He is an expert in bacteriology.

He is majoring in zoology at university.

In geology, morphology is the field that studies the shape and structure of the terrain.

Geomorphology is the science that studies the surface shape of the earth.

He is an expert in pathology.

He is an expert in anthropology.

He is an expert in virology.

He has a deep interest in teratology.

He is an expert in embryology, studying the developmental processes of many kinds of organisms.

He is majoring in political science at university.