"(生物)多样性、变异和进化"一节教学的实践与思考

1　教学实践1.1　 BSCS教材“通过进化而延续”一章的内容简介　“通过进化而延续”是美国 BSCS生物学教材 (绿皮本 )第 2篇“生物圈中的延续性”中的最后一章。全章共分 3节 ,第 1节“多样性、变异及进化”包括 :1总结已学知识 ,介绍并引导观察周围生活实际现象 ,归纳生物的相似和相异之处 ,引出生物进化的课题。 2安排一个用数学方法处理的寻找差异的实验 ,引导总结出研究进化的一般方法。3介绍物种形成过程 ,并归纳物种的概念。第2节“进化与自然选择”包括 :1安排“模拟自然选择”实验。 2以达尔文实践为例 ,介绍研究进化的科学思想…     

2003年广东"文理综合"生物试题特点与考生答卷分析

1　试题考点分布题号分值比例主要考点所属章节19 3 2 4%细胞器的功能第 1章2 0 3细胞成分第 1章2 13 2 4%光合作用与呼吸作用的关系矿质代谢与影响光合作用因素的联系第 2章2 2 3动物新陈代谢中能量代谢第 2章2 3 3 2 4%生物变异第 5章2 43伴性遗传第 5章3 9( 3 ) 2 2 8% CO2 与“温室效应”第 7章40 5影响生态系统的因子与生态平衡第 7章2　试题特点与考生答卷常见问题浅析2 .1　试题体现了“综合能力测试”考查学生学科主干基础知识的教学要求　从上表统计可见 ,今年“综合能力测试”生物学科考查的知识都落在学科主干知识——细胞、新…     

"现代生物进化理论简介"一节课的教学设计

“现代生物进化理论简介”是现行高中《生物》(人教版)第7章“生物的进化”的中心内容。也是对以前学过的生物学知识综合运用并与后续一章“生物与环境”有一定联系的教学内容。教学大纲对这一节的要求是识记。在我们所见到的对这一节课的教学设计上,多数教师都是通过以讲授为主线进行教学活动     

"蝗虫"和"蜜蜂"两节教学设计

1　教学设计形式师生共同维持网站——“昆虫的世界”。2　教学设计依据现代教学与传统教学相比 ,师生在教学中的角色发生了根本性的转变 ,要求学生通过协作化学习、主动学习 ,掌握的是获取知识的过程、方法和途径。教师在课堂上充当的是组织者、管理者 ,是学生的学习伙伴 ,也就是要从以前“带领学生学”转变为“引导学生学”。3　教学设计意图3.1　教学内容分析　针对初一动物学中“节肢动物”一章里“蝗虫”和“蜜蜂”两节内容而设计的。教学大纲要求学生通过学习蝗虫、蜜蜂的知识 ,了解昆虫纲的主要特征、昆虫的发育及昆虫与人类的关系等…     

通过课外科技活动加深对"完全变态"的理解

“完全变态”是昆虫纲部分动物的发育特点。在初中《生物》下册第七章第二节“蜜蜂”一课中出现 ,“完全变态”发育过程的昆虫还有菜粉蝶等。怎样才能使学生牢固掌握“完全变态”的理性知识呢 ?我们根据理性知识是由感性知识转变来的道理 ,通过课外科技活动教学来达到使学生对书本理性知识的掌握和进一步理解。通过“对菜粉蝶的生殖发育的观察”课外科技教学活动 ,加深学生对“完全变态”的深刻理解。每年 9月至 10月上旬是菜粉蝶的产卵较盛时期 ,此时可看到菜粉蝶在小白菜、甘蓝菜地的上空成对地翩翩起舞。教师应抓紧时机组织指导学生进行…     

