There are many 14-letter biology terms, depending on what you're looking for. Here are a few examples:

* Photosynthesis

* Immunoglobulin

* Electrophysiology

* Nucleoprotein

* Biotechnology

Can you provide more context about what you're looking for? For example, do you want a term related to a specific field of biology, or are you looking for something more specific, like a process or a structure?