Cell Division and the Cell Cycle: AQA A Level Biology Exam Questions by Topic

AQACell Division and the Cell CycleExam Questions
Written by Tom Whitburn

All cells arise from other cells (AQA 3.2.2) covers how new cells are made: the eukaryotic cell cycle, with DNA replication in interphase, the behaviour of chromosomes and spindle fibres in prophase, metaphase, anaphase and telophase, and cytokinesis; why uncontrolled division leads to tumours and cancer, and how cancer treatments target cell division; binary fission in prokaryotes; and how a host cell replicates virus particles. It comes up on every AS and A-level paper, often as a photo or drawing of a cell you have to explain.

The examiners' reports show the same slips each year. Students write 'fission' or 'binary fusion', lump the circular DNA and plasmids together as 'genetic material', forget that centromeres divide in anaphase, say cancer cells divide faster rather than uncontrollably, say the cell-surface membrane 'splits' in cytokinesis, and stop a description of viral replication before the virus is assembled.

Start with the cell cycle and the stages of mitosis, then cancer, then binary fission and viruses, and finish with a short calculation. Answer each on paper before you open the mark scheme. If you'd like help with this topic, my AQA masterclasses run online on Tuesdays at 5.15pm for Year 12 and on Wednesdays or Thursdays at 6.30pm for Year 13.

What you need from GCSE and Year 12

Each question on this page assumes you're secure on these GCSE and Year 12 ideas. If any of them feels shaky, revise it before you start.

  • GCSE: chromosomes are made of DNA and found in the nucleus; body cells have pairs of chromosomes.
  • GCSE: in the cell cycle, the DNA is copied, then mitosis produces two genetically identical cells for growth and repair.
  • GCSE: cancer is the result of changes in cells that lead to uncontrolled growth and division.
  • Year 12 (AQA 3.1.5.2): semi-conservative replication of DNA by DNA helicase and DNA polymerase. See the DNA replication page.
  • Year 12 (AQA 3.2.1.2): prokaryotic cells have circular DNA and often plasmids; virus particles have genetic material, a capsid and attachment proteins. See the Prokaryotic cells and viruses page.

Key terms

These words come up in the questions and mark schemes. Examiners expect you to use them exactly.

  • Cell cycle: the sequence of interphase, mitosis and usually cytokinesis in a eukaryotic cell that keeps the ability to divide.
  • Interphase: the longest part of the cell cycle, when the cell grows, makes proteins and organelles and replicates its DNA.
  • Chromatid: one of the two identical copies of a chromosome after DNA replication, joined to the other at the centromere.
  • Centromere: the region that holds two sister chromatids together and attaches to the spindle fibres; it divides in anaphase.
  • Spindle fibres: protein fibres that attach to the centromeres and shorten to pull the chromatids to opposite poles.
  • Prophase, metaphase, anaphase, telophase: chromosomes condense; chromosomes line up on the equator; centromeres divide and chromatids are pulled to opposite poles; chromatids reach the poles and nuclear envelopes re-form.
  • Cytokinesis: division of the cytoplasm: the cell-surface membrane pinches in to make two new cells.
  • Tumour: a mass of abnormal cells produced by uncontrolled mitosis.
  • Binary fission: how prokaryotes divide: the circular DNA and plasmids replicate, then the cytoplasm divides into two daughter cells.
  • Viral replication: attachment proteins bind to receptors, viral nucleic acid enters the host cell, the cell copies it and makes viral proteins, and new particles are assembled and released.

What these questions cover (AQA 3.2.2)

The questions test these statements from the AQA AS and A-level Biology specification (7401/7402):

