Evaluative coursework

Question 1

What type of behaviour do woodlice exhibit?

Answer 1

Kinesis.

Question 2

What is kinesis?

Answer 2

A non-directional orientation response whereby the rate of movement of an organism increases when put in unfavourable conditions but not in a particular direction. The organism moves quickly in random directions until more favourable conditions are found, when it slows down and eventually stops.

Question 3

What is the mechanism behind kineses?

Answer 3

• When in unfavourable conditions, the rate of movement of an organism increases. This increases the probability of the organism leaving the area where conditions are unfavourable.
• When in more favourable conditions, the rate of movement of an organism decreases/ organism stops. This allows the organism to remain in areas with more favourable conditions.

Question 4

What conditions do woodlice prefer an why?

Answer 4

• Woodlice prefer dark/damp conditions.

- This protects them from predation and prevents them from drying out.

Question 5

How can the behaviour of woodlice be tested?

Answer 5

Using choice chambers.

Question 6

How can dry/damp conditions be established in a choice chamber?

Answer 6

• Place a chemical (desiccant) such as calcium chloride beneath one half of the chamber, which absorbs water. This keeps the half dry.
• Place water beneath the other half of the chamber to keep the half damp.

Question 7

How can dark/light conditions be established in a choice chamber?

Answer 7

• Cover up one half of the chamber with black card to establish dark conditions.
• Illuminate the other half of the chamber with a lamp to establish light conditions.

Question 8

What is a chi squared test?

Answer 8

To test the statistical significance of a set of test results compared to expected results.

Question 9

What degree of confidence is used?

Answer 9

5%.

Question 10

What is a null hypothesis?

Answer 10

A hypothesis stating that there is no difference between the expected and experimental values?

Question 11

What does a chi squared value smaller than the critical value indicate?

Answer 11

Accept null hypothesis. There is no significant difference between the observed values and the expected values. Any differences are probably due to chance.

Question 12

What does a chi squared value greater than the critical value indicate?

Answer 12

Reject null hypothesis. There is a significant difference between the observed values and the expected values. It is unlikely the differences are due to chance.

Question 13

What variables should be controlled specifically in a dry/damp choice chamber experiment?

Answer 13

1. The light intensity should be constant across whole of test chamber.
2. Temperature should be the same across the whole test chamber.

Question 14

What variable should be controlled specifically in a light/dark choice chamber experiment?

Answer 14

1. To avoid external light sources, the experiment room should be kept dark, with the only light source being the lamp.
2. The lamp used should be a fluorescent tube lamp or kept at a suitable distance away from the test chamber to prevent much temperature variation across the test chamber.

Question 15

What variables should be controlled generally in a choice chamber experiment?

Answer 15

1. Surface should be the same across whole chamber. Make sure there’s no water or holes/defects on the test platform at any point during experiment.
2. Make sure all the woodlice start at the same point, at the same time.
3. All the woodlice should be the same species, of similar size, and should have been kept under the same conditions prior to the experiment.

Question 16

What precautions need to be taken during the experiment?

Answer 16

1. Woodlice need to be handled gently to prevent injury which may change the behaviour of the woodlice or make them less active.
2. Fresh woodlice should be used for each new repeat if repeating experiment to keep the tests fair.
3. No not move the apparatus (choice chamber/ light source) during experiment. Moving test chamber disturbs woodlice and may change their behaviour. Moving light source changes conditions.