Biology 5090/61 — May/June 2021
Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme
Topics Experimental Contexts · Analysis, Conclusions and Evaluation · Observations and Measurements · Planning Experiments and Investigations · Microscopy and Biological Drawing
A student investigated the response of some small animals called woodlice to various stimuli.
A circular container with a lid called a ‘choice chamber’ was used.
This had four distinct areas:
- dry and light
- damp and light
- dry and dark
- damp and dark.
The diagram shows the choice chamber viewed from above.
The student put 10 woodlice in the choice chamber and left them for 20 minutes. The woodlice were free to move anywhere they wanted in the choice chamber during that time.
After 20 minutes she drew a diagram to show the position of the woodlice in the choice chamber. This is shown in diagram A.
She repeated this procedure twice, with the results shown in diagrams B and C.
She recorded her observations in the table.
Count the numbers of woodlice in each area of choice chamber C and record them in the table.
| conditions | number of woodlice A | number of woodlice B | number of woodlice C | mean number of woodlice |
|---|---|---|---|---|
| dry and dark | 2 | 2 | ||
| damp and dark | 6 | 5 | ||
| damp and light | 1 | 1 | ||
| dry and light | 1 | 2 |
Calculate the mean number of woodlice in each of the four areas of the choice chamber to the nearest whole number. Record these results in the table.
Construct a bar chart on the grid provided to show the mean number of woodlice (to the nearest whole number) found in each area of the choice chamber.
Using the data in the table and your bar chart, state which area of the choice chamber the woodlice preferred.
______
Suggest where the student should have placed the 10 woodlice when she first put them into the choice chamber. Explain your answer.
______
Suggest two ways in which the results of this investigation could be made more reliable.
- ______
- ______
Another student says that it would be a good idea to make some holes in the lid of the choice chamber. Suggest one advantage and one disadvantage of doing this.
advantage = ______
disadvantage = ______
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