Practical questions
You will complete eight required practical activities if you are studying GCSE Biology and eighteen if you are studying GCSE Combined Science. You could be asked questions about the methods, safety precautions you might take, results and conclusions of these experiments.
In this Cell Biology section there are four core practical activities:
- Core practical 1: Investigating biological specimens using microscopes, including magnification calculations and labelled scientific drawings from observations
- Core practical 2: Investigating the effect of pH on enzyme activity
- Core practical 3: Investigating the use of chemical reagents to identify starch, reducing sugars, proteins and fats
- Core practical 4: Investigating osmosis in potatoes
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
Describe how you would make a light microscope slide of a human cheek cell. [4 marks]
Answer (four from):
- put a small drop of water on the microscope slide
- gently swab the inside of your mouth with a clean cotton bud
- the cotton bud should be disposed of into alcohol, used end down
- gently rub the cotton bud in the drop of water
- cover the sample with a glass cover slide
- if stained with methylene blue the nucleus will appear blue
- dispose of the slide into disinfectant
Sample question 2 - Foundation
Question
Describe how you would use a light microscope to view a slide. [4 marks]
Answer (four from):
- rotate the objectives so that the low power, eg ×10, is in line with the stage
- turn the coarse focus to give space between the stage and the objective lens
- place the microscope slide on the stage
- line it up so that the specimen is in the centre of the stage, where the light passes through
- focus the slide by turning the coarse focus adjustment
- draw a low power image
- rotate the objectives so that the high power objective, eg ×40, is in line with the stage
- bring the slide back into focus using the fine focus adjustment
Sample question 3 - Higher
Question
You have just completed a practical into the effects of temperature of the rate of an enzyme reaction. Describe the graph of results you would expect. [3 marks]
- as the temperature increases so does the rate of reaction
- this will continue until the optimum temperature is reached
- at this point the enzyme’s rate of reaction is highest
- further increases in temperature will reduce the rate of reaction
- high temperatures will denature the enzyme and stop all reactions from occurring
Sample question 4 - Higher
Question
Describe the method you would investigate the effect of pH on enzyme activity. [6 marks]
Answer (six from):
- place a beaker of water on a Bunsen burner at about 35°C
- put two drops of iodine solution into each spot of a spotting tile
- add 2cm3 of amylase enzyme solution to a test tube
- place 2cm3 of starch solution into the same tube
- add 1cm3 of pH solution to the tube
- mix the solution in the test tube and place it into the beak of water on the Bunsen burner
- use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile
- repeat until the iodine solution stops turning black
- record the time this takes
- repeat with different pH solutions
Note: Marks may be still be given for variations in method, solutions and volumes.