📚 Year 10 SQA Science: Case Study Practical Drill | Year 10 SQA 科学：案例分析实战演练
Case studies are a central feature of the SQA Science course, designed to test your ability to apply scientific knowledge, analyse experimental data, and evaluate procedures. This article provides a practical drill through essential skills and five realistic case studies, helping you build confidence in tackling these open-ended, context-based questions.
案例分析是 SQA 科学课程的核心部分，旨在考察你应用科学知识、分析实验数据和评估过程的能力。本文通过必备技能讲解与五个真实的案例演练，帮助你从容应对这些以情境为基础的开阔题。
1. Understanding Case Studies in SQA Science | 理解 SQA 科学中的案例分析
A typical case study presents a scientific scenario, often with a table of results or a description of an experiment. You will be asked to process data, explain trends using scientific models, and sometimes suggest improvements to the method.
典型的案例分析会给出一个科学情境，通常附带实验结果表或实验描述。你需要处理数据、运用科学模型解释趋势，有时还要提出方法的改进建议。
To succeed, read the entire stem carefully, highlight the independent and dependent variables, and note the type of relationship being investigated. Then move step-by-step through calculation, description, explanation and evaluation.
想要成功，应仔细阅读题干，标出自变量和因变量，注意所研究的关系类型。然后一步步完成计算、描述、解释和评估。
2. Analysing Experimental Data | 分析实验数据
Begin by identifying the numerical patterns. Calculate the mean where repeated readings exist, and determine the range or percentage difference to comment on precision. In rate-based questions, convert raw data using 1/time or volume/time.
从识别数值规律开始。有重复读数时计算平均值，并确定极差或百分差以评价精确度。在涉及速率的题目中，用 1/时间 或 体积/时间 转换原始数据。
Always attach correct units to your answers. For example, rate of reaction may be expressed as s⁻¹ or cm³/s. Use standard notation and avoid leaving quantities without units.
答案务必带上正确单位。例如反应速率可以表示为 s⁻¹ 或 cm³/s。使用标准符号，不要让物理量缺少单位。
An example data set is shown below:
| Concentration (mol/dm³) | Time for cross to disappear (s) | Rate (s⁻¹) |
| 0.1 | 85 | 0.012 |
| 0.2 | 42 | 0.024 |
下表是一个数据示例：
| 浓度 (mol/dm³) | 十字消失所需时间 (s) | 速率 (s⁻¹) |
| 0.1 | 85 | 0.012 |
| 0.2 | 42 | 0.024 |
me = 1 ÷ 85 = 0.0118 s⁻¹, rounded to 0.012 s⁻¹. This transparency earns marks for working.
计算时清晰展示每一步：速率 = 1 / 时间 = 1 ÷ 85 = 0.0118 s⁻¹，四舍五入为 0.012 s⁻¹。这样透明的步骤能赢得过程分。
3. Applying Scientific Principles | 应用科学原理
Once you have processed the data, you must explain it underpinning scientific theory. For instance, if rate increases with temperature, invoke kinetic theory – more particles have energy greater than the activation energy, leading to more frequent successful collisions.
完成数据处理后，你必须用科学理论加以解释。例如，若速率随温度升高而增加，则可引用动力学理论——更多粒子的能量超过活化能，导致更频繁的有效碰撞。
Always link the evidence in front of you to a named principle, law or model. 'The resistance remained constant because the resistor is ohmic and obeys Ohm's Law (V = IR).' This shows you can connect data with classroom learning.
永远将眼前的证据与某个已学过的原理、定律或模型联系起来。“电阻保持不变是因为该电阻是欧姆性的并遵守欧姆定律 (V = IR)。”这显示你能够将数据与课堂知识挂钩。
4. Evaluating Experimental Design | 评估实验设计
A strong evaluation identifies the independent, dependent and controlled variables and then judges how well they were managed. Ask yourself: was the range of the independent variable suitable? Were controls kept constant? Was the measurement method precise enough?
优秀的评估会识别自变量、因变量和控制变量，并判断它们是否被妥善管理。问自己：自变量的范围是否合适？控制变量是否保持恒定？测量方法是否足够精确？
Common improvements include using a water bath instead of a Bunsen burner for temperature control, repeating readings to calculate a mean, or using a datalogger to reduce human reaction time errors.
常见的改进包括使用水浴代替本生灯来控温、通过重复读数计算平均值、或使用数据采集器以减少人为反应时间误差。
5. Interpreting Graphs and Tables | 解读图表
When describing a graph, always refer to the axes: 'As temperature increases from 10 °C to 40 °C, the time decreases, so the rate of reaction increases.' Mention any plateau, peak or anomaly, and support with data points.
