# Practical: Ethical Use of Organisms ## The safe and ethical use of organisms to measure plant or animal responses or physiological functions - When using **live animals** in biological experiments, care must be taken to **avoid harming them** - Examples include: - **Aquatic animals** should only be observed for a **short time** before being promptly returned to their main container - Think of it like borrowing something delicate—you handle it briefly and return it quickly to where it belongs - **Microscopic aquatic animals** (e.g. from pond water samples) should only be observed using **cavity slides** - Cavity slides have a small indentation or 'well' in them that can hold a small amount of water - This ensures the organisms have enough water available to **prevent dehydration or heat damage** from the microscope light - The cavity acts like a tiny swimming pool, keeping microscopic creatures hydrated while you observe them

Cavity slides prevent microscopic aquatic organisms from drying out under the microscope light

- Biological investigations (especially those investigating **physiological functions and adaptations**) may involve **humans** and so it is important they are **safe** - For example: - For **pulse rate experiments** and other studies into the effects of exercise, the type of exercise and how it will be carried out should be **carefully planned** in order to **prevent injury** - Just like a gym instructor would assess your fitness level before prescribing exercises, you need to ensure any physical activity in an experiment is appropriate and safe - Chemicals such as **caffeine or alcohol** should **not be administered** to human participants in a school environment - This is both an ethical and safety concern—school labs aren't medical facilities

Never administer substances like caffeine or alcohol to human participants in a school or college setting

## Example of the safe and ethical use of organisms - Experiments can be carried out to investigate the **effect of abiotic factors** on the **movement of animals** - **Choice chambers** and **mazes** are often used in these experiments - **Woodlice** and **maggots** are commonly the model animals - A scientist called **J. Cloudsley-Thompson** carried out the first experiments on woodlouse behaviour - One of his experiments focused on the **response of woodlouse to humidity** - He used large choice chambers that were **divided into two sections** ### Apparatus - Choice chambers - Lids - Distilled water (fixed volume in each choice chamber) - Drying agent (fixed volume in each choice chamber) - Gauze platforms - Woodlice - A dark cupboard - A bright well-lit room ### Method 1. **Divide** each choice chamber into two sections 2. Add a **fixed volume of distilled water** to one side and a **fixed volume of drying agent** to the other - This allows for the **humidity to be controlled** in each section 3. **Insert gauze platforms** into the choice chambers - This keeps the woodlice at a **safe distance** from the water and drying agent - Like a raised platform above water, it protects them from direct contact with potentially harmful substances - Note that woodlice are able to **move between sections** 4. **Divide the woodlice** into two even-sized groups 5. Drop the woodlice from **group A** into choice chambers **kept in the dark** 6. Drop the woodlice from **group B** into choice chambers **kept in the light** - The woodlice can be dropped gently into the chamber using the hole in the lid so that they fall into the centre of the choice chamber - This gentle introduction minimises stress and potential harm 7. **Record the position** of the woodlice in each choice chamber after **15 minutes** - They should fall into the following categories: **moving around**, **stationary on the dry side**, **stationary in the centre** or **stationary on the humid side** 8. **Repeat** the experiment several times for all conditions - Repetition ensures reliability and accounts for natural variation in animal behaviour

Gauze platforms protect organisms from direct contact with water or drying agents while allowing movement between sections

### Results and analysis - A **significant percentage** of the woodlice (in all groups) **moved to the humid side** - This is a **beneficial response** as it helps to **prevent water loss** from the respiratory surfaces of the woodlice - The woodlice **responded to humidity more actively when in the light** - This is advantageous—if the woodlice are subject to dry conditions during the day when they are more likely to dehydrate, then they are even more likely to move towards humid conditions (under a stone, log etc.) - It's like how you might seek shade more urgently on a hot, sunny day than on a cool, overcast one - The woodlice tended to **stop moving when in humid conditions** - This means they are able to **remain within favourable conditions** that reduce water loss - Once they find their ideal environment, they settle there—a bit like finding the perfect temperature spot in a room and staying put

Abiotic factors are non-living environmental factors that affect organisms, such as humidity, light intensity, and temperature

## Key ethical principles demonstrated - The experiment demonstrates several important ethical practices: - **Minimal handling**—woodlice are dropped gently through a hole in the lid to reduce stress - **Short observation periods**—experiments run for just 15 minutes before organisms are presumably returned to their habitat - **Physical protection**—gauze platforms prevent direct contact with potentially harmful substances - **Appropriate species selection**—woodlice are resilient invertebrates suitable for classroom study - **No permanent harm**—the experimental conditions don't cause lasting damage to the organisms - These principles ensure that valuable scientific data can be gathered while **respecting animal welfare**

Always return organisms to their natural habitat or appropriate containers promptly after brief observations