Required Prac 10

Question 1

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

Answer 1

1. Set up choice chamber (different compartments) 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
   ○ Eg. if investigating humidity control light intensity with a dim even light above
3. Use a teaspoon to 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 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. (2)

Answer 2

● Time to establish humidity / for substance to absorb water /
water from paper to evaporate
● Woodlice no longer affected by handling

Question 3

Explain how you would ensure the
safe and ethical handling of animals.
(2)

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. (1)

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 (eg. maggots) can be investigated using a maze

Answer 5

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

Question 6

Explain why the same organism is not
used more than once. (2)

Answer 6

● Reduces stress on maggots
● Prevents chance of learned behaviours

Question 7

Explain why a clean petri dish / maze is
used each time. (2)

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