In the box labelled Figure 8, design a suitable results table.

• Enter the student's results into the table. • Calculate the mean results and include these in the table. • Use 1 decimal place for both mean results.

Figure 8

Suggest and explain why the results for variety D are different from the results for variety E.

The student repeated the investigation but made one change to the method used to prepare the apple tissue.

The student then observed shorter times for the brown pigment to appear in both apple varieties.

Suggest the change the student made to the method of preparing the apple tissue.

Explain why the brown pigment appeared in a shorter time.

Do not suggest using a different volume or mass of apple.

Change to method

Explanation

The student wants to change the procedure to obtain a measure of PPO activity either in terms of how much substrate is used or how much product is produced.

Which change in procedure will provide a successful measure of PPO activity for the student?

Tick (✓) one box.

☐ Measure the increase in oxygen concentration in the air around the cube of apple tissue on a plate.

☐ Measure the intensity of brown colour by comparing apple tissue with a colour chart showing a range of apple tissues of known pigment concentration.

☐ Measure the intensity of colour produced from brown apple tissue in a biuret test.

☐ Measure the percentage of light transmitted through a cube of brown apple tissue using a colorimeter.