描述图表时，务必参照坐标轴：“当温度从 10 °C 升高到 40 °C 时，所需时间减少，因此反应速率加快。” 要提及任何平台、峰顶或异常值，并用数据点支撑。
For a table, compute derived quantities such as 1/time or rate, and compare the proportionality. A common question asks you to state whether results show direct or inverse proportion – check if doubling one quantity doubles the other, or halves it.
对于表格，计算派生量如 1/时间 或速率，并比较比例关系。常见问法是判断结果是否显示正比或反比——检查一个量加倍时另一个量是加倍还是减半。
6. Making Predictions | 做出预测
Many case studies ask: 'Predict what would happen if...' Use the trend observed in the data. For a straight-line graph that passes through the origin, you can confidently extrapolate and state the expected value, provided conditions remain the same.
许多案例分析会问：“如果……会怎样？” 利用数据中观察到的趋势。对于经过原点的直线图，只要条件相同，你可以自信地进行外推并给出预期值。
Always justify your prediction using scientific reasoning. ' doubled while force remains constant, the acceleration will halve, because a = F/m (Newton's second law).' This proves you are not guessing.
务必用科学推理证明你的预测。“如果质量加倍而力保持不变，加速度将减半，因为 a = F/m（牛顿第二定律）。” 这表明你不是在猜测。
7. Drawing Conclusions | 得出结论
A solid conclusion states the relationship between the independent and dependent variable, includes supporting figures, and matches the aim. 'The results show that as the concentration of acid increases, the time taken to collect 50 cm³ of gas decreases, indicating a higher rate of reaction.'
可靠的结论会陈述自变量和因变量之间的关系，包含支持性数据，并与实验目的相符。“结果表明，随着酸浓度的增加，收集 50 cm³ 气体所需时间减少，说明反应速率更高。”
Avoid adding new information not present in the investigation. Stick to what the data actually shows, and if there are anomalies, comment on their possible causes without undermining the overall trend.
不要添加调查中未出现的新信息。紧扣数据实际显示的内容，如果存在异常点，可以评论其可能的成因而不贬低整体趋势。
8. Case Study 1: Enzyme Activity and Temperature | 案例分析1：酶活性与温度
Background: A student investigated how temperature affects catalase activity. Catalase breaks down hydrogen peroxide into water and oxygen. The time needed to produce 10 cm³ of oxygen was recorded at six temperatures. The results are shown below:
背景：一名学生研究了温度如何影响过氧化氢酶活性。该酶将过氧化氢分解为水和氧气。记录了在六个温度下产生 10 cm³ 氧气所需的时间。结果如下表：
| Temperature (°C) | 10 | 20 | 30 | 40 | 50 | 60 |
| Time (s) | 85 | 45 | 25 | 18 | 40 | 120 |
Question 1: Calculate the rate of reaction at 30 °C. Give the unit.
问题 1：计算 30 °C 下的反应速率。给出单位。
C the reaction rate is 0.04 per second, showing a relatively fast turnover of hydrogen peroxide compared with lower temperatures but slowing again at higher temperatures due to enzyme denaturation.
速率 = 1 / 时间 = 1 / 25 s = 0.04 s⁻¹。在 30 °C 时反应速率为 0.04 s⁻¹，与较低温度相比反应较快，但随着温度继续升高酶会变性，速率又会减慢。
Question 2: Describe the overall trend and explain it using your knowledge of enzymes.
问题 2：描述总体趋势，并运用酶的知识加以解释。
From 10 °C to 40 °C the time to produce gas decreases, meaning reaction rate increases. The optimum temperature appears to be around 40 °C. Above 40 °C the rate falls sharply; at 60 °C the reaction is very slow. This is because the enzyme’s active site changes shape and the substrate can no longer bind – the enzyme has been denatured.
从 10 °C 到 40 °C，产气时间缩短，即反应速率增加。最适温度约为 40 °C。超过 40 °C 后速率急剧下降；60 °C 时反应非常慢。这是因为酶的活性位点形状发生改变，底物无法再结合——酶已变性。
Question 3: Evaluate the experimental design and suggest two improvements.
问题 3：评估实验设计并提出两项改进。
The procedure should control the volume and concentration of hydrogen peroxide and the mass of enzyme used. A water bath is essential to maintain each temperature accurately. Repeating each measurement three times and calculating a mean would improve reliability. An improvement could be to use a data logger with a pressure sensor to track oxygen production continuously.
