person with cataracts'.
The full worked answer — June 2023
Cataracts occur when protein builds up in the lens of the eye, making it become cloudy rather than clear. Because the lens is cloudy, light passing through it is dispersed rather than travelling in a clear, focused path, so not all the light rays reach the retina correctly, which is why the image appears blurred and hazy rather than sharp.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise the nervous systemWhat the mark scheme rewarded
- Protein has built up (in the lens), accept cloudy lens
- Light is dispersed, accept not all the light rays pass through
- Cataracts are most common in older age, as proteins in the lens gradually clump together over decades
- Treatment is surgery to remove the cloudy lens and replace it with an artificial or plastic lens
Traps examiners saw
- Writing 'blurry vision' as the explanation rather than the actual physical cause (protein clouding, light scattering), which the mark scheme specifically told examiners to ignore as too vague
Full-mark self-check 0 of 2
1×asked“The optic nerve is 47 mm in length. Nerve impulses travel at 75 metres per second. Calculate the time an impulse takes to travel the length of the optic nerve.”
“The optic nerve is 47 mm in length. Nerve impulses travel at 75 metres per second. Calculate the time an impulse takes to travel the length of the optic nerve.”
What it’s really asking
It wants unit conversion (mm to m, or the speed to mm per second) followed by correct rearrangement and substitution into time = distance divided by speed.
The full worked answer — June 2022
Rearranging speed = distance / time gives time = distance / speed. Converting 47 mm to metres: 47 divided by 1000 equals 0.047 m.
Substituting into the equation: time = 0.047 divided by 75 = 0.0006267 seconds.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise the nervous systemWhat the mark scheme rewarded
- Correctly rearranged equation: time = distance / speed
- Correct unit conversion, either 47 mm to 0.047 m, or 75 m/s to 75000 mm/s
- Correct final value of approximately 0.0006267 seconds (any correctly rounded equivalent accepted)
- Myelinated neurones conduct impulses much faster than unmyelinated ones, which is one reason nerve impulse speeds can reach tens of metres per second
- The optic nerve carries visual information from the retina to the occipital lobe of the brain for processing
Traps examiners saw
- Substituting 47 directly without converting to metres, which mismatches the units of the given speed and produces an answer 1000 times too large
- Forgetting to rearrange the equation before substituting, which some candidates attempted to do only after substitution and made an arithmetic error
Full-mark self-check 0 of 3
1×asked“The impulse travels to the occipital lobe of the brain. Which part of the brain contains the occipital lobe? State the sense most likely to be affected if the occipital lobe is damaged.”
“The impulse travels to the occipital lobe of the brain. Which part of the brain contains the occipital lobe? State the sense most likely to be affected if the occipital lobe is damaged.”
What it’s really asking
It wants recognition that the occipital lobe is part of the cerebral hemispheres, and that damage to it affects vision/sight specifically.
What the sources actually showed — June 2022
An image of a human brain from the side, with the occipital lobe (the rear, lower portion of the outer brain surface) labelled.
The full worked answer — June 2022
The occipital lobe is part of the cerebral hemispheres.
If the occipital lobe is damaged, the sense most likely to be affected is sight, since the occipital lobe is responsible for processing visual information from the optic nerve.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise the nervous systemWhat the mark scheme rewarded
- Cerebral hemispheres
- Sight, or eyesight, or vision, or seeing, or being able to see
- The cerebral hemispheres are the large, wrinkled outer part of the brain responsible for conscious thought, memory, language, and processing sensory information including vision
- The cerebellum controls balance and coordination, the medulla oblongata controls involuntary actions such as breathing and heart rate, and the hypothalamus regulates body temperature and hormone release, none of which process visual information
Traps examiners saw
- Confusing the occipital lobe (vision) with the cerebellum (balance/coordination), since both are 'brain regions' but have very different functions
Full-mark self-check 0 of 2
The method for every Q4 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Correctly identifying eye and brain structures from labelled diagrams
- Explaining defects (short-sightedness, cataracts) in terms of light focusing on the wrong point or being scattered/blocked
- Correct unit conversion and substitution in speed/distance/time calculations
The steps
- For structure ID questions, use the visual landmark (position, shape) rather than guessing from memory alone
- For defect explanations, state the physical cause (eyeball shape, cornea/lens curvature, or protein clouding) before the consequence (image forms in the wrong place or light is scattered)
- For speed calculations, always convert units to match (mm to m, or m to mm) BEFORE substituting into the equation
What are the two organs that make up the central nervous system (CNS)?
The eye and brain question is worth around 11 marks every sitting and mixes structure ID with real calculations. Learn both together.
Practise the nervous system“Describe the structure and function of a reflex arc”
This is a 6-mark, asterisked extended-response question in the sitting we have it, marked against a 3-level indicative-content scheme rather than a simple list.
1×asked“The doctor also tested the reaction time of the patient. Describe the structure and function of a reflex arc.”
“The doctor also tested the reaction time of the patient. Describe the structure and function of a reflex arc.”
What it’s really asking
It wants a complete, ordered structural pathway from stimulus to response, explicitly linked to why a reflex is both fast and protective, written with clear structure since this question rewards logical organisation.
