Studied were selected aspects of the learning process related to biological concepts and the processes leading to their acquisition. Data were obtained using a series of structured interviews based on jury-graded check lists. The population consisted of 36 randomly-selected students from three randomly-selected classes using Green Version BSCS Biology. The students were divided into three ability levels. Determined were that (1) students developed concepts at all ability levels, (2) the middle and upper range of students acquired more comprehensive concepts than the lower group, (3) auditory and associative (thought) experiences had more impact on concept formation than did visual and direct (manipulative) experiences, (4) the laboratory did not contribute directly to the acquisition of factual knowledge relative to conceptualization, but did contribute significantly to those mental abilities and processes prerequisite to conceptualization, (5) the laboratory was improtant in developing essential mental abilities such as critical thinking and reasoning, (6) concept formation occurred primarily by interrelating small amounts of factual material through the ability to think and to reason effectively, and (7) conceptualization depended more on the ability to think critically and reason effectively than any other factors. (RS)