2. Cambium - Parallel rows of cells that form new layers of bark and wood

3. Sapwood - Wood that lies between the cambium and the heartwood. It acts as a major conductor of water and minerals for the tree

4. Heartwood - The hard, inactive wood at the center of the tree

5. Roots - The tree parts below ground that hold the tree. Root hairs, which push their way through the soil and absorb moisture, send water and nutrients up into the tree.

6. Chlorophyll - The green substance found in leaves and needles

7. Photosynthesis - The process of producing food for trees by combining sun light, water, chlorophyll and carbon dioxide

8. Oxygen - An element found freely in nature that is necessary for humans and animals to breathe and is needed for nearly all combustion to occur

9. Carbon Dioxide - A colorless, odorless, incombustible gas that is formed during respiration, combustion, and organic decomposition