AQA GCSE Combined Science Foundation (8464), Foundation tier · Biology › Cell biology › Cell division
Practise Mitosis and the cell cycle. 6 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The three stages of the cell cycle, what happens in mitosis, and why mitosis matters for growth, development and repair. Expect 'describe the stages' questions, questions asking you to spot where mitosis is happening, and data questions on dividing cells.
Key facts
Cell cycle stage 1: cell grows, more ribosomes and mitochondria, DNA replicates
Stage 2, mitosis: one set of chromosomes pulled to each end; nucleus divides
Stage 3: cytoplasm and cell membrane divide
Mitosis → two genetically identical cells with the same number of chromosomes as the parent
Mitosis is for growth, development, repair and replacement (and asexual reproduction)
Notes
The cell cycle
diagram
Body cells divide in a series of stages called the cell cycle. The genetic material is doubled, then divided between two identical cells.
Stage 1: growth and DNA replication. The cell grows and increases the number of sub-cellular structures, such as ribosomes and mitochondria. The DNA replicates, forming two copies of each chromosome.
Stage 2: mitosis. One set of chromosomes is pulled to each end of the cell, and the nucleus divides.
Stage 3: cell division. The cytoplasm and cell membrane divide to form two identical cells.
The cell cycle: each new cell gets one copy of every chromosome (blue from one parent, red from the other).
You do not need to know the names of the phases within mitosis.
The result
Mitosis produces two cells that are genetically identical to each other and to the parent cell.
Each new cell has the same number of chromosomes as the parent cell: 46 in a human body cell.
Why mitosis matters
Growth and development of multicellular organisms, e.g. an embryo developing or a root getting longer.
Repair and replacement of damaged or worn-out cells, e.g. healing a cut or replacing skin cells.
Asexual reproduction in some organisms, e.g. strawberry plants growing new plants on runners.
Mitosis does not make gametes (sperm and egg cells): they are made by a different type of cell division, meiosis.
How to answer each type of question
Recognise where mitosis is happening
1 to 2 marksGrade 5
Look for cells being made to grow, repair or replace tissue: that is mitosis.
Making sperm or egg cells is not mitosis.
Example. Which two of these involve cell division by mitosis? Tick (✓) two boxes. ☐ A cut in the skin healing ☐ Egg cells being made in an ovary ☐ A seedling's root getting longer ☐ Sperm cells being made in the testes
Show the model answerHide the model answer
A cut in the skin healing (1) A seedling's root getting longer (1)
Describe the stages of the cell cycle
3 to 4 marksGrade 5
Go in order: growth, mitosis, division of the cell.
In stage 1 mention growth, more sub-cellular structures and DNA replication.
In mitosis, say one set of chromosomes is pulled to each end and the nucleus divides.
Finish with the cytoplasm and cell membrane dividing to form two identical cells.
Example. Describe what happens during the cell cycle. [4 marks]
Show the model answerHide the model answer
The cell grows and the number of sub-cellular structures, such as mitochondria and ribosomes, increases (1). The DNA replicates / each chromosome is copied (1). One set of chromosomes is pulled to each end of the cell and the nucleus divides (1). The cytoplasm and cell membrane divide to form two identical cells (1).
Don’t lose marks
Leaving out DNA replication, or putting it after mitosis. The DNA is copied before the nucleus divides.
Saying mitosis makes gametes. Gametes are made by meiosis.
Saying the new cells have half the number of chromosomes. Mitosis keeps the number the same.
Using 'mitosis' to mean the whole cell splitting. Mitosis is the division of the nucleus; the cytoplasm and membrane divide afterwards.
Writing that the chromosomes 'split in half'. Say one set of chromosomes is pulled to each end of the cell.
More tips
Memory tricks
Order of the stages: Grow and copy, then split the nucleus, then split the cell.
MiTosis makes Two identical cells; mEiosis makes Eggs (and sperm).
Sense check: after mitosis each human body cell still has 46 chromosomes.
Exam technique
For 'describe' questions, give the stages in order and use the key phrases: 'DNA replicates', 'nucleus divides', 'two identical cells'.
In context questions (a cut healing, a root growing), look for new cells being made for growth or repair.
Show each step of a cell cycle calculation, including the percentage and any unit conversion.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
State what mitosis producesTwo genetically identical cells.
Grade 4
Name the three stages of the cell cycleGrowth and DNA replication; mitosis; division of the cytoplasm and cell membrane.
Grade 5
Describe what happens in each stageThe cell grows, copies its sub-cellular structures and DNA, divides its nucleus, then splits in two.
Grade 5
State why mitosis is importantFor the growth and development of multicellular organisms, and to repair and replace cells.
Grade 5
Recognise where mitosis is happeninge.g. a root tip growing, a cut healing, an embryo developing.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
The statements describe three stages of the cell cycle. A One set of chromosomes is pulled to each end of the cell and the nucleus divides. B The cell grows, the number of sub-cellular structures increases and the DNA replicates. C The cytoplasm and the cell membrane divide to form two cells. Write the letters A, B and C in the order in which the stages happen. Start with the stage that happens first after a new cell has formed.
B, A, C
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Cells divide in a series of stages called the cell cycle.
(a) The statements describe three stages of the cell cycle. A One set of chromosomes is pulled to each end of the cell and the nucleus divides. B The cell grows, the number of sub-cellular structures increases and the DNA replicates. C The cytoplasm and the cell membrane divide to form two cells. Write the letters A, B and C in the order in which the stages happen. Start with the stage that happens first after a new cell has formed.[1]
(b) Which type of cell division produces two genetically identical cells? Tick (✓) one box.[1]
Differentiation
Fertilisation
Meiosis
Mitosis
(c) Give two reasons why mitosis is important in multicellular organisms.[2]
Show the answer and mark scheme
(a)Answer: B, A, C
B → A → C
(b)Answer: Mitosis
(c)
growth / development
repair (of damaged tissue)
replacement (of worn-out / dead cells)
asexual reproduction
Question 2Medium5 marks
Mitosis happens in many parts of the human body.
(a) In which two of these is mitosis happening? Tick (✓) two boxes.[2]
A child’s bones getting longer
Egg cells forming in an ovary
Skin cells replacing cells at the edge of a cut
Sperm cells forming in a testis
(b) Explain why it is important that the new skin cells are genetically identical to the skin cells they replace.[2]
(c) A skin cell divides by mitosis. Each new cell then also divides by mitosis. This continues until there have been 5 rounds of cell division. Calculate the number of cells at the end.[1]
Show the answer and mark scheme
(a)Answer: A child’s bones getting longer; Skin cells replacing cells at the edge of a cut
(b)
the new cells have the same genes / chromosomes / a full set of chromosomes
so they can carry out the same function / become the same type of cell