What the sources actually showed — June 2023
A table showing a patient's BMI, waist-to-hip ratio, alcohol units and cigarettes smoked alongside published healthy-range guidance for each measurement.
| Measurement | Patient's data | Guidance |
|---|---|---|
| BMI | 28 | 18-25 healthy, 26-30 overweight, 30+ obese |
| Waist : hip ratio | 0.85 | <0.9 healthy, >0.9 abdominal obesity |
| Alcohol units | 3-4 units per day | <14 units per week |
| Number of cigarettes smoked | 0 | do not smoke or vape |
The full worked answer — June 2023
A stimulus, such as a painful or dangerous object, is detected by a receptor. The receptor transfers the signal, as an electrical impulse, along a sensory neurone towards the central nervous system, either the spinal cord or the brain.
Within the central nervous system, the signal passes to a relay neurone, which connects the sensory neurone directly to a motor neurone without the signal needing to travel all the way to the brain for conscious processing. Many neurones, including these, have a myelin sheath surrounding the axon, which speeds up the transmission of the electrical impulse along the neurone.
The motor neurone then transmits the signal to an effector, which is either a muscle or a gland. If the effector is a muscle, it contracts to produce the response, for example pulling a hand away from a hot object.
Because the relay neurone in the spinal cord allows the signal to bypass the brain, a reflex arc produces a very rapid response, much faster than a response that requires conscious decision-making. This speed is also what makes a reflex an automatic, involuntary, protective response: the body reacts to protect itself from harm, such as pulling away from something hot or sharp, before the person has consciously registered pain or made a decision to move.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise the reflex arcWhat the mark scheme rewarded
- Structure: stimulus detected by a receptor; receptor transfers signal to sensory neurone; sensory neurone transfers signal to the CNS/brain/spinal cord/relay neurone; signal transferred to a motor neurone; myelin sheath speeds transmission of the electrical impulse; motor neurone transmits signal to the effector; effector produces the response
- Function: rapid response; to protect the body/response to danger; involuntary automatic response
- Level 3 (5 to 6 marks) requires the FULL structural pathway AND both rapid and protective linked together, not either alone
- A reflex arc bypasses conscious brain processing by routing the signal through a relay neurone in the spinal cord, which is what makes reflexes faster than voluntary responses
- Common reflex examples include the knee-jerk reflex and pulling a hand away from a hot surface
- Reaction time testing (such as the ruler-drop practical) measures voluntary response time, which is distinct from an involuntary reflex, since it does require conscious brain processing
Traps examiners saw
- Only mentioning that a reflex is 'fast' without also explaining it is protective/automatic, which caps the answer at Level 2 even with a perfect structural description
- Missing the relay neurone stage entirely and jumping from sensory neurone straight to motor neurone
- Writing the stages out of order (for example, describing the effector before the motor neurone), which weakens the 'well-developed structure' criterion for Level 3
Full-mark self-check 0 of 4
The method for every Q9 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- A complete structural pathway: receptor, sensory neurone, CNS/relay neurone, motor neurone, effector
- Function points: rapid, involuntary/automatic, protective response
- A well-structured, coherent, logically ordered answer, not just a list of correct facts in any order
The steps
- Start at the stimulus and receptor, then trace the full pathway in order: sensory neurone to CNS, relay neurone, motor neurone, to effector
- Name the myelin sheath's role in speeding transmission if you want to reach the top of the structural detail
- Explicitly state BOTH that the response is rapid AND that it is protective/automatic, since Level 3 needs both, not just one
- Write in a clear, ordered structure (this is an asterisked question, structure itself is credited)
Which word best describes a reflex action?
The reflex arc extended-response question needs the full 5-stage pathway AND both rapid and protective function stated together for full marks.
Practise the reflex arc“Order the stages of mitosis, explain stem cell differentiation, and calculate a mitotic index”
Both sittings test the correct order of mitosis stages and how stem cells produce specialised cells, and one sitting adds a real mitotic-index calculation from slide data.
1×asked“After a mouse egg cell is fertilised, cell division produces a ball of genetically identical stem cells. Which is the correct order for the stages of one cell division? Describe how stem cells produce the cells of an embryo.”
“After a mouse egg cell is fertilised, cell division produces a ball of genetically identical stem cells. Which is the correct order for the stages of one cell division? Describe how stem cells produce the cells of an embryo.”
What it’s really asking
It wants the correct stage order of one round of mitosis, then a description linking mitosis (the division process) to differentiation (cells becoming specialised) to explain how an embryo's cells are produced.
What the sources actually showed — June 2023
A diagram of a mouse sperm cell with two internal structures labelled A and B.
The full worked answer — June 2023
The correct order is prophase, then metaphase, then anaphase, then telophase.
