A muscle cell is damaged during exercise. Describe how mitosis allows the body to replace the damaged muscle cell, and explain why it is important that the new cells produced are identical to the original.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
A damaged muscle cell (or a nearby satellite cell) undergoes mitosis. Before division the chromosomes are replicated, so each daughter cell receives a complete set of DNA. Mitosis produces two daughter cells that are genetically identical to each other and to the parent cell. Because the new cells are identical, they contain the same genes and therefore give the same instructions for muscle contraction and metabolism. If the new cells were not identical or had altered genetic information, they would not function correctly as muscle cells and could even become harmful, for example by forming tumours.
Examiner tips
- Use the word ‘mitosis’ and mention chromosome replication; link this to identical daughter cells.
- Explain that identical cells mean the same genes for muscle function; mention potential problems if not identical.
Common mistakes
- Confusing mitosis with meiosis; not stating chromosome replication; saying new cells are ‘different’ instead of ‘identical’.
Mark scheme (5 marks)
- The damaged cell (or a nearby cell) undergoes cell division / mitosis
- The chromosomes / DNA are copied / replicated before division so each daughter cell receives a full set
- Two daughter cells are produced that are genetically identical to each other and to the parent cell
- The new cells are identical so they have the same genes / instructions to carry out the same function as the original muscle cell
- If the new cells were not identical / had different genetic information, they could not function correctly as muscle cells / could be harmful (e.g. cancer)
Key terms in this question
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Describe and Explain" question →
- Decode the mark scheme abbreviations →
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