A student cuts a small piece of skin after an accident. New skin cells are produced to repair the damaged area. Explain how the cell cycle produces new skin cells that are genetically identical to the original skin cells.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Skin repair requires rapid production of new cells. The cells produced must be genetically identical to the surrounding skin cells so that the tissue functions correctly.
Model answer (5 marks)
The cell cycle has two main stages: interphase and mitosis.
1. In interphase the cell grows and synthesises new organelles.
2. DNA replication occurs, so each chromosome is copied.
3. Mitosis then separates the duplicated chromosomes.
4. Cytokinesis divides the cytoplasm, forming two daughter cells.
5. Each daughter cell receives an identical set of chromosomes, so they are genetically identical to the parent cell and to each other.
1. In interphase the cell grows and synthesises new organelles.
2. DNA replication occurs, so each chromosome is copied.
3. Mitosis then separates the duplicated chromosomes.
4. Cytokinesis divides the cytoplasm, forming two daughter cells.
5. Each daughter cell receives an identical set of chromosomes, so they are genetically identical to the parent cell and to each other.
Examiner tips
- Use the word "interphase" and "mitosis"; mention DNA replication and cytokinesis; show that the daughter cells are identical to the parent.
- Structure answer in five clear points to match the 5 marks.
Common mistakes
- Confusing interphase with mitosis; not mentioning DNA replication; saying the cells are just similar instead of genetically identical; omitting cytokinesis.
Mark scheme (5 marks)
- The cell cycle involves interphase, in which DNA replication occurs so each chromosome is copied
- During interphase the cell also grows and new organelles are synthesised
- During mitosis the chromosomes are separated so that each daughter cell receives an identical full set of chromosomes
- Cytokinesis divides the cytoplasm to produce two new daughter cells
- The two daughter cells are genetically identical to each other and to the original parent cell because they each contain the same DNA / chromosomes
Key terms in this question
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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