3 marksFig.1 shows the lower surface of a leaf from a dicotyledonous plant, on a 1cm2 grid.
Fig. 1
Calculate the surface area of the leaf in Fig.1.
[1]
Describe the method you used to determine the surface area of the leaf.
2 marksFig. 2 shows the upper and lower surfaces of the same leaf of another dicotyledonous plant.
Upper surface Lower surface
Fig. 2
Describe two ways, visible in Fig. 2, in which the upper surface of the leaf is different from the lower surface.
11 marksA student investigated the effect of different wind speeds on the rate of transpiration of some leaves.
The student took five leaves from a tree and weighed each of them on a balance.
Each of the leaves was then hung from a different piece of wire.
Fans were used to blow air at different speeds over each leaf.
After 12 hours, the student weighed each leaf again. The results are shown in Table 1.
Table 1
| Wind speed / m per s | Mass of leaf at the start / g | Mass of leaf at the end / g | Loss in mass / g |
| 0 | 5.7 | 3.8 | |
| 1 | 5.3 | 3.3 | |
| 3 | 5.9 | 3.7 | |
| 6 | 5.1 | 2.6 | |
| 8 | 5.3 | 2.6 |
Calculate the loss in mass for each leaf. Complete Table 1.
[2]
Construct a graph to show the loss in mass against wind speed.
[5]
Use your graph to determine the loss in mass at a wind speed of 10 m per s. Show on the graph how you obtained your answer.
Give your answer in grams.
[2]
A student criticised the results by saying that the loss in mass does not allow for a fair comparison between leaves.
Suggest a more appropriate calculation and explain why it gives a fairer comparison.
[2]
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