core prac 18

Question 1

What is the independent variable for the habituation prac?

Answer 1

The number of pokes with a paintbrush

Question 2

What is the dependent variable for the habituation prac?

Answer 2

The time taken for the eye stalks to reemerge from the shell (in secounds)

Question 3

What are the control variables for the habituation prac?

Answer 3

• Age/size of snails used for repeats
• Handling history (all snails should have developed in same habitat)
• Point where bud touches (between eye stalks gently)
• same paintbrush used each time.
• Repeats carried out on same surface.
• when to stop stopwatch (when both eye stalks are fully extended)

Question 4

Method for the habituation prac…

Answer 4

1. Collect one snail and place it on a clean, firm surface. Allow the snail to get used to its surroundings and wait until it’s fully emerged from its shell.
2. dampen the paintbrush with water and touch the snail between the eye stalks, immediately start the stopwatch.
3. Measure the length of time between touch and snail fully emerging from its shell with eye stalks fully extended
4. repeat for total of 15 touches, timing how long it takes to reemerge each time.
5. Record results in a suitable table.

Question 5

What stats test should be used for the habituation prac?

Answer 5

• Spearman’s rank to look for correlation between two data sets.
• Value of around -1 should be obtained
• negative correlation should be seen on graph once plotted.

Question 6

What are the random errors for the habituation prac?

Answer 6

• unable to tell when eye stalks are fully extended (measure then at certain time after each trial)
• previous levels of habituation may already have taken place.

Question 7

What are possible systematic errors in habituation prac?

Answer 7

• lack of moisture encouraging snail to stay in shell (should put then on damp paper and allow to acclimatise for longer)