IGCSE Chapter 3

Osmosis is the movement of ......

• molecules from high concentration to low concentration

• water molecules down a water potential gradient across a partially permeable membrane

• water molecules down a water potential gradient

• water molecules down a water potential gradient using energy

When water moves into plant cells, the plant cells become

• plasmolysed

• turgid

• inflated

• flaccid

When water molecules moves into animal cell, the cell

• burst

• becomes turgid

• becomes plasmolysed

• nothing happens

Cylinders of potato tissue were left in different concentrations of sucrose solution for one hour. The graph shows the percentage change in the length of the potato cylinders after one hour.

What can be concluded about the cells of the potato cylinders that were left in 0.2 mol dm–3 sucrose solution?

• The cells in the potato cylinders became flaccid.

• The cells in the potato cylinders became plasmolysed.

• The net movement of water into the potato cells was equal to the net movement of water out of the potato cells

• The water potential of the potato cells was zero.

The diagram represents a substance moving across a cell membrane, using energy from respiration.

Which method of transport does the diagram represent?

• active transport

• diffusion

• evaporation

• osmosis

The diagram shows an experiment demonstrating osmosis using a dialysis tubing bag.

After 30 minutes, the level of the liquid in the glass tube goes ......1...... because the water had a ......2...... water potential than the sugar solution. Which words correctly complete the statement?

• 1- down

  2- lower

• 1- down

  2- higher

• 1- up

  2- lower

• 1- up

  2- higher

The diagram shows a root hair cell.

When does water enter the cell by osmosis?

• when the concentration of solutes outside the cell is greater than inside the cell

• when the concentration of solutes inside and outside the cell are equal

• when the water potential inside the cell is higher than outside the cell

• when the water potential outside the cell is higher than inside the cell