“伴性遗传”一节教学设计

1教材分析 “伴性遗传”是浙科版普通高中课程标准实验教科书《遗传与进化》第2章第3节第2课时内容.《普通高中生物课程标准》对本节内容的要求为:“概述伴性遗传.”     

"DNA的复制"一节的教学设计

1 教材分析 本节内容选自人教版课程标准实验教科书高中生物学“遗传与进化”第3章第3节。DNA复制是生物遗传信息得以世代相传和延续的基础，也是生物变异的基础。对本节的学习有助于学生更好地认识基因的本质。     

指导学生从“做科学”中学习概念

生物教学《纲规定：“通过科学方法训练,培养学生的科学素质”,是生物教学的目的要求之一。教学中怎样进行科学方法训练,基本途径是什么？带着这个问题,我们进行了“过程式教学”模式的实验工作。1995年开始用人教版教材实验了一年,1996年暑假后又改用北京版教材实验。成立了“五校教科研群体”,由北京第101中学、北京钢院附中、北京农大附中、北医附中和北京市双榆树中学的初一年级生物教师组成,在市教研部生物教研室支持下及区教师进修学校生物教研组的统一部署下开展工作。实验的第一年,我们着重摸索过程式教学的实施步骤。第二…     

"生物多样性及其保护"一节的教学设计

“生物多样性及其保护”是高二《生物》第2册第9章“人与生物圈”中的第2节内容,也是高中《生物》必修教材的最后一节。本节内容包括3方面：生物多样性的价值;我国生物多样性概况;生物多样性的保护。本节对于提高学生的环保意识。进而提高全民族的环保意识具有重要的意义。     

介绍台湾的《高中基础生物》全一册

这本1987年出版的教材是依照1983年7月台湾教育部关于高级中学基础生物课程标准编辑,由国立台湾师范大学科学教育中心任主编、国立编译局出版。教材要求使学生了解生物学的基本概念、原理,为进一步学习生物学打好基础。学生通过学习,掌握基本的科学方法,培养正确的科学态度以及解决问题的能力,进一步认识生物学对于人类的贡献与影响,了解人类在生命世界中的地位与责任。全一册供高中一年级第一学期使用(每周3课时)。配套教材还有学生实验纪录簿和教师手册。教材共有6个大实验,1个补充实验,各类插图159幅。该课本注意讲课和实验并重,学生从实验中去探讨、思考,了解科学的一般概念、原理,并培养对自然现象分析与综合的能力。全一册共分五章:第一章“生物的基本构造——细胞”;第二章“生命的维持”;第三章“生命的延续与演化”;第四章“生物与环境”;第五章“人类与自然界     

“能量的释放和利用（第1课时）”的情境教学

1教学背景分析 1．1内容分析本节课是苏科版生物学教材7（上）第2单元“生物从环境中获取物质和能量”第6章“能量与呼吸”第1节“能量的释放和利用”的起始课能量的释放需要氧是本节课的重点．对呼吸和呼吸作用进行区别,理解什么是呼吸作用是本节课的难点。     

"(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…     

例谈高三实验复习的课堂教学设计

高中《生物》必修教材第1册中,“激素等药物饲喂小动物的实验”属于选学内容,笔者认为,该实验涉及利用小动物进行对照实验的一般操作方法,对于提高中学生实验能力和科学研究能力有很大的帮助。1教材分析该实验涉及到多方面的知识,综合性比较强,与高二生物学必修教材中的其他章节、初中生物学教材中有关内容,以及物理、化学等相关学科都有着密切的联系。因此加强本节内容的教学,既有助于加强对过去已学生物学知识的运用,促进学生对已学知识的升华,     

利用"比较不同蔬菜或水果中维生素C的含量"探究实验进行实验考试的尝试

1实验考试背景 1）本实验考试内容选自人教版义务教育课程标准实验教科书《生物学》7年级下册第2章“人体的营养”第1节“食物中的营养物质”内容中“进一步探究”栏目。     

对“生物组织中脂肪的检测”实验的改进

“检测生物组织中的糖类、脂肪和蛋白质”实验是人教版普通高中生物学新教材必修1第2章第1节“细胞中的元素和化合物”中的内容。该实验的目的是要在学生掌握构成细胞的主要有机物的基础上,让学生尝试用化学试剂检测生物组织中的还原糖、脂肪和蛋白质。笔者在这几年的教学实践中,发现了实验操作过程中的一些问题。下面以“脂肪的检测”一个教学环节为例,谈谈对教材的改进建议。     

Global monthly water scarcity: blue water footprints versus blue water availability

