In this study, pupils' constructions of some concepts related to biodiversity like classifying living things, variation in living things and ecosystem elements, and the concept of life were investigated in the light of constructivist theory of learning. For this purpose, a biological diversity conceptual understanding test formed by a series of open ended questions was developed and applied to 191 first class high school pupils in seven different high schools in the city of Izmir-Turkey. For the clarification of the responses taken from the test and to follow up some responses a semi-structured interview was developed and applied 14 pupils among the 191. Moreover, to understand the teaching style in seven different schools and to find out the reasons of some responses taken from the pupils a semi-structured teacher interview was developed and applied to seven teachers - one from each school. The results of the study implicated that although pupils' views towards living things and the nature were similar to holistic understanding, their constructions of the topics of nutrition relationship and energy flow were weak, and the idea of anthropocentric view in which human beings are in the centre of all living things were seem to be widespread among them. (Contains 1 table.)