Stem cells produce the cells of an embryo by first dividing through mitosis, which produces more genetically identical stem cells. These cells then differentiate to become specialised, developing into the different cell types the embryo needs, such as muscle, nerve, or blood cells.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise mitosis and stem cellsWhat the mark scheme rewarded
- Stage order: B, prophase then metaphase then anaphase then telophase
- Stem cells divide by mitosis (reject meiosis)
- Cells differentiate/to become specialised cells (accept produce cells with a specific function)
- Mitosis produces two genetically identical daughter cells, each with the same number of chromosomes as the parent cell
- Differentiation is the process by which a stem cell becomes specialised for a particular function, such as a muscle cell or a nerve cell
- Embryonic stem cells are described as pluripotent, meaning they can differentiate into almost any cell type in the body
Traps examiners saw
- Confusing the order and putting anaphase before metaphase, since chromosomes must line up at the equator before being pulled apart
- Naming meiosis instead of mitosis, meiosis produces genetically different gametes, not the genetically identical cells described in this question
Full-mark self-check 0 of 2
1×asked“The student observed 89 cells on the microscope slide. Use this equation to calculate the mitotic index for this slide. Give your answer to three significant figures.”
“The student observed 89 cells on the microscope slide. Use this equation to calculate the mitotic index for this slide. Give your answer to three significant figures.”
What it’s really asking
It wants you to sum the cells in every stage of mitosis except interphase, substitute this and the total cell count into the given equation, and round correctly to 3 significant figures.
What the sources actually showed — June 2022
A table listing the number of cells observed at each stage of the cell cycle on a microscope slide: interphase (44), prophase (12), metaphase (6), anaphase (18), telophase (9).
| Stage of cell cycle | Number of cells observed |
|---|---|
| Interphase | 44 |
| Prophase | 12 |
| Metaphase | 6 |
| Anaphase | 18 |
| Telophase | 9 |
The full worked answer — June 2022
The number of cells in mitosis is the sum of prophase, metaphase, anaphase, and telophase, since interphase is not part of mitosis itself. That is 12 + 6 + 18 + 9 = 45 cells in mitosis.
Substituting into the equation: mitotic index = (45 divided by 89) multiplied by 100 = 50.561.
Rounded to three significant figures, the mitotic index is 50.6.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise mitosis and stem cellsWhat the mark scheme rewarded
- Selecting 45 cells in mitosis (excluding interphase)
- Correct substitution: (45 / 89) x 100 = 50.561
- Correctly rounded final answer: 50.6
- Interphase is when the cell grows and copies its DNA, but is not undergoing division, so it is excluded from the count of cells 'in mitosis'
- The mitotic index is used clinically to help diagnose cancer, since a higher mitotic index indicates a higher proportion of actively dividing cells, which can suggest uncontrolled cell division
Traps examiners saw
- Accidentally including interphase in the 'cells in mitosis' total, which would use 89 instead of 45 and give a completely wrong answer
- Forgetting to round to exactly three significant figures as instructed, giving 50.561 instead of 50.6
Full-mark self-check 0 of 3
The method for every Q5/Q7 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Correct stage order: prophase then metaphase then anaphase then telophase
- Linking mitosis (division) to differentiation (becoming specialised) as two separate, sequential steps
- Correct substitution into the mitotic index equation and rounding to the stated number of significant figures
The steps
- Memorise the stage order as a single chain: prophase, metaphase, anaphase, telophase
- For stem cell questions, always state BOTH that division is by mitosis AND that the resulting cells differentiate, since these are two separate credited points
- For mitotic index calculations, first identify which stages count as 'in mitosis' (usually all stages except interphase), sum them, then substitute into the given formula
What is mitosis?
Mitosis questions mix stage-order recall with real mitotic-index calculations from slide data. Practise both.
Practise mitosis and stem cells“Complete Punnett squares for dominant/recessive and sex-linked alleles”
Both sittings use a real Punnett square task, one with Mendel's classic pea plant cross and one with the sex-linked disorder haemophilia.
1×asked“Haemophilia is a sex-linked genetic disorder caused by a recessive allele on the X chromosome. Complete the Punnett square to show the genotypes of a male who is not affected by haemophilia, a female who is a carrier of the haemophilia allele and their possible offspring. Use the letters H and h for the alleles.”
“Haemophilia is a sex-linked genetic disorder caused by a recessive allele on the X chromosome. Complete the Punnett square to show the genotypes of a male who is not affected by haemophilia, a female who is a carrier of the haemophilia allele and their possible offspring. Use the letters H and h for the alleles.”
What it’s really asking
It wants the correct sex-linked genotype notation (allele attached to X) for an unaffected male, a carrier female, and all four possible offspring combinations.
The full worked answer — June 2023
The unaffected male parent has the genotype XHY, since males only have one X chromosome and are unaffected, so their single allele must be the dominant H. The carrier female parent has the genotype XHXh, since a carrier has one dominant allele and one recessive allele but shows no symptoms herself.
Completing the square with one allele from each parent across the top and side gives four possible offspring: XHXH, XHXh, XHY, and XhY. This means an unaffected male and a carrier female can produce an unaffected daughter, a carrier daughter, an unaffected son, or a son with haemophilia.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise genetic inheritanceWhat the mark scheme rewarded
- Correct female parent genotype: XHXh
- Correct male parent genotype: XHY
- Correct offspring genotypes in all four boxes (error carried forward from an incorrect parental genotype was still allowed for this final mark)
- Haemophilia is caused by a recessive allele carried on the X chromosome, which is why it is far more common in males, who have only one X chromosome and no second copy to mask the recessive allele
- A male with genotype XhY is affected, since he has no second X chromosome carrying the dominant allele to compensate
Traps examiners saw
- Writing the allele letters without attaching them to X (writing just 'Hh' rather than 'XHXh'), which loses marks since the whole point of sex-linked notation is showing the allele is carried ON the X chromosome
- Forgetting that the male offspring only inherit a Y chromosome from their father, never an X, so a father's X-linked allele can only be passed to daughters
Full-mark self-check 0 of 3
1×asked“Complete the Punnett square to show the outcome of a cross where both parent pea plants are heterozygous. Show the percentage probability of homozygous recessive offspring in your answer.”
