📚 Case Study Practice for Year 10 Edexcel Science | Year 10 Edexcel 科学：案例分析实战演练
Case study questions are an integral part of the Edexcel Year 10 Science course. They challenge you to apply your knowledge to unfamiliar, real-world scenarios, interpret data, draw conclusions, and evaluate investigations. This article provides a structured approach to mastering case study questions, with worked examples, key skills development, and exam-style practice.
案例分析题是 Edexcel 十年级科学课程的重要组成部分。这类题目要求你将所学知识应用于不熟悉的真实情境中，解读数据、得出结论并评估研究。本文将提供一套系统方法，帮助你掌握案例分析题，并通过实例解析、关键技能训练和考试模拟练习，提升解题能力。
1. Understanding Science Case Studies | 理解科学案例研究
A science case study presents a scenario—often based on a laboratory experiment, an environmental issue, or a health investigation—and asks a series of linked questions. The aim is to assess not just recall, but how well you can think like a scientist: analysing evidence, spotting patterns, and suggesting improvements.
科学案例研究会给出一个场景——通常基于实验室实验、环境问题或健康调查——然后提出一系列相互关联的问题。其目的不仅是考查记忆，更是评估你能否像科学家一样思考：分析证据、发现规律并提出改进建议。
In Edexcel exams, case studies may appear in any of the three sciences. A typical question will provide background information, a table of results, and perhaps a graph. You then need to use this data to support or refute a hypothesis, identify variables, and discuss the reliability of the method.
在 Edexcel 考试中，案例分析可能出现在物理、化学、生物任一学科。典型题目会提供背景信息、结果表格甚至图表。你需要利用这些数据支持或反驳假设，识别变量，并讨论方法的可靠性。
2. Key Skill: Extracting Information from Text and Data | 关键技能：从文本和数据中提取信息
Start by reading the scenario carefully. Underline or highlight the independent variable, dependent variable, and any control variables mentioned. Identify what is being measured and what is being changed. This quick scan ensures you answer only what the question asks.
先仔细阅读场景描述。划出或标亮自变量、因变量以及提到的任何控制变量。确认测量对象和改变量。这种快速扫描能确保你只回答题目要求的内容。
Next, look at tables of results. Check the headings and units. If a table shows time in seconds and volume in cm3, make sure you use the correct unit in your answers. Look for trends: does the value increase, decrease, or stay constant? Use comparative words like 'faster', 'greater', 'decreased rapidly'.
接下来，查看结果表格。检查表头和单位。如果表格显示时间单位为秒、体积单位为 cm3，在你的答案中务必使用正确的单位。寻找变化趋势：数值是增加、减少还是保持不变？使用比较性词语，如“更快”、“更大”、“急剧下降”。
Often a case study will include a graph. Practise reading off values accurately and describing the relationship between variables. For a straight line through the origin, use phrases like 'directly proportional'. If a curve levels off, say 'the rate of reaction slows down and eventually stops'.
案例分析经常包含图表。练习精确读取数值并描述变量之间的关系。对于过原点的直线，使用“成正比”这样的表述。如果曲线趋于平缓，可以说“反应速率减慢并最终停止”。
3. Case Study 1: Investigating Photosynthesis | 案例一：探究光合作用
A student used pond weed to investigate the effect of light intensity on the rate of photosynthesis. The weed was placed in a beaker of water, and a lamp was set at different distances. The number of oxygen bubbles produced per minute was recorded.
一名学生利用池塘水草研究光照强度对光合作用速率的影响。水草置于装有水的烧杯中，将一盏灯放置在不同距离处，记录每分钟产生的氧气气泡数。
The data table below shows the results. Distances were: 10 cm, 20 cm, 30 cm, 40 cm, 50 cm. The corresponding bubble counts per minute were: 120, 70, 50, 35, 25. The room temperature was kept constant at 22 °C.
