DISCUSSION. The Discussion section is an opportunity for you to show that you understand the background principles to the techniques you learned in the exercises, and did not blindly follow the protocols outlined in the manual. The discussion presents an analysis of your results and the significance of your findings. Each item you discuss must be clearly supported by the results (refer to figures or quote values in tables, etc. ) if your experiments did not work, include some possibilities as to why(e.g, technique used or inaccuracy in methodology ) The discussion should end with a short concluding sentence summarizing the entire report with final results and major conclusions GRAPHS AND DIAGRAMS 1. A proper title is extremely important 3. The figure must be referred to within the text prior to its presentation 2. The title must be self-explanatory so that the figure may stand on its ov 4. Plot the known quantity being systematically changed (independent variable), such as time, substrate concentration, temperature etc, on the horizontal x-axis or abscissa The unknown or measured quantity (dependent variable), such as absorbance, enzyme activity etc, is plotted on the vertical y-axis or ordinate 5. Use clearly defined symbols(⊕,◇,◆,口o…etc) Dand not x,+, or a small point‘’,fi each set of data Time(minutes)
DISCUSSION. The Discussion section is an opportunity for you to show that you understand the background principles to the techniques you learned in the exercises, and did not blindly follow the protocols outlined in the manual. The discussion presents an analysis of your results and the significance of your findings. Each item you discuss must be clearly supported by the results (refer to figures or quote values in tables, etc.). if your experiments did not work, include some possibilities as to why (e.g., technique used or inaccuracy in methodology). The discussion should end with a short concluding sentence summarizing the entire report with final results and major conclusions. GRAPHS AND DIAGRAMS 1. A proper title is extremely important. 