Misconceptions, shown to be prevalent in students even at the college level, may affect the cognitive process of making predictions in biology. The purpose of this study was to: (1) identify students' misconceptions about important biological concepts; (2) identify students' cognitive behaviors associated with making predictions about these concepts; and (3) examine the relationship between students' misconceptions and their cognitive behaviors of prediction. Information processing theory provided the theoretical framework for this research. Think-aloud interviews were employed in this study to collect videotape data on students' cognitive processes associated with their misconceptions and subsequent predictions about selected biological concepts. A computer simulation program,"Pollute," allowed students to manipulate five independent variables affecting water quality. Three-stage instruction was given based on the learning cycle. This paper found that subjects who were successful were formal operational and exhibited fewer misconceptions than unsuccessful subjects. Misconceptions identified are listed. Recommendations are made for science teaching techniques that will help to identify and eliminate students' misconceptions. Forty-six references are listed. (Author/YP)