📚 Case Study Practice in CIE Biology | CIE 生物案例分析实战演练
Case studies form a critical part of the CIE Biology assessment for Year 10, testing your ability to apply biological concepts to unfamiliar, real-world situations. This article presents a series of guided practice scenarios covering disease, genetics, ecology, and physiology, helping you develop the analytical skills needed to interpret data, recognise patterns, and draw evidence-based conclusions.
案例分析是CIE Year 10生物考试的重要组成部分，旨在考查你将生物学概念应用于陌生现实情境的能力。本文提供了一系列指导性练习场景，涵盖疾病、遗传学、生态学和生理学，帮助你培养解读数据、识别规律并得出基于证据的结论所需的技能。
1. Understanding Case Studies | 理解案例分析题型
CIE Biology case studies typically provide a short passage, often accompanied by graphs, tables, or diagrams, that describes a biological problem or investigation. Questions ask you to identify variables, suggest explanations using your knowledge, analyse trends, and evaluate experimental design.
CIE生物案例分析通常提供一段短文，常附有图表、表格或示意图，描述一个生物学问题或探究。问题要求你识别变量，运用知识给出解释，分析趋势，并评价实验设计。
Common command words include 'suggest', 'explain', 'calculate', and 'evaluate'. For example, you might be shown data on the effect of temperature on enzyme activity and asked to suggest why the rate drops above 40 °C. Your answer must link the observation to denaturation of the enzyme's active site.
常见的指令词包括“建议”、“解释”、“计算”和“评价”。例如，你可能会看到温度对酶活性影响的数据，并被要求推测为何速率在40°C以上下降。你的回答必须将观察结果与酶活性部位的变性联系起来。
Always use precise biological vocabulary: 'denaturation' rather than 'the enzyme stopped working'. Marks are awarded for clear reasoning that combines the stimulus material with your own understanding.
务必使用精确的生物学词汇：用“变性”而不是“酶停止工作了”。将题目所提供的素材与你自己的理解相结合的清晰推理才能得分。
2. The Malaria Menace: Disease Transmission | 疟疾威胁：疾病传播
Malaria remains a major global health challenge, particularly in tropical regions. The disease is caused by single-celled Plasmodium parasites, which are transmitted to humans through the bite of infected female Anopheles mosquitoes.
疟疾仍然是全球主要的健康挑战，尤其是在热带地区。该疾病由单细胞疟原虫引起，通过受感染的雌性按蚊叮咬传播给人类。
The parasite has a complex life cycle involving two hosts: humans and mosquitoes. In the human liver, sporozoites multiply before invading red blood cells, where they burst cells synchronously, causing periodic fevers. In the mosquito gut, gametocytes fuse to form a zygote that produces new sporozoites, which migrate to the salivary glands ready for the next bite.
这种寄生虫拥有涉及两个宿主（人类和蚊子）的复杂生活史。在人肝脏中，子孢子增殖后入侵红细胞，同步破裂细胞引起周期性发热。在蚊子肠道中，配子体融合形成合子，产生新的子孢子，迁移至唾液腺准备下一次叮咬。
Table 2.1 summarises key transmission factors and prevention strategies.
表2.1总结了关键的传播因素和预防策略。
| Factor / 因素 | Description / 描述 |
|---|---|
| Vector (传播媒介) | Female Anopheles mosquito (雌性按蚊) |
| Pathogen (病原体) | Plasmodium falciparum, P. vivax, etc. (恶性疟原虫等) |
| Control (控制) | Insecticide-treated bed nets, antimalarial drugs, draining stagnant water (药浸蚊帐、抗疟药、排干积水) |
Analyse a scenario: In a village, health workers introduced bed nets and noticed a 60% reduction in malaria cases over two years. Explain why. The nets act as a physical barrier, reducing the frequency of mosquito bites, and the insecticide kills mosquitoes on contact, lowering the vector population.