  • The cell cycle: Within multicellular organisms, not all cells retain the ability to divide.
  • The cell cycle: Eukaryotic cells that do retain the ability to divide show a cell cycle.
  • The cell cycle: DNA replication occurs during the interphase of the cell cycle.
  • The cell cycle: Mitosis is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication.
  • Mitosis: The behaviour of chromosomes during interphase, prophase, metaphase, anaphase and telophase of mitosis. The role of spindle fibres attached to centromeres in the separation of chromatids. (meiosis is in section 3.4.3)
  • Mitosis: Division of the cytoplasm (cytokinesis) usually occurs, producing two new cells.
  • Students should be able to: recognise the stages of the cell cycle: interphase, prophase, metaphase, anaphase and telophase (including cytokinesis)
  • Students should be able to: explain the appearance of cells in each stage of mitosis. (root tip squashes, the mitotic index and measuring cells (required practical 2) have their own page)
  • Cancer: Mitosis is a controlled process. Uncontrolled cell division can lead to the formation of tumours and of cancers. Many cancer treatments are directed at controlling the rate of cell division.
  • Binary fission in prokaryotic cells involves: replication of the circular DNA and of plasmids
  • Binary fission in prokaryotic cells involves: division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.
  • Viruses: Being non-living, viruses do not undergo cell division. Following injection of their nucleic acid, the infected host cell replicates the virus particles.

How to use this page

Write your answer on paper before you open the mark scheme. Allow about 1.3 minutes per mark: the 18 questions are worth 45 marks, so about 58 minutes in total. Then mark your answer strictly against the mark scheme and read the examiners' tip underneath it. If you'd rather print the questions, download the PDF pack.

The cell cycle (3.2.2)

Question 1

A level Paper 1 · June 2019 · Q06.1 · 2 marks

Describe and explain the falling percentage of mouse heart cells in mitosis and DNA replication.

Table 4: percentage of mouse heart cells undergoing mitosis and DNA replication at ages −6, 4, 14 and 21 days; mitosis falls from 13.9 to 0.6% and DNA replication from 8.5 to 0.0%.
Show the mark scheme Mark scheme: the percentage undergoing mitosis or DNA replication decreases from before birth to 21 days; DNA replication happens before mitosis, or the heart is fully developed, or these cells lose the ability to divide.

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From the examiners' report: There's no examiners' report for this paper, so this tip comes from the mark scheme. Describe the trend with the ages, then explain it: heart cells lose the ability to divide once the heart is developed.

Question 2

AS Paper 2 · June 2023 · Q07.1 · 3 marks · Hard

Use your knowledge of the cell cycle to explain a graph of the number of cells against DNA mass.

Figure 4: histogram of number of cells against mass of DNA per cell in arbitrary units; a tall peak at 1, low bars between 1 and 2, and a medium peak at 2.
Show the mark scheme Mark scheme: mass 1 shows (early) interphase, and none below 1 shows only mitosis is happening; mass 2 shows cells in mitosis, each chromosome with two chromatids; between 1 and 2 some DNA has been replicated (S phase).

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From the examiners' report: Students struggled: the y-axis is the number of cells, not the DNA mass. Most cells have a mass of 1 because they're in interphase; between 1 and 2 they're replicating DNA.

Question 3

AS Paper 2 · June 2025 · Q05.2 · 4 marks · Medium

Use a table of cell cycle phases to give similarities and differences with binary fission.

Table 2: features of the phases of the eukaryotic cell cycle: first phase of interphase, ribosomes and proteins synthesised; second phase, DNA replicated, histones synthesised and associated with DNA; third phase, accuracy of DNA replication checked and membrane-bound organelles replicated; then the stages of mitosis and cytokinesis.
Show the mark scheme Mark scheme: similarities, DNA replication, division of the cytoplasm or one cell into two, synthesis of proteins or ribosomes; differences, no histones in binary fission, no mitosis or interphase, no membrane-bound organelles replicated. Max 4.

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From the examiners' report: Almost a third got full marks. Use the table, not circular v linear DNA. 'No histones synthesised' and 'no histones with DNA' are one difference, so don't use both.

Mitosis and cytokinesis (3.2.2)

Question 4

A level Paper 1 · June 2024 · Q05.1 · 4 marks · Easy

Describe the appearance and behaviour of chromosomes during prophase and anaphase.

Question text: describe the appearance and behaviour of chromosomes during prophase and during anaphase of mitosis, 4 marks.
Show the mark scheme Mark scheme (max 2 for prophase): chromosomes condense; become visible; attach to spindle fibres by their centromeres. Anaphase: centromeres divide; chromatids pulled to opposite poles. Reject homologous chromosomes moving to opposite sides.

