Explain why organisms use mitosis
Mitosis produces genetically identical daughter cells for growth, cell replacement, tissue repair and asexual reproduction.
AS Level · Cambridge International Biology 9700, 2028–2030. These lessons explain cell-cycle concepts and image interpretation. Written practice is self-checked; it does not demonstrate practical microscopy competence or replace teacher-reviewed assessment.
Before you begin
- Recognise DNA as genetic material and use the terms cell, nucleus and chromosome accurately.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which process normally produces genetically identical daughter nuclei?
What you will learn
- Explain how genetically identical daughter cells support growth, replacement and repair
- Relate mitosis to asexual reproduction
Mitosis preserves genetic information
Before mitosis, DNA is replicated. Mitosis separates the replicated chromosomes so that each daughter nucleus receives one copy of each chromosome. This supports genetically identical daughter cells, barring mutation or copying errors.
In multicellular organisms, an increase in cell number through mitosis contributes to growth. Mitosis also replaces damaged or dead cells and repairs tissues by replacing cells.
Asexual reproduction uses cell division
In asexual reproduction, one parent can produce offspring without fusion of gametes. Mitosis can produce offspring cells with the same genetic information as the parent, apart from mutation.
Do not confuse mitosis with meiosis. Mitosis supports growth, repair, replacement and asexual reproduction; meiosis produces haploid cells for sexual reproduction.
Pause and explain
Which is a role of mitosis in multicellular organisms?
Worked example
A skin wound closes as new cells replace damaged ones. Explain how mitosis contributes.
Show the worked solution
- Mitosis produces additional cells.
- Daughter cells replace damaged or dead tissue cells.
Answer Mitosis produces genetically identical daughter cells. These cells increase cell number and replace damaged or dead cells, contributing to tissue repair.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Explain how mitosis contributes to growth and tissue repair.
Give me a hint
Link cell division to daughter cells and cell number.
Compare my reasoning
- Mitosis produces genetically identical daughter cells.
- More cells support growth and can replace damaged or dead cells.
Mitosis produces genetically identical daughter cells. Increasing cell number contributes to growth, while new cells replace damaged or dead cells during tissue repair.
Look for these in your work
- Daughter cells described
- Growth and repair linked
A unicellular organism reproduces asexually by cell division. Explain why mitosis can support this.
Give me a hint
Relate nuclear division to the genetic information of offspring.
Compare my reasoning
- Mitosis separates replicated chromosomes into equivalent nuclei.
- A daughter cell can receive the same genetic information as the parent.
Mitosis separates replicated chromosomes so the daughter nucleus receives the same genetic information as the parent, apart from mutation. This can support asexual reproduction.
Look for these in your work
- Chromosome separation stated
- Genetic similarity bounded
A student says mitosis is the process that makes sperm and egg cells. Correct the statement.
Give me a hint
Distinguish cell replacement from gamete production.
Compare my reasoning
- Mitosis supports growth, repair, replacement and asexual reproduction.
- Meiosis produces haploid gametes.
Mitosis is used for growth, replacement, tissue repair and asexual reproduction. Meiosis produces haploid gametes such as sperm and egg cells.
Look for these in your work
- Mitosis roles stated
- Meiosis distinguished
Common mistakes
- Saying mitosis makes genetically different cells by design
- Claiming mitosis alone explains every aspect of healing
- Confusing asexual mitosis with gamete formation by meiosis
What can you explain now?
Which process normally produces genetically identical daughter nuclei?
Compare with the explanation
Mitosis
Mitosis separates replicated chromosomes into daughter nuclei.
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Make it stick
How does mitosis provide cells for growth, replacement, repair and asexual reproduction?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.