Welcome to allnurses
When I trained, a hundred years ago, biology was a requirement, but I think now it depends on the country you're studying in.
I work in an acute hospital, which means we (at least theoretically) look after patients who have conditions that have recently manifested or become worse. My hospital is tertiary, which means we get patients that are sicker or more complicated than average, and I get to see rare and unusual things I wouldn't otherwise. The patients I look after are primarily medical, which means that they are admitted for treatments other than surgery, though many of them have operations anyway.
Other options for institution-based nurses include working in less acute hospitals, rehabilitation facilities, surgical nursing, intensive care, theatre, casualty, among many other options. That's one of the things that I think makes nursing unique - there are practically as many places to work as there are nurses!