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From the examiners' report: Generally well answered, but few said the centromere splits in anaphase, and spindle attachment was less well known. Homologous pairs and crossing over belong to meiosis.

Question 5

A level Paper 1 · November 2021 · Q06.2 · 5 marks

Name phases C, D and E on a graph and describe the spindle and chromosomes in each.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Figure 7: graph of mean distance between centromeres and the poles of the spindle against time from 0 to 2500 s, with phases C, D and E marked; the distance rises from about 10 to 20 µm in C, stays level in D, and falls in E. The context crop also shows the earlier calculation part.
Show the mark scheme Mark scheme: C prophase, D metaphase, E anaphase; prophase, chromosomes condense; centromeres attach to spindle fibres; metaphase, chromosomes line up at the equator; anaphase, centromeres divide and chromatids are pulled to opposite poles; spindle fibres shorten. Max 4 if the stages are wrong.

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From the examiners' report: Many didn't match the stages to the graph. Distance to the poles stays the same while chromosomes sit on the equator (metaphase), then falls as chromatids are pulled apart (anaphase).

Question 6

AS Paper 2 · June 2018 · Q05.5 · 3 marks

Suggest how a chemical stops root growth, using a drawing of an anaphase cell.

Question text and Figure 3: a chemical stops onion roots growing; a drawing of the chromosomes in one anaphase cell shows them in a tangled group, not separated to two poles.
Show the mark scheme Mark scheme, any three: stops anaphase or mitosis; by disrupting spindle fibres forming, attaching or pulling; preventing separation of sister chromatids; so no new cells are added to the root tip.

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From the examiners' report: Most linked the chemical to spindle fibres. Say chromatids, not homologous chromosomes, fail to separate, and finish with no new cells being made.

Question 7

AS Paper 1 · June 2024 · Q03.4 · 2 marks · Hard

Identify the stage of the cell cycle in a photo of an animal cell and explain its appearance.

Figure 4: micrograph of one animal cell pinched in the middle into two rounded halves.
Show the mark scheme Mark scheme: cytokinesis or telophase; division of cytoplasm, pinching of the cell-surface membrane, a new membrane forming, or chromosomes not visible. Ignore the nucleus and organelles.

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From the examiners' report: Many identified cytokinesis or telophase. The membrane pinches in; it doesn't split down the middle. The question bans organelles, so don't mention nuclei.

Question 8

A level Paper 1 · June 2023 · Q08.1 · 2 marks · Easy

Explain why drawing A shows cancer cells treated with MiTMAB, which inhibits cytokinesis.

Figure 8: drawings of cancer cells; in A most cells contain two nuclei, in B (control) each cell has one nucleus.
Show the mark scheme Mark scheme: two nuclei in the cells, or cells stopped at telophase; cytokinesis prevented, so no new membrane forms or the cytoplasm doesn't divide.

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From the examiners' report: 80% got at least one mark. Spot the two nuclei in each cell; they aren't separate cells inside one membrane.

Question 9

AS Paper 2 · June 2024 · Q07.3 · 1 mark · Hard

Explain how mosaic trisomy 18 produces body cells with different chromosome numbers.

Question text: in mosaic trisomy 18 a chromosome mutation happens after fertilisation, so the body has cells with an extra chromosome 18 and cells with the correct number; explain how, 1 mark.
Show the mark scheme Mark scheme: cells with the extra chromosome come from (by mitosis) the cell with the mutation; cells with the correct number come from cells without it.

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From the examiners' report: Many left this blank or blamed gametes, though the question says the mutation is after fertilisation. Mitosis copies a cell exactly, so every cell descended from the mutant cell has it.

Cancer and cell division (3.2.2)

Question 10

AS Paper 1 · June 2022 · Q07.1 · 2 marks

What is a tumour?

Question text: what is a tumour? 2 marks.
Show the mark scheme Mark scheme: a mass of cells or tissue, or abnormal cells; produced by uncontrolled mitosis or cell division. Ignore growth.

