9 (c) When the lights are on in the glasshouse, the stomata on the lettuce leaves open. This allows carbon dioxide to enter the leaves. Describe how stomata open. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (d) Lettuce leaves contain xylem vessels. Describe the structure of xylem vessels. ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] [Total: 8]
Section B begins on page 10
Š OCR 2013
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