Required practical 10

• Describe how the effect of an environmental variable on the movement of an animal can be investigated

  Set up choice chamber to create different environmental conditions

  ○ Eg. humidity → add a drying agent to one side and damp filter paper to other

  ○ Eg. light → shine a light but cover one half with black card

  2. Control other environmental conditions

  3. place a set number of animals eg. 12 woodlice on centre of mesh platform and cover with lid

  4. After a set amount of time eg. 10 mins record the number of animals in each section

  5. Repeat after moving woodlice back to centre
• The woodlice were left for 15 minutes

  before their movement was recorded

  when investigating the effect of

  humidity. Explain why. (2)

  ● Time to establish humidity / for substance to absorb water /

  water from paper to evaporate

  ● Woodlice no longer affected by handling

  ● So that behaviour is typical of that humidity
• Explain how you would ensure the

  safe and ethical handling of animals.

  (2)

  ● Safely - cover open wounds / wash hands with soap after

  ○ To minimise risk of infection

  ● Ethical - handle carefully / return to habitat ASAP
• Explain why a mesh platform is used

  when investigating the effect of

  humidity. (1)

  ● To keep woodlice a safe distance from drying agent
• Describe how the effect of an environmental variable on the movement of

  an animal (eg. maggots) can be investigated using a maze

  Mazes are used to investigate turning behaviour in response to different environmental conditions:

  1. Change environment at one end of T shape eg. add food source

  2. Place animal eg. maggot in stem of T

  3. Record whether animal turns towards or away from food source

  4. Repeat with a large number of maggots

  ○ Wipe / clean maze between trials

  5. Repeat with food on other side of T
• Explain why the same organism is not

  used more than once. (2)

  ● Reduces stress on maggots

  ● Prevents chance of learned behaviours
• Explain why a clean petri dish / maze is

  used each time. (2)

  ● Animals may leave chemicals / scents

  ● Which influence behaviour of other animals
• Explain which statistical test should be used to analyse results

  ● Chi-squared

  ● As data are categorical and comparing frequencies

  ● To see if there is a significant difference between observed and expected frequencies

  ○ Expected = equal numbers each side