“Complete the Punnett square to show the outcome of a cross where both parent pea plants are heterozygous. Show the percentage probability of homozygous recessive offspring in your answer.”
What it’s really asking
It wants a completed heterozygous by heterozygous Punnett square (Aa x Aa) and the correct percentage of homozygous recessive (aa) offspring read from it.
The full worked answer — June 2022
Both parents are heterozygous, so each has the genotype Aa. Crossing the gametes A and a from one parent with A and a from the other parent gives four possible offspring combinations: AA, Aa, Aa, and aa.
Of the four possible offspring, only one combination, aa, is homozygous recessive. This gives a percentage probability of homozygous recessive offspring of 25%.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise genetic inheritanceWhat the mark scheme rewarded
- Correct gametes (A and a from each parent)
- Correct offspring (AA, Aa, Aa, aa)
- Correct percentage: 25%
- Mendel's pea plant experiments showed that crossing two heterozygous plants (Aa x Aa) produces offspring in a 3:1 ratio of dominant to recessive phenotype, corresponding to a 1:2:1 genotype ratio of AA:Aa:aa
- Homozygous recessive (aa) is the only genotype that shows the recessive phenotype, since both other combinations (AA and Aa) contain at least one dominant allele
Traps examiners saw
- Forgetting to convert the fraction (1 in 4) into a percentage (25%) when the question specifically asks for a percentage
- Mixing up the parental cross type, this question specifically requires heterozygous x heterozygous, not the original yellow x green pea pod cross from earlier in the same question
Full-mark self-check 0 of 3
The method for every Q1/Q10 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Correctly completing all four boxes of the Punnett square with the right genotype combinations
- Correctly identifying the parental genotypes before filling in the grid
- Correctly stating a ratio or percentage derived from the completed square
The steps
- Write the parental genotypes at the top and side of the grid first, before filling in any boxes
- For sex-linked disorders, always attach the allele letter to the X chromosome (e.g. XH or Xh), never write the allele alone
- Fill in all four boxes systematically, combining one allele from each parent
- Read off the ratio or percentage from the completed square only after every box is correct
What is the term for an allele that is always expressed when present?
Punnett square questions want every box correct AND the ratio or percentage read off correctly. Practise both standard and sex-linked crosses.
Practise genetic inheritance“Explain DNA base pairing, the effect of mutations, and how mutations lower protein production”
Both sittings test DNA structure directly (base pairing, complementary strands, double helix shape) and both also test what happens when mutations occur in coding or non-coding regions.
1×asked“DNA molecules contain base pairs. Describe how the base pairs are bonded together in a DNA molecule.”
“DNA molecules contain base pairs. Describe how the base pairs are bonded together in a DNA molecule.”
What it’s really asking
It wants the specific bonding detail: weak hydrogen bonds between complementary base pairs (A-T, C-G).
The full worked answer — June 2022
The base pairs in DNA are held together by weak hydrogen bonds, always joining complementary bases: adenine always pairs with thymine, and cytosine always pairs with guanine.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise DNA and the genomeWhat the mark scheme rewarded
- Any two of: weak, hydrogen bonds, complementary bases, A-T/C-G pairing
- The double helix shape of DNA relies on these specific, weak hydrogen bonds between bases, which is why DNA strands can be 'unzipped' relatively easily during replication and transcription
- Complementary base pairing means the sequence of one strand always determines the exact sequence of the other strand
Traps examiners saw
- Saying the bonds are 'strong' rather than 'weak', hydrogen bonds are specifically weak, which is functionally important for DNA replication
Full-mark self-check 0 of 2
1×asked“Figure 1 shows part of a DNA molecule. Write the code for the complementary DNA strand in Figure 1.”
“Figure 1 shows part of a DNA molecule. Write the code for the complementary DNA strand in Figure 1.”
What it’s really asking
It wants every base in the given strand correctly matched to its complementary partner (A to T, T to A, C to G, G to C) across the whole sequence.
What the sources actually showed — June 2022
A row of boxes showing a DNA base sequence (T T G A T T G C G T A A) with an empty row of boxes directly beneath it for the complementary strand to be written in.
The full worked answer — June 2022
The given strand reads T T G A T T G C G T A A. Applying complementary base pairing (A pairs with T, C pairs with G) to every position in order gives the complementary strand: A A C T A A C G C A T T.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise DNA and the genomeWhat the mark scheme rewarded
- All of the As and Ts in the given strand correctly paired (1 mark)
- All of the Cs and Gs in the given strand correctly paired (1 mark)
- Lower case letters were also accepted
- The two strands of a DNA double helix always run antiparallel and are exact complements of each other, which is the basis of accurate DNA replication
Traps examiners saw
- Losing concentration partway through a long sequence and mismatching one or two bases, which loses the mark for that half of the sequence even if the rest is correct
Full-mark self-check 0 of 3
1×asked“Describe how a mutation in the non-coding region of a gene can lead to the production of less protein.”
