Transport in Cells Practice Questions

Which statement describes diffusion?

Tick (✓) one box.

• The movement of particles from a lower concentration to a higher concentration
• The movement of water through a partially permeable membrane
• The net movement of particles from a higher concentration to a lower concentration
• The movement of particles using energy from respiration

Urea is a waste product made in liver cells. It passes out of the liver cells into the blood plasma.

Name the process by which urea moves out of the liver cells into the blood plasma.

In the lungs, oxygen moves from the air in the alveoli into the blood by diffusion.

Explain, in terms of concentration, why oxygen moves in this direction.

Complete the definition of osmosis.

Osmosis is the diffusion of __________ from a __________ solution to a __________ solution through a partially permeable membrane.

Water moves across the membrane in Figure 1.

Give the direction of the net movement of water and explain your answer.

What is meant by active transport?

Name the process in cells that supplies the energy for active transport.

The surface area of block X is $24\ \text{cm}^2$ and its volume is $8.0\ \text{cm}^3$.

Give the surface area to volume ratio of block X.

Calculate the surface area to volume ratio of block Y.

Both blocks were placed in a dye solution for the same length of time.

Suggest which block, X or Y, would have the greater percentage of its volume coloured by the dye. Give a reason for your answer.

Calculate the percentage change in mass of the swede piece in the $0.2\ \text{mol/dm}^3$ sucrose solution.

Explain the change in mass of the swede piece placed in the $0.8\ \text{mol/dm}^3$ sucrose solution.

The student plotted a graph of percentage change in mass against concentration of sucrose solution.

Describe how the student could use this graph to estimate the concentration of the solution inside the swede cells.

Suggest one improvement the student could make to obtain more reliable results.

A single-celled organism can obtain all the oxygen it needs by diffusion across its surface. A fish cannot.

Explain why, in terms of surface area to volume ratio.

Fish gills are made up of many gill filaments. Water flows over the gill filaments and blood flows through them.

Explain how three features of the gills make them an effective exchange surface.

Explain how glucose is absorbed into the blood in these conditions.

Give one way the small intestine is adapted to absorb glucose quickly.

The rate of diffusion can be calculated using:

$$\text{rate} = \frac{1}{\text{time}}$$

Calculate the rate of diffusion at $40\ ^\circ\text{C}$.

Give your answer in $\text{s}^{-1}$.

Explain why increasing the temperature increased the rate of diffusion.

A student wrote:

'Diffusion, osmosis and active transport all move substances across cell membranes, so they are really the same process.'

Explain why the student is wrong.

Use examples of substances moved in living organisms in your answer.

Calculate the surface area to volume ratio of model Q.

Show your working.

A flatworm can supply all of its cells with oxygen by diffusion alone, but an animal of the same volume with the shape of model P would find this much more difficult.

Explain why.

Calculate the mean rate of water uptake by the visking tubing during the first 20 minutes.

Give your answer in g/minute.

Explain the results shown in Table 3 between 0 and 50 minutes.