📚 Year 8 WJEC Biology: Formula & Theorem Quick Reference Handbook | Year 8 WJEC 生物：公式定理速查手册
This quick reference handbook brings together all the essential formulas, equations and key theorems you will meet in the Year 8 WJEC Biology course. Use it to review the principles of photosynthesis, respiration, microscopy, enzymes, food tests, movement across membranes and more. Each entry is written to match the WJEC specification and is presented with a clear explanation, ready for revision and homework help.
这本速查手册汇集了你在 Year 8 WJEC 生物课程中会遇到的所有基本公式、方程式和关键定理。你可以用它来复习光合作用、呼吸作用、显微镜、酶、食物测试、跨膜运输等原理。每个条目都紧扣 WJEC 大纲编写，并配有清晰解释，方便随时翻查和复习。
1. Photosynthesis Word Equation | 光合作用文字方程式
Photosynthesis is the process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen. It takes place in chloroplasts, which contain chlorophyll. The overall word equation is shown below.
光合作用是绿色植物利用光能，将二氧化碳和水转化为葡萄糖和氧气的过程。它发生在含有叶绿素的叶绿体中。总文字方程式如下所示。
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The reaction requires light energy and chlorophyll, which can be written above the arrow. Without these conditions, photosynthesis cannot proceed. The glucose produced is used for respiration, stored as starch or used to build other substances such as cellulose.
该反应需要光能和叶绿素，这些条件可以写在箭头上方。如果没有这些条件，光合作用就无法进行。产生的葡萄糖用于呼吸作用、转化为淀粉储存或用来合成纤维素等其他物质。
2. Aerobic Respiration Word Equation | 有氧呼吸文字方程式
Aerobic respiration is the process by which cells release energy from glucose in the presence of oxygen. This energy is used for many life processes, including growth, movement and keeping warm. The equation is the reverse of photosynthesis in terms of reactants and products.
有氧呼吸是细胞在有氧气的情况下从葡萄糖中释放能量的过程。这些能量用于生长、运动和维持体温等众多生命活动。从反应物和产物的角度看，这个方程式与光合作用互为逆反应。
glucose + oxygen → carbon dioxide + water (+ energy)
葡萄糖 + 氧气 → 二氧化碳 + 水 (+ 能量)
Energy is shown in brackets because it is not a chemical substance. In humans and other animals, aerobic respiration takes place continuously in the mitochondria of cells. Carbon dioxide and water are waste products that are removed by breathing and excretion.
能量写在括号里是因为它不是一种化学物质。在人类和其他动物体内，有氧呼吸在细胞的线粒体中持续进行。二氧化碳和水是需要通过呼吸和排泄清除的废物。
3. Anaerobic Respiration Equations | 无氧呼吸方程式
When oxygen is not available, cells can carry out anaerobic respiration to release a smaller amount of energy. In humans, this produces lactic acid and causes muscle fatigue. The word equation is simpler than the aerobic one.
当没有氧气时，细胞可以进行无氧呼吸以释放较少量的能量。在人体内，这会产生乳酸并导致肌肉疲劳。文字方程式比有氧呼吸更简短。
glucose → lactic acid (+ some energy)
葡萄糖 → 乳酸 (+ 少量能量)
In plants and yeast, anaerobic respiration produces ethanol and carbon dioxide instead. This process is called fermentation and is used in baking and brewing.
在植物和酵母中，无氧呼吸会产生乙醇和二氧化碳。这一过程被称为发酵，用于烘焙和酿造。
glucose → ethanol + carbon dioxide (+ some energy)
葡萄糖 → 乙醇 + 二氧化碳 (+ 少量能量)
4. Magnification Formula | 放大倍数公式
When using a light microscope, you can calculate the magnification of an image or the real size of a specimen using the formula below. Measurements are usually given in millimetres (mm) or micrometres (µm).
