📚 Year 13 WJEC Science: Case Study Practical Drills | Year 13 WJEC 科学：案例分析实战演练
Case studies are a core component of the WJEC Year 13 Science specification, requiring students to apply knowledge to real-world scenarios. This article offers a hands-on guide to mastering case study analysis, covering key skills from data interpretation to evaluation.
案例研究是WJEC Year 13科学课程的核心组成部分，要求学生将知识应用于真实场景。本文提供了一份实战指南，涵盖从数据解读到评估的关键技能，助你掌握案例分析。
1. Understanding Case Studies in WJEC Science | 理解 WJEC 科学中的案例研究
In WJEC Science, case studies present a narrative or set of data around a scientific issue. You are expected to demonstrate understanding of scientific concepts, analyse information, and make evidence-based recommendations.
在WJEC科学中，案例研究通常围绕某个科学议题提供叙述或数据集。你需要展示对科学概念的理解、分析信息，并提出基于证据的建议。
2. Deconstructing the Scenario | 解构情景
Start by reading the scenario carefully. Highlight key variables, stakeholders, and the problem to be solved. Identify what type of science is involved – biology, chemistry, or physics.
首先仔细阅读情景。标出关键变量、利益相关方和待解决的问题。识别所涉及的科学类型——生物、化学或物理。
3. Identifying Relevant Scientific Principles | 识别相关科学原理
Link the scenario to core scientific principles. For example, a case on pollution may require knowledge of diffusion, chemical equilibria, and bioaccumulation. Explain the ‘why’ behind the phenomena.
将情景与核心科学原理联系起来。例如，一个关于污染的案例可能需要扩散、化学平衡和生物富集的知识。解释现象背后的“为什么”。
4. Data Analysis and Interpretation | 数据分析与解读
Case studies often include tables, graphs, or charts. Practise extracting trends, calculating percentages, and identifying anomalies. Use appropriate units and significant figures when presenting derived data.
案例研究通常包含表格、图表。练习提取趋势、计算百分比并识别异常值。在呈现推导数据时使用正确的单位和有效数字。
5. Evaluating Evidence and Sources | 评估证据与来源
Critically assess the reliability and validity of the data. Consider the sample size, possible bias, and whether the methodology is reproducible. Distinguish between correlation and causation.
批判性地评估数据的可靠性和有效性。考虑样本量、可能的偏差以及方法是否可重复。区分相关性和因果关系。
6. Applying Mathematical Skills | 运用数学技能
WJEC often requires calculations such as rates of reaction, energy efficiency, or statistical tests. For instance, you might calculate the percentage decrease in bacterial count: (initial − final) / initial × 100. Represent these using correct notations like 5.0 × 10−³ g L−¹.
WJEC经常要求进行反应速率、能效或统计检验等计算。例如，你可能需要计算细菌数量的下降百分比：(初始值 − 终值) / 初始值 × 100。使用正确的符号如5.0 × 10−³ g L−¹。
7. Risk Assessment and Ethical Considerations | 风险评估与伦理考量
Consider safety hazards, environmental impact, and ethical dilemmas. Propose precautionary measures: ‘Wear eye protection when handling NaOH (≥ 0.1 mol dm−³).’ Evaluate the balance between scientific progress and societal values.
考虑安全隐患、环境影响和伦理困境。提出预防措施：‘处理NaOH (≥ 0.1 mol dm−³) 时需佩戴护目镜。’评估科学进步与社会价值之间的平衡。
8. Designing Further Investigations | 设计进一步的调查
Suggest follow-up experiments. Define independent, dependent, and control variables. Outline a clear method: ‘Measure the mass of CO&sub2; lost from a conical flask every 30 s using a balance to calculate rate.’
提出后续实验。定义自变量、因变量和控制变量。概述清晰的方法：‘使用天平每30秒测量锥形瓶中CO&sub2;的质量损失以计算速率。’
9. Crafting a Coherent Conclusion | 撰写连贯的结论
Synthesise your analysis into a logical conclusion. Reference the data explicitly, weigh up pros and cons, and justify your final stance. Avoid introducing new information.
将分析综合成合乎逻辑的结论。明确引用数据，权衡利弊，并证明你的最终立场。避免引入新信息。
10. Practice Case Study: Biodegradable Plastics Dilemma | 实战案例：生物可降解塑料的困境
Let’s apply the skills developed above to a realistic case. A biotech firm, GreenPoly, claims its PLA plastic is environmentally superior. Analyse the provided data and evaluate the claim.
