Practical questions
You will complete twenty-one required practical activities if you are studying GCSE combined science: Trilogy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
In this Cell Biology section there are two required practical activities:
- Required Practical Activity 1: Use a light microscope to observe, draw and label a selection of plant and animal cells. A magnification scale must be included.
- Required Practical Activity 3: Investigate the effect of a range of concentrations of salt or sugar solution on the mass of plant tissue.
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.
These questions have been written by Bitesize consultants as suggestions to the types of questions that may appear in an exam paper.
Sample question 1 - Foundation
Question
A student is investigating the process of mitosis with a microscope.
The hazard warning label on the chromosome stain they use states:
- may cause skin irritation
- may cause eye irritation
- may be harmful if swallowed
- non-flammable
Suggest three safety precautions they should take.
[3 marks]
- they should avoid contact with hands/skin and they could also wear gloves
- they should wear safety googles
- they should wash their hands after handling the bottle or slide, or not drink the stain
Sample question 2 - Foundation
Question
Describe how to prepare a stained slide of onion epidermal tissue.
[6 marks]
- take an onion bulb and remove one of the leaves
- peel a piece of inner epidermis from the leaf using forceps
- trim the piece of epidermis and place in one drop of water on a microscope slide
- lower a coverslip on top, taking care not to trap any air bubbles
- place one drop of iodine solution next to the coverslip
- draw the iodine solution under the slide by placing a piece of filter paper on the other side of the coverslip
These are the main points that the examiner will be looking for, but you do not have to match every word.
In questions based on Required Practicals, the examiner will make allowances for instances where the equipment used in one school may be slightly different from another, the level of detail you’ve added, or if your answer is worded in a slightly different way.
Sample question 3 - Higher
Question
(a) A student investigated the effects of osmosis in potato tissue by placing potato cylinders in different concentrations of sugar solution.
Their results are shown below (as a percentage).
Identify the anomalous result. [1 mark]
| Experiment | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Sugar solution - low concentration | +4 | +5 | +4 | +6 | +5 | +6 | +5 | +6 | +6 |
| Sugar solution - high concentration | -12 | -13 | -15 | -11 | -16 | -2 | -15 | -17 | -15 |
| Experiment | Sugar solution - low concentration |
|---|---|
| 1 | +4 |
| 2 | +5 |
| 3 | +4 |
| 4 | +6 |
| 5 | +5 |
| 6 | +6 |
| 7 | +5 |
| 8 | +6 |
| 9 | +6 |
| Experiment | Sugar solution - high concentration |
|---|---|
| 1 | -12 |
| 2 | -13 |
| 3 | -15 |
| 4 | -11 |
| 5 | -16 |
| 6 | -2 |
| 7 | -15 |
| 8 | -17 |
| 9 | -15 |
Experiment 6, high concentration of sugar.
Question
(b) Calculate the mean change in mass for each concentration. Do not include the anomalous result from Experiment 6 in your calculations.
Give your answer to one decimal place. [2 marks]
- low concentration = 5.2
- high concentration = -14.3
Question
(c) Explain why the student expressed change in mass as a percentage. [3 marks]
- the mass of the potato cylinders would be different
- because of this, the results of the experiments for cylinders in low and high concentrations could not be compared
- apparent differences in mass could be as much the result of differences in the initial masses as the effects of osmosis
Sample question 4 - Higher
Question
Describe how you would set up a microscope to examine a prepared slide under high power. [6 marks]
Your answer should be made up from the following points:
- select the lower power objective
- move the stage as close to the objective as possible
- place the prepared slide on the stage
- focus away from the slide, using the coarse focusing adjustment, until the specimen is in focus
- move the high power objective in line with the slide
- use the fine focusing adjustment to bring the specimen back into focus
- if the specimen cannot be brought back into focus, refocus under low power and repeat stages 5-6
Explore questions about practicals with Dr Alex Lathbridge.
Listen to the full series on BBC Sounds.
Questions about Practicals with Dr Alex Lathbridge.