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From the examiners' report: Most knew a tumour comes from uncontrolled mitosis but didn't also say it's a mass (lump) of cells.

Question 11

AS Paper 2 · June 2023 · Q07.2 · 2 marks · Medium

Suggest how the DNA mass graph would differ for tumour cells, and justify it.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Context: Figure 4, number of cells against mass of DNA per cell, with peaks at 1 and 2. Question asks how the graph would differ if the cells were tumour cells.
Show the mark scheme Mark scheme: fewer cells with a DNA mass of 1, or more with a mass between 1 and 2 or of 2; because cell division is faster or uncontrolled. 'Mass of DNA is higher' is not enough.

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From the examiners' report: Almost three-quarters got one mark, for uncontrolled cell division. For the second, say which bar changes: more cells replicating DNA (between 1 and 2) or at 2.

Question 12

A level Paper 1 · November 2020 · Q05.4 · 2 marks

Use a graph to suggest why high cyclin D concentrations could result in a tumour.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Figure 5: percentage of rat cells undergoing DNA replication against time from 0 to 25 hours; with cyclin D it peaks at about 47% at 13 hours, without cyclin D at about 50% at 19 hours.
Show the mark scheme Mark scheme, any two: shortens interphase or DNA replication starts earlier; faster or uncontrolled cell cycle or mitosis; a mass of abnormal cells.

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From the examiners' report: Figure 5 shows DNA replication starting earlier with cyclin D, not more cells replicating. Then link a faster, uncontrolled cell cycle to a mass of cells.

Question 13

AS Paper 1 · June 2019 · Q09.2 · 1 mark

Explain why a drug that stops spindle fibres could treat cancer though it affects healthy cells.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Passage: the drug ABZ stopped mitosis in stomach tumour cells by preventing spindle fibres forming, and affected some healthy cells; it raised cyclin B and changed the Bcl-2 to Bax ratio to promote apoptosis. Question asks why ABZ could still be used as a cancer treatment.
Show the mark scheme Mark scheme: cancer cells divide more, uncontrollably or rapidly, or healthy cells divide less.

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From the examiners' report: There's no examiners' report for this paper, so this tip comes from the mark scheme. Cancer treatments target dividing cells. Tumour cells divide far more often than most healthy cells, so they're affected most.

Binary fission and viral replication (3.2.2)

Question 14

A level Paper 3 · June 2025 · Q01.1 · 3 marks · Easy

Describe binary fission in bacteria.

Question text: describe binary fission in bacteria, 3 marks.
Show the mark scheme Mark scheme: replication of circular DNA; replication of plasmids; division of the cytoplasm or a new membrane forms. Reject chromosome, mitosis and single strand of DNA.

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From the examiners' report: About 40% got all three. Give the circular DNA and the plasmids as two separate points, not 'genetic material replicates'.

Question 15

A level Paper 1 · June 2025 · Q08.5 · 3 marks · Medium

Use a graph to conclude when binary fission and plasmid replication happen in a growing population.

Figure 11: mean plasmid B copy number per cell and cloudiness of a Bacillus thuringiensis culture over 15 hours in germination, growth and dormant phases; copy number falls slightly then stays at about 2.4 in germination, rises in growth and levels at about 6 in dormancy, while cloudiness only rises in the growth phase.
Show the mark scheme Mark scheme: germination, no plasmid replication or binary fission; growth, plasmid replication and binary fission happen; dormant, plasmid replication but no binary fission. Each point must be linked to a phase.

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From the examiners' report: Under 10% got all three. Don't just describe the lines: turn cloudiness into binary fission and copy number into plasmid replication, phase by phase.

Question 16

A level Paper 1 · June 2022 · Q04.1 · 3 marks · Medium

Describe viral replication.

Question text: describe viral replication, 3 marks.
Show the mark scheme Mark scheme, any three: attachment proteins attach to receptors; viral nucleic acid enters the cell; it is replicated (or reverse transcriptase makes DNA from RNA); the cell makes viral proteins; viruses are assembled and released.

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From the examiners' report: About a third scored zero. Viruses don't use binary fission or mitosis. Link attachment proteins to receptors, and include assembly before release.

