A farmer stores freshly harvested carrots in a very salty brine solution overnight. The next morning, the carrots are noticeably soft and floppy. Explain why the carrots became soft and floppy when stored in the brine solution.

Cambridge International IGCSE Biology (0610) — 3.2 Osmosis · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

The brine solution is more concentrated than the carrot cells, so it has a lower water concentration.
Water therefore moves out of the carrot cells by osmosis.
The cells lose water and their volume decreases, becoming flaccid.
With less turgor pressure the cells can no longer support the carrot tissue, so the carrot becomes soft and floppy.

Examiner tips

  • Use the term ‘osmotic gradient’ to show understanding of concentration difference.
  • Explain the direction of water movement and its effect on cell volume and turgor.
  • Link loss of turgor to the soft, floppy appearance of the carrot.
  • Use correct terminology: osmosis, turgor pressure, flaccid cells.

Common mistakes

  • Saying water moves into the cells instead of out. Failing to mention turgor pressure or cell flaccidity. Using vague terms like ‘water loss’ without linking to cell volume or turgor.

Mark scheme (4 marks)

  1. The brine solution is more concentrated than the cell contents / the brine has a lower water concentration than the carrot cells
  2. Water moves out of the carrot cells by osmosis
  3. The cells lose water so the volume of the cells decreases / cells become flaccid
  4. Turgor pressure is reduced / cells are no longer turgid so cannot support the carrot tissue

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