Empirical analysis of secondary biology classrooms revealed that, on average, 68% of teaching time in Germany revolved around processing tasks. Quality of instruction can thus be assessed by analyzing the quality of tasks used in classroom discourse. This quasi-experimental study analyzed how teachers used tasks in 38 videotaped biology lessons pertaining to the topic "blood and circulatory system". Two fundamental characteristics used to analyze tasks include: (1) required cognitive level of processing (e.g. low level information processing: repetiition, summary, define, classify and high level information processing: interpret-analyze data, formulate hypothesis, etc.) and (2) complexity of task content (e.g. if tasks require use of factual, linking or concept level content). Additionally, "students' cognitive knowledge structure" about the topic "blood and circulatory system" was measured using student-drawn concept maps (N = 970 students). Finally, linear multilevel models were created with "high-level cognitive processing tasks" and "higher content complexity tasks" as class-level predictors and "students' prior knowledge", "students' interest in biology", and "students' interest in biology activities" as control covariates. Results showed a positive influence of high-level cognitive processing tasks (ß = 0.07; p <0.01) on "students' cognitive knowledge structure". However, there was no observed effect of "higher content complexity tasks" on "students' cognitive knowledge structure." Presented findings encourage the use of "high-level cognitive processing tasks" in biology instruction.