GCSE Combined Science (AQA)

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Comparing Water Concentrations

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Cell Biology Transport in Cells

Comparing Water Concentrations

4:26 Osmosis
Spec 4.1.3.2
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  • Solutions with different water concentrations can be compared to observe water movement.
  • Two solutions can be separated by a partially permeable membrane.
  • The left side of the image shows a higher concentration of water molecules, indicated by more blue dots.
  • The right side has a lower concentration of water molecules and a higher solute concentration, shown by more orange dots.
  • Understanding water movement by osmosis is crucial in contexts like animal and plant cells.
  • When water and solute concentrations are equal on both sides of a membrane, the solution is isotonic.
  • A cell membrane is partially permeable, containing cytoplasm with water and solutes like sugars.
  • An isotonic solution outside a cell causes no net movement of water.
  • In a highly concentrated solution like salty water, water moves out of the cell by osmosis.
  • If a cell is placed in a dilute solution, water moves into the cell by osmosis.
  • Osmosis effects on cells can be observed by placing animal cells in different solutions.
  • In isotonic solutions, there is no net movement of water into or out of the cell.
  • In salt water, water leaves the cell, causing it to shrink and shrivel.
  • In pure water, an animal cell will burst due to excessive water intake.
  • Plant cells have a cell wall that prevents bursting when water is gained by osmosis.
  • In isotonic solutions, there is no net movement of water in plant cells.
  • In salt water, the cytoplasm of a plant cell shrinks, causing the plant to wilt.
  • In pure water, a plant cell swells but the cell wall prevents it from bursting, maintaining plant structure.

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