Explain why mitosis is important for the growth and repair of organisms.

WJEC GCSE Biology (Wales) — 2.2.1 Mitosis and meiosis · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A dog cuts its paw on a sharp stone. Over the next few days, new cells form to heal the wound. At the same time, the dog continues to grow because it is still a young animal.

Model answer (4 marks)

Mitosis produces genetically identical cells, so the new cells are the same as the parent cell.
The daughter cells have the same diploid chromosome number as the parent.
Because each division doubles the number of cells, mitosis increases cell numbers, allowing the animal to grow.
The identical replacement cells are required for repair so that the tissue retains its normal structure and function.

Examiner tips

Use the word "genetically identical" and mention "diploid" to hit the key points.
Show the link between cell number increase and growth, and between identical cells and correct tissue function.
Keep each point short and to the point to fit the 4‑mark structure.

Common mistakes

Confusing mitosis with meiosis or omitting the diploid detail.
Failing to state that the new cells are identical to the parent cell.
Giving extra information about cell cycle phases that is not required for the marks.

Mark scheme (4 marks)

Mitosis produces genetically identical cells (to the parent cell / to each other)
The new cells have the same number of chromosomes as the parent cell / are diploid
Mitosis allows the number of cells to increase (cell division produces more cells for growth)
Genetically identical replacement cells are needed for repair so that the tissue functions correctly / has the correct proteins / has the same characteristics

Key terms in this question

mitosis