Chemical processes and living organisms are studied in what section of biology ?
Subdisciplines of biology are defined by the scale at which organisms are studied , the kinds of organisms studied , and the methods used to study them : Biochemistry examines the rudimentary chemistry of life ; molecular biology studies the complex interactions among biological molecules ; botany studies the biology of plants ; cellular biology examines the basic building - block of all life , the cell ; physiology examines the physical and chemical functions of tissues , organs , and organ systems of an organism ; evolutionary biology examines the processes that produced the diversity of life ; and ecology examines how organisms interact in their environment .