This study aimed to determine the cognitive structures of preservice primary school teachers for basic biology concepts using Word Association Test (WAT). The study group consists of 50 preservice teachers studying in a university in Western Black Sea Region in Turkey. Four separate cut-off points were determined and analysed. Organ, living things, microscope were the most common response words. The conceptual network was structured as three different islets that were disconnected from each other at the third cut-off point. The desired conceptual network was formed only when cut-off point was taken further than the last cut-off point, and that these desired interconnections, network structure were formed in some students. It is suggested that this situation should be taken into consideration while determining cognitive structures using WAT and that lecturing should be performed according to the structure of the conceptual network that is desired to be shaped in the students' memory.