The study of tissue is known as histology or histopathology (if the tissue is diseased), a branch of anatomy. Therefore a scientific professional who studies this subject would be call a histologist.
A scientist that studies bears would be called an ursinologist.
An aviologist.
pomology
Gunsmith? look at the yahoo Canada answer for this.
A scientist that studies motion, forces and energy would be called a physicist.
A biotechnology scientist.
An Oceanographer. Marine Biologist, that sort of thing.
A scientist that studies viruses is called a virologist.
A scientist who studies mollusks is called a teuthologist.
A scientist that studies bears would be called an ursinologist.
virologist
An aviologist.
A meteorologist.
biologist
A vulcanologist
Mineralogists
Bridgeologist