使用光学显微镜时，你可以借助以下公式计算图像的放大倍数或标本的实际大小。测量单位通常用毫米（mm）或微米（µm）。
Magnification = Image size ÷ Actual size
放大倍数 = 图像大小 ÷ 实际大小
You can rearrange the formula to find the actual size: Actual size = Image size ÷ Magnification. Always check that both measurements are in the same unit before calculating. Remember that 1 mm = 1000 µm.
你可以把公式变形来求实际大小：实际大小 = 图像大小 ÷ 放大倍数。计算前务必确保两个测量值单位一致。记住 1 mm = 1000 µm。
5. Enzyme Action and Denaturation | 酶作用与变性
Enzymes are biological catalysts that speed up chemical reactions in living organisms. Each enzyme has an active site that is specific to its substrate. The general equation for an enzyme‑controlled reaction can be written as follows.
酶是生物催化剂，能加速生物体内的化学反应。每种酶都有一个与底物特异性结合的活性位点。酶促反应的一般式子可以这样表示。
substrate → enzyme → products
底物 → 酶 → 产物
Enzymes work best at an optimum temperature and pH. If the temperature rises too high or the pH changes beyond the enzyme’s tolerance, the active site changes shape and the enzyme becomes denatured. This means the substrate can no longer fit, and the reaction stops.
酶在最适温度和 pH 下活性最高。如果温度过高或 pH 超出酶的耐受范围，活性位点的形状会发生改变，酶就会变性。这意味着底物不再能与之结合，反应便停止。
6. Food Tests Summary | 食物测试总结表
We can identify key nutrients in food using specific reagents. The following table summarises the four main food tests you need to know, including the reagent, the method and the positive result expected.
我们可以使用特定试剂来鉴别食物中的关键营养素。下表总结了你需要掌握的四种主要食物测试，包括所用试剂、方法和预期的阳性结果。
| Nutrient | Reagent | Positive result |
|---|---|---|
| Starch | Iodine solution | Turns blue‑black |
| Glucose (reducing sugar) | Benedict’s solution, heat | Blue to brick‑red |
| Protein | Biuret reagent | Turns purple |
| Lipids (fats) | Ethanol, then water | Cloudy white emulsion |
Remember that a control experiment using water instead of the food sample should be carried out to show that the colour change is only due to the nutrient.
要记住，应使用水代替食物样品进行对照实验，以证明颜色变化仅由该营养素引起。
7. Digestive Enzymes | 消化酶公式
Large food molecules must be broken down into smaller, soluble molecules that can be absorbed into the blood. Digestive enzymes are produced by glands and act in specific parts of the digestive system.
大分子食物必须分解成较小的、可溶的小分子，才能被吸收进入血液。消化酶由腺体分泌，并在消化系统的特定部位发挥作用。
-
Amylase breaks down starch into maltose (and eventually glucose). It is produced in the salivary glands and pancreas and works in the mouth and small intestine.
淀粉酶将淀粉分解为麦芽糖（并最终分解为葡萄糖）。它由唾液腺和胰腺分泌，在口腔和小肠中起作用。
starch → amylase → maltose
淀粉 → 淀粉酶 → 麦芽糖
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Protease breaks down proteins into amino acids. It is produced in the stomach, pancreas and small intestine.
蛋白酶将蛋白质分解为氨基酸。它由胃、胰腺和小肠分泌。
protein → protease → amino acids
蛋白质 → 蛋白酶 → 氨基酸
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Lipase breaks down lipids (fats) into fatty acids and glycerol. It is produced in the pancreas and works in the small intestine. Bile helps by emulsifying fats, increasing the surface area for lipase action.
脂肪酶将脂肪分解为脂肪酸和甘油。它由胰腺分泌，在小肠中起作用。胆汁通过乳化脂肪，增大脂肪酶作用的表面积来辅助消化。
lipids → lipase → fatty acids + glycerol
脂肪 → 脂肪酶 → 脂肪酸 + 甘油
8. Diffusion, Osmosis and Active Transport | 扩散、渗透与主动运输
Substances move into and out of cells by three main processes. Understanding the definitions and differences between them is essential for the WJEC course.