下面的数据表展示了结果。距离分别为：10 cm、20 cm、30 cm、40 cm、50 cm。对应的每分钟气泡数为：120、70、50、35、25。室温恒定在 22 °C。
light intensity ∝ 1 / d2
First, calculate the light intensity in arbitrary units using 1/d2. For 10 cm, 1/102 light intensity falls, the bubble count drops, showing a positive correlation. You could then plot a graph of bubble count (y-axis) against light intensity (x-axis).
首先，使用 1/d2 计算以任意单位表示的光照强度。对于 10 cm，1/102 = 0.0100；对于 20 cm，1/400 = 0.0025。随着光照强度下降，气泡数减少，呈现正相关。你可以绘制气泡数（y 轴）对光照强度（x 轴）的图表。
A typical exam question would ask: 'Explain why the number of bubbles decreases as distance increases.' The answer should link light energy to the light-dependent reactions of photosynthesis. More light means more ATP and reduced NADP is produced, leading to a faster Calvin cycle and more oxygen released.
典型的考试题目会问：“解释为何随着距离增加气泡数减少。”答案应将光能与光合作用的光反应联系起来。更多的光能意味着产生更多的 ATP 和还原型 NADP，从而加速卡尔文循环并释放更多氧气。
Also consider the limitations of the method. Bubbles are not always the same size; using a gas syringe to collect oxygen over time would give a more accurate volume measurement.
还要考虑方法的局限性。气泡并不总是大小一致；使用气体注射器收集氧气并测量累积体积，能得到更精确的体积数据。
4. Case Study 2: Reaction of Metals with Acid | 案例二：金属与酸的反应
In a rate of reaction investigation, three metals—magnesium, zinc, and iron—were reacted with excess dilute hydrochloric acid. The volume of hydrogen gas produced was recorded every 10 seconds for 1 minute. The balanced equations are:
在一个反应速率研究中，三种金属——镁、锌、铁——分别与过量稀盐酸反应。每 10 秒记录一次产生的氢气体积，持续 1 分钟。配平化学方程式为：
Mg + 2HCl → MgCl2 + H2
Zn + 2HCl → ZnCl2 + H2
Fe + 2HCl → FeCl2 + H2
The results showed that magnesium produced 60 cm3 of H2 in the first 10 s, zinc produced 8 cm3, and iron produced 2 cm3. This order (Mg > Zn > Fe) reflects the reactivity series. The steeper the initial gradient on a volume–time graph, the faster the reaction.
结果显示，镁在前 10 秒产生 60 cm3 氢气，锌产生 8 cm3，铁产生 2 cm3。这一顺序（Mg > Zn > Fe）反映了金属活动性顺序。在体积–时间图中，初始斜率越陡，反应越快。
A common case study task is to calculate the mean rate of reaction. For magnesium over the first 30 s, if total volume is 85 cm3, the mean rate = 85 cm3 / 30 s = 2.83 cm3/s. Remember to give units and round to an appropriate number of significant figures.
一个常见的案例分析任务是计算平均反应速率。对于镁，若前 30 秒总产气 85 cm3，则平均速率 = 85 cm3 / 30 s = 2.83 cm3/s。记得写明单位并修约到合适的有效数字位数。
To evaluate the experiment, consider variables that must be controlled: temperature, concentration of acid, surface area of the metal. Using a water bath maintains constant temperature; cutting metal pieces to the same dimensions controls surface area.
评估实验时，思考必须控制的变量：温度、酸的浓度、金属的表面积。使用水浴保持恒温；将金属切成相同尺寸能控制表面积。
5. Case Study 3: Air Pollution and Respiratory Health | 案例三：空气污染与呼吸系统健康
A public health study monitored the concentration of nitrogen dioxide (NO2) and particulate matter (PM2.5) in two cities, A and B, over one year. Hospital admissions for asthma attacks were recorded monthly. City A had average NO2 = 48 μg/m3 and PM2.5 = 17 μg/m3; City B had 22 μg/m3 and 9 μg/m3 respectively. Asthma admissions were 180 in City A and 95 in City B.
