You were told to wipe the inside of the maze between trials. Suggest why. (2)
Maggots may leave trail;
Which could affect the behaviour of other
... [Show More] maggots
Light intensity affects the behaviour of maggots. Describe how you might use a lamp to minimise the effect of changes in light intensity. Explain your answer. (2)
Method which would even out light intensity in maze;
To produce constant light intensity
Temperature also affects the behaviour of maggots. Describe how you would find out if there were temperature changes that could have affected the behaviour of maggots
in your investigation. (2)
Take temperature continually;
Determine if changes have occurred during the experiment
Is it possible to conclude from your data that maggots turn left or right at random when given the choice? Explain your answer. (2)
No
Low sample size;
Statistical test not carried out
The maggots used for the investigation should be as similar as possible. Describe two ways in which the maggots should be similar. (2)
Same size;
Same species
State your null hypothesis. (1)
There is no difference in the frequency in which maggots make a right or left turn.
Give your choice of statistical test. (1)
Chi-squared
Give a reason for your choice of statistical test. (1)
Because right turn and left turn are categories
What sample size did you use in your investigation? Give two reasons why you used this sample size. (2)
Large enough for statistical test;
The larger the sample the more representative of the population it will be
Did you use a maggot more than once in your investigation? Give a reason for your answer. (1)
No
Reduces stress on maggots;
A student carried out an investigation similar to the one you carried out in Task 2. He obtained the following data.
He decided that the one maggot that turned right was an anomaly. Was he correct to do so? Explain your answer. (1)
No
Can be explained by natural variation
What is a taxis? (1)
Directional response to stimulus
Describe how you could try to ensure that the response of the maggots in your investigation was not a taxis in response to light. Explain your answer. (2)
Method to keep light source non-directional e.g. lamp above;
So that it is not possible to show a directional response
Maggots detect the presence of food by its scent. Describe how you could use the maze to investigate whether maggots detect the scent of raw meat.
You may assume that all confounding variables are controlled. (3)
Use large number of maggots;
Put food at one end of T- shape;
Repeat with food on the other side of T
Describe the response of woodlice to increased distance between turns. (2)
Decrease (woodlice turning in opposite direction to forced turn with increasing distance between turns) then more rapid decrease;
Rapid decrease when distance between turns is 9cm
Can you conclude that woodlice show turn alternation behaviour when the distance between the forced turn and the second turn was 10 cm? Explain your answer. (2)
No
Equal numbers turn each way;
Would expect this is by chance
The student suggested that the difference in turning behaviour of the woodlice in her investigation was due to the distance between the first and second turn. Her friend
suggested that it was due to the time taken to get from the first to the second turn and not the distance. Suggest how you could investigate which of these two possibilities is
more likely. (3)
Keep distance the same;
Decrease speed of woodlice
Increase time between forced and second turns
Woodlice usually live in areas where stones and twigs form obstacles. Obstacles in the path of woodlice cause them to make forced turns. The more obstacles there are in
the path, the shorter the distance between the forced turns.
Use the data in Figure 3 to explain how the behaviour of woodlice results in them moving rapidly out of unfavourable areas.
Short distances result in more woodlice showing turn alternation;
Keeps woodlice going in one direction
The woodlice were left for 15 minutes before their movement was recorded. Give two reasons for this. (2)
Time to establish humidity to that required;
So that their behaviour is typical of that humidity
It is not possible to conclude that the change in the behaviour of the woodlice shown in Figure 5 is caused by changes in humidity. Explain why. (2)
Correlation does not show causal link;
May be due to other factors
The points in Figure 5 do not all fall on the curve. Suggest why. (3)
It is a line of best fit;
Variation in woodlice;
Variation in environmental conditions
Woodlice in Group B had a greater percentage loss in mean mass during the investigation than woodlice in Group A. Explain why. (3)
Gills more exposed to air;
Not clumped so lower humidity around each woodlouse;
So greater evaporation
It would be useful to give the loss in mean mass as a percentage in this investigation. Explain why. (1)
Initial masses different
The movement of the woodlice in low relative humidity is an advantage to their survival. Explain how. (2)
Low humidity results in more woodlice moving;
So increased movement increased chance of leaving unfavourable environment [Show Less]