“节肢动物门”小结

在现行中师生物课本中,“节肢动物”一章篇幅多,内容丰富,比初中动物课本增加了昆虫纲分目及检索表等知识。“节肢动物”是动物学的重点章节,教学大纲规定要用15节课的时间完成这章的教学任务。为了使学生通过“节肢动物”一章的学习,能对整章知识加以整理、提高和系统化,归纳出节肢动物门各纲的主要特征,进一步掌握一般昆虫分类知识及其与人类的关系,从而懂得消灭害虫的方法,我在教学计划中特地安排了一节“节肢动物门”的小结课。具体做法如下:     

"生命起源和生物进化"专题的复习建议

高中教材“生命起源和生物进化”一章 ,由于历史的原因 ,内容较单薄 ,观念较陈旧 ,课时较少 ,过去一直被视为“角落知识”,没有引起师生们足够的重视。但随着近年来 ,生物学科思想的发展 ,生物学课程观念的演变 ,这部分内容已愈来愈显现出其重要的科学价值、社会价值、人文价值、创新价值和能力价值。自 1999年高考实施“3+ X”以来 ,这部分内容已成为考查学生思维品质、科学方法、价值取向、人文素质的极好素材 ,成为高考命题的一个新观点。因此 ,师生需加强对此内容复习策略的研究。本文拟从复习方式、知识视野、学科思想、题型示例 4个…     

"免疫"一节教改尝试

１　导入新课本课独立成章,采用提问法导入。①人是否接触病原体就生病？为什么？②你曾接受过什么预防接种？其防病原理是什么？问题联系学生日常生活和亲身经历,十分熟悉又答不准为什么,很自然就能激发起学生的学习兴趣。２　讲授２．１　人体的三道防线　从初中学生的认知水平出发,课本采用了三道防线的形象化语言,并配以插图。我发给每个学生一张白纸,一分为三,分别写上“皮肤和粘膜”、“杀菌物质和吞噬细胞”、“免疫器官和免疫细胞”。然后引导学生回忆里面哪些内容曾学过,并回答有关知识,实现知识的迁移。第１次出现的名词…     

"植物元素缺乏症"实验教学方法的改进

大学课程里开设“植物元素缺乏症”实验对理解掌握植物生理学矿质营养这一章内容非常重要。我们在按张志良和瞿伟菁（2003）主编的《植物生理学实验指导》（以下简称“指导”）进行的实验教学中感到,学生在长时间的实验过程中往往会失去耐心和兴趣,实验结果出来后也只是被动地核对检索表,而且还缺少必要的实验考核措施,致使学生对植物元素缺乏症记忆不深刻。对此,我们进行了一些改进,提出了一种集知识与趣味于一体的教学方法。     

初中植物学“結語”課的教学法

一.教材分析“结语”是初中植物学中最后一个课题,一个很重要的课题。本课题包括“植物的进化”和“栽培植物的起源和发展”二节内容,总结了植物学的全部教材,以进化发展的思想,将分散在植物学各课题中有关植物个体发育的知识,植物基本群的知识,人类利用和改造植物的知识加以概括和引深,阐明地球上多种多样的野生植物和栽培植物是怎样起源和发展的。“植物的进化”一节,紧接在“植物的类群”一章后,和该章有直接的联系。“植物的类群”阐明植物各类群构造和生活上的特点,各基本群的区别,揭露植物的多     

Nitration in neurodegeneration: deciphering the "Hows" "nYs"

Recent literature has ushered in a new awareness of the diverse post-translational events that can influence protein folding and function. Among these modifications, protein nitration is thought to play a critical role in the onset and progression of several neurodegenerative diseases. While previously considered a late-stage epiphenomenon, nitration of protein tyrosine residues appears to be an early event in the lesions of amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. The advent of highly specific biochemical and immunological detection methods reveals that nitration occurs in vivo with biological selectively and site specificity. In fact, nitration of only a single Tyr residue is often sufficient to induce profound changes in the activity of catalytic proteins and the three-dimensional conformation of structural proteins. Presumably, nitration modifies protein function by altering the hydrophobicity, hydrogen bonding, and electrostatic properties within the targeted protein. Most importantly, however, nitrative injury may represent a unifying mechanism that explains how genetic and environmental causes of neurological disease manifest a singular phenotype. In this review and synthesis, we first examine the pathways of protein nitration in biological systems and the factors that influence site-directed nitration. Subsequently, we turn our attention to the structural implications of site-specific nitration and how it affects the function of several neurodegeneration-related proteins. These proteins include Mn superoxide dismutase and neurofilament light subunit in amyotrophic lateral sclerosis, alpha-synuclein and tyrosine hydroxylase in Parkinson's disease, and tau in Alzheimer's disease.     

