The stomatal density is the number of stomata per area of leaf epidermis. A study was done on the stomatal density of the lower epidermis of leaves from Protium decandrum, a tree found in the Amazon forest. The image shows the epidermis stripped from the lower surface of a leaf.

• Calculation: Size of bar $\div 30 \, \mu \mathrm{m}$ ($3 \, \mathrm{cm} \div 30 \, \mu \mathrm{m}$ or $30000 \, \mu \mathrm{m} \div 30 \, \mu \mathrm{m}$); 1 mark

• Answer: $1000 \, \mathrm{x}$; 1 mark

• First marking point is for division by $30 \, \mu \mathrm{m}$.

• Second marking point is for the correct answer; accept $930$ and $1070 \, \mathrm{x}$.

• (Upper surface/epidermis usually has) fewer stomata/lower stomatal density/no stomata/OWTTE; 1 mark

Don't accept a numerical value only.