Physiology, responses respiration — OCR GCSE Biology
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Physiology, responses respiration explained
Measuring respiration and behavioral responses in living organisms (such as germinating seeds, yeast, woodlice, or maggots) requires strict ethical protocols.
Read the full explanation
In choice chamber assays investigating taxis responses to light or humidity, invertebrates must be transferred gently using a soft paintbrush or specimen spoon to avoid mechanical trauma. Organisms must never be exposed to lethal temperatures, bright heat lamps, or dehydrating conditions, and must be returned to their natural damp habitat immediately following the experiment. In respirometer setups, invertebrates must be protected from direct contact with corrosive chemical carbon dioxide absorbents (such as soda lime pellets) by a secure wire mesh barrier.
Your focus
- Apply ethical standards and gentle handling techniques when using live invertebrates in physiology and behavior assays.
- Explain the necessity of isolating living specimens from corrosive chemical absorbents like soda lime in respirometers.
- Design choice chamber experiments that protect organism welfare while testing environmental preference responses.
Physiology, responses respiration exam tips
Marking Points
- Transfer small invertebrates gently using a soft camel-hair brush to prevent crushing or mechanical injury.
- Ensure organisms in respirometers are physically separated from caustic soda lime or potassium hydroxide by a mesh barrier.
- Minimize environmental stress by avoiding extreme temperatures, bright lights, or excessive confinement times.
- Return living animals promptly to their natural habitat after completing behavioral or physiological observations.
Examiner Tips
- 💡In questions about ethical handling of invertebrates, write: 'handle gently with a soft brush' and 'return to natural habitat after use'.
- 💡Always identify the mesh barrier in respirometer diagrams and explain that it protects living organisms from toxic, corrosive soda lime.
Common Mistakes
- Handling invertebrates with metal forceps or bare fingers, causing mechanical trauma or crushing injuries.
- Allowing animals to touch caustic soda lime or potassium hydroxide pellets in respirometers, causing chemical burns.
- Leaving organisms in choice chambers or closed tubes for extended periods without adequate moisture or ventilation.