“Describe how a mutation in the non-coding region of a gene can lead to the production of less protein.”
What it’s really asking
It wants the mechanism specific to non-coding region mutations: they affect how well RNA polymerase can bind, reducing the amount of mRNA transcribed, rather than changing the amino acid sequence directly.
The full worked answer — June 2023
A mutation in the non-coding region can change the sequence of bases where RNA polymerase normally binds, causing RNA polymerase to bind less well, or not bind at all, to that region of the DNA.
Because RNA polymerase cannot bind as effectively, less transcription occurs, so less mRNA is produced from that gene, which in turn means less protein is made overall.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise DNA and the genomeWhat the mark scheme rewarded
- RNA polymerase binds less well/cannot bind (accept alternative words for bind, e.g. attach; ignore 'affects the binding' alone as too vague)
- Less mRNA is produced (accept no mRNA produced, or less transcription)
- Non-coding regions of DNA include promoter regions, which are the specific sequences RNA polymerase must recognise and bind to before transcription can begin
- This contrasts with a mutation in the CODING region, which changes the sequence of amino acids in the protein itself rather than the amount of mRNA transcribed
Traps examiners saw
- Confusing this with a coding-region mutation and describing a changed amino acid sequence instead of reduced transcription, the multiple-choice follow-up in the same question specifically tests this distinction
Full-mark self-check 0 of 2
The method for every Q10/Q2 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Naming complementary base pairing (A-T, C-G) and hydrogen bonding correctly
- Distinguishing mutations in the coding region (changes amino acid sequence) from mutations in the non-coding region (changes how well RNA polymerase binds)
- Correctly completing a complementary DNA strand from a given sequence
The steps
- Always pair A with T and C with G, never mix them up under exam pressure
- For non-coding region mutations, remember these do not change the amino acid sequence directly, they change how well the gene is transcribed (RNA polymerase binding)
- For coding region mutations, remember these DO change the amino acid sequence, which can change the protein's shape/function
Which of the following base pairing rules is correct for DNA?
DNA questions test base pairing mechanics AND the difference between coding and non-coding region mutations. Know both cold.
Practise DNA and the genome“Explain natural selection, the risk of low genetic diversity, and evidence for evolution from limb structure”
Both sittings test the natural selection mechanism directly and use a real conservation or comparative-anatomy example to test how well you can apply it.
1×asked“There is some concern that the bitterns in the UK are all closely related. This could make them susceptible to extinction. Explain, using your knowledge of natural selection, why being closely related could make the bitterns susceptible to extinction.”
“There is some concern that the bitterns in the UK are all closely related. This could make them susceptible to extinction. Explain, using your knowledge of natural selection, why being closely related could make the bitterns susceptible to extinction.”
What it’s really asking
It wants the mechanism linking low genetic diversity to extinction risk: less variation means less chance any individual can survive a new selection pressure, so the whole population could be wiped out together.
What the sources actually showed — June 2023
A photograph of a bittern, a wetland bird, standing among reeds near water.
The full worked answer — June 2023
Because all the UK bitterns are closely related, they are genetically similar, meaning there is less variation within the population.
If a selection pressure occurs, such as a new disease or a change in their wetland environment, there is a much lower chance that any individual bittern will happen to carry a helpful adaptation, so the birds will be susceptible to that pressure, or may all die, rather than some individuals surviving because of natural variation.
This means fewer birds will survive to reproduce, so the population cannot evolve or adapt to the new pressure, which puts the whole species at a much higher risk of extinction.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise evolution and natural selectionWhat the mark scheme rewarded
- All genetically similar/there is less variation (accept decreased gene pool or similar DNA/genes/alleles)
- If there is a selection pressure (accept examples e.g. disease, change in the environment)
- They will be susceptible/die (due to the selection pressure)/no survival of the fittest (accept affected for susceptible)
- Fewer birds will be able to reproduce (accept fewer offspring are produced)
- The species cannot evolve
- Bitterns became extinct in the UK in the 19th century due to wetland habitat destruction and have only recovered following habitat restoration
- A genetically similar population is more vulnerable to a single disease or environmental change wiping out most or all individuals, since there is little variation for natural selection to act on
Traps examiners saw
- Stopping at 'less variation is bad' without naming a specific selection pressure or continuing the chain through to reproduction and the inability to evolve
Full-mark self-check 0 of 3
1×asked“Describe the theory of evolution by natural selection.”
“Describe the theory of evolution by natural selection.”
What it’s really asking
It wants the full mechanism in sequence: overproduction, variation, competition, survival of the best-adapted, inheritance of the advantageous characteristic, repeated over generations.
The full worked answer — June 2022
Organisms in a species produce more offspring than the environment can support, and there is variation between individuals due to mutations and genetic differences.
Because resources are limited, there is a struggle for existence, or competition, between individuals, sometimes described as a selection pressure. Organisms that are better adapted to their environment are more likely to survive this competition.
