Ethics, safety and working with living organisms

Ethics with organisms

• Use invertebrates or plants where possible; the WBI16 specimen paper asked for an ethical reason for using Daphnia (a small invertebrate thought less able to feel pain, and returned unharmed).
• Minimise harm and stress: short exposure times, suitable temperatures, return animals to their habitat (CP11, CP12).
• Use the smallest number of organisms that gives valid results.
• Human volunteers (CP17): informed consent, the right to withdraw, a medical questionnaire to exclude people with heart or breathing problems, stop if they feel unwell, keep data confidential.
• Field work: replace stones and logs, avoid trampling, take permission for land access.

Safety: specific risks and precautions

Answering safety questions well

The October 2023 mark scheme for a spirometer volunteer needed a risk and a matching way to reduce it; 'clean' alone was not enough. Link each precaution to its hazard and give the reason.

Worked example

Give one ethical issue and one safety precaution when using student volunteers to investigate the effect of exercise on breathing (CP17).

1. Ethical: obtain informed consent and allow the volunteer to withdraw at any time.
2. Safety: use a medical questionnaire to exclude anyone with asthma or heart conditions, because exercise and rebreathing could cause breathing difficulties.

Answer: Informed consent with the right to withdraw; a medical questionnaire before exercise.

Check yourself

1. Which is an ethical reason for using Daphnia in heart rate experiments?
   • It has no heart
   • It is an invertebrate with a less developed nervous system and can be returned unharmed
   • It is not a living organism
   • It is too small to see
   Show answer

   It is an invertebrate with a less developed nervous system and can be returned unharmed. The specimen paper asked for an ethical reason for using Daphnia.

2. Which is an ethical requirement when using human volunteers?
   • Volunteers must exercise until exhausted
   • Data must be published with names
   • Only the fittest volunteers may take part
   • Informed consent and the right to withdraw
   Show answer

   Informed consent and the right to withdraw. Volunteers must know what is involved and may stop.

3. What is the hazard of the potassium hydroxide in a respirometer?
   • It releases oxygen
   • It is corrosive to skin and eyes
   • It is radioactive
   • It makes seeds germinate
   Show answer

   It is corrosive to skin and eyes. KOH absorbs CO₂ but is corrosive.

4. Which precaution reduces the risk of infection when using a spirometer?
   • Use more soda lime
   • Breathe faster
   • Sterilise or replace the mouthpiece between volunteers
   • Use a smaller spirometer
   Show answer

   Sterilise or replace the mouthpiece between volunteers. The October 2023 mark scheme credited sterilising the mouthpiece.

5. Why is soda lime in a spirometer replaced regularly?
   • So carbon dioxide does not build up in the air being rebreathed
   • So oxygen is removed
   • So the trace is darker
   • Soda lime adds oxygen
   Show answer

   So carbon dioxide does not build up in the air being rebreathed. Exhausted soda lime stops absorbing CO₂.

6. Which practice reduces the environmental impact of a rocky shore survey?
   • Remove all organisms to count in the lab
   • Collect as many specimens as possible
   • Replace stones and seaweed where they were found
   • Survey only at high tide
   Show answer

   Replace stones and seaweed where they were found. Habitats are left as found.

Practise with instant feedback Print this lesson

Sources

• Pearson Edexcel International Advanced Level in Biology specification (XBI11/YBI11, first teaching 2018): Unit 3, Unit 6 and Appendix 6 mathematical skills
• Pearson mark scheme WBI16/01, October 2023 (via Physics & Maths Tutor)
• Pearson WBI16/01 specimen paper (2019) with Spearman's rank critical values (via Physics & Maths Tutor)

Last updated 8 November 2026. Spotted a mistake? Tell us.