实验应控制过氧化氢的体积和浓度以及酶的质量。必须使用水浴锅来精确维持每档温度。每个测量重复三次并计算平均值可提高可靠性。改进之一是可以使用压力传感器和数据采集器连续追踪氧气生成。
9. Case Study 2: Ohm's Law in a Circuit | 案例分析2：电路中的欧姆定律
Background: A student connects a fixed resistor to a variable power supply and records the current through it for different voltages.
背景：一名学生将一固定电阻连接到可调电源，记录不同电压下通过电阻的电流。
| Voltage (V) | 1.0 | 2.0 | 3.0 | 4.0 | 5.0 |
| Current (mA) | 50 | 100 | 150 | 200 | 250 |
r every pair, confirming that the resistor is ohmic. A graph of V (y-axis) against I (x-axis) would be a straight line through the origin.
将电流转换为安培：50 mA = 0.050 A，100 mA = 0.100 A，等等。每个数据对计算的电阻 R = V / I 恒为 20 Ω，证明该电阻是欧姆性的。V (纵轴) 对 I (横轴) 的图将是一条通过原点的直线。
To ensure valid results, the temperature of the resistor must stay constant; otherwise resistance would drift. Use a heat sink or avoid high currents. The ammeter must be connected in series and the voltmeter in parallel with the resistor.
为确保结果有效，电阻的温度必须恒定；否则电阻会漂移。可使用散热片或避免过大电流。电流表应串联在电路中，电压表应并联在电阻两端。
10. Case Study 3: Rate of Reaction and Concentration | 案例分析3：反应速率与浓度
Marble chips (calcium carbonate) were reacted with four different concentrations of hydrochloric acid. The volume of the acid and mass of chips were kept constant. The time to collect 50 cm³ of carbon dioxide was measured.
大理石碎片（碳酸钙）与四种不同浓度的盐酸反应。酸的体积和大理石碎片的量保持不变。测量收集 50 cm³ 二氧化碳所需的时间。
| Concentration of HCl (mol/dm³) | 0.5 | 1.0 | 1.5 | 2.0 |
| Time (s) | 120 | 65 | 42 | 30 |
Calculate the rate as 1/time (s⁻¹): 0.0083, 0.0154, 0.0238, 0.0333. The rate increases with concentration. Collision theory explains that a higher concentration means more reactant particles per unit volume, leading to a greater frequency of successful collisions per second.
以 1/时间 (s⁻¹) 计算速率：0.0083，0.0154，0.0238，0.0333。速率随浓度升高而增加。碰撞理论解释说，浓度越高意味着单位体积内反应物粒子越多，导致每秒有效碰撞频率增大。
For evaluation, note that the marble chips should have the same surface area; using a balance to control mass is good, but surface area can vary between chips. Repeating the experiment and also measuring the volume at regular intervals (e.g. every 10 s) would give a more detailed picture of the rate change.
评估时，注意大理石碎片应保持相同的表面积；用天平控制质量很好，但不同碎片表面积可能不同。重复实验并每隔一定时间（如每 10 秒）记录气体体积能更详细地反映速率变化。
11. Case Study 4: Sampling a Habitat | 案例分析4：栖息地取样
rea 0.25 m²) to estimate the number of daisies in a field of area 100 m². Ten random samples gave the following counts: 5, 8, 0, 12, 7, 4, 10, 6, 9, 3.
一名学生用 0.5 m × 0.5 m 的样方（面积 0.25 m²）估算一块 100 m² 草地上雏菊的数量。十次随机取样得到如下计数：5, 8, 0, 12, 7, 4, 10, 6, 9, 3。
.25 m², which is 25.6 daisies per m². For the entire 100 m² field, the total population estimate is 25.6 × 100 = 2560 daisies.
计算每个样方的雏菊平均数：(5+8+0+12+7+4+10+6+9+3) / 10 = 64 / 10 = 6.4。估算的种群密度为每 0.25 m² 6.4 株，即每平方米 25.6 株。对于整个 100 m² 的草地，总种群数量估算为 25.6 × 100 = 2560 株。
To improve reliability, increase the number of quadrat throws and ensure they are truly random, for example by using a random number table to generate coordinates. Also, being consistent in what counts as 'inside' the quadrat is important for accuracy.
为提高可靠性，应增加样方投掷次数，并确保其真正随机，例如利用随机数表生成坐标。此外，对于何谓“在样方内”的计数标准保持一致对准确性也至关重要。
12. Case Study 5: Force, Mass and Acceleration | 案例分析5：力、质量与加速度
A dynamics
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