Morphology, which is a part of linguistics, studies the structure of words.

He devoted his life to the study of science.

He is an expert in chemistry.

He is an expert in bibliography and has many publications.

He is very interested in ecology.

He is majoring in agronomy.

He is globally recognized as an expert in epidemiology.

I am majoring in nutrition science at university.

He used a large sum of money for investment.

He used a large amount of money for investment.