Nancy Wallace, age 11, of Perth, New Brunswick. Canada, for her question:

What exactly is wood made from?

The main ingredient in wood is cellulose, the same tough fibrous material used to make cotton. Materials called lignins are used as cements to bind the cellulose fibers together. Woods also contain various minerals. Some contain resins and some contain a little sugar. All wood is built from boxy plant cells, stacked tightly together.

Each tree uses a number of family recipes to build its own type of wood. However, the main ingredients are very similar. Almost all woods are about 60 per cent cellulose. About 28 per cent of the total material is lignin, cementing the stiff cell walls. The remaining 12 per cent contains an assortment of minerals. If the sample is sapwood from near the tree's outer bark, it contains sugary moisture. If the sample is from any part of a piny conifer, it contains gummy resins. All the ingredients in wood are manufactured by the tree from water, carbon dioxide and dissolved chemicals.