Required Practical 10

Question 1

Describe how the effect of an environmental variable on the movement of an animal (e.g. woodlice) can be investigated using a choice chamber.

Answer 1

1. Set up choice chamber (different compartments) to create different environmental conditions.
   
   • e.g. humidity -> add a drying agent to one side and damp filter to other.
   • e.g. light -> shine a light but cover one half with black card.
2. Control other environmental conditions.
   
   • e.g. if investigating humidity control light intensity with a dim even light above.
3. Use a teaspoon to place a set number of animals e.g. 12 woodlice on centre of mesh platform and cover with lid.
4. After a set amount of time e.g. 10 minutes record the number of animals in each section.
5. Repeat after gently moving woodlice back to centre.

Question 2

The woodlice were left for 15 minutes before their movement was recorded when investigating the effect of humidity. Explain why.

Answer 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.

Question 3

Explain how you would ensure the safe and ethical handling of animals.

Answer 3

• Safely - cover open wounds / wash hands with soap after.
  
  • To minimise risk of infection.
• Ethical - handle carefully / return to habitat ASAP.

Question 4

Explain why a mesh platform is used when investigating the effect of humidity.

Answer 4

• To keep woodlice a safe distance from drying agent.

Question 5

Describe how the effect of an environmental variable on the movement of an animal (e.g. maggots) can be investigated using a maze.

Answer 5

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

1. Change environment at one end of T shape e.g. add food source.
2. Place animal e.g. maggot in stem of T.
3. Record whether animal turns towards or away from food source.
4. Repeat with a large number of maggots.
5. Repeat with food on other side of T.

Question 6

Explain why the same organism is not used more than once.

Answer 6

• Reduces stress on maggots.
• Prevents chance of learned behaviours.

Question 7

Explain why a clean petri dish / maze is used each time.

Answer 7

• Animals may leave chemicals / scents.
• Which influence behaviour of other animals.

Question 8

Explain which statistical test should be used to analyse results.

Answer 8

• 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.