Stomata are small pores in the surface of a leaf. Each stoma is surrounded by two guard cells.
A student counted the stomata on the upper and lower surfaces of a leaf.
The Table shows the results.
Table
| Surface of leaf | Number of stomata per mm2\text{mm}^2mm2 |
|---|---|
| upper | 40 |
| lower | 280 |
Calculate how many times more stomata there are on the lower surface than on the upper surface.
Suggest why having most stomata on the lower surface of the leaf is an advantage to the plant.
Describe how guard cells control the loss of water from a leaf.
Stomata usually close at night.
Explain why.
43 exam-style questions on Edexcel GCSE Biology 6.2 Transport in plants, covering 6.2.1 Root hair cell adaptations, 6.2.2 Structure of xylem and phloem, 6.2.3 Transpiration and stomata, 6.2.4 Translocation of sucrose, 6.2.5 Leaf structure for photosynthesis, 6.2.6 Environmental factors on water uptake, 6.2.7 Rate calculations for transpiration, and 6.2.8 Plant adaptations to extreme environments. Each one has a worked solution and a mark scheme showing where the marks go.