分析一个情境：在一个村庄，卫生工作者引入了蚊帐，两年内疟疾病例减少了60%。解释原因。蚊帐作为物理屏障，减少了蚊子叮咬的频率，杀虫剂接触杀死蚊子，降低了媒介数量。
3. Tackling Sickle Cell Anaemia: Genetic Inheritance | 应对镰刀型细胞贫血症：遗传与进化
Sickle cell anaemia is an inherited blood disorder caused by a mutation in the gene for haemoglobin. The allele for normal haemoglobin is HbA, while the sickle cell allele is HbS. A person with genotype HbS HbS produces abnormally shaped red blood cells that block capillaries and cause pain, anaemia, and organ damage.
镰刀型细胞贫血症是一种遗传性血液疾病，由血红蛋白基因突变引起。正常血红蛋白的等位基因为HbA，镰刀型细胞等位基因为HbS。基因型为HbS HbS的人产生形状异常的红细胞，堵塞毛细血管，导致疼痛、贫血和器官损伤。
Interestingly, heterozygous individuals (HbA HbS) do not suffer severe symptoms and are resistant to malaria. This heterozygote advantage explains why the HbS allele remains relatively common in malaria-endemic regions: natural selection favours carriers.
有趣的是，杂合子个体（HbA HbS）没有严重症状，并且能抵抗疟疾。这种杂合子优势解释了为何HbS等位基因在疟疾流行地区仍然相对普遍：自然选择有利于携带者。
us parents (HbA HbS × HbA HbS). Complete a Punnett-square analysis: the offspring has a 25% probability of being homozygous normal (HbA HbA), 50% probability of being heterozygous (HbA HbS, carriers), and 25% probability of being homozygous affected (HbS HbS).
考虑两个杂合子父母（HbA HbS × HbA HbS）之间的遗传杂交。完成旁氏表分析：后代表型概率：25%为纯合正常（HbA HbA），50%为杂合子（HbA HbS，携带者），25%为纯合患病（HbS HbS）。
In a case study, you may be given pedigree diagrams showing the inheritance pattern. Look for affected individuals appearing in every generation if the condition is dominant; sickle cell anaemia is recessive, so unaffected parents can produce affected children only if both are carriers.
在案例研究中，你可能会看到显示遗传模式的系谱图。如果疾病是显性的，寻找每代都出现的患病个体；镰刀型细胞贫血症是隐性的，因此未患病的父母只有双方都是携带者时才能生出患病孩子。
4. Enzyme Action in Washing Powders: Biological Detergents | 洗衣粉中的酶作用：生物洗涤剂
Biological washing powders contain enzymes, such as proteases and lipases, that break down stubborn stains like blood, egg, and grease. Proteases hydrolyse proteins into amino acids, while lipases break fats into fatty acids and glycerol, making stains water-soluble and easier to wash away.
生物洗衣粉含有蛋白酶和脂肪酶等酶，能分解血液、蛋液和油脂等顽固污渍。蛋白酶将蛋白质水解为氨基酸，脂肪酶将脂肪分解为脂肪酸和甘油，使污渍溶于水，更容易洗掉。
A student investigated the effect of temperature on the activity of a protease in washing powder by measuring the time taken to clear a gelatin layer on photographic film. Results are shown below.
一名学生通过测量清除照相底片明胶层所需的时间，研究了温度对洗衣粉中蛋白酶活性的影响。结果如下。
| Temperature (°C) / 温度 (°C) | Time to clear gelatin (min) / 清除明胶时间 (分钟) |
|---|---|
| 20 | 9.5 |
| 30 | 4.2 |
| 40 | 1.8 |
| 50 | 2.5 |
| 60 | 8.1 |
The shortest clearing time occurs at 40 °C, indicating the optimum temperature for this protease. Below 40 °C, the enzyme and substrate molecules have lower kinetic energy, so collisions are less frequent. Above 40 °C, the enzyme's three-dimensional shape is altered by heat, causing the active site to lose its complementary fit to the substrate — the enzyme denatures.
