AQA A Level Biology复习笔记6.1.6 Causes of Animal Movement

Investigating Environmental Factors That Cause Animal Movement

 

  • Environmental factors can be abiotic or biotic
  • Abiotic factors are the non-living parts of an environment
    • For example: temperature, wind, humidity and soil pH

     

  • Biotic factors are the living parts of an environment
    • For example: competition, predation and disease

     

  • Experiments can be carried out to investigate the effect of abiotic factors on the movement of animals
    • Choice chambers and mazes are often used in these experiments and woodlice and maggots are commonly the model animals

     

  • A scientist called J. Cloudsley-Thompson carried out the first experiments on woodlouse behaviour
  • One of his experiments focused on the response of woodlouse to humidity
  • He used large choice chambers that were divided into two sections

Apparatus

  • Choice chambers
  • Lids
  • Distilled water (fixed volume in each choice chamber)
  • Drying agent (fixed volume in each choice chamber)
  • Gauze platforms
  • Woodlice
  • A dark cupboard
  • A bright well-lit room

Method

  • Divide each choice chamber into two sections
    • Add a fixed volume of distilled water to one side and a fixed volume of drying agent to the other
    • This allows for the humidity to be controlled in each section

     

  • Insert gauze platforms into the choice chambers
    • This keeps the woodlice at a safe distance from the water and drying agent
    • Note that woodlice are able to move between sections

     

  • Divide the woodlice into two even-sized groups
    • Drop the woodlice from group A into choice chambers kept in the dark
    • Drop the woodlice from group B into choice chambers kept in the light

     

  • The woodlice can be dropped into the chamber using the hole in the lid so that they fall into the centre of the choice chamber
  • Record the position of the woodlice in each choice chamber after 15 minutes
    • They should fall into the following categories: moving around, stationary on the dry side, stationary in the centre or stationary on the humid side

     

  • Repeat the experiment several times for all conditions

Results and analysis

  • A significant percentage of the woodlice (in all groups) moved to the humid side
    • This is a beneficial response as it helps to prevent water loss from the respiratory surfaces of the woodlice

     

  • The woodlice responded to humidity more actively when in the light
    • This is advantageous - if the woodlice are subject to dry conditions during the day when they are more likely to dehydrate then they are even more likely to move towards humid conditions (under a stone, log etc)

     

  • The woodlice tended to stop moving when in humid conditions
    • This means they are able to remain within favourable conditions that reduce water loss

     

Limitations

  • In this experiment, the conditions that the woodlice were kept in prior to the experiment have not been stated
    • If the woodlice were kept in dark or light conditions it could affect their response during the experiment

     

  • The behaviour of the woodlice was not observed during the experiment
    • It can not be said if their behaviour was taxis (directional response) or kinesis (non-directional response) that randomly caused them to end up in the humid section

     

Choice-chamber-humidity

The choice chamber has two sections, one with low humidity and one with higher humidity

 

 

转载自savemyexams

更多Alevel课程
翰林国际教育资讯二维码