2. The title must be self-explanatory so that the figure may stand on its own. 3. The figure must be referred to within the text prior to its presentation. 4. Plot the known quantity being systematically changed (independent variable), such as time, substrate concentration, temperature etc., on the horizontal x-axis or abscissa. The unknown or measured quantity (dependent variable), such as absorbance, enzyme activity etc., is plotted on the vertical y-axis or ordinate. 5. Use clearly defined symbols (⊕,◇,◆,□,o,…etc.)and not x, +, or a small point‘.’,for each set of data. 11
实验1质壁分离法测定植物组织渗透势 【实验目的】 了解植物体內不同组织和细胞之间丶植物与环境之间水分的转移与植物组织渗 透势的矢系·学习测定植物组织渗透势的基本方法 【实验原理】 植物细胞的渗透势主要取决于液泡的溶质浓度·因此又称溶质势。植物细胞的 渗透势是反映植物水分代谢丶生长发育及抗逆性的重要指标。在干旱丶盐渍等许多 逆境条件下·一些植物常表现为细胞內主动积累溶质·以降低其渗透势·增加吸水 能力·在一定程度上维持膨压·保障细胞的生长和气孔的开放·这种现象叫做渗透 调节作用。渗透调节能力的大小可以用逆境条件下细胞渗透势的降低值来表示·因 此·在水分生理与抗逆性生理研究中渗透势是必不可少的测定指标。渗透势的测定 方法可分为二类:一类是液相平衡法(质壁分离法)·另一类是气相平衡法(热电 偶湿度计法丶露点法丶压力室法等)。质壁分离法是目前测定植物组织渗透势常用 的方法·其主要原理是:捋植物组织放入一糸列不同浓度的蔗糖溶液中·经过一段 时间·植物细胞与蔗糖溶液间将达到渗透平衡状态。如果在某一溶液中细胞脱水达 到平衡时刚好处于初始质壁分离状态·则细胞的压力势(甲p)将下降为零。此时 细胞液的渗透势(甲s)等于外液的渗透势(s0)。此溶液称为该组织的等渗溶液 其浓度称为该组织的等渗浓度。 根据下述公式即可计算出细胞液的渗透势(s) /CRT 式中:s0——供试溶液的渗透势·MPa; i:溶质的解离系数(蔗糖为1); c:供试溶液的质量摩尔浓度(mol·Kg-1,以水作溶剂); R:气体常数,000831Kg·MPa·mol-·K-1或00031Kg·KJ·mol-1·K-1; T一一热力学温度,K。 实际测定时·初始质壁分离状态难以在显微镜下直接观察到·所以一般均以质 壁分高的最低浓度与不发生质壁分离的最高浓度的平均值作为判断等渗浓度标准
实验1 质壁分离法测定植物组织渗透势 【实验目的】 了解植物体内不同组织和细胞之间、植物与环境之间水分的转移与植物组织渗 透势的关系，学习测定植物组织渗透势的基本方法。 【实验原理】 植物细胞的渗透势主要取决于液泡的溶质浓度，因此又称溶质势。植物细胞的 渗透势是反映植物水分代谢、生长发育及抗逆性的重要指标。在干旱、盐渍等许多 逆境条件下，一些植物常表现为细胞内主动积累溶质，以降低其渗透势，增加吸水 能力，在一定程度上维持膨压，保障细胞的生长和气孔的开放，这种现象叫做渗透 调节作用。渗透调节能力的大小可以用逆境条件下细胞渗透势的降低值来表示，因 此，在水分生理与抗逆性生理研究中渗透势是必不可少的测定指标。渗透势的测定 方法可分为二类：一类是液相平衡法（质壁分离法），另一类是气相平衡法（热电 偶湿度计法、露点法、压力室法等）。质壁分离法是目前测定植物组织渗透势常用 的方法，其主要原理是：将植物组织放入一系列不同浓度的蔗糖溶液中，经过一段 时间，植物细胞与蔗糖溶液间将达到渗透平衡状态。如果在某一溶液中细胞脱水达 到平衡时刚好处于初始质壁分离状态，则细胞的压力势（Ψp）将下降为零。此时 细胞液的渗透势（Ψs）等于外液的渗透势（Ψs0）。此溶液称为该组织的等渗溶液， 其浓度称为该组织的等渗浓度。 根据下述公式即可计算出细胞液的渗透势（Ψs）： ΨsΨ s0 icRT 式中：Ψs0——供试溶液的渗透势，MPa； i：溶质的解离系数（蔗糖为1）； c：供试溶液的质量摩尔浓度（mol·Kg-1，以水作溶剂）； R：气体常数，0.00831 Kg·MPa·mol-1·K-1或0.00831 Kg·KJ·mol-1·K-1； T ——热力学温度，K。 实际测定时，初始质壁分离状态难以在显微镜下直接观察到，所以一般均以质 壁分离的最低浓度与不发生质壁分离的最高浓度的平均值作为判断等渗浓度标准
