Animal Responses
Biology: AQA A Level, topic 6.1.3
Responses in Animals
Simple animals respond to stimuli to increase their chance of survival. This allows them to maintain a favourable environment. There are two ways in which simple animals respond:
Tactic responses (taxes)
- The stimulus is positively or negatively directional, e.g. light.
- E.g. Woodlice move away from a light source.
- Dark environments (e.g. under stones) are favourable for woodlice to protect them from predators.
- Being able to detect the direction of light and move away helps woodlice locate a more favourable habitat.
Kinetic responses (kineses)
- The stimulus is non-directional, e.g. humidity.
- E.g. Woodlice move more slowly and turn less in high humidity but move faster and turn more in low humidity.
- Damp environments are favourable for woodlice to reduce water loss.
- When woodlice detect a drier environment they move more. This increases the chance woodlice will find a more favourable habitat.
- When woodlice detect a damper environment they move less. This ensures the woodlice stay in the more favourable habitat.
Choice Chambers
Choice chambers can be used to study how animals respond to environmental stimuli. In this experiment, four different conditions are created to see how woodlice respond to light and humidity.
Step 1 - Build choice chamber
- Divide a petri dish base into two halves with a divider between them.
- Place damp filter paper into one half and nothing into the other half. Place a piece of fine mesh on top.
- Cover half the petri dish lid with black card and leave the other half as transparent.
Step 2 - Add woodlice
- Place 10 woodlice in the centre of the mesh.
- Put the petri dish lid on top of the petri dish base so that four different environments are created:
- Dark and damp.
- Dark and dry.
- Light and damp.
- Light and dry.
Step 3 - Collect results
- After 10 minutes, remove the lid and record the number of woodlice in each quarter.
Step 4 - Repeat the experiment
- Carefully move the woodlice back to the centre of the fine mesh and repeat the experiment two more times.
- The same experiment could be replicated using a maze.
Test yourself on Animal Responses
What are the two types of animal responses?
How do woodlice respond to light?
Which of the following statements about animal responses are true?
Why are damp/humid environments more favourable for woodlice?
Stages Involved in the Choice Chambers Experiment