清除时间最短在40°C，表明该蛋白酶的最适温度。低于40°C时，酶和底物分子动能较低，碰撞不频繁。超过40°C后，酶的三维结构因热而改变，活性部位失去与底物的互补性——酶变性。
When evaluating experimental design, consider variables such as pH and enzyme concentration; these must be kept constant for a fair test. Repeats increase reliability, and quantitative measurement of clearing time is more objective than a subjective 'end-point' judgement.
评价实验设计时，需考虑pH和酶浓度等变量；必须保持恒定以确保公平测试。重复实验可提高可靠性，且定量测量清除时间比主观判断“终点”更客观。
5. Eutrophication Crisis: Pollution in Waterways | 富营养化危机：水体污染
Farmers often apply nitrate and phosphate fertilisers to increase crop yields. When heavy rain washes these nutrients into nearby rivers and lakes, a sequence of events called eutrophication can occur, severely damaging aquatic ecosystems.
农民常施用硝酸盐和磷酸盐肥料以提高作物产量。当大雨将这些营养物质冲入附近的河流和湖泊时，可能发生一系列称为富营养化的事件，严重破坏水生生态系统。
Step 1: The influx of nutrients causes a rapid growth of algae and water plants, forming an algal bloom on the water surface. This blocks sunlight, so submerged plants cannot photosynthesise and begin to die.
第1步：营养物的流入导致藻类和水生植物迅速生长，在水面形成水华。这遮蔽了阳光，沉水植物无法进行光合作用并开始死亡。
Step 2: Bacteria and decomposers break down the dead organic matter, using up dissolved oxygen in the water during aerobic respiration. The biochemical oxygen demand (BOD) rises sharply.
第2步：细菌和分解者分解死去的有机物，在需氧呼吸过程中耗尽水中的溶解氧。生化需氧量（BOD）急剧上升。
Step 3: As oxygen concentration falls below the level needed for aerobic organisms, fish and other aquatic animals suffocate and die. The community structure shifts to a few tolerant species, such as sludge worms, drastically reducing biodiversity.
第3步：当氧浓度降至需氧生物所需水平以下时，鱼类和其他水生动物窒息死亡。群落结构转变为少数耐受性物种，如污泥蠕虫，生物多样性急剧降低。
In a case study, you might be given data on nitrate concentration and fish species richness along a river. Explain the negative correlation: as nitrate rises, eutrophication intensifies, oxygen depletion worsens, and fewer fish species can survive.
在案例研究中，你可能会得到沿某河流的硝酸盐浓度与鱼类物种丰富度的数据。解释其负相关：随着硝酸盐浓度增加，富营养化加剧，氧耗竭加重，能够存活的鱼类物种减少。
6. Diabetes Management: Hormonal Control | 糖尿病管理：激素调控
Type 1 diabetes is a condition in which the pancreas fails to produce sufficient insulin. Without insulin, cells cannot take up glucose effectively, causing blood glucose concentration to remain dangerously high after meals (hyperglycaemia) and the body to break down fat and protein for energy.
1型糖尿病是一种胰腺无法产生足够胰岛素的疾病。没有胰岛素，细胞无法有效摄取葡萄糖，导致餐后血糖浓度保持在危险的高水平（高血糖），身体通过分解脂肪和蛋白质获取能量。
Case study data: Table 6.1 shows the blood glucose concentration of a person with type 1 diabetes monitored over 8 hours. Insulin injections were administered at 08:00 and 12:00.
案例研究数据：表6.1显示了一名1型糖尿病患者在8小时内监测的血糖浓度。胰岛素注射分别在08:00和12:00进行。
| Time / 时间 | Blood glucose (mmol dm⁻³) / 血糖 (mmol dm⁻³) |
|---|---|
| 07:00 (before breakfast) | 7.2 |
| 09:00 (after breakfast) | 15.3 |
| 11:00 | 8.1 |
| 13:00 (after lunch) | 14.8 |
| 15:00 | 6.9 |
At 09:00, after the morning meal, glucose spikes to 15.3 mmol dm⁻³. The insulin injected at 08:00 is not yet fully active, but by 11:00 the concentration has returned to near-normal, showing that insulin stimulates the conversion of glucose to glycogen in the liver and increases cellular uptake. A similar pattern repeats after lunch.
