He is majoring in mineralogy at university.

He is an expert in entomology, especially knowledgeable about butterflies.

Cytology is a branch of biology that studies the structure and function of cells.

He is majoring in economics.

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 majoring in geology.

He is an expert in pathology.