These surviving, better-adapted organisms are then more likely to reproduce, passing on the genes or alleles for their advantageous characteristics or adaptations to their offspring. This process is repeated over many generations, so the proportion of individuals carrying the advantageous adaptation increases over time.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise evolution and natural selectionWhat the mark scheme rewarded
- Overproduction of offspring
- Organisms in a species have variation/mutations (accept there are differences within species/organisms)
- There is a struggle for existence/selection pressure/competition (accept named selection pressure, e.g. change in the environment)
- The adapted organisms survive (accept survival of the fittest, accept not adapted organisms die)
- Reproduction leads to offspring inheriting characteristics/gene/allele/adaptation/trait
- This is repeated over many generations
- Charles Darwin and Alfred Russel Wallace independently developed very similar theories of evolution by natural selection in the 1800s
- Antibiotic resistance in bacteria is a modern, observable example of natural selection acting within a human lifetime
Traps examiners saw
- Only describing 'survival of the fittest' without the preceding overproduction and variation, or the following inheritance and repetition over generations, all six stages are needed for full marks
Full-mark self-check 0 of 4
1×asked“Figure 7 shows the limbs of five animals. Describe how the structure of these limbs provides scientists with evidence for evolution.”
“Figure 7 shows the limbs of five animals. Describe how the structure of these limbs provides scientists with evidence for evolution.”
What it’s really asking
It wants recognition of the shared pentadactyl limb structure across different species as evidence of a common ancestor, plus how that same basic structure has been adapted for different functions.
What the sources actually showed — June 2022
A diagram showing the forelimb bones of five animals side by side: human, cow, horse, whale, and bird, with the individual bones shaded to show corresponding sections across each limb.
The full worked answer — June 2022
All five limbs shown, from the human, cow, horse, whale and bird, share the same basic pentadactyl (five-digit) limb structure, made up of corresponding bones in a similar arrangement even though the overall limbs look very different.
This shared structure across such different species suggests they all descended from a common ancestor that also had this same basic pentadactyl limb, since it is highly unlikely that five unrelated species would independently evolve identical bone arrangements by chance.
Since that common ancestor, the same basic limb structure has been adapted differently in each species for its own particular function, for example becoming a flipper for swimming in the whale, a wing for flight in the bird, and a weight-bearing limb for walking in the horse and cow.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise evolution and natural selectionWhat the mark scheme rewarded
- They have a pentadactyl limb (accept similar bone structure/description of the bone structure)
- Suggesting a common ancestor
- That also had a pentadactyl limb/this limb structure
- How the structure has been adapted to different functions/description of the adaptations for a function
- Structures that share an underlying similarity due to common ancestry but which may look and function very differently are called homologous structures
- The pentadactyl limb pattern is found across all mammals, birds, reptiles and amphibians, reflecting their shared evolutionary origin from a common four-limbed ancestor
Traps examiners saw
- Only describing that the limbs 'look different' without identifying the underlying shared bone structure that is actually the evidence for evolution
- Forgetting to name a common ancestor, describing similarity alone is not enough, the inference of shared ancestry is the actual evolutionary evidence
Full-mark self-check 0 of 3
The method for every Q6/Q8 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- The full natural selection chain: overproduction, variation, competition/selection pressure, survival of the adapted, inheritance of the advantageous trait, repeated over generations
- Linking genetic similarity specifically to vulnerability to a single selection pressure wiping out a whole population
- Recognising pentadactyl limb structure as evidence of common ancestry, with adaptation to different functions
The steps
- For natural selection, always include overproduction/variation as the starting condition, not just 'survival of the fittest' alone
- For genetic-similarity risk questions, walk the full chain: less variation, more vulnerable to a selection pressure, cannot adapt, species at risk
- For limb-structure evidence, name the shared basic structure (pentadactyl limb), state it suggests common ancestry, and describe how the same basic structure has been adapted differently
What is evolution?
Natural selection questions want the full chain of stages, not just 'survival of the fittest'. Practise the whole sequence.
Practise evolution and natural selection“Explain why an organism is genetically engineered and why stem cells are used for the process”
In the sitting we have it, this is tested through a real, applied scenario (growing human kidneys in genetically modified pig embryos using human stem cells).
1×asked“State why the embryo of the pig must be engineered so it does not grow pig kidneys. Explain why human stem cells are used for this process.”
“State why the embryo of the pig must be engineered so it does not grow pig kidneys. Explain why human stem cells are used for this process.”
What it’s really asking
It wants the reason pig kidney growth must be blocked (so human kidneys can grow instead without competing tissue), and why stem cells specifically, rather than any other cell type, can produce a working human kidney inside the pig.
What the sources actually showed — June 2022
A four-step diagram showing human stem cells taken from a patient, injected into an early-stage genetically engineered pig embryo, the pig growing human kidneys rather than pig kidneys, and the human kidneys later being transplanted back into the patient.
The full worked answer — June 2022
Pig kidneys cannot be used directly in humans, since they would be rejected by the patient's immune system as foreign tissue. Engineering the embryo so it does not grow its own pig kidneys prevents competition between the developing pig organ and the human kidney tissue, allowing the human kidneys to form properly in that space instead.
