A redwood tree in california can grow from a tiny seed into a tree so big that cars can drive through a tunnel cut into its trunk. The tallest redwood trees grow more than 110m tall (120yd). If one of these trees were cut and laid on a football field , the tree would be as long as the entire field plus the two end zones. As you might imagine, these trees need a lot of food and energy to grow. You might already know that trees get energy from the sun. But how do trees use this energy? How do you think that plants use light energy to do things?