Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
Q: Sentence1: Plants use the direct light energy from the sun to grow. 
Sentence2: Plants have more difficulty growing when a hemisphere is tilted away from the sun.
A: 
grow