Birgitta Mc Ewen

Photoactivation and Photoinhibition Are Competing in a Mutant of Chlamydomonas reinhardtii Lacking the 23-kDa Extrinsic Subunit of Photosystem II

The process of photoactivation has been studied in dark grown cells of Chlamydomonas reinhardtii. A mutant, FUD 39, lacking the Cl−-concentrating 23-kDa psbP protein of photosystem II was found to have a decreased capability to perform photoactivation. The yield of the process never reached wild type level, and contrary to the wild type, it was highly dependent on the intensity of the activating light, with a very narrow optimum around 1 μE m−2 s−1. The different behavior in the mutant can be explained by a requirement for a longer dark period, between the two photoacts, during the photoactivation. This is proposed to reflect the decreased Cl− affinity in the mutant. Photoactivation in the mutant was also found to be very sensitive to competing photoinhibitory processes. The inhibition was located to the donor side of photosystem II and affected the photoactivation capability before electron transfer from Tyrz was inhibited. We propose an extended model for photoactivation in which an intermediate that is sensitive to photoinhibition is formed if Cl− is not functionally bound to the manganese cluster.

Enhancing primary science : An exploration of teachers' own ideas of solutions to challenges in inquiry. and context-based teaching

ABSTRACT Studies of inquiry- and context-based science education (IC-BaSE) have shown that teachers find these approaches problematic. In this study, 12 primary school teachers’ reflections on challenges related to IC-BaSE are explored. The aim of the study was to investigate which challenges primary teachers experience when working with IC-BaSE and how these may be solved. Group discussions and individual portfolios were used for data collection. Content analysis showed that the challenges teachers experienced were mainly practical relating to: how to find contexts, lack of time, handling big classes, students working at different paces, handling materials, and the teachers need of control. The teachers also presented their own ideas of solutions to the challenges.

Epigenetics and Learning

Abstract Epigenetics, the new field of biology, has given us a scientific explanation model for how the environment influences gene expressions. ‘Epi’ means ‘above’ and describes mechanisms that are situated ‘above’ the base-pair order in the DNA. The benefits of our increased understanding of epigenetics encompass many fields, among them learning. Since the same epigenetic mechanisms seem to be involved in learning, stress and physical exercise, we have a scientific tool to conduct investigations of the correlations between these. In a broader sense, epigenetics brings scientific data to the classical gene-environment-debate. It is important for school staff and school policy-makers to grasp the key concepts of epigenetics, as it probably soon will be part of the scientific literacy.

Teachers’ and principals’ reflections on student participation in a school science and technology competition

ABSTRACT Background The European Union asks for renewed pedagogies in schools according to teaching strategies and necessary competences for the twenty-first century, instead of the often-used transmissive pedagogies. The national Swedish competition in science and technology for grade eight, The Technology Eight, provides an opportunity for teachers to work with instructional strategies in line with suggested pedagogies. Purpose To investigate teachers’ and principals’ reflections on the competition in schools. Sample Seventeen secondary school teachers and three principals from districts in the south-western part of Sweden participated in the study. All teachers had long experience of the competition, and their classes had reached at least the regional finals during the last year. Design and methods Semi-structured interviews were recorded, transcribed verbatim, and then analysed using content analysis. Focus was put on why the teachers decided to participate, how the teachers integrated the competition in their education and roles of the principals. Results There were various reasons for participating in the competition. Teachers reported development of twenty-first-century skills such as better cooperation between the students. They also noticed an increased interest in science and technology and how learning in the subjects was stimulated. Furthermore, the teachers found participation in the competition to be positive for them too. They integrated the competition in ordinary education and gained teaching ideas as well as found connections to the curriculum. Participating in the competition seemed to be a tradition in most of the schools. The principals’ role was to facilitate the organisation around the competition and to provide social support. Conclusions Participation in a school competition was considered as an instructional strategy with several positive outcomes. Use of this strategy can be supported by earlier suggestions to use pedagogies that are opposite to transmissive methods, enhancing students’ development of important skills for the future.