This study examined a network of concepts used in the curriculum, textbooks, instruction, and assessment in relation to somatic cell division and investigated the alignment of science concepts used in them. Textbooks and teachers' instruction and evaluation questions were collected to analyse the alignment between the concepts and the conceptual network used in the curriculum, textbooks, instruction, and assessment on the basis of the national science curriculum in the Republic of Korea. The findings of this study suggest that the concept of a cell was used as a linkage, and a lack of conceptual linkage prevailed between the curriculum, textbooks, instruction, and assessment in the somatic cell division unit. In comparison with the curriculum, a rapid increase in the number of concepts presented in classes led to a complicated conceptual network. As the conceptual network was complex and ambiguous, the concepts that students can learn are more likely to be ambiguous. Therefore, the conceptual network could be instrumental for facilitating students' conceptual understanding of somatic cell division. The alignment of concepts and conceptual linkage in the teaching of somatic cell division could contribute to improving conceptual associations between the curriculum, textbooks, instruction, and assessment.