📚 Edexcel Combined Science 097: Core Practical Skills and Key Concepts | 爱德思综合科学097：核心实验技能与关键概念
This revision guide covers the essential knowledge and practical skills for the Edexcel International GCSE Combined Science (097) qualification. It focuses on the cross-topic skills examined across Biology, Chemistry and Physics papers, including planning investigations, handling data, using equations and evaluating methods.
本复习指南涵盖爱德思国际GCSE综合科学（097）资格的核心知识与实验技能，重点关注生物、化学和物理试卷中都会考查的跨主题实验与数据处理能力，包括实验设计、数据处理、公式运用和方法评价。
1. Understanding the 097 Specification and Assessment Structure | 了解097大纲与考试结构
The Edexcel International GCSE Combined Science (097) specification is divided into three science disciplines: Biology, Chemistry and Physics. Each discipline contributes one third of the final grade, and all papers include both theory questions and practical-based questions.
爱德思国际GCSE综合科学（097）大纲分为生物、化学和物理三个学科，每个学科占最终成绩的三分之一。所有试卷都包含理论题和基于实验的题目。
You must be familiar with the core practicals listed in the specification, because exam questions often ask you to describe the method, identify variables, explain results or suggest improvements. Revising the purpose and limitations of each core practical is just as important as learning the theory.
你必须熟悉大纲列出的核心实验，因为考试题目经常要求描述方法、识别变量、解释结果或提出改进建议。复习每个核心实验的目的和局限性与学习理论知识同样重要。
Combined Science 097 also rewards accurate use of scientific vocabulary, correct units and the ability to convert between units. Keep a unit checklist in your notes and practise using standard form and significant figures.
综合科学097还考查科学术语的准确使用、单位书写以及单位换算能力。在笔记中准备一份单位清单，并练习使用标准形式和有效数字。
2. Planning Investigations: Variables, Hypotheses and Risk Assessments | 实验设计：变量、假设与风险评估
Before carrying out any experiment, you must be able to identify the independent variable, the dependent variable and the control variables. The independent variable is the one you change, the dependent variable is the one you measure, and control variables are kept constant to make the test fair.
在进行任何实验之前，你必须能够识别自变量、因变量和控制变量。自变量是你改变的变量，因变量是你测量的变量，控制变量则保持不变以确保实验公平。
- Independent variable: the factor you deliberately change.
自变量：你故意改变的因素。 - Dependent variable: the factor you observe or measure.
因变量：你观察或测量的因素。 - Control variables: factors kept the same to prevent them affecting results.
控制变量：保持不变以防止影响结果的因素。
A good hypothesis links the independent and dependent variables and gives a scientific reason. For example: ‘If the concentration of glucose solution increases, then the rate of carbon dioxide production by yeast increases because more substrate molecules are available for respiration.’
一个好的假设将自变量和因变量联系起来，并给出科学原因。例如：“如果葡萄糖溶液浓度增加，那么酵母产生二氧化碳的速率会增加，因为有更多底物分子可用于呼吸作用。”
Risk assessments must identify hazards, the associated risks and the precautions you will take. Common hazards in Combined Science practicals include hot liquids, corrosive acids, electrical equipment and sharp tools.
风险评估必须识别危险源、相关风险以及你将采取的预防措施。综合科学实验中的常见危险包括热液体、腐蚀性酸、电气设备和锋利工具。
For instance, when using a water bath at 60 °C, the hazard is hot water causing burns; the risk is skin contact; the precaution is to use tongs and keep the water bath in a stable position.
例如，使用60 °C水浴时，危险源是热水导致烫伤；风险是皮肤接触热水；预防措施是使用夹子并保持水浴稳定。
3. Measuring and Recording Data Accurately | 准确测量与记录数据
Accuracy means how close a measurement is to the true value, while precision means how close repeated measurements are to each other. A sensible experiment should aim for both, but you must also understand that no measuring instrument is perfect.
准确度是指测量值接近真实值的程度，精确度是指重复测量值彼此接近的程度。一个合理的实验应该同时追求两者，但你也必须明白没有任何测量仪器是完美的。
Always choose the most appropriate instrument for the quantity you are measuring. For example, use a measuring cylinder for approximate volumes, a burette for accurate titration volumes, and a digital balance for mass to 0.01 g.
始终为你测量的量选择最合适的仪器。例如，使用量筒粗略测量体积，使用滴定管精确测量滴定体积，使用精度为0.01 g的电子天平测量质量。
Read the meniscus at eye level for liquids, and record readings to the resolution of the instrument. For an analogue thermometer with 1 °C divisions, the resolution is 0.5 °C, but many schools use digital thermometers with 0.1 °C resolution.
液体读数时在眼睛水平位置读取弯月面，并按仪器分辨率记录读数。对于分度值为1 °C的模拟温度计，分辨率为0.5 °C，但许多学校使用分辨率为0.1 °C的数字温度计。
Record data in a table with the independent variable in the first column and the dependent variable in the second. Always include units in the header, for example ‘Time / s’ or ‘Volume of gas / cm³’.
