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 section there is one core practical activity:
Core Practical 5: Investigate the effects of antiseptics, antibiotics or plant extracts on microbial cultures.
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 a method to investigate the growth of bacteria in the presence of plant extracts. [4 marks]
Answer (four from):
- soak identically sized disks of filter paper in different plant extracts
- soak one disk in water to act as a control
- place each disk on an agar plate covered with a bacterial colony
- incubate for 24 hours
- measure the area without bacterial growth around the disks
- compare these areas of clearing with the control
Sample question 2 - Foundation
Question
Two students are investigating the effects of antiseptics on the growth of bacteria.
State the safety precautions that they should take. [2 marks]
Answer (two from):
- wear safety googles
- tie their hair back if it is long
- work standing up
- wash hands after the experiment is finished
- use aseptic technique (examples of aseptic techniques can be used for additional marks)
Sample question 3 - Higher
Question
These are the results of an experiment investigating the effectiveness of six antibiotics.
a. Identify which of these antibiotics is the most effective. [1 mark]
b. Explain your answer. [1 mark]
c. The petri dish is 10 cm in diameter. Calculate the area of clearing around antibiotic disk A. [2 marks]
Answers:
a. E
b. Because it has killed the largest area of bacteria surrounding it.
c. The petri dish is 10cm in diameter and so the clearing around A is 1.6 cm. Area = 蟺r2 = 3.14 脳 1.62 = 8 cm2.
Sample question 4 - Higher
Question
Describe two examples of aseptic technique. [2 marks]
Answer (two from):
- killing all microorganisms on equipment such as inoculating loops by flaming them in a Bunsen burner or dipping them in alcohol
- keeping all lids on equipment when not in use
- wearing gloves, eye goggles, lab coats or other protective equipment