The purpose of this study is to investigate the effect of the use of group works and demonstration experiments based on conceptual change approach in the elimination of misconception about the subject of photosynthesis and respiration in plants in pre-service science teachers. This study was conducted with 78 pre-service science teachers including 2 groups, the control and experimental, at the third grade student level of the Science Education Department at Gazi University in the Faculty of Education. The control group consists of 40 pre-service science teachers, and the experimental group consists of 38 pre-service science teachers. In addition, the study was conducted within the course of "Science Laboratory Application II" in 2007-2008 spring semester. Photosynthesis and respiration in plants concept test, developed by Kose (2004), was administered to pre-service teachers. The test was examined by scholars in the course field. The reliability co-efficient of the test was found as 0.78. According to the results, the academic achievement of students who take science and laboratory courses with an emphasis on the conceptual change approach was higher than the students who take the course using traditional approaches. (Contains 4 tables and 5 figures.)