“活动导学、自主互助”教学模式在中学生物教学中的初探

推进课程改革的关键是实现课堂教学的高效,而高效课堂来自于课堂教学过程中师生双方主观能动性的充分发挥,通过教师课前设计学生学习活动方案(活动单),学生在课堂上开展"自主学习、活动探究"式学习,可以实现教师的主导性和突出学生的主体地位。通过实施"活动导学、自主互助"课堂教学模式,取得了一点认识,希望能为当前普通高中生物课堂教学改革提供一点借鉴。     

高中生物学实验中的显色原理

高中生物学新课程实验中涉及到相当多的物质检测与鉴定的显色方法。其原理多样,既有利用氧化还原反应原理,也有利用络合物的特性,还有利用有机染色剂染色的和酸碱指示剂变色特性的。作为学习者来说知其所以然有利于知识的构建。     

在校高中生的生物学学习态度的调查研究

我们生活在一个科学技术飞速发展的时代 ,其中生物科学的发展速度更是以往任何时代都不能比拟的。新知识带来新的挑战和机会 ,影响着当今社会的每一个成员 ,并且对公众的科技水准及科学素养的要求比以往更加苛刻。当学校面临着如何提高学生在这些领域的素养的挑战时 ,我们首先要做的是 ,了解学生对科学、数学和技术的态度 ,这样才能使我们的努力更加有效 ,毫无疑问 ,了解学生学习生物学的态度 ,以及不同类别的学生之间在学习态度方面存在的差异 ,是生物学教育工作者的首要任务。依此来改进我们的教学方法 ,因材施教 ,合理运用恰当的教学策略…     

同位素示踪技术在高中生物学实验中的应用小结

同位素示踪技术是生物学实验中常用的技术手段。将高中教材中所涉及到的利用同位素示踪技术研究的相关内容进行了归纳总结,便于学生对同位素示踪技术的理解和掌握。     

高中生学习生物学动机的初步研究

动机是影响学生学习的要素之一,为了解高中生学习生物学的动机,采用Paul L．Gardener和Pinchas Tamir开发的量表,对378名高中生学习生物学的动机进行了调查与分析。研究结果表明,学生学习生物学的主要动机是“问题解决”,“考试成功”则居次要地位。本研究旨在为中学生物学教学中教学策略的运用及课程改革与开发提供基本的信息。     

初中生物学教学课程资源开发与利用的实践探索

基于初中生物学教学课程资源开发与利用的实践探索,丰富的根植本土的教学案例的呈现与分析,再现了黑龙江垦区生物学教师可喜的研究成果,对初中生物学教学具有一定的指导作用。     

High school students' study of sex preselection

A study was designed and conducted by high school students to analyse the effects of age, sex, and family composition on students' preferences for the sex and birth order of their offspring. The study was based on the observation that sex preselection technology will be a reality in the near future.

The results showed that boys responded differently than girls. Typical ‘boy’ and ‘girl’ responses were identified, but these tended to disappear with age. Family composition had a minimal effect on sex preferences, but it provided a possible pattern on which a subject could make a judgement on sex preferences.

The study further provided the students with an opportunity to become involved in a socially relevant issue, with many of the polled students becoming equally involved. Other social questions were raised by the students.     

Biochemical basis for the biological clock

NADH oxidases at the external surface of plant and animal cells (ECTO-NOX proteins) exhibit stable and recurring patterns of oscillations with potentially clock-related, entrainable, and temperature-compensated period lengths of 24 min. To determine if ECTO-NOX proteins might represent the ultradian time keepers (pacemakers) of the biological clock, COS cells were transfected with cDNAs encoding tNOX proteins having a period length of 22 min or with C575A or C558A cysteine to alanine replacements having period lengths of 36 or 42 min. Here we demonstrate that such transfectants exhibited 22, 36, or 40 to 42 h circadian patterns in the activity of glyceraldehyde-3-phosphate dehydrogenase, a common clock-regulated protein, in addition to the endogenous 24 h circadian period length. The fact that the expression of a single oscillatory ECTO-NOX protein determines the period length of a circadian biochemical marker (60 X the ECTO-NOX period length) provides compelling evidence that ECTO-NOX proteins are the biochemical ultradian drivers of the cellular biological clock.     