【实验材料】 洋葱鳞茎或鸭跖草。 【设备与试剂 显微镜·载玻片·盖玻片·温度计·尖头镊子·刀片·小培养皿(直徑为6cm) 试剂瓶·烧杯·容量瓶·量筒·吸管·吸水纸等 0.03%中性红溶液。 蔗糖系列标准溶液的配制∵蔗糖预先在60~80℃下烘干。配制0.30、0.35 0.40、0.45、0.50、0.55、0.60、065、0.70mo·L-1等一系列不同浓度的蔗糖溶 液·具体范围可根据材料不同而加以调整·配好后贮于试剂瓶中·瓶口加塞以防蒸 发 【实验步骤】 1配制溶液 取干燥丶洁净的培养皿9套编号·捋配制好的不同浓庋的蔗糖溶液按顺序加入 各培养皿成一薄层·备用 (二)取材染色 用镊子撕取(或用刀片刮取)供试材料的表皮·大小以0.5cm2左右为宜,迅 速投入各种浓度的蔗糖溶液中·使其完全浸入·每一浓度放4~5片·同时记录室 温·为了便于观察·先捋表皮置于0.03%中性红內染色5min左右后·吸去水分 再浸入蔗糖溶液中。如果不染色即能区別质壁分离·可以不经染色直接镜检观察 (三)徒手制片 5~10min后,取出表皮薄片放在滴有同样蔗糖浓度溶液的载玻片上,盖上盖 (四)显微观察 在低倍显微镜下观察·如果所有细胞都产生质壁分离现象·则取低浓度溶液中 的制片作同样观察·并记录质壁分离的相对程度。如果在两个相邻浓度的切片中 个切片没有发生质壁分离·另一个切片发生质壁分离的细胞数超过50%·则这两 个浓度的平均值为其等渗浓度。每一制片观聚的细胞不应少于100个。检查时可先 从高浓度开始。在找到上述浓度极限时·用新的溶液和新鲜的叶片重复进行几次
【实验材料】 洋葱鳞茎或鸭跖草。 【设备与试剂】 显微镜，载玻片，盖玻片，温度计，尖头镊子，刀片，小培养皿（直径为6 cm）， 试剂瓶，烧杯，容量瓶，量筒，吸管，吸水纸等。 0.03％中性红溶液。 蔗糖系列标准溶液的配制：蔗糖预先在60～80℃下烘干。配制0.30 、0.35、 0.40、0.45、0.50、0.55、0.60、0.65、0.70 mol·L-1等一系列不同浓度的蔗糖溶 液，具体范围可根据材料不同而加以调整，配好后贮于试剂瓶中，瓶口加塞以防蒸 发。 【实验步骤】 1.配制溶液 取干燥、洁净的培养皿9 套编号，将配制好的不同浓度的蔗糖溶液按顺序加入 各培养皿成一薄层，备用。 （二）取材染色 用镊子撕取（或用刀片刮取）供试材料的表皮，大小以0.5 cm2左右为宜，迅 速投入各种浓度的蔗糖溶液中，使其完全浸入，每一浓度放4～5 片，同时记录室 温。为了便于观察，先将表皮置于0.03％中性红内染色5 min 左右后，吸去水分， 再浸入蔗糖溶液中。如果不染色即能区别质壁分离，可以不经染色直接镜检观察。 （三）徒手制片 5～10 min 后，取出表皮薄片放在滴有同样蔗糖浓度溶液的载玻片上，盖上盖 玻片。 （四）显微观察 在低倍显微镜下观察，如果所有细胞都产生质壁分离现象，则取低浓度溶液中 的制片作同样观察，并记录质壁分离的相对程度。如果在两个相邻浓度的切片中， 一个切片没有发生质壁分离，另一个切片发生质壁分离的细胞数超过50％，则这两 个浓度的平均值为其等渗浓度。每一制片观察的细胞不应少于100 个。检查时可先 从高浓度开始。在找到上述浓度极限时，用新的溶液和新鲜的叶片重复进行几次， 13
直至有把握为止·在此条件下·细胞的渗透势与两个极限溶液浓度之平均值的渗透 势相等。 (五)记录结果 将实验结果记录于表1中。 表1-1植物细胞渗透势测定记录表 实验人 日期 材料名称 实验室温度 蔗糖浓度(mol·L-)质壁分离的相对视野中发生质壁分离的百分率 程度(作图表示) 0.30 0.35 0.45 0.55 0.65 0.70 视野中发生质壁分离的百分率以大于50%或小于50%表示。 由所得到的等渗浓度和测定的室温·用屮ss0 iCRT计算供试溶液的渗 透势(甲s)·即为细胞的渗透势 (六)注意事项 撕下的表皮组织必须完全浸没于蔗糖溶液中·浸没时间不能过短·否则会影响 实验结果 六、讨论 1.发生细胞质壁分离时·植物细胞的水势由什么组成? 2.哪些情况下可能发生细胞质壁分高?采用什么措施才能使发生质壁分离的 细胞复原?
