Case Study Practice Drills | 案例分析实战演练

📚 Case Study Practice Drills | 案例分析实战演练

In Year 9 Edexcel Biology, case studies provide a powerful way to apply theoretical knowledge to real-world scenarios. This article offers a series of practical drills covering key topics, from ecology to genetics, to sharpen your analytical skills and exam technique. Each drill presents a realistic problem, data to interpret, and guided reasoning – just like the challenges you will meet in assessments.

在九年级爱德思生物课程中，案例分析是将理论知识应用于真实情境的有效途径。本文提供一系列覆盖生态学、遗传学等重点的实战演练，帮助你提升分析能力和应试技巧。每个演练都包含真实问题、待解读的数据和推理引导，完全模拟考试中会遇到的挑战。

1. Investigating Pond Life: Sampling Techniques | 池塘生物调查：取样技术

A student used a 0.5 m² quadrat to sample aquatic plants and animals in a pond. She placed the quadrat randomly ten times and recorded the presence and abundance of different species. The table below shows the mean number of individuals per quadrat for the most common organisms.

一名学生用0.5平方米的样方对池塘中的动植物进行取样。她随机放置样方十次，记录不同物种的出现与数量。下表显示了最常见生物每个样方的平均个体数。

Species	Mean count per quadrat
Daphnia (water flea)	45
Dragonfly nymph	3
Water snail	12
Tubifex worm	8
Mosquito larva	20

Species richness is simply the total number of different species found – here, five species. To estimate population density, the student multiplied the mean count per quadrat by 2, because the quadrat area is 0.5 m². For Daphnia, that gives 90 individuals per m².

物种丰富度简单来说就是发现的不同物种总数——这里为五个物种。为了估算种群密度，学生将每个样方的平均个体数乘以2，因为样方面积是0.5平方米。对水蚤而言，这相当于每平方米90只。

The researcher concluded that the pond has moderate biodiversity. However, using more quadrats would increase reliability, and identifying specimens to species level would improve accuracy. Sampling at different times of day could also reveal species that are only active at certain times.

研究者得出结论：池塘具有中等生物多样性。然而，使用更多样方可以提高可靠性，将标本鉴定到物种水平能改善准确性。在不同时间取样还可能发现只在特定时段活动的物种。

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2. Food Chains and Trophic Levels: Energy Transfer Analysis | 食物链与营养级：能量传递分析

Consider a simple freshwater food chain: algae → water fleas → small fish → heron. Ecologists measured the total biomass energy at each level over one year. The data are shown below.

考虑一条简单的淡水食物链：藻类 → 水蚤 → 小鱼 → 鹭。生态学家在一年内测量了各营养级的总生物质能量，数据如下。

Trophic level	Energy (kJ/m²/yr)
Producers (algae)	10 000
Primary consumers (water fleas)	1 000
Secondary consumers (small fish)	100
Tertiary consumers (heron)	10

In each step, roughly 90% of the energy is lost, mainly as heat from respiration, undigested material and uneaten parts. The transfer efficiency can be calculated by (energy in next level ÷ energy in previous level) × 100%, giving about 10% at each link.

每一步大约损失90%的能量，主要以呼吸热、未消化的物质和未被取食的部分散失。传递效率可用（下一营养级能量 ÷ 前一营养级能量）× 100%计算，每一环节约10%。

This explains why food chains rarely have more than four or five trophic levels: there is insufficient energy to support another level. It also highlights the importance of producers in capturing solar energy.

这解释了为何食物链很少超过四或五个营养级：没有足够能量支持下一个层级。这也凸显了生产者在固定太阳能方面的重要性。

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3. Enzyme Activity: A Temperature Case | 酶活性：温度案例

An investigation measured the activity of catalase (from potato tissue) by counting oxygen bubbles released per minute at different temperatures. The substrate was 2% hydrogen peroxide (H₂O₂). The results are recorded below.

一项研究通过计数不同温度下每分钟释放的氧气气泡来测量（土豆组织中的）过氧化氢酶的活性。底物为2%过氧化氢（H₂O₂）。结果记录如下。

Temperature (°C)	Bubbles per minute
10	3
20	7
30	14
37	22
45	15
55	5
60	0

The optimum temperature is around 37°C, where the reaction is fastest. At lower temperatures, molecules have less kinetic energy, so collisions between enzyme and substrate are fewer. Above 45°C, the enzyme starts to denature – its active site changes shape and the substrate no longer fits.

