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IGCSE · Cambridge (CIE) · 0654

Explain the role of mitosis in repair of damaged tissues

Mitosis can supply cells for damaged-tissue repair. Invented counts of thirty-five survivors plus twenty new cells give fifty-five, five below a target of sixty.

Cell division · Cambridge IGCSE 0654 · B16.2

Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.

Before you begin

  • Recall chromosomes, genes, chromosome sets, selective gene expression and the distinction between a nucleus and a whole cell.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

What is the relevant role of mitosis in tissue repair?

What you will learn

  • Connect replacement production with repair
  • Separate counts from restored function

Original teaching model. Counts and records are stipulated; drawings are schematic.

Explain the role of mitosis in repair of damaged tissuesMitosis can supply cells for damaged-tissue repair. Invented counts of thirty-five survivors plus twenty new cells give fifty-five, five below a target of sixty.RoleSupply suitable cells fordamaged-tissue repairInvented record35 surviving + 20 new = 55Invented target60 cells; deficit 5LimitCell count alone does not establishrestored function
Mitosis can supply cells for damaged-tissue repair. Invented counts of thirty-five survivors plus twenty new cells give fifty-five, five below a target of sixty.
Division, chromosome count and cell-state key
FeatureMeaning
RoleSupply suitable cells for damaged-tissue repair
Invented record35 surviving + 20 new = 55
Invented target60 cells; deficit 5
LimitCell count alone does not establish restored function

Connect replacement production with repair

Mitosis contributes to repair of damaged tissues by producing cells that can replace cells lost or damaged in the tissue. Dividing surviving cells or appropriate stem-cell populations supply daughter cells with preserved genetic information. The role is to generate cells for repair; their later growth, specialisation and organisation also matter for a functioning tissue.

This explanation does not mean every mature cell can divide or every damaged structure can be restored completely. Different tissues have different capacities, and not all specialised cells behave as actively dividing precursors. The syllabus asks for the role of mitosis in repair, not a promise of a particular medical outcome or instructions for treating an injury.

Separate counts from restored function

A fictional tissue record specifies a target of sixty functioning cells, thirty-five surviving cells and twenty newly added replacement cells. On those supplied counts alone, the represented population reaches fifty-five, leaving a deficit of five relative to the target. Those values are invented to practise a complete count; they are not clinical thresholds or a model of a real wound.

Even a restored count of sixty would not prove restored tissue function without further evidence. Cells must be appropriate for the tissue and arranged so that they can work together. Explain the causal contribution at the right level: mitotic production can help replenish cells, while a simple count cannot demonstrate every functional step of repair or prove which process created an observed increase.

Sources for this lesson

Pause and explain

A target is sixty; thirty-five survive and twenty new cells are added. What is the numerical deficit?

Put the idea to work

Worked example

Thirty-five survivors plus twenty new cells are recorded against a target of sixty. What remains?

Show the worked solution
  1. Add the supplied populations.
  2. Compare with the target.

Answer Fifty-five cells are recorded, leaving five below the target; function is not established by the count alone.

Try a topic test

Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.

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From guided practice to a new situation

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.

1 · Guided

Explain why accurate mitosis can contribute to repair.

Give me a hint

Connect cell production and lost tissue cells.

Compare my reasoning
  1. Describe production of genetically matching daughters.
  2. Explain that suitable products can replace lost cells.

Accurate mitosis produces genetically matching daughter cells that, with suitable growth and organisation, can help replace damaged or lost tissue cells.

Look for these in your work

  • Explain production
  • Avoid guaranteeing all repair
2 · Independent

Calculate the recorded total and deficit for thirty-five survivors plus twenty new cells against a target of sixty.

Give me a hint

Add first, then compare.

Compare my reasoning
  1. Calculate thirty-five plus twenty.
  2. Subtract the total from sixty.

The recorded total is fifty-five cells and the deficit is five cells.

Look for these in your work

  • Show the addition
  • Label the deficit
3 · Transfer

A fictional tissue returns to its earlier cell count. Explain why that does not by itself prove complete functional repair.

Give me a hint

Ask about cell type and organisation.

Compare my reasoning
  1. Identify the limited count evidence.
  2. State the missing functional evidence.

The count alone does not show that the cells are the appropriate types, correctly organised or performing the required functions; those aspects need further evidence.

Look for these in your work

  • Acknowledge the count
  • State additional evidence needs

Common mistakes

  • Mitosis contributes to repair without guaranteeing complete recovery.
  • A restored cell count is not proof of restored tissue function.
Recall without your notes

What can you explain now?

A target is sixty; thirty-five survive and twenty new cells are added. What is the numerical deficit?

Compare with the explanation

Five cells

Sixty minus fifty-five is five.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Without your notes, connect replacement production with repair and separate counts from restored function. Distinguish nuclear division, chromosome copies and completed daughter cells before opening the solutions.

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.

Keep learning Sciences — Co-ordinated (Double)

Course scope and assessment

This 2028–2029 pathway maps all 152 detailed subject-content sections in the published 0654 syllabus to original teaching and staged practice. It adapts teaching from the related single-science pathways and excludes clear 0610-only topics such as classification systems, human excretion, tropic responses, food supply, population dynamics, detailed pollution and biotechnology. Some explanations may include wider single-science context. A 0654-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The 2025–2027 syllabus has not been reconciled here; choose the 2028–2029 syllabus only.

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