将数据记录在表格中，第一列为自变量，第二列为因变量。表头中始终写明单位，例如“时间 / s”或“气体体积 / cm³”。
Repeat each measurement at least three times and calculate a mean. Exclude any anomalous values from the mean, and explain in your write-up why a value was excluded.
每个测量至少重复三次并计算平均值。在计算平均值时排除任何异常值，并在实验报告中解释排除该值的原因。
4. Using Tables and Graphs to Present Data | 使用表格与图表展示数据
Tables should have clear headings with units, and the independent variable should be placed in the first column. The dependent variable is then placed in later columns, especially if there are repeated readings and a mean column.
表格应有清晰的标题和单位，自变量应放在第一列。因变量放在后面的列中，如果有重复读数和平均值列，也应如此安排。
Choose a line graph when both variables are continuous, such as temperature against time. Use a bar chart when the independent variable is categorical, such as different metals or different types of surface.
当两个变量都是连续变量时，例如温度随时间变化，选择折线图。当自变量是类别变量时，例如不同金属或不同表面类型，使用条形图。
Plot points with a small cross (×) and draw a best-fit line or smooth curve. Do not join the points dot-to-dot unless the question specifically asks you to. Label both axes with the quantity and unit, for example ‘Temperature / °C’.
用小叉号（×）描点，并画出最佳拟合线或平滑曲线。除非题目特别要求，不要逐点连线。两个坐标轴都标注量和单位，例如“温度 / °C”。
If the relationship is proportional, the graph should show a straight line passing through the origin. If the line does not pass through the origin, say there is a linear relationship but not a direct proportion.
如果关系成正比，图像应显示一条过原点的直线。如果直线不过原点，则说明存在线性关系，但不是正比关系。
Use a ruler for straight lines and extend the line beyond the data range if you need to estimate a value. For curved graphs, draw a smooth curve that best fits the general trend.
对于直线图，使用直尺画线；如果需要估算数值，可以将直线延伸到数据范围之外。对于曲线图，画出最符合总体趋势的平滑曲线。
5. Analyzing Results: Patterns, Anomalies and Conclusions | 分析结果：规律、异常值与结论
When describing a graph, state the general trend first. Use phrases like ‘as the independent variable increases, the dependent variable increases’ or ‘decreases at a decreasing rate’ to describe the shape accurately.
描述图像时，首先陈述总体趋势。使用“随着自变量增加，因变量增加”或“以递减速率下降”等短语来准确描述形状。
An anomaly is a data point that does not fit the general pattern. It may be caused by a random error such as misreading a thermometer, losing some solution, or changing an uncontrolled variable during the experiment.
异常值是不符合总体规律的数据点。它可能由随机误差引起，例如读错温度计、损失部分溶液，或在实验过程中某个未控制的变量发生变化。
Always calculate the mean of the remaining values after removing anomalies. In your conclusion, quote specific data to support the trend, for example: ‘At 20 °C the volume of oxygen was 5.0 cm³, but at 40 °C it was 9.5 cm³, showing that increasing temperature increased the rate of reaction.’
移除异常值后，始终计算剩余值的平均值。在结论中引用具体数据来支持趋势，例如：“在20 °C时氧气体积为5.0 cm³，在40 °C时为9.5 cm³，说明升高温度提高了反应速率。”
If the data do not support the original hypothesis, you must say so and suggest why. A conclusion should explain the outcome using scientific principles, not just restate the numbers.
如果数据不支持原假设，你必须说明，并解释原因。结论应使用科学原理解释结果，而不仅仅是复述数字。
You may be asked to compare repeatability and reproducibility. Repeatability is how similar repeated results are when the same person repeats the experiment using the same equipment; reproducibility is how similar results are when a different person uses different equipment.
你可能会被要求比较重复性和再现性。重复性指同一人使用相同设备重复实验时结果的相似程度；再现性指不同人使用不同设备得到结果的相似程度。
6. Evaluating Methods and Suggesting Improvements | 评价方法并提出改进建议
Evaluation questions ask you to assess the strengths and limitations of a method. Start by identifying sources of error, then suggest how the method could be improved to produce more valid and reliable data.
评价题要求你评估实验方法的优缺点。首先找出误差来源，然后建议如何改进方法以获得更有效、更可靠的数据。
Random errors affect precision and can be reduced by taking more repeats and calculating a mean. Examples include small variations in reaction time when starting a stopwatch or fluctuations in temperature.
随机误差影响精密度，可以通过增加重复次数并计算平均值来减小。例如，启动秒表时反应时间的微小差异或温度波动都属于随机误差。
Systematic errors affect accuracy and cannot be reduced by repeating. Examples include a balance that reads 0.5 g too high, a ruler with worn ends, or a thermometer calibrated incorrectly.
系统误差影响准确度，且不能通过重复实验来减小。例如，天平读数比真实值高0.5 g、尺子端部磨损或温度计校准不准都属于系统误差。
Suggest improvements that are specific and realistic. For example, in a rate of reaction experiment, use a gas syringe instead of an inverted measuring cylinder to reduce gas loss, or use a water bath to control temperature more precisely.