最适温度约为37°C，此时反应最快。温度较低时，分子动能较小，酶与底物的碰撞较少。超过45°C，酶开始变性——其活性部位形状改变，底物不再契合。

At 60°C the enzyme is completely denatured. The data illustrate that while temperature can speed up reactions, extreme heat irreversibly destroys enzyme function.

在60°C时酶完全变性。数据表明，尽管温度可加快反应，但极端高温会不可逆地破坏酶的功能。

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4. The Heart and Circulatory System: A Cardiovascular Case | 心脏与循环系统：心血管案例

A 55-year-old man visited his doctor complaining of chest pain during exercise. The table compares his measurements with those of a healthy individual of the same age.

一名55岁男性因运动时胸痛就医。下表对比了他与同龄健康者的测量数据。

Measurement	Patient	Healthy reference
Resting heart rate (bpm)	78	68
Blood pressure (mmHg)	150/95	120/80
Heart rate 5 min after exercise	105 bpm	75 bpm

The patient has elevated resting heart rate and high blood pressure, suggesting his heart works harder at rest. After exercise, his heart rate remains high, indicating poor recovery. These signs point to narrowed coronary arteries, likely due to fatty plaque build-up.

该患者静息心率偏高且血压升高，表明其心脏在休息时负担更重。运动后心率依然很高，说明恢复不佳。这些迹象指向冠状动脉变窄，可能是脂肪斑块堆积所致。

Reduced blood flow to the heart muscle causes angina (chest pain). Risk factors such as smoking, high saturated fat intake and lack of exercise probably contributed. Lifestyle changes and medication can help manage the condition.

流向心肌的血流减少会引起心绞痛。吸烟、高饱和脂肪饮食和缺乏锻炼等风险因素可能有所贡献。改变生活方式与药物治疗有助于控制病情。

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5. Photosynthesis: Light Intensity Investigation | 光合作用：光照强度调查

An experiment used pondweed (Elodea) to measure the rate of photosynthesis at different light intensities. The number of oxygen bubbles produced per minute was recorded while a lamp was moved to different distances, giving different lux values.

一项实验利用伊乐藻测量不同光照强度下的光合作用速率。移动台灯达到不同距离，产生不同勒克斯值，记录每分钟释放的氧气气泡数。

Light intensity (lux)	Bubbles per minute
0	0
500	4
1000	12
2000	24
3000	32
4000	35
5000	35

At 0 lux, no photosynthesis occurs; only respiration takes place. Around 500–1000 lux, the rate rises sharply, and the light compensation point (where photosynthesis rate equals respiration rate) lies in that region. Beyond 3000 lux, the curve flattens because light is no longer the limiting factor – carbon dioxide concentration or temperature may now limit the rate.

在0勒克斯时没有光合作用，只有呼吸作用。在500–1000勒克斯区间，速率急剧上升，光补偿点（光合速率等于呼吸速率）就位于该范围。超过3000勒克斯后曲线趋于平缓，因为光已不再是限制因子——二氧化碳浓度或温度可能正在限制速率。

Understanding limiting factors helps horticulturists optimise conditions in greenhouses to maximise plant growth.

理解限制因子有助于园艺工作者优化温室条件，以最大化植物生长。

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6. Genetics: A Family Pedigree Case | 遗传学：家系图案例

Sickle cell disease is caused by a recessive allele (s). The pedigree below shows a family where some members are affected. Squares represent males and circles females; filled symbols indicate the disease.

镰刀型细胞贫血症由隐性等位基因（s）引起。以下家系图显示一个家族中有成员患病。方块代表男性，圆形代表女性；实心符号表示患病。

Individual I-1 is a normal male (genotype SS or Ss? Since his son is affected, he must carry the allele – Ss). I-2 is an unaffected female who is a carrier (Ss). Their children: II-1 affected male (ss), II-2 normal female (SS or Ss), II-3 carrier male (Ss).

个体I-1是正常男性（基因型SS或Ss？因其儿子患病，他必须携带该等位基因——Ss）。I-2是未

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