Human stem cells are used because they are undifferentiated and unspecialised, meaning they have the ability to differentiate into any type of cell, including kidney cells. This means the stem cells taken from the patient can specifically produce the kidney tissue needed, and because this tissue is grown from the patient's own cells, it will match the patient's own tissue type and will not be rejected once it is transplanted back.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise genetic engineeringWhat the mark scheme rewarded
- Pig kidneys cannot be used in humans, OR pig kidneys would be rejected (by humans), OR to prevent competition between the pig and the human organ, OR so the human kidneys form properly (accept so there is room for the human kidneys)
- Stem cells are undifferentiated/unspecialised/can differentiate/become specialised/form any type of cell
- So can produce the kidney/kidney cells/kidney tissue that won't be rejected (when transplanted)
- Organ rejection occurs when a recipient's immune system recognises transplanted tissue as foreign because it does not match their own tissue type
- Using the patient's own stem cells to grow the replacement organ means the resulting tissue carries the patient's own genetic markers, greatly reducing the risk of rejection
Traps examiners saw
- Explaining why organ transplants in general are needed rather than specifically why the PIG embryo must be engineered not to grow its own kidneys
- Describing stem cells generically without linking their unspecialised property to the specific outcome (kidney tissue that will not be rejected)
Full-mark self-check 0 of 3
The method for every Q9 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Explaining the specific engineering purpose in context (preventing an organism's own tissue growing, so a different tissue can grow instead)
- Linking stem cells' defining property (being unspecialised/able to differentiate into any cell type) to why they specifically are used for this process
The steps
- Read the scenario carefully and state the reason for engineering in terms of what it prevents or enables specifically in that scenario
- For stem cell questions, always state the defining property (unspecialised, can differentiate into any cell type) before linking it to the specific outcome needed
Which of the following is a benefit of genetic engineering?
Genetic engineering questions often use real medical scenarios. Practise linking the technique to the specific reason it solves a real problem.
Practise genetic engineering“Describe how a pregnancy test uses monoclonal antibodies to detect a hormone”
In the sitting we have it, this is tested through the pregnancy test scenario specifically, which needs the hormone-antibody-colour-line chain in the right order.
1×asked“Monoclonal antibodies can be used in the diagnosis of genetic disorders and pregnancy testing. Describe how a pregnancy test uses monoclonal antibodies to show that a woman is pregnant.”
“Monoclonal antibodies can be used in the diagnosis of genetic disorders and pregnancy testing. Describe how a pregnancy test uses monoclonal antibodies to show that a woman is pregnant.”
What it’s really asking
It wants the full mechanism of a home pregnancy test: detecting a specific hormone in urine using antibodies with an attached colour marker, producing a visible line where those antibodies become immobilised.
The full worked answer — June 2023
A pregnancy test detects a hormone called hCG in a woman's urine, which is only present in significant amounts if she is pregnant.
If the hormone is present, it binds to a monoclonal antibody on the test strip that is specifically complementary in shape to that hormone.
This antibody has a coloured bead or dye attached to it, so when the hormone binds, the coloured antibody-hormone complex moves along the strip.
Further along the strip, there are immobile antibodies fixed in the test window, and these catch and hold the coloured antibody-hormone complex in place. Because the coloured complex builds up in one fixed location, a visible coloured line appears in the test window, showing that the hormone, and therefore pregnancy, has been detected.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise monoclonal antibodiesWhat the mark scheme rewarded
- (Pregnancy test detects) a hormone in urine (accept hCG for hormone)
- (Hormone/antigen) binds to the antibody (on the test) (accept antibodies are complementary to the hormone)
- Which have a coloured (bead) attached to them (accept a named colour/idea that a colour, dye or tag is attached)
- (A line appears because) there are immobile antibodies (in the test window) (accept there are antibodies fixed down, accept the antibodies move up the strip and colour appears)
- hCG stands for human chorionic gonadotropin, a hormone produced by the placenta shortly after a fertilised egg implants in the uterus
- Monoclonal antibodies are all identical and produced to be specific to one particular antigen or hormone, which is what allows the test to react only to hCG and not other substances in urine
Traps examiners saw
- Stopping the explanation at 'the antibody binds to the hormone' without explaining WHY a visible line then appears, the immobile/fixed antibody step is what actually produces the visible result
Full-mark self-check 0 of 4
The method for every Q10 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Naming the specific hormone detected (or accepting hCG) in urine
- Describing the antibody-hormone binding step
- Describing how the colour/dye attached to the antibody produces a visible line result
The steps
- Start with what is being detected (a hormone in urine, accept hCG by name)
- State that the hormone binds specifically to an antibody designed to be complementary to it
- Explain that this antibody carries a coloured marker (a dye, bead, or tag)
- Explain that a line appears because there are also fixed/immobile antibodies further along the test strip that the coloured antibody complex gets caught on
What does the term 'monoclonal antibody' mean?
Monoclonal antibody questions want the full chain from binding to a visible result, not just 'the antibody detects it'. Learn the whole test mechanism.