Investigating the basis of substrate recognition in the pC221 relaxosome

The nicking of the origin of transfer (oriT) is an essential initial step in the conjugative mobilization of plasmid DNA. In the case of staphylococcal plasmid pC221, nicking by the plasmid-specific MobA relaxase is facilitated by the DNA-binding accessory protein MobC; however, the role of MobC in this process is currently unknown. In this study, the site of MobC binding was determined by DNase I footprinting. MobC interacts with oriT DNA at two directly repeated 9 bp sequences, mcb1 and mcb2, upstream of the oriT nic site, and additionally at a third, degenerate repeat within the mobC gene, mcb3. The binding activity of the conserved sequences was confirmed indirectly by competitive electrophoretic mobility shift assays and directly by Surface Plasmon Resonance studies. Mutation at mcb2 abolished detectable nicking activity, suggesting that binding of this site by MobC is a prerequisite for nicking by MobA. Sequential site-directed mutagenesis of each binding site in pC221 has demonstrated that all three are required for mobilization. The MobA relaxase, while unable to bind to oriT DNA alone, was found to associate with a MobC-oriT complex and alter the MobC binding profile in a region between mcb2 and the nic site. Mutagenesis of oriT in this region defines a 7 bp sequence, sra, which was essential for nicking by MobA. Exchange of four divergent bases between the sra of pC221 and the related plasmid pC223 was sufficient to swap their substrate identity in a MobA-specific nicking assay. Based on these observations we propose a model of layered specificity in the assembly of pC221-family relaxosomes, whereby a common MobC:mcb complex presents the oriT substrate, which is then nicked only by the cognate MobA.     

Investigating the biological and clinical significance of human dysbioses

Culture-independent microbiological technologies that interrogate complex microbial populations without prior axenic culture, coupled with high-throughput DNA sequencing, have revolutionized the scale, speed and economics of microbial ecological studies. Their application to the medical realm has led to a highly productive merger of clinical, experimental and environmental microbiology. The functional roles played by members of the human microbiota are being actively explored through experimental manipulation of animal model systems and studies of human populations. In concert, these studies have appreciably expanded our understanding of the composition and dynamics of human-associated microbial communities (microbiota). Of note, several human diseases have been linked to alterations in the composition of resident microbial communities, so-called dysbiosis. However, how changes in microbial communities contribute to disease etiology remains poorly defined. Correlation of microbial composition represents integration of only two datasets (phenotype and microbial composition). This article explores strategies for merging the human microbiome data with multiple additional datasets (e.g. host single nucleotide polymorphisms and host gene expression) and for integrating patient-based data with results from experimental animal models to gain deeper understanding of how host-microbe interactions impact disease.     

例谈高中数学知识在生物学解题中的应用

举例说明了数学归纳法和极限、加法定律和乘法定律、集合、排列组合等高中数学知识在生物学解题中的应用。例如,用数学归纳法归纳计算公式;用加法定律和乘法定律、集合计算遗传病的发病率;用排列组合计算基因型的种类和氨基酸形成多肽的种类等。     

Genetic clues to the biological basis of autism

Autism, the prototypical pervasive developmental disorder, is characterized by impaired communication and social interaction, and by repetitive interests and behaviours. The core disorder probably affects around 5:10 000 individuals, of whom some three-quarters are male. Onset is in the first three years of life, and the disorder is associated with lifelong disabilities. Because of the clear evidence that idiopathic autism has a strong genetic basis, many groups are undertaking whole genome screens to identify susceptibility loci. We review the first results, and briefly consider the implications of molecular genetic findings for future research, diagnosis and management.     