一项公共卫生研究监测了两个城市 A 和 B 一年内的二氧化氮 (NO2) 和细颗粒物 (PM2.5) 浓度，并记录了哮喘发作入院人数。A 市平均 NO2 = 48 μg/m3，PM2.5 = 17 μg/m3；B 市分别为 22 μg/m3 和 9 μg/m3。A 市哮喘入院 180 人，B 市 95 人。
From this data, you can see a correlation: higher pollutant levels are associated with more hospital admissions. However, correlation does not prove causation. Other factors such as smoking rates, humidity, or access to healthcare could also influence the results.
从这些数据可以看出相关性：污染物水平越高，入院人数越多。但相关性不等于因果关系。其他因素，如吸烟率、湿度或医疗可及性，也可能影响结果。
When answering a case study question, always distinguish between 'describe' and 'explain'. Describe the trend: 'As NO2 concentration rises, asthma admissions increase.' Then explain using scientific knowledge: 'NO2 irritates the lining of the airways, causing inflammation and triggering asthma.'
回答案例分析题时，务必要区分“描述”与“解释”。描述趋势：“随着 NO2 浓度升高，哮喘入院人数增加。”然后利用科学知识解释：“NO2 刺激气道内壁，引发炎症并诱发哮喘。”
This case study might also ask how data collection could be improved. Suggestions: use more sampling sites, measure pollutants continuously rather than monthly, and include a control city with similar climate but low pollution.
这个案例还可能问到如何改进数据收集。建议：使用更多采样点，连续监测污染物而非每月一次，并纳入一个气候相似但污染较低的控制城市。
6. Handling Data and Drawing Graphs | 处理数据与绘图技巧
Drawing a graph from a table of results is a core skill. Ensure you label the axes with the variable name and unit, e.g. 'Time (s)' or 'Volume of H2 (cm3)'. The independent variable goes on the x-axis, the dependent on the y-axis.
根据结果表格绘制图表是一项核心技能。务必用变量名称和单位标注坐标轴，例如“Time (s)”或“Volume of H2 (cm3)”。自变量放在 x 轴，因变量放在 y 轴。
Choose a scale that uses more than half the graph paper. Use a pencil for neat plotting, and if the points form a straight line, draw a line of best fit that passes through as many points as possible, ignoring obvious outliers.
选择合适的比例，使图形占满大半坐标纸。用铅笔整齐描点，如果各点呈直线趋势，画出最佳拟合线，使其尽可能穿过更多的点，忽略明显的异常值。
For curved graphs, draw a smooth curve. If asked to calculate a rate at a specific point, draw a tangent and find its gradient: rise / run. Use units from the axes.
对于曲线图，画出平滑曲线。如果要求计算某点的瞬时速率，画出切线并求其斜率：垂直高度 / 水平宽度。单位取自坐标轴。
Always double-check that you have plotted the correct variables. A common mistake is swapping the axes—this reverses the relationship and would lose marks, even if the description is correct.
始终反复检查是否绘入了正确的变量。常见错误是颠倒坐标轴——这会颠倒变量关系，即使描述正确也会失分。
7. Evaluating Experiments and Suggesting Improvements | 评估实验与提出改进
Evaluation questions award marks for identifying flaws and suggesting realistic modifications. If an experiment only used one trial, you can suggest repeating and calculating a mean to improve reliability.
评估题会因识别缺陷并提出合理改进而得分。如果实验仅做了一次，你可以建议重复实验并计算平均值以提高可靠性。
If the temperature was not controlled, recommend a thermostatically controlled water bath. If a measuring cylinder was used instead of a gas syringe, point out that some gas may dissolve in water, making the volume reading inaccurate.
若温度未得到控制，建议使用恒温水浴。若用量筒代替气体注射器，应指出部分气体可能溶于水，导致体积读数不准确。
Use phrases like: 'The method could be improved by...', 'This would increase accuracy because...', 'To ensure a fair test, the same concentration of acid must be used throughout.'
使用类似这样的表述：“该方法可通过……加以改进”、“这将提高准确性，因为……”、“为确保公平测试，整个过程必须使用相同浓度的酸”。
For case studies involving living organisms, ethical considerations may be relevant. For example, when investigating enzyme action, you might note that the procedure should minimise harm to the organism or that an in vitro alternative could be used.
