A seed buried in the dark still knows which way to send its root. Ins certain ce of t root c sit de grains o starch, a these gra fall t whatever sur is lowest. The cell reads their position as a signal and passes a hormone to one side of the root, which then grows more slowly than the other and bends the growing point downwards until it is pointing at the centre of the earth.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.