I made a couple of nice photos of a model organism I used in the research at my educational institution. The organism was provided to us students by the educational institution. I was wondering, is a student allowed to sell such photos online? Does the copyright belong to me or my educational institution?
The copyright of each photo almost certainly belongs to you if you are the one who took them, but the actual taking of photos may have been unpermitted.
Selling them is abrogating the ability of the institution to take their own photos and sell those. You will probably not face copyright issues, but the institution could sue for their destruction and a handover of any profit derived, along with any contractual or academic or other penalties that apply.