Evolution of the "autophagamiR"

MicroRNAs (miRs) are increasingly important diagnostic and prognostic markers in cancer but have not been defined in medullary thyroid carcinoma (MTC). MiR microarray profiling was performed on 19 primary MTC tumors, validated with qPCR in 45 cases and correlated with clinical outcomes. MiRs-183 and 375 were overexpressed and miR-9* underexpressed in sporadic vs. hereditary MTC (SMTC; HMTC). MiR-183 and 375 overexpression predicted lateral nodal metastases, residual disease, distant metastases and mortality. MiR-183 knockdown in an MTC cell line (TT cells) reduced cellular proliferation in association with elevated LC3B expression. This is suggestive of increased autophagic flux and potential cell death via autophagy induction. MiRs may subsequently be shown to serve as efficacious therapeutic strategies in MTC with a mechanism based upon autophagy.     

"Fingering" the vertebrate limb

A detailed and precise picture is being pieced together about how the pattern of digits develops in vertebrate limbs. What is particularly exciting is that it will soon be possible to trace the process all the way from establishment of a signalling centre in a small bud of undifferentiated cells right through to final limb anatomy. The development of the vertebrate limb is a traditional model in which to explore mechanisms involved in pattern formation, and there is accelerating knowledge about the genes involved. One reason why the limb is holding its place in the post-genomic age is that it is rich in pre-genomic embryology. Here, we will focus on recent findings about the aspect of vertebrate limb development concerned with digit pattern across the anteroposterior axis of the limb. This process is controlled by a signalling region in the early limb bud known as the polarizing region. Interactions between polarizing region cells and other cells in the limb bud ensure that a thumb develops at one edge of the hand (anterior) and a little finger at the other (posterior).     

Coding "what" and "when" in the Archer fish retina

Traditionally, the information content of the neural response is quantified using statistics of the responses relative to stimulus onset time with the assumption that the brain uses onset time to infer stimulus identity. However, stimulus onset time must also be estimated by the brain, making the utility of such an approach questionable. How can stimulus onset be estimated from the neural responses with sufficient accuracy to ensure reliable stimulus identification? We address this question using the framework of colour coding by the archer fish retinal ganglion cell. We found that stimulus identity, “what”, can be estimated from the responses of best single cells with an accuracy comparable to that of the animal''s psychophysical estimation. However, to extract this information, an accurate estimation of stimulus onset is essential. We show that stimulus onset time, “when”, can be estimated using a linear-nonlinear readout mechanism that requires the response of a population of 100 cells. Thus, stimulus onset time can be estimated using a relatively simple readout. However, large nerve cell populations are required to achieve sufficient accuracy.

Authors Summary

In our interaction with the environment we are flooded with a stream of numerous objects and events. Our brain needs to understand the nature of these complex and rich stimuli in order to react. Research has shown ways in which a ‘what’ stimulus was presented can be encoded by the neural responses. However, to understand ‘what was the nature of the stimulus’ the brain needs to know ‘when’ the stimulus was presented. Here, we investigated how the onset of visual stimulus can be signalled by the retina to higher brain regions. We used archer fish as a framework to test the notion that the answer to the question of ‘when’ something has been presented lies within the larger cell population, whereas the answer to the question of ‘what’ has been presented may be found at the single-neuron level. The utility of the archer fish as model animal stems from its remarkable ability to shoot down insects settling on the foliage above the water level, and its ability to distinguish between artificial targets. Thus, the archer fish can provide the fish equivalent of a monkey or a human that can report psychophysical decisions.