3 marksPhotosynthesis occurs in leaves.
(1)
| ☐ | A | carbon dioxide | |
| ☐ | B | glucose | |
| ☐ | C | oxygen | |
| ☐ | D | nitrogen |
(2)
.................................... mm
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2 marksState the role of lignin in xylem cells.
2 marks(1)
(1)
1 markSelect the primary substance transported in phloem cells.
| ☐ | A | Water | |
| ☐ | B | Sucrose | |
| ☐ | C | Minerals | |
| ☐ | D | Amino acids |
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4 marksComplete Table 1 by comparing the characteristics of xylem and phloem cells.
Table 1
| Characteristic | Xylem cells | Phloem cells |
| Type of cells | ||
| Main function |
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1 markFigure 1 shows how the leaves are arranged on a plant.
Figure 1
Which reason explains why the leaves are arranged in this way?
| ☐ | A | the upper leaves allow more light to reach the lower leaves | |
| ☐ | B | the leaves do not need stomata | |
| ☐ | C | the phloem in the leaves will absorb more water | |
| ☐ | D | more insects will be attracted to the plant to eat the leaves |
3 marksFigure 2 shows guard cells and stomata on the lower surface of a leaf.
A ruler has been overlayed on the image for scale purposes.
Figure 2
Use the ruler overlay to measure the length of the line on the labelled guard cell in mm.
The actual length of the labelled guard cell is 0.05 mm.
Calculate the magnification of this image.
2 marksFigure 3 shows the number of stomata per mm2 on the lower surface of leaves from plants growing in soils with different water content.
Figure 3
Explain the difference in the number of stomata per mm2 on the leaves of the plants grown in dry and wet soils.
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4 marksFigure 1 shows part of a root as seen using a light microscope.
Figure 1
Figure 2 shows information about the two types of cells labelled in Figure 1.
| type of cell | surface area in µm2 | volume in µm3 | surface area to volume ratio |
| root surface cell | 4 000 | 220 000 | 1:55 |
| root hair cell | 37 000 | 259 000 |
Figure 2
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(2)
2 marksRoot hair cells can be viewed using an electron microscope.
Describe and explain how the image in Figure 1 would appear different if taken using an electron microscope.
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4 marksXylem and phloem are both types of vessels that transport substances through plants.
During periods of drought, xylem and phloem can experience shrinkage. This can be observed by measuring the circumference of the trunks of trees.
Figure 1 shows the difference in circumference of three trees before and after a seven day period of drought.
| species name | trunk circumference before drought (mm) | trunk circumference after drought (mm) |
| Cedrela montana | 315 | 313 |
| Handroanthus chrysanthus | 358 | 355 |
| Podocarpus oleifolius | 276 | 275 |
Figure 1
Calculate the percentage decrease in the trunk circumference of Handroanthus chrysanthus before and after the period of drought.
(2)
Suggest why this might have led to a greater decrease in trunk circumference in the Handroanthus chrysanthus.
(2)
4 marksFigure 2 shows the structure of a xylem and a phloem vessel.
Figure 2
(2)
(2)
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