Basics of Diffusion and Osmosis

Which of the following is not considered partially permeable?

• cell membrane

• cell wall

• nuclear envelope (or nuclear membrane)

• tonoplast (the membrane surrounding the large central vacuole)

• Visking tubing (or dialysis tubing)

A 10 % sucrose solution is considered to be more ............... than a 20 % sucrose solution.

• dilute

• concentrated

A 0.5 mol dm^-3 sucrose solution has a ..................... water potential than a 1.0 mol dm^-3 sucrose solution. (Note: mol dm^-3 is a unit for concentration)

• lower

• higher

Which of the following has the highest water potential?

• 0.1 mol dm^-3 salt solution

• 0.5 mol dm^-3 salt solution

• 1.0 mol dm^-3 salt solution

• 2 mol dm^-3 salt solution

Which of the following has the highest water potential?

• 1 % salt solution

• 5 % salt solution

• 10 % salt solution

• 20 % salt solution

If two regions have the same concentration of a substance X, will diffusion of the particles of substance X take place?

• Yes

• No

• It depends.

Which of the following statements is / are incorrect?

• Diffusion is a passive process.

• Diffusion stops when equilibrium is reached.

• The rate of diffusion can be increased by shortening the diffusion distance.

• When diffusion stops, the particles stop moving.

Which of the following is missing in the explanation provided below (with reference to the 5-step method)?

The water in the Visking tubing has a lower water potential than the sucrose solution around it. Hence, water molecules move across its partially permeable membrane by osmosis, causing the water level in it to drop.

• concentration / water potential

• direction (of movement of particles)

• membrane

• process

• outcome

Which of the following is missing in the explanation provided below (with reference to the 5-step method)?

When a red blood cell is placed in pure water, there is a net movement of water molecules across the cell membrane and into the red blood cell by osmosis. This causes the cell to expand and burst (or lyse).

• concentration / water potential

• direction (of movement of particles)

• membrane

• process

• outcome

Which of the following is missing in the explanation provided below (with reference to the 5-step method)?

When a plant cell is placed in a concentrated salt solution, it becomes plasmolysed and shrinks in size.

This is because it has a higher water potential than the salt solution around it. Water molecules are drawn out from the plant cell across its cell membrane and into the salt solution. This loss of water causes the shrinkage of cell membrane and cytoplasm away from the cell wall.

• concentration

• direction (of movement of particles)

• membrane

• process

• outcome