Year 13 WJEC Biology: Practical Assessment Key Points | Year 13 WJEC 生物：实践考核要点

📚 Year 13 WJEC Biology: Practical Assessment Key Points | Year 13 WJEC 生物：实践考核要点

Mastering practical skills is integral to the Year 13 WJEC Biology specification. Assessment of experimental work spans planning, risk assessment, accurate data collection, graphing, statistical analysis and critical evaluation. This guide walks you through the core practical competencies and frequently tested techniques, ensuring you are fully prepared for any hands-on question or assessed task.

掌握实验技能是 Year 13 WJEC 生物课程的核心。实验考核涵盖方案设计、风险评估、精确数据采集、图表绘制、统计分析以及批判性评估。本指南将带你梳理核心实验能力与常见操作技术，助你从容应对所有动手考核题目。

1. Microscopy Skills and Biological Drawing | 显微镜技能与生物绘图

The compound light microscope must be set up correctly. Start with the lowest power objective, centre the condenser and adjust the iris diaphragm to optimise contrast and resolution. For high-resolution work at 100x, a drop of immersion oil is placed between the slide and the objective lens to reduce light refraction.

正确安装复合光学显微镜。先用最低倍物镜，将聚光器居中并调节光圈以优化对比度和分辨率。使用100倍油镜时，在载玻片与物镜间加一滴镜油以减少光线折射。

To measure cell size, calibrate the eyepiece graticule using a stage micrometer. Count how many graticule divisions match a known distance (e.g., 10 µm) on the micrometer. Calculate the length per eyepiece division, then multiply by the number of divisions occupied by the specimen.

测量细胞大小时，需先用镜台测微尺校准目镜测微尺。计算多少个目镜尺格对应测微尺上的已知长度（如10 µm），求得每格代表的实际长度，再乘以标本所占格数。

Biological drawings must be produced with a sharp HB pencil, using single continuous outlines. Do not shade or colour. Label lines should be drawn with a ruler and touch the structure being labelled; annotate to the right where possible. Always include a scale bar or a statement of magnification.

生物绘图必须使用削尖的HB铅笔，用单线连续勾勒轮廓，不得涂抹或上色。标注线用直尺绘制，准确指向结构，尽量向右标注。务必添加比例尺或放大倍数说明。

2. Biochemical Tests for Biological Molecules | 生物分子的生化测定

Reducing sugars are detected using Benedict’s test: add 2 cm³ of Benedict’s solution to the sample and heat in a boiling water bath for 5 minutes. A colour change from blue through green, yellow and orange to brick‑red indicates increasing concentration of reducing sugar.

还原糖通过班氏试剂检测：向样品中加入2 cm³班氏溶液，沸水浴加热5分钟。颜色由蓝变绿、黄、橙至砖红色沉淀，表明还原糖浓度依次增高。

Starch gives a blue‑black colour with iodine in potassium iodide solution. The test is semi‑quantitative: deeper colour suggests more starch. Proteins produce a violet/lilac colour when treated with sodium hydroxide and dilute copper sulfate (Biuret test), due to peptide bonds complexing with Cu²⁺ ions.

淀粉遇碘‑碘化钾溶液呈蓝黑色，颜色越深含量越高。蛋白质在氢氧化钠和稀硫酸铜作用下呈紫色或淡紫色（双缩脲试验），因为肽键与Cu²⁺形成络合物。

Lipids are confirmed by the emulsion test: dissolve the sample in ethanol, decant into water and shake. A cloudy white emulsion indicates the presence of lipid. For non‑reducing sugars, first boil the sample with dilute hydrochloric acid, neutralise with sodium hydrogencarbonate, then carry out Benedict’s test.

脂质采用乳浊试验：用乙醇溶解样品，倒入水中振荡，若出现白色乳浊则证实脂质存在。非还原糖需先用稀盐酸煮沸水解，用碳酸氢钠中和后，再进行班氏试验。

Quantitative analysis can be performed with a colorimeter. Measure absorbance of standards to construct a calibration curve, then read the concentration of the unknown sample against this curve.

定量分析可使用比色计。测量系列标准溶液的吸光度并绘制校准曲线，再将未知样品的吸光度代入曲线求浓度。

3. Enzyme Kinetics and Reaction Rates | 酶动力学与反应速率

Initial rates of reaction are obtained by following product formation (e.g., O₂ from catalase + H₂O₂) over time. Plot a progress curve and draw a tangent at time zero; the slope equals the initial rate. This eliminates errors from substrate depletion or product inhibition.

初始反应速率通过跟踪产物生成（如过氧化氢酶分解H₂O₂产氧）随时间的变化获得。绘制进度曲线，在时间零点作切线，切线斜率即为初始速率。这能消除底物耗尽或产物抑制的干扰。

When investigating temperature, measure rate at 10 °C intervals. Calculate the temperature coefficient Q₁₀ using the formula: Q₁₀ = rate at (T+10) °C / rate at T °C. A sharp drop above optimum is due to denaturation.

探究温度影响时，每隔10 °C测一次速率。用下式计算温度系数Q₁₀：Q₁

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