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IGCSE · Practice questions · Mitosis

Same again, exactly.

Six original Cambridge-style questions on what mitosis is, why genetically identical cells matter, chromosome numbers before and after division and the role of stem cells.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Identical cells, same number.

01
Recall
[2 marks]

Describe what is meant by mitosis.

  • Nuclear division (division of the nucleus). ✓
  • That gives rise to genetically identical cells. ✓
02
Recall
[4 marks]

State four roles of mitosis in living organisms, with an example of each.

  • Growth, for example a zygote developing into an embryo. ✓
  • Repair of damaged tissues, for example healing a wound in the skin. ✓
  • Replacement of cells, for example replacing worn-out red blood cells. ✓
  • Asexual reproduction, for example potato tubers or strawberry runners. ✓
03
Explain
[3 marks]

Extended. Explain how mitosis makes sure that each daughter cell has the same chromosomes as the parent cell.

  • Before mitosis each chromosome is replicated exactly, making two identical copies. ✓
  • During mitosis the copies of each chromosome separate and move to opposite ends of the cell. ✓
  • So each daughter cell receives one copy of every chromosome, keeping the chromosome number (and the alleles) the same. ✓
04
Data
[3 marks]

Extended. The mass of DNA in the nucleus of a cell was measured over time. It was 6 arbitrary units at the start, rose to 12 units, and then fell to 6 units in each of the two new cells. (a) Explain why the mass of DNA doubled. (b) Explain why it then halved.

  • (a) The chromosomes (DNA) were replicated exactly before mitosis. ✓
  • (b) During mitosis the copies separated into two nuclei, one for each new cell. ✓
  • So each new cell has the same mass of DNA (6 units) as the original cell. ✓
05
Explain
[3 marks]

Extended. Describe stem cells and explain why they are useful in the body.

  • Stem cells are unspecialised cells. ✓
  • They divide by mitosis to produce daughter cells that can become specialised for specific functions. ✓
  • So they supply new cells for growth and to replace or repair tissues, for example new blood cells from bone marrow. ✓
06
Explain
[2 marks]

A gardener takes cuttings from one rose plant. Explain why all the new plants have flowers of exactly the same colour as the parent.

  • The new plants are produced by asexual reproduction, so their cells are made by mitosis. ✓
  • Mitosis gives genetically identical cells, so the new plants have the same alleles as the parent. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.