对于涉及生物体的案例研究，伦理考量可能很重要。例如，在研究酶的作用时，你可以指出实验步骤应尽量减少对生物体的伤害，或可采用体外替代方案。
8. Applying Formulas and Calculations | 公式应用与计算
ry case, use: energy (J) = mass of water (g) × 4.2 J/g°C × temperature rise (°C). Make sure you memorise these key equations.
许多案例分析要求进行计算。对于反应速率，使用公式：速率 = 生成的产物量 / 时间。对于量热法案例中的能量转移，使用：能量 (J) = 水的质量 (g) × 4.2 J/g°C × 温度升高 (°C)。务必熟记这些关键公式。
In a case study on Hooke' ral. If given an extension-load graph, the gradient gives the spring constant k. Pay attention to unit conversions: if extension is in mm, but force in N, convert to metres before using in formulas.
在胡克定律的案例研究中，核心公式为 F = kx。若给出伸长量–载荷图，其斜率即为弹簧常数 k。注意单位换算：若伸长量单位为 mm，力为 N，代入公式前需将其转换为米。
ort conclusions. Percentage change = ((final value − initial value) / initial value) × 100%. This is useful when comparing the growth of plants under different light colours.
计算百分数和百分比变化以支撑结论。百分比变化 = ((最终值 − 初始值) / 初始值) × 100%。这在比较不同光色下植物的生长情况时非常有用。
Always show your working. Even if the final answer is wrong, you can gain marks for the correct substitution and working steps. Write down the formula before plugging in numbers.
始终展示计算步骤。即便最终答案有误，正确的代入和运算过程也能获得分数。在代入数值前，先写出公式。
9. Exam-Style Worked Example: Food Energy Content | 考试风格精讲：食物能量含量
Scenario: A student burned a piece of bread to heat 20 g of water. The initial water temperature was 22 °C, and after burning, it rose to 42 °C. The bread sample had a mass of 0.5 g.
场景：一名学生燃烧一片面包加热 20 克水。水的初始温度为 22 °C，燃烧后温度升至 42 °C。面包样品质量为 0.5 克。
the equation energy = mass × specific heat capacity × temperature change (c = 4.2 J/g°C).
问题：计算每克面包释放的能量。使用公式：能量 = 质量 × 比热容 × 温度变化 (c = 4.2 J/g°C)。
= 20 g × 4.2 J/g°C × 20 °C = 1680 J. Energy per gram of bread = 1680 J / 0.5 g = 3360 J/g.
解答：温度上升 = 42 − 22 = 20 °C。水吸收的能量 = 20 g × 4.2 J/g°C × 20 °C = 1680 J。每克面包释放的能量 = 1680 J / 0.5 g = 3360 J/g。
The follow-up question might ask: 'Why is this value lower than the one stated on the food packet?' Possible reasons: heat was lost to the surroundings, incomplete combustion occurred, and not all energy was transferred to the water. Suggest improvements: use a draught shield, stir the water, and repeat the experiment.
后续问题可能会问：“为什么这个数值低于食品包装上标注的数值？”可能原因有：热量散失到周围环境中、燃烧不充分、并非所有能量都传递给了水。提出改进建议：使用防风罩、搅拌水并重复实验。
10. Common Mistakes and How to Avoid Them | 常见错误与避免方法
Avoid vague language: instead of writing 'it went up', say 'the rate of reaction increased steadily until 40 s, then levelled off because the reaction was complete'. Precision in words reflects precision in thinking.
避免使用模糊语言：不要写“它上升了”，而应写“反应速率在 40 秒前稳步上升，随后趋于平稳，因为反应已完毕”。语言精准体现了思考的严谨。
Many students lose marks by forgetting units. If a question asks for a rate, always give the unit, such as cm3/s or g/min. In graphs, missing axis labels is a common and costly error.
