Practical questions

You will complete 21 required practical activities if you are studying GCSE combined science: Synergy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.

There will be a number of different types of practical based questions. Some will be on the set required practicals, some will cover the working scientifically terms and some will be on other science practicals which you might have done in class. Use all the information given in the question particularly any diagrams to help you understand what the question is about.

This page contains AQA material which is reproduced by permission of AQA.

Sample question 1 – Foundation

A student used paper chromatography to identify the pigments in spinach leaves.

She used propanone as the solvent.

The figure below shows the student's results.

Displaced pigments on a used piece of chromatography paper
Question

a) Name the mobile phase and the stationary phase in the student's experiment. [2 marks]

b) What does the figure tell you about the green pigment from the spinach? [3 marks]

a) Mobile phase – propanone [1]. Stationary phase – paper [1].

b) Any three from:

  • contains chlorophyll a, b and carotene [1]
  • contains Pigment B [1]
  • does not contain pheophytin [1]
  • contains (at least) one unknown substance [1]
  • contains five substances [1]
  • contains a substance that does not dissolve in the solvent [1]

Sample question 2 – Foundation

Question

Lipase is an enzyme that digests fat.

Some students investigated the effect of bile on the digestion of fat by lipase.

This is the used method.

  1. Mixed milk and bile in a beaker.
  2. Put the pH sensor of a pH meter into the beaker.
  3. Added lipase solution.
  4. Recorded the pH at 2-minute intervals.
  5. Repeated steps 1 to 4, but used water instead of bile.

Suggest two variables that the students should have controlled in this investigation. [2 marks]

Any two from:

  • type of milk [1]
  • volume/amount of milk [1]
  • volume of bile needs to be equal to volume of water [1]
  • volume of lipase [1]
  • concentration of lipase [1]
  • temperature [1]

Sample question 3 – Higher

Question

A student used paper chromatography to identify the pigments in spinach leaves.

She used propanone as the solvent.

A piece of chromatography paper partially submerged in propanone

The student did not set up the apparatus correctly.

Identify the errors the student made.

Explain how the errors would affect her results. [4 marks]

These terms should be used to gain all marks:

origin line drawn in ink [1]

so it will run or dissolve in the solvent or split up [1]

spots under solvent or solvent above spots/origin line [1]

so they will mix with solvent or wash off paper or colour the solvent or dissolve in the solvent [1]

Sample question 4 – Higher

Question

A student investigates the rate of respiration in maggots.

This diagram shows the equipment he uses.

A practical set up of the investigation into the respiration of maggots

Why does the student put the maggots on gauze? [1 mark]

To stop them falling in the solution or to stop them drowning in the solution [1].