Osmosis refers to the movement of which molecules?

Water molecules.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the definition of osmosis?

The net movement of water particles, from an area of higher water concentration, to an area of lower water concentration, across a partially permeable membrane.

Answer in your head, out loud, or on paper, then tap the card to flip.

Is osmosis an active or passive process?

Osmosis is a passive process because it doesn’t require any energy from the cell.

Answer in your head, out loud, or on paper, then tap the card to flip.

Cell membranes are said to be 'partially permeable'. What does this mean?

Only some types of molecules can pass through the membrane - other types of molecules can't pass through.

Answer in your head, out loud, or on paper, then tap the card to flip.

In the above diagram, which way would you expect the water molecules to move?

From outside the cell to inside the cell, because there's a greater concentration of water outside the cell.

Answer in your head, out loud, or on paper, then tap the card to flip.

What happens if you place a plant cell in a very salty solution?

  1. There will be a higher water concentration (water potential) within the plant cell than in the salty solution surrounding it.
  2. So water will move from the inside of the plant cell to the outside, by osmosis.
  3. This will cause the cell to shrink and become plasmolysed.

Answer in your head, out loud, or on paper, then tap the card to flip.

What happens if you place a plant cell in a beaker of pure water?

  1. There will be a lower water concentration (water potential) within the plant cell than in the pure water surrounding it.
  2. So water will move from the beaker into the plant cell, by osmosis.
  3. This will cause the cell to expand, and become turgid.

Answer in your head, out loud, or on paper, then tap the card to flip.

When animal cells are placed in pure water they burst, whereas plant cells become turgid. Why is this?

Plant cells have a strong cell wall made of cellulose, which prevents them from bursting.

Answer in your head, out loud, or on paper, then tap the card to flip.

If you add sugars and salts to a beaker of water, what will happen to the water concentration (or 'water potential')?

The water concentration (or 'water potential') will decrease.

Answer in your head, out loud, or on paper, then tap the card to flip.