Required Practical 10 - Investigation of the effect of an environmental variable on the movement of an animal using ether a choice chamber or a maze

Choice Chamber method

Choice chamber with different environmental conditions

e.g. humidity → add a drying agent to one side and a damp filter paper to other

e.g. light → shine a light but cover one half with black card

Control other environmental conditions

dim even light above all chambers

use a teaspoon to place 12 woodlice on centre of mesh platform and cover with lid

After a set amount of time e.g. 10 minutes record the number of animals in each section

Repeat after gently moving woodlice back to centre

why woodlice would be left for 15 mins before their movement was recorded

gives enough time to establish humidity/ evaporation

woodlice no longer affected by handling

so that behaviour is typical of that humidity

ethical handling of woodlice

safety - cover open wounds / wash hands with soap after

to minimise risk of infection

Ethical - handle carefully / return to habitat ASAP

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

keeps woodlice a safe distance from drying agent

Maze method

Change environment at one end of T shape e.g. food source

place animal e.g. maggot in stem of T

record whether animal turns towards or away from food source

repeat with a large number of maggots

clean maze between trials

repeat with food on the other side of T

Why the same organism is not used more than once

reduces stress on maggots

prevents chance of learnt behaviours

why a clean maze/petri dish is used each time

animals may leave chemicals/scents

which may influence behaviour of other animals

Statistical test used for 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)