Candidate: Mary H. Brown

Degree of: Doctor of Philosophy

Department: Science Studies

Title: Understanding PhotosynTheses and Plant Cellular Respiration as “Nested Systems”: The Characterization of Pre-Service Teachers' Conceptions

Committee: Dr. Renee Schwartz, Chair
Dr. Margaret Clark-Elias
Dr. Bill Cobern
Dr. David Schuster

Date: Friday, March 25, 2005 3:00 p.m.-5:00 p.m.
2734 Wood Hall

Abstract:This dissertation project focused on pre-service elementary teachers' conceptions of the plant processes of photosynTheses and cellular respiration as being connected processes, occurring at multiple ecological levels, and working within “nested systems”. Both plant processes are very complex, involve a number of components, and can be viewed from the perspective of biological systems. Systems are one of the unifying themes of science. Therefore, the pre-service teacher should consider photosynTheses and plant cellular respiration as connected subsystems, with the purpose of energy transformation, taking place a multiple levels within the biological system, the plant. The pre-service teacher should further recognize that these multiple levels work in “nested systems” within the ecosystem.
This project investigated pre-service teachers' conceptions of photosynTheses and plant cellular respiration as viewed through a biological systems perspective. Participants enrolled in a biology course designed for elementary education majors provided their views of the processes through a series of tasks with a peer, a semi-structured interview, and clarified both photosynTheses and plant cellular respiration directly following classroom instruction on the two topics. The instructor of the course was also interviewed after a preliminary analysis of the participants' responses. Data were analyzed using the qualitative analysis computer program The Ethnograph v.5, with attention to whether the participants viewed the energy reactions as related to one another, within multiple ecological levels of the plant system, and as “nested systems” of the global ecosystem.
Participants did view the photosynTheses process as an energy process, but were less committed to cellular respiration as an energy process. While most participants described the processes within multiple ecological levels of the plant system, their accuracy of the concepts within the levels varied. Many participants simplified the two processes in a manner that matched the evaluation of their instruction. Few participants held a “nested systems” view of the global ecosystem. Responses suggested a level of understanding that included only a few of the multiple ecological levels in which the processes operate. Instruction included all multiple ecological levels with a focus on the biochemical level. Participants focused their descriptions of the processes primarily on the organism level. Justifications provided for their explanations were authoritarian, with teleological, tautological reasons also expressed. The pre-service teachers did compare plant functions with analogous human functions; potentially suggesting an intuitive conception. In general, the pre-service teachers view plants as dependent on humans, and having use within human society.
This project may have implications for the instruction of photosynTheses and cellular respiration. Analogy of plant processes with humans' use of energy, and the utility of plants for human society may be a motivating factor for instruction. Instruction that focuses on the organism level first, and provides explicit signposts when moving from one ecological level to another may provide a clearer understanding of the processes.

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