Freshwater scarcity is a growing concern, placing considerable importance on the accuracy of indicators used to characterize and map water scarcity worldwide. We improve upon past efforts by using estimates of blue water footprints (consumptive use of ground- and surface water flows) rather than water withdrawals, accounting for the flows needed to sustain critical ecological functions and by considering monthly rather than annual values. We analyzed 405 river basins for the period 1996-2005. In 201 basins with 2.67 billion inhabitants there was severe water scarcity during at least one month of the year. The ecological and economic consequences of increasing degrees of water scarcity--as evidenced by the Rio Grande (Rio Bravo), Indus, and Murray-Darling River Basins--can include complete desiccation during dry seasons, decimation of aquatic biodiversity, and substantial economic disruption.     

Soil water availability for plants as quantified by conventional available water, least limiting water range and integral water capacity

There are different approaches to define the soil available water (SAW) for plants. The objectives of this study are to evaluate the SAW values of 12 arable soils from Hamadan province (western Iran) calculated by plant available water (PAW), least limiting water range (LLWR) and integral water capacity (IWC) approaches and to explore their relations with Dexter’s index of soil physical quality (i.e., S-value). Soil water retention and mechanical resistance were determined on the intact samples which were taken from the 5–10 cm layer. For calculation of LLWR and IWC, the van Genuchten-Mualem model was fitted to the observed soil water retention data. Two matric suctions (h) of 100 and 330 cm were used for the field capacity (FC). There were significant differences (P?<?0.01) between the SAW values calculated by PAW₁₀₀, PAW₃₃₀, LLWR₁₀₀, LLWR₃₃₀ and IWC. The highest (i.e., 0.210 cm³ cm^?3) and the lowest (i.e., 0.129 cm³ cm^?3) means of SAW were calculated for the IWC and LLWR₃₃₀, respectively. The upper limit of LLWR₃₃₀ for all of the soils was h of 330 cm, and that of LLWR₁₀₀ (except for one soil that was air-filled porosity of 0.1 cm³ cm^?3) was h of 100 cm. The lower limit of LLWR₃₃₀ and LLWR₁₀₀ for five soils was h of 15,000 cm and for seven soils was mechanical resistance of 2 MPa. The IWC values were smaller than those of LLWR₁₀₀ for two soils, equal to those of LLWR₁₀₀ for three soils and greater than those of LLWR₁₀₀ for the rest. There is, therefore, a tendency to predict more SAW using the IWC approach than with the LLWR approach. This is due to the chosen critical soil limits and gradual changes of soil limitations vs. water content in the IWC calculation procedure. Significant relationships of SAW with bulk density or relative bulk density were found but not with the clay and organic matter contents. Linear relations between IWC and LLWR₁₀₀ or LLWR₃₃₀ were found as: IWC?=??0.0514 + 1.4438LLWR₁₀₀, R ²?=?0.83; and IWC?=??0.0405 + 2.0465LLWR₃₃₀, R ²?=?0.84, respectively (both significant at P?<?0.01). Significant relationships were obtained between the SAW values and S indicating the suitability of the index S to explain the availability of soil water for plants even when complicated approaches like IWC are considered. Overall, the results demonstrate the importance of the choice of the approach to be used and its critical limits in the estimation of the soil available water to plants.     

Role of water transport in origin of water stress

Intensity of transpiration, intensity of water absorption, water saturation deficit (w.s.d.) in different parts of samples and rate of water transport was investigated in samples from leaf tissue of fodder cabbage and banana-tree. In all experiments (at initial w.s.d. 0% and 20%, in samples from upper, middle and lower leaves of fodder cabbage and from leaves of banana-tree) a distinct gradient of w.s.d. in the direction of transport of water was determined, therefore the limiting factor in the water balance was rate of water transport and not rate of water absorption. The lowest amount of water was always transported within transpiring part of sample. When the initial w.s.d. was 0% not only the water transported by tissue from the environment, but also the water of the leaf tissue itself took part in water lost by transpiration and therefore water stress originated in the whole sample. At an initial w.s.d. of 20%, the rate of water absorption was higher than the rate of water transport and therefore the increase of w.s.d. in the transpiring part of the sample was accompanied by a simultaneous decrease of w.s.d. in the transporting part. An increase in the value of w.s.d. in leaf tissue proportionally increased the resistance of water transport in the liquid phase (on the average from 1·7 . 10³ to 6·7 . 10³ atm min cm² g^?1) and also in the gaseous phase (on the average from 2·7 . 10^?2 to 14·0 . 10^?2 min cm^?1). It was proved that insufficient rate of water transport can be responsible for the origin of water stress. At the same time the rate of water transport was influenced by the value of the w.s.d. since every change of w.s.d. in leaf tissue not only the gradient of water potential changed but also the resistance to water transport.     