The biological basis of human history

Well-known physiological peculiarities of human bodies had much to do with raising our ancestors to the top of the food chain: erect posture, binocular vision, an unusually efficient cooling system, and an omnivorous diet. But these capabilities pale beside the advantages that accrued to proto-humans and then to humans from expanding and more precise modes of communication: first dance, then language. Still later, transportation and communication transcended limits set by human muscles with the invention of wind-propelled flotation and animal caravans, while writing overcame limits of personal memory and face-to-face dissemination of information. Contacts across local social and cultural boundaries tended to propagate best practices, making humankind a uniquely dangerous, constantly changing parasite upon other forms of life.     

Structural basis of biological nitrile reduction

The enzyme QueF catalyzes the reduction of the nitrile group of 7-cyano-7-deazaguanine (preQ(0)) to 7-aminomethyl-7-deazaguanine (preQ(1)), the only nitrile reduction reaction known in biology. We describe here two crystal structures of Bacillus subtilis QueF, one of the wild-type enzyme in complex with the substrate preQ(0), trapped as a covalent thioimide, a putative intermediate in the reaction, and the second of the C55A mutant in complex with the substrate preQ(0) bound noncovalently. The QueF enzyme forms an asymmetric tunnel-fold homodecamer of two head-to-head facing pentameric subunits, harboring 10 active sites at the intersubunit interfaces. In both structures, a preQ(0) molecule is bound at eight sites, and in the wild-type enzyme, it forms a thioimide covalent linkage to the catalytic residue Cys-55. Both structural and transient kinetic data show that preQ(0) binding, not thioimide formation, induces a large conformational change in and closure of the active site. Based on these data, we propose a mechanism for the activation of the Cys-55 nucleophile and subsequent hydride transfer.     

美国“2061计划”高中生物学教材评估内容、特点及启示

介绍了美国“2061计划”高中生物学教材评估工具的研制背景及目的．分析了“2061计划”高中生物学教材评估的维度和标准。并对我国生物学课程改革中生物学教材评估提出了一些建议。     

The neural basis of perceptual learning

Perceptual learning is a lifelong process. We begin by encoding information about the basic structure of the natural world and continue to assimilate information about specific patterns with which we become familiar. The specificity of the learning suggests that all areas of the cerebral cortex are plastic and can represent various aspects of learned information. The neural substrate of perceptual learning relates to the nature of the neural code itself, including changes in cortical maps, in the temporal characteristics of neuronal responses, and in modulation of contextual influences. Top-down control of these representations suggests that learning involves an interaction between multiple cortical areas.     

Monitoring urban environments on the basis of biological traits

Urbanization induces changes in species abundance and richness that are beginning to be extensively described. However, the functional structure of urban communities still requires attention to provide a basis for a more accurate understanding of urban ecosystems’ functioning. This study has been performed in order to assess functional changes in ecological communities related to changes of urban landscape features along an urbanization gradient. Species abundance and richness of birds and butterflies in the city parks of Marseille (south-east France) have been used to assess these changes. On the basis of easily accessible traits (reproduction parameters, size, feeding habits), we have examined whether different contexts of urbanization favour some strategies more than others. Some differences occur between butterflies and birds in terms of species abundance and richness through the urbanization gradient, showing that at least some species of birds manage to colonize city centre and/or exploit urban resources better than butterflies. But our results also clearly reveal general patterns in biological traits for both birds and butterflies that further reflect the gradient of urban features from outskirts to city centre. Species associated with the city centre tolerate a wide range of conditions whereas species associated with city outskirts have more specialized abilities. Urbanization acts as an environmental filter for bird and butterfly communities selecting species able to colonize and settle in the city centre on the basis of their biological traits. In our context, environmental filters induce a biotic homogenization with urbanization through loss of species (taxonomic homogenization) and over-representation of generalist species (functional homogenization). This homogenization reflects an underlying process of disruption of biotic interactions for butterflies and birds. This study has enabled us to identify a combination of biological traits sensitive to urban features that may represent useful indicators for both theoretical and applied purposes in order to understand the impact of urbanization on animal communities.