Question 17

AS Paper 1 · June 2024 · Q03.2 · 1 mark

Explain the clear zones on a Petri dish of bacteria mixed with a virus.

Figure 3: Petri dish of cloudy agar with growing bacteria and five small clear zones, after a virus was mixed with the bacterial culture and incubated for 24 hours.
Show the mark scheme Mark scheme: the virus (replicating) killed, lysed or burst the bacteria in the clear zones.

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From the examiners' report: This new context confused some. Say the virus killed the bacteria: they replicate inside and burst the cells. Antibiotics and antiseptics aren't involved.

Using numbers (3.2.2)

Question 18

AS Paper 1 · June 2018 · Q04.4 · 2 marks · Medium

Calculate the number of prokaryotic cells after 3 hours of dividing every 30 minutes.

Question text: some prokaryotic cells divide every 30 minutes; a culture starts with 1.35 × 10⁴ cells; calculate how many cells there will be after 3 hours, assuming none die.
Show the mark scheme Mark scheme: 8.64 × 10⁵ (864 000) for 2 marks; 1 mark for 2⁶ = 64.

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From the examiners' report: Just under half got both marks. Three hours is six divisions, so multiply by 2⁶ (64), not by 6 or 24.

Where students lose marks (from AQA examiners' reports and mark schemes)

Each point below is followed by wording that gained marks.

  • Binary fission, not fission or mitosis: 57% named the process by which prokaryotes divide. Those who failed usually wrote just 'fission' or 'mitosis'; 'binary fusion' was rejected.

    ✔ Gains credit: "Binary fission".

  • Replicate the circular DNA and the plasmids: Only about 40% got all three marks for describing binary fission: many merged the first two points into 'genetic material replicates'.

    ✔ Gains credit: "Replication of (circular) DNA; replication of plasmids; division of cytoplasm (to produce daughter cells)."

  • Centromeres divide in anaphase: Prophase condensing was well known, but spindle attachment less so, and few said the centromere splits in anaphase. Some described meiosis: homologous chromosomes separating and crossing over.

    ✔ Gains credit: "(Prophase) chromosomes condense; centromeres attach to spindle fibres. (Anaphase) centromeres divide; chromatids pulled to opposite poles."

  • The membrane pinches in: Many identified cytokinesis or telophase but lost the explanation by saying the cell-surface membrane splits down the middle; few mentioned the chromosomes.

    ✔ Gains credit: "Division of cytoplasm; pinching of cell-surface membrane / new cell-surface membrane forming; chromosomes are not visible."

  • A DNA mass of 2 means replicated DNA: Students struggled with a graph of number of cells against DNA mass: many wrote about the DNA mass going up and down, not the number of cells, and few linked a mass of 1 to interphase.

    ✔ Gains credit: "Mass of 1 = (early) interphase; mass of 2 = each chromosome has two chromatids / mitosis; between 1 and 2 = DNA being replicated."

  • Uncontrolled division, not just faster: Asked why a virus can cause cancer, over half got the mark, but a common error was that cancer cells divide faster rather than uncontrollably. For 'what is a tumour?' most forgot to say it is a mass of cells.

    ✔ Gains credit: "Uncontrolled cell cycle/division/mitosis" and "mass of abnormal cells".

  • Attach to receptors, then assemble: About a third scored nothing on viral replication. Errors included binary fission or mitosis, mRNA being injected, attachment proteins not linked to receptors, and stopping before the virus is assembled.

    ✔ Gains credit: "Attachment proteins attach to receptors; nucleic acid enters cell and is replicated; cell produces viral proteins; virus assembled and released."

  • Six divisions means 2⁶: Just under half got both marks for cells dividing every 30 minutes for 3 hours: a common error was multiplying by 6 or 24 instead of 2⁶.

    ✔ Gains credit: 1.35 × 10⁴ × 2⁶ = 8.64 × 10⁵ cells.

Download the questions

Download the PDF pack (18 questions, mark schemes at the end)

Keep practising

Questions, mark schemes and examiners' report extracts © AQA.

Tom Whitburn
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