在09:00，早餐后，血糖飙升至15.3 mmol dm⁻³。08:00注射的胰岛素尚未完全起效，但到11:00，浓度恢复到接近正常水平，表明胰岛素刺激肝脏将葡萄糖转化为糖原，并增加细胞摄取。午餐后呈现相似模式。
In a question, you may be asked to discuss the importance of timing insulin injections with meals. Timely injection ensures that insulin is present in the bloodstream when glucose is absorbed from the gut, preventing prolonged hyperglycaemia and reducing the risk of long-term complications such as kidney damage.
在问题中，你可能会被要求讨论餐前准时注射胰岛素的重要性。准时注射确保葡萄糖从肠道吸收时，血液中已有胰岛素，防止长时间高血糖，并降低肾脏损害等长期并发症的风险。
7. Photosynthesis Investigation: Elodea Experiment | 光合作用探究：伊乐藻实验
A classic investigation of photosynthesis uses the aquatic plant Elodea. As the plant photosynthesises, it releases oxygen gas, which can be collected and measured. The number of bubbles produced per minute indicates the rate of photosynthesis.
一项经典的光合作用探究使用水生植物伊乐藻。当植物进行光合作用时，会释放氧气，可以收集并测量。每分钟产生的气泡数量表示光合作用速率。
A student placed Elodea in a beaker of water and shone a lamp at different distances, counting bubbles per minute. The results are tabulated.
一名学生将伊乐藻置于装有水的烧杯中，用不同距离的灯照射，计数每分钟气泡数。结果列于表中。
| Distance of lamp (cm) / 灯距离 (cm) | Light intensity (arbitrary units) / 光强度 (任意单位) | Bubbles per minute / 每分钟气泡数 |
|---|---|---|
| 10 | 100 | 45 |
| 20 | 50 | 32 |
| 30 | 25 | 20 |
| 40 | 12 | 10 |
The relationship shows that as light intensity increases (lamp closer), the rate of photosynthesis rises, but not linearly; the rate plateaus at very high intensities because another factor, such as CO₂ concentration or temperature, becomes limiting.
该关系表明，随着光强度增加（灯更近），光合作用速率上升，但并非线性；在很高强度下速率趋于平稳，因为其他因素（如CO₂浓度或温度）成为限制因子。
To answer case-study questions, identify the independent variable (light intensity), dependent variable (bubble rate), and controlled variables (water temperature, NaHCO₃ concentration if added). Note that bubble counting is a simple but crude method; gas collection in a measuring cylinder using an inverted funnel is more accurate.
回答案例研究问题时，识别自变量（光强度）、因变量（气泡速率）和控制变量（水温、若添加了NaHCO₃则其浓度）。注意，气泡计数简便但粗略；使用倒置漏斗在量筒中收集气体更为精确。
8. Food Chains and Energy Transfer: Pyramid of Biomass | 食物链与能量传递：生物量金字塔
Energy flows through ecosystems via food chains. At each trophic level, energy is lost through respiration, excretion, and uneaten parts. Typically, only about 10% of the energy is transferred to the next level, which limits the length of food chains.
能量通过食物链流经生态系统。在每个营养级，能量通过呼吸、排泄以及未被取食的部分而损失。通常仅约10%的能量传递至下一营养级，这限制了食物链的长度。
umer) → frog (secondary consumer) → snake (tertiary consumer). Biomass data are collected.
一个案例研究考察草原生态系统：草（生产者）→ 蚱蜢（初级消费者）→ 青蛙（次级消费者）→ 蛇（三级消费者）。收集了生物量数据。
| Trophic level / 营养级 | Organism / 生物 | Biomass (g m⁻²) / 生物量 (g m⁻²) |
|---|---|---|
| 1 (Producer / 生产者) | Grass (草) | 840 |
| 2 (Primary / 初级) | Grasshopper (蚱蜢) | 90 |
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