直至有把握为止。在此条件下，细胞的渗透势与两个极限溶液浓度之平均值的渗透 势相等。 （五）记录结果 将实验结果记录于表1中。 表1-1 植物细胞渗透势测定记录表 由所得到的等渗浓度和测定的室温，用ΨsΨ s0 icRT 计算供试溶液的渗 透势（Ψs），即为细胞的渗透势。 （六）注意事项 撕下的表皮组织必须完全浸没于蔗糖溶液中，浸没时间不能过短，否则会影响 实验结果。 六、讨论 1. 发生细胞质壁分离时，植物细胞的水势由什么组成？ 2. 哪些情况下可能发生细胞质壁分离？采用什么措施才能使发生质壁分离的 细胞复原？ 14
Experiment 1 Measuring Osmetic Potential of Plant Tissues by Plasmolysis Approaches Goals To understand the relation of water movement. including the movement between different tissues or cells, and between plant and environment, with the water potential of plant tissue To learn the general methods of measuring osmetic potential of plant tissues Introduction Water potential() defines the energy content of the water in the cell or plant and provides a convenient summation of all factors influencing the water status of that tissue It is expressed in terms of pressure(bars or, more correctly, MPa, 1 MPa=10 bars). The ater potential of pure water is zero bars. The addition of salts, as in plant cells, lowers the energy content of the water(it can do less work), i.e., it lowers the This effect represents one component of the osmotic potential (4 I ) With no external pressure or suction on the water, =4 I. Adding pressure greater than atmospheric, as in the case of turgor in most plant cells, will increase the energy content of the water(it can do more work), i.e., it raises the 4. Likewise, adding suction or tension on the water lowers the p This represents another component of the total the pressure potential( p). Other factors also influence the energy content ( )of the water in the cell, but these two are the main ones. It is important to realize that these are only components of the total water potential, and it is the total which determines the water status of the tissue and, hence, the directionality of water movement(always high to low energy; high to low ) In summary, the water potential of a cell or tissue can be expressed as such 屮=甲丌+甲 In the experiments described below, the principle of water movement until equilibration of 4 will be employed as indicators of t and 4 J tissues at unknown will be placed in sugar solutions of known and varying Since water always moves from high to low t (energetically downhill), the plant tissue will lose water to a solution
Experiment 1 Measuring Osmetic Potential of Plant Tissues by Plasmolysis Approaches Goals To understand the relation of water movement, including the movement between different tissues or cells, and between plant and environment, with the water potential of plant tissue. To learn the general methods of measuring osmetic potential of plant tissues. Introduction Water potential (Ψ) defines the energy content of the water in the cell or plant and provides a convenientsummation of all factors influencing the water status of that tissue. It is expressed in terms of pressure (bars or, more correctly, MPa, 1 MPa = 10 bars). The water potential of pure water is zero bars. The addition of salts, as in plant cells, lowers the energy content of the water (it can do less work), i.e., it lowers the Ψ. This effect represents one component of Ψ, the osmotic potential (Ψπ). With no external pressure or suction on the water, Ψ = Ψπ. Adding pressure greater than atmospheric, as in the case of turgor in most plant cells, will increase the energy content of the water (it can do more work), i.e., it raises the Ψ. Likewise, adding suction or tension on the water lowers the Ψ. This represents another component of the total Ψ, the pressure potential(Ψp). Other factors also influence the energy content (Ψ) of the water in the cell, but these two are the main ones. It is important to realize that these are only components of the total water potential, and it is the total Ψ which determines thewater status of the tissue and, hence, the directionality of water movement (always high to low energy; high to low Ψ). In summary, the water potential of a cell or tissue can be expressed as such: Ψ = Ψπ + Ψp In the experiments described below, the principle of water movement until equilibration of Ψ will be employed as indicators of Ψ and Ψπ. tissues at unknown Ψ will be placed in sugar solutions of known and varying Ψ. Since water always moves from high to low Ψ (energetically downhill), the plant tissue will lose water to a solution of 15