让我们将上述技能应用于一个真实案例。生物技术公司GreenPoly声称其PLA塑料对环境更有利。请分析所提供的数据并评估该声明。
| Material | Degradation time in industrial composter (weeks) | Degradation time in marine environment (weeks) | Carbon footprint (kg CO&sub2; per kg plastic) | Cost per kg (£) |
| PLA | 12 | 52 | 1.8 | 3.5 |
| PET | >500 | >500 | 2.3 | 1.2 |
First, identify the relevant science: PLA is a polyester derived from corn starch; degradation involves hydrolysis and microbial action. PET is a non-biodegradable petrochemical polymer. This links to topics on polymers, energy resources, and environmental chemistry.
首先，识别相关科学：PLA是一种衍生自玉米淀粉的聚酯；降解涉及水解和微生物作用。PET是一种不可生物降解的石化聚合物。这与聚合物、能源资源和环境化学等主题相关。
Next, interpret data: In industrial composting, PLA degrades completely in 12 weeks, whereas PET shows no measurable decay. However, in marine conditions, PLA still requires 52 weeks — much slower. The carbon footprint of PLA is 1.8 kg CO&sub2; per kg, 22% lower than PET’s 2.3 kg. But cost is almost three times higher (£3.5 vs £1.2).
接下来解读数据：在工业堆肥条件下，PLA在12周内完全降解，而PET没有可测量的降解。但在海洋环境中，PLA仍需52周——慢得多。PLA的碳足迹为每公斤1.8 kg CO&sub2;，比PET的2.3 kg低22%。但成本几乎是PET的三倍（£3.5对£1.2）。
Apply mathematical skills: Calculate the CO&sub2; saving: 2.3 − 1.8 = 0.5 kg per kg of plastic. For a production of 1000 kg, saving = 500 kg CO&sub2;. Express the percentage reduction: (0.5 ÷ 2.3) × 100 ≈ 21.7%. The degradation rate in compost is roughly 8.33% mass loss per week (assuming linear), while marine rate is 1.92% per week.
运用数学技能：计算CO&sub2;的节省量：2.3 − 1.8 = 0.5 kg每公斤塑料。若生产1000 kg，节省500 kg CO&sub2;。计算减少百分比：(0.5 ÷ 2.3) × 100 ≈ 21.7%。堆肥降解速率约为每周8.33%质量损失（假设线性），而海洋中约为每周1.92%。
Evaluate evidence: The data lack information on sample size and variability. No error margins are given. The marine degradation data for PLA might come from warm waters; colder seas could slow it further. The carbon footprint may not include land-use change for growing corn. Also, industrial composting facilities are not universally available.
评估证据：数据缺少样本量和变异性的信息。没有给出误差范围。PLA的海洋降解数据可能来自温暖水域；较冷的海水可能进一步减慢。碳足迹可能未包括种植玉米的土地利用变化。而且，工业堆肥设施尚未普遍普及。
Risk and ethics: PLA production requires agricultural land, potentially competing with food crops. Disposal in landfills may produce methane if anaerobic. However, reduced fossil fuel use is an ethical benefit. One must balance trade-offs.
风险与伦理：PLA生产需要农业用地，可能与粮食作物竞争。若在垃圾填埋场厌氧处置可能产生甲烷。然而，减少化石燃料使用是一个伦理效益。必须权衡取舍。
Design further investigation: Test degradation under different temperatures and pH. Include a control with cellulose paper. Measure CO&sub2; evolution using a gas sensor to monitor microbial respiration. Repeat three times for reproducibility.
设计进一步研究：测试不同温度和pH下的降解情况。包含纤维素纸作为对照。使用气体传感器测量CO&sub2;释放以监测微生物呼吸。重复三次以确保可重复性。
Conclusion: While PLA appears promising, its efficacy is context-dependent. It offers clear CO&sub2; savings and compostability, but marine persistence and high cost limit its immediate replacement of PET. I recommend targeted use in closed-loop systems with composting infrastructure, and caution against marketing it as ‘biodegradable’ without qualifying the environment.
结论：尽管PLA看起来有前景，其功效取决于使用环境。它可明显节省CO&sub2;并适于堆肥，但海洋中的持久性和高成本限制了它立即替代PET。我建议在具备堆肥基础设施的闭环系统中针对性使用，并提醒在没有限定环境的条件下，不要将其宣传为“可生物降解”。
Published by TutorHao | Science Revision Series | aleveler.com
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