Practise monoclonal antibodies“Explain a potato cube's mass change in salt solution using osmosis”
This appears as a full required-practical style question in the sitting we have it, using real potato-cube mass data across three solution concentrations.
1×asked“One cube was placed in water and each of the other two cubes were placed in solutions with different concentrations of salt. Explain the mass change in the cube in the concentrated salt solution.”
“One cube was placed in water and each of the other two cubes were placed in solutions with different concentrations of salt. Explain the mass change in the cube in the concentrated salt solution.”
What it’s really asking
It wants the full osmosis explanation for why a potato cube LOSES mass in a concentrated salt solution: water moves out of the cube, across the partially permeable membrane, from a high water concentration inside the cell to the lower water concentration in the concentrated solution outside.
What the sources actually showed — June 2023
A table showing the starting and final mass in grams of three identical potato cubes after 20 minutes: one in water (0.95g to 1.08g), one in dilute salt solution (0.95g to 0.98g), and one in concentrated salt solution (0.94g to 0.88g).
| Solution | Starting mass (g) | Final mass after 20 minutes (g) |
|---|---|---|
| Water | 0.95 | 1.08 |
| Dilute salt solution | 0.95 | 0.98 |
| Concentrated salt solution | 0.94 | 0.88 |
The full worked answer — June 2023
The mass of the potato cube decreased, from 0.94 g to 0.88 g, because water has moved out of the cube.
This water movement happens by osmosis, the movement of water across a partially permeable membrane.
Water moves from a high water molecule concentration, inside the potato cell, to a low water molecule concentration, in the concentrated salt solution outside, since the concentrated solution has less free water and more dissolved salt than the cell's contents.
Could you have written this? Every fact in this answer is drilled in our quizzes — the writing is the easy part once the evidence is automatic.
Practise cell transport and osmosisWhat the mark scheme rewarded
- Mass has decreased
- Water has moved out (of the cube) (accept the cube/potato has lost water)
- Water moves by osmosis
- Across a partially permeable membrane (accept semi-permeable membrane)
- From a high water molecule concentration to a low water molecule concentration (accept down a water potential gradient)
- Osmosis is the net movement of water molecules from a region of high water concentration to a region of low water concentration, through a partially permeable membrane
- A concentrated salt solution has a lower water concentration than the cell's cytoplasm, so water leaves the cell to try to balance the concentrations either side of the membrane
Traps examiners saw
- Naming diffusion instead of osmosis, osmosis is specifically the diffusion of water molecules across a partially permeable membrane, the more precise term is required here
- Getting the direction backwards, water moves from HIGH water concentration (inside the cell) to LOW water concentration (in the concentrated solution), not the other way round
Full-mark self-check 0 of 4
The method for every Q8 — same every sittingMark bands, steps, timing
What this question type rewards
The topic changes by sitting — the mark scheme never does. Learn this once, then open your question above for that sitting’s sources and a full worked answer.
- Naming osmosis specifically, not just 'water moves'
- Stating the direction of water movement in terms of water concentration/potential, high to low
- Correctly identifying the partially permeable membrane involved
The steps
- State the observed change (mass decreased/water left the cube) before naming the process
- Name osmosis specifically as the process, across a partially permeable membrane
- State the direction using water concentration or water potential language: from high to low
Which statement best describes diffusion?
Osmosis practical questions want the full chain: mass change, osmosis, membrane, and direction of water movement, all four linked together.
Practise cell transport and osmosisThe topics that keep coming up
Across the 2 sittings we have full papers for, these are the topics with the most exam appearances and marks at stake in Biology Paper 1.
Not the primary focus in the 2 sittings we have full papers for
Vaccination and herd immunity as a standalone extended-response topic · Adaptive immunity as a standalone extended-response topic · Cancer and cell control beyond the brief mitotic-index link in June 2022 · Sex determination beyond the ZW bird cross in June 2023 · Cell structure and microscopy as a standalone practical description question · Variation as a standalone topic separate from natural selection · Selective breeding as a standalone topic
These topics have not been the main focus of a Paper 1 question in the two sittings we analysed directly, but the specification still covers them, so do not skip them.
Before you revise
Are these real mark-scheme answers?
The sources and diagrams are described in our own words, not reproduced, and the worked answers are written entirely by us, aimed at what the real Edexcel mark schemes for June 2022 and June 2023 actually rewarded. They are not copied from Edexcel's own exemplar answers, since that would breach copyright, but every mark point traces back to a real, published mark scheme. PrepWise is independent of Pearson and Edexcel and not endorsed by them.
Why is June 2019 missing from this page?
Pearson has removed the June 2019 question paper and mark scheme for this paper from their own official filestore. We only build from papers we can verify directly on Pearson's own site, so this page currently covers June 2022 and June 2023 only, and we will add further sittings as they are published or become available from Pearson directly.
Will the exact same questions come up again this year?
Sometimes the underlying topic returns closely (the eye and brain, antibiotic resistance, and mitosis have appeared in both sittings we have), but the exact numbers, diagrams and scenarios change every time. Use this page to learn which TOPICS keep returning and build a strong evidence bank for each one, rather than memorising one year's exact answer.
Is PrepWise free to use for this?
Yes, PrepWise is free during alpha. You can practise every topic on this page without paying anything right now.
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