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.

Sentence1: hearing is used for sensing sound by animals. 
Sentence2: functioning ears are used for sensing sound by animals.
animals

Sentence1: Genetics is the study and application of principles of inheritance to plants and animals . 
Sentence2: Pedigrees are useful tools for studying Genetics.
Genetics

Sentence1: Bacteria are very small. 
Sentence2: an electron microscope is used for seeing bacteria by making them appear bigger.

Bacteria