许多学生因忘记写单位而失分。如果题目要求计算速率，务必给出单位，如 cm3/s 或 g/min。在图表中，遗漏坐标轴标注是常见且代价高昂的错误。
Another pitfall is confusing correlation with cause. Just because two variables change together does not prove one causes the other. Use phrases like 'there is a positive correlation, suggesting...' rather than flat-out stating causation unless evidence supports it.
另一个陷阱是将相关性与因果关系混为一谈。两个变量同步变化并不能证明一个导致另一个。应使用“存在正相关，这暗示……”这样的措辞，而不是直接断定因果关系，除非有证据支持。
Read the question carefully. Highlight command words such as 'explain', 'evaluate', 'calculate', and 'suggest'. The required answer style differs for each: 'explain' wants scientific reasoning; 'evaluate' requires you to discuss pros and cons; 'calculate' needs a numerical answer.
仔细审题。标亮指令词，如“解释”、“评估”、“计算”、“建议”。不同指令词的答题要求各异：“解释”需要科学推理；“评估”要求你讨论优缺点；“计算”需要给出数值答案。
11. Practice Activity: Fossil Fuels and Climate | 练习活动：化石燃料与气候
Use your skills on this mini-case study: A power station burns coal, releasing CO2 and SO2. Data over 30 years show atmospheric CO2 increased from 330 ppm to 410 ppm, and average global temperature rose by 0.8 °C. Describe the relationship speculatively linking the two, then explain using the greenhouse effect.
请运用所学技能分析这个微型案例：一座发电站燃烧煤炭，释放 CO2 和 SO2。30 年的数据显示，大气 CO2 浓度从 330 ppm 升至 410 ppm，全球平均气温上升了 0.8 °C。请描述这两个变量之间的推测性关系，然后用温室效应加以解释。
Possible answer: There is a positive correlation between CO2 levels and global temperature. CO2 is a greenhouse gas that traps infrared radiation in the atmosphere, increasing the Earth's average temperature. However, other factors such as solar activity and deforestation also need to be considered before drawing firm conclusions.
参考回答：CO2 浓度与全球气温之间存在正相关。CO2 是一种温室气体，能将红外辐射捕获在大气中，导致地球平均温度升高。然而，在得出确切结论前，还需考虑太阳活动和森林砍伐等其他因素。
Now try to evaluate a proposed solution: 'Replace coal with natural gas.' Natural gas produces less CO2 per unit energy, but methane leaks are a potent greenhouse gas. Discuss the trade-offs and suggest an even better alternative, such as renewable energy sources.
现在尝试评估一个提议方案：“用天然气替代煤炭”。天然气单位能量产生的 CO2 较少，但甲烷泄漏是一种强效温室气体。讨论利弊权衡，并提出更优替代方案，如可再生能源。
12. Final Tips and Exam Strategy | 最后提示与考试策略
Manage your time: case study questions can be lengthy. Skim the introduction, read the questions, then go back to the data with a focus. Allocate about 1.5 minutes per mark as a rule of thumb.
管理好时间：案例分析题可能篇幅较长。快速浏览引言，先看问题，再带着重点回去查看数据。大致可按每分 1.5 分钟分配时间。
Use the data provided—even if your personal knowledge tells you something slightly different, the exam expects you to base your answer on the given evidence. Quote figures from the table or graph to back up your answer.
使用所提供的数据——即使你的个人知识告诉你略有差异，考试期望你基于给定证据作答。引用表格或图表中的具体数字来支撑你的答案。
Always leave a few minutes to review your answers, check for unit errors, and ensure your graph is neat and properly labelled. A well-structured answer that uses scientific terminology will always stand out to examiners.
务必留出几分钟检查答案，排查单位错误，确保图表整洁、标注正确。结构清晰、运用科学术语的答案总能给考官留下深刻印象。
Practice with past papers and mark schemes. Over time, you will notice patterns in the types of questions asked and learn how to phrase your responses to match what examiners are looking for. Confidence comes from familiarity.
利用历年真题和评分方案进行练习。久而久之，你会发现出题模式，并学会如何措辞以契合考官的期待。熟能生巧，信心自来。
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