(h) safe and ethical use of organisms to measure:

The idea

This practical technique requires you to plan and carry out measurements using living organisms so that both safety and ethics are satisfied. Safety means controlling biological, chemical and physical hazards: wear eye protection and gloves, disinfect surfaces, handle allergens and microorganisms aseptically, and dispose of waste correctly. Ethics means treating organisms with care and justifying their use: use the minimum number of organisms, choose the least sentient suitable species, avoid unnecessary pain or stress, keep conditions humane, and obtain approval where required. You must also ensure measurements are valid: control variables, use replicates, and record data accurately.

What earns the marks

• Identifies biological, chemical and physical hazards when using living organisms and states a control for each, such as gloves, eye protection, disinfection or aseptic technique.
• Explains ethical justification for using organisms, including using the minimum number, the least sentient suitable species and avoiding unnecessary pain or stress.
• Describes humane handling and housing so organisms are kept in suitable conditions during measurement.
• Explains how valid measurements are obtained, for example controlling variables, using replicates and recording data accurately.
• States correct disposal or return of organisms after measurement in line with safety and ethical requirements.

Common mistakes and how to put them right

• Treating safety as only about the learner's own protection.

  Put it right: Safety also covers the organism's welfare and the environment, including disposal and containment.

• Assuming any organism may be used freely.

  Put it right: Ethical use requires justification, minimal numbers and humane treatment, and approval where required.

• Ignoring validity when focusing on ethics.

  Put it right: Measurements must still control variables and use replicates so the data are trustworthy.

Exam tips

• When a question names an organism, state one specific hazard and its control rather than a generic 'be careful'.
• Link each ethical point to a concrete action, such as reducing sample size or choosing a less sentient species.
• Separate safety, ethics and validity into distinct points so each is credited clearly.