1H-nuclear magnetic resonance of intercalators and rGCA: a potential mutagenicity probe

Variable temperature 1H-nuclear magnetic resonance (NMR) has been used to study the interaction of the RNA trimer, GpCpA, with the intercalators ethidium bromide and the acridine derivatives; proflavin, 9-amino-acridine, acridine orange, acridine yellow and acriflavin. The complexes formed were studied at nucleic acid to drug ratios of 1:1 and 5:1, the latter being useful in defining the effects of structural variation in the acridine series and in determining the site of intercalation. All the intercalators greatly stabilized the oligonucleotide duplex, the average melting temperature (Tm) increasing by up to 30 degrees C. Significant changes in individual Tms and chemical shifts were observed for all the GpCpA protons. 9-Amino-acridine and acriflavin did not stabilize the GpCpA duplex as substantially as the other acridine derivatives. It is suggested that this intercalator:GpCpA system, and its associated NMR-derived Tm, is a useful physical probe for potential mutagens.     

对高中生物纸笔测验改革的思考

讨论了高中生物新课程改革背景下,教学评价方式之一的纸笔测验的改革问题。通过对纸笔测验在检测学生知识性目标达成方面的改革、在能力考核方面如何强化、在情感态度与价值观考核方面的尝试进行了深刻的思考,并对纸笔测验的形式变革、结果处理方面提出了一些看法。     

Constructing a Cotton-Ball Catapult: An Interdisciplinary STS Learning Experience

The need for all students to develop a stronger ability to express their science knowledge in writing is important. In this article, the authors take you on a journey in an elementary school classroom with tools to help foster deeper learning and stronger writing skills in science content. With many students in high school required to pass end-of-semester science exams to receive a diploma, teaching writing at an early age across various content areas is an even more critical component of today’s curriculum. Presenting curriculum material through multiple means (Universal Design for Learning-Representation) allows students to gain information through a learning approach that best fits the students’ learning needs. The authors examine multiple means of representing science curriculum to engage students in creating detailed and comprehensive concept maps and to provide supportive scientific evidence in written explanations as they gain more content knowledge in science.     

Teaching biology in the thirties

Ernest J. Holmes, one of the first teachers of ‘biology’ in secondary schools and co-author of a seminal biology textbook, writes a personal account of teaching at a time when ‘biology’ as a school subject was just beginning to become accepted.     

Assessing students’ knowledge of owls from their drawings and written responses

Many children learn about and experience animals in the everyday environment where they live and attend school. One way to obtain information about children’s understanding of concepts or phenomena is by using their drawings in combination with written responses or interviews. This study assesses how much Slovenian students 10–15 years old (in sixth to ninth grade) know about owls by analysing their drawings and written responses. The study included 473 students. From assessing students’ drawings and written responses, it can be concluded that the respondents had some knowledge of owls’ appearance, their behaviours, diet and habitats. The differences between students in different grades regarding the representations of owls was not statistically significant. Some students had misconceptions about owls, such as the idea that owls can turn their heads 360 degrees, or they confused the long ear-tufts with external parts of the ears. The students’ written responses provided additional information on their ideas about owls; particularly about owls’ specific behaviours, diet, and conservational status. However, some information, such as depicting owls’ body parts and body proportions or their habitats, was more clearly depicted with drawings. One third of the students drew owls in trees and forests, which makes owls good candidates for promoting forest conservation.