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CAIE A-Level Biology A2 Practical Assessment Skills Questions

Practise the AO3 skills assessed in Paper 3 and Paper 5, including experimental work, observation, presentation, analysis, planning and evaluation.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Covered syllabus points

Paper 5 Planning, Analysis and Evaluation

Question 1

[Maximum number: 5]

The light dependent stage of photosynthesis in a suspension of isolated chloroplasts can be investigated using the Hill reaction.

Dichlorophenolindophenol (DCPIP) can be used to follow the process. DCPIP is a blue dye which turns colourless when it is reduced by accepting hydrogen and electrons.

 oxidised DCPIP → reduced DCPIP  blue → colourless \begin{array}{clc} \text { oxidised DCPIP } & \rightarrow & \text { reduced DCPIP } \\ \text { blue } & \rightarrow & \text { colourless } \end{array}

Question (a)

(a)

Explain the reasons for:
the colour standard tube A
covering the beaker containing the chloroplast-DCPIP mixture with foil.

[ 4 ]

Question (b)

(b)

Table 2.1 shows the results of the experiment.

Table 2.1

Table 2.1

[ 1 ]

Question (i)

(i)

Complete Table 2.1 by calculating the rate of the light dependent stage of photosynthesis for the orange wavelength, using the formula:

 rate =1000t where t= time in seconds. \text { rate }=\frac{1000}{t} \text { where } t=\text { time in seconds. }
[ 1 ]

Question 2

[Maximum number: 2]

Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method:
- insecticide was sprayed into each tree
- this killed the insects, which fell onto a sheet below the tree
- the dead insects were collected, identified and counted.

Table 5.1 shows summary statistics for some of the trees sampled in this study. The leaf canopy area is a measure of the size of the tree and the extent of its leaf cover.

Table 5.2 shows the diversity and abundance of some different taxonomic groups of insects in the study.

Table 5.1

Table 5.1

Table 5.2

Table 5.2

Comment on the effects of sample size on the quality and accuracy of the data in Table 5.1.

Question 3

[Maximum number: 1]

There is considerable variation in the ecosystems that occur in the continent of North America. These include coniferous forest, prairie grassland, scrub and desert. Large areas of land that once contained natural ecosystems are now used for agriculture.

The diversity of some beetle species that feed on animal dung (faeces) was investigated at two types of grassland site in North America. The first type of grassland site was grazed by cattle and the second type of site was not grazed.

Dung beetles were collected, identified and counted from two areas of the same total size. Some of the results are shown in Table 8.1.

Table 8.1

Table 8.1

State the null hypothesis for a statistical test comparing the data from the two types of site.

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