提出的改进建议应具体且切实可行。例如，在反应速率实验中，使用气体注射器代替倒置量筒以减少气体损失，或使用水浴更精确地控制温度。
Other common improvements include using a digital instrument with higher resolution, adding a control group, checking for zero errors before measuring, and controlling more variables such as room temperature and light intensity.
其他常见改进包括使用分辨率更高的数字仪器、增设对照组、测量前检查零点误差，以及控制更多变量，如室温和光照强度。
When evaluating, always comment on validity and reliability. A valid experiment measures what it is supposed to measure, with all key control variables held constant. A reliable experiment has repeatable results from several trials.
评价时，始终评论效度和信度。有效实验测量的是它应该测量的量，所有关键控制变量保持不变。可靠实验由多个试验得出可重复的结果。
7. Core Practical: Investigating Enzyme Activity (Biology) | 核心实验：研究酶活性（生物）
One common Biology core practical investigates the effect of pH on the activity of amylase, an enzyme that breaks down starch into maltose. Iodine solution is used to test for the presence of starch.
一个常见的生物核心实验研究pH对淀粉酶活性的影响。淀粉酶将淀粉分解为麦芽糖，碘液用于检测淀粉是否存在。
Method: place a fixed volume of starch solution and a buffer solution at the chosen pH into a test tube in a water bath at 30 °C. Add amylase solution and start timing. Every 30 seconds, transfer one drop of the mixture to a spotting tile containing iodine solution.
方法：将固定体积的淀粉溶液和所选pH的缓冲溶液放入30 °C水浴中的试管内。加入淀粉酶溶液并开始计时。每30秒取一滴混合液滴到含碘液的点滴板上。
Record the time taken for iodine to remain orange-brown, indicating that all starch has been digested. Repeat for a range of pH values, for example pH 4, 5, 6, 7, 8 and 9.
记录碘液保持橙棕色的时间，这表明所有淀粉已被消化。对一系列pH值重复实验，例如pH 4、5、6、7、8和9。
The independent variable is pH, the dependent variable is time taken for starch to disappear, and controlled variables include temperature, enzyme concentration, starch concentration and volume of solutions.
自变量是pH，因变量是淀粉消失所需时间，控制变量包括温度、酶浓度、淀粉浓度和溶液体积。
Calculate the rate of enzyme activity using the formula:
rate = 1 ÷ time
计算酶活性速率的公式为：
速率 = 1 ÷ 时间
Plot rate against pH. The graph should show an optimum pH around 7 for amylase from human saliva, with the rate falling sharply above and below this value.
绘制速率随pH变化的图像。来自人类唾液的淀粉酶最适pH约为7，图像应在该值两侧速率急剧下降。
If the iodine turns blue-black immediately at pH 3, it suggests the enzyme has been denatured by the acidic conditions and can no longer break down starch.
如果在pH 3时碘液立即变为蓝黑色，说明酶在酸性条件下已经变性，无法再分解淀粉。
8. Core Practical: Carrying Out an Acid–Base Titration (Chemistry) | 核心实验：酸碱滴定（化学）
Titration is used to determine the concentration of an unknown acid or alkali by reacting it with a solution of known concentration. You must be able to use a pipette and burette safely and accurately.
滴定用于通过与已知浓度的溶液反应来确定未知酸或碱的浓度。你必须能够安全、准确地使用移液管和滴定管。
First, rinse the burette with the solution it will contain, then fill it and record the initial volume to the nearest 0.05 cm³. Use a pipette filler to transfer a fixed volume, usually 25.0 cm³, of the other solution to a conical flask.
首先用将要装入的溶液润洗滴定管，然后加入溶液并记录初始体积至0.05 cm³。使用移液管吸球将固定体积（通常为25.0 cm³）的另一溶液转移到锥形瓶中。
Add a few drops of a suitable indicator, such as phenolphthalein. Run the acid from the burette into the alkali while swirling the flask until the indicator changes colour at the end point.
加入几滴合适的指示剂，如酚酞。将酸从滴定管滴入碱液中，同时摇动锥形瓶，直到指示剂在终点变色。
Record the final burette reading. The titre is the volume of solution added. Repeat the titration until you obtain concordant titres that agree within 0.10 cm³.
记录滴定管最终读数。滴定体积为加入的溶液体积。重复滴定，直到得到相互一致且差值在0.10 cm³以内的滴定结果。
For a 1:1 reaction, use the equation:
c₁V₁ = c₂V₂
对于1:1反应，使用公式：
c₁V₁ = c₂V₂
Rearrange to find the unknown concentration:
c₁ = (c₂ × V₂) ÷ V₁
重新整理以求出未知浓度：
c₁ = (c₂ × V₂) ÷ V₁
For example, if 25.0 cm³ of hydrochloric acid neutralises 23.50 cm³ of 0.100 mol dm⁻³ sodium hydroxide, then the concentration of the acid is (0.100 × 23.50) ÷ 25.0 = 0.0940 mol dm⁻³.
例如，如果25.0 cm³盐酸中和23.50 cm³的0.100 mol dm⁻³氢氧化钠，则盐酸浓度为
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