The turbulent boundary between water science and water management

SUMMARY. 1. It is common to observe friction between limnologists and the managers of water resources. This is often a result of misunderstandings about the cultures within which each works.
2. There are a number of ways that science can contribute to effective management of water resources, but limnologists must appreciate that there are value questions which are not the sole prerogative of science to answer.
3. Managers often misunderstand science and expect it to deliver a truth that is non-arguable. They fail to understand the very process of science demands no such truths, so that assumptions, methods and conclusions can always be challenged.
4. One way to bridge this boundary is to develop the scientific broking role. Another is to do better and more relevant science. Ways of doing both are discussed.     

Relative water content and water potential of tissue 1

Relative water content (RWC) and water potential as measuredwith the pressure chamber were evaluated as indicators of waterstatus of tissue-cultured apple shoots and plantlets (shootswith roots). During the hydration required for RWC measurement,both water content and water potential exhibited the same hydrationkinetics, indicating that 10 h were required for full hydration.Once full hydration was reached, shoot mass remained relativelyconstant. Moisture release characteristics were also constructedand the associated shoot and plantlet water relations parameterswere estimated. Underin vitroconditions, both shoot and plantletwater potential were similar to the water potential of the culturemedium in which they were grown. The moisture release characteristicof shoots and plantlets was consistent with that expected fortypical plant tissues, and gave estimates of maximum modulusof elasticity (6.201.14 MPa), osmotic potential at saturation(–0.85 0.10 MPa), osmotic potential at zero turgor (–1.16 0.14 MPa) and RWC at zero turgor (78 2%) which were similarto values in the literature. Higher values of leaf conductanceand RWC were found in shoots and plantlets placed at 95% RH(21 C) compared to those at 90% RH. Plantlets had higher valuesof both conductance and RWC compared to shoots, suggesting thatinvitroroots are functional in water uptake. Relative water contentwas related to measures of physiological activity such as leafconductance, and it was also easier to measure than water potential.Relative water content is suggested as a sound index of waterstatus in tissue culture plants. Key words: Conductance, microculture, water status, water stress.     

Growth-induced water potentials may mobilize internal water for growth

Abstract. Wphen there is no external source of water, plants can grow by mobilizing internal water from nongrowing tissues. We investigated how this internal water moves by measuring continuously and simultaneously the water potential (ψ_w) of soybean ( Glycine max L. Merr.) seedlings in the upper, growing stem tissues and the lower, non-growing stem tissues. When external water was available to the roots, the stems grew rapidly and the ψ_w of the growing tissue was continually below that of the nongrowing tissue and the medium around the roots. This indicated that a growth-induced gradient in ψ_w favoured water movement from the external source to the growing cells. When the external source was removed, the ψ_w of the growing tissue remained constant for a time and the ψ_w of the nongrowing tissue decreased somewhat. Growth took place slowly as water was withdrawn from the nongrowing tissue but ψ_w gradients continued to favour water transport to the growing cells. On the other hand, if this internal source was removed by excision, growth ceased abruptly. In this case, the cell walls relaxed and the ψ_w of the growing tissue decreased by about 0.1 MPa instead of remaining constant. The ψ_w of the detached nongrowing tissues remained constant instead of decreasing. This indicates not only that water mobilization required attached nongrowing or slowly growing tissues but also that mobilization affected wall relaxation. Thus, ψ_w differences may mobilize internal water, may explain the continued growth of plants and plant parts removed from external sources of water, and may account for discrepancies in measurements of cell wall properties in growing tissues.     

An ambient water loop system for USP purified water

An ambient loop USP purified water system has been designed and implemented using carbon and ion exchange resin beds, ultraviolet light systems and polishing filters to produce water consistently meeting or exceeding all USP XXIII quality specifications for purified water. The circulation system is constructed of PVDF plastic piping material installed in a continuous fully-drainable loop. The system was sized for a pilot scale fermentation/harvest process at the 1000?l cultivation scale. This system passed all installation and operational qualification testing as well as sixty days of continuous performance qualification testing before entering into an ongoing monitoring regimen. Excursions outside acceptable water quality parameters during this extensive monitoring regimen were minimal. Sanitization of the system, along with bed and filter changes at the time of sanitization, was conducted every 3 to 6 months to insure consistent water quality.