物质进出细胞主要通过三种过程。理解它们的定义和区别对 WJEC 课程至关重要。
Diffusion is the net movement of particles from a region of high concentration to a region of low concentration until they are evenly spread. It is a passive process that does not require energy. Examples include oxygen entering blood from alveoli and carbon dioxide leaving cells.
扩散是粒子从高浓度区域向低浓度区域的净移动，直至均匀分布。这是一个不消耗能量的被动过程。例子包括氧气从肺泡进入血液以及二氧化碳离开细胞。
Osmosis is the net movement of water molecules from a region of high water concentration (dilute solution) to a region of low water concentration (concentrated solution) through a partially permeable membrane. It is also passive. Plant cells rely on osmosis to become turgid and support the plant.
渗透是水分子通过半透膜从高水浓度区域（稀溶液）向低水浓度区域（浓溶液）的净移动。这同样是被动过程。植物细胞依靠渗透变得坚挺，以支撑植物体。
Active transport is the movement of substances against the concentration gradient, from low to high concentration. It requires energy from respiration and special carrier proteins. An example is the absorption of mineral ions by root hair cells.
主动运输是物质逆浓度梯度、从低浓度向高浓度的移动。它需要呼吸作用提供的能量和特殊的载体蛋白。例如根毛细胞吸收矿物质离子。
9. The Lock and Key Model | 锁钥模型
The lock and key model is a theorem used to explain enzyme specificity. The shape of the enzyme’s active site is complementary to the shape of its substrate, just like a specific key fits into a specific lock.
锁钥模型是用来解释酶专一性的一个定理。酶活性位点的形状与其底物的形状互补，就像一把特定的钥匙只能插入特定的锁。
Once the substrate binds, an enzyme‑substrate complex is formed. The reaction takes place and the products are released, leaving the enzyme unchanged and ready to bind another substrate. This model helps us understand why denaturation stops enzyme activity: if the active site changes shape, the ‘key’ no longer fits.
底物一旦结合，就会形成酶-底物复合物。反应发生后产物被释放，酶恢复原样并可结合另一个底物。这个模型有助于理解为什么变性会使酶失活：如果活性位点形状改变，“钥匙”就不匹配了。
10. Surface Area to Volume Ratio | 表面积与体积比
The surface area to volume ratio is an important concept that explains why organisms are made of many small cells rather than just a few large ones. It also helps explain adaptations in gas exchange surfaces.
表面积与体积比是一个重要概念，它解释了为什么生物体由许多小细胞组成，而非仅由少数几个大细胞构成。它也有助于解释气体交换表面的适应性特征。
As an object gets larger, its volume increases much faster than its surface area. This means the ratio decreases. A smaller ratio makes it harder for substances to diffuse in and out quickly enough to meet demand. Cells are therefore small, and large organisms have specialised exchange surfaces (like lungs, gills, roots) with folds or flattened shapes to maximise surface area.
当物体变大时，其体积增长远快于表面积增长，导致比值下降。较小的比值使得物质难以足够快地扩散进出以满足需求。因此细胞都很小，大型生物则具有特化的交换表面（如肺、鳃、根），并借助褶皱或扁平形状使表面积最大化。
You can calculate the ratio using: Surface area to volume ratio = Surface area ÷ Volume. Simple shapes are often used for practice, such as cubes with side length 1 cm (ratio 6:1) compared with a cube of side length 2 cm (ratio 3:1).
你可以用这个公式计算比值：表面积与体积比 = 表面积 ÷ 体积。练习时常使用简单形状，比如边长为 1 cm 的立方体（比值为 6:1），与边长为 2 cm 的立方体（比值为 3:1）对比。
11. Sampling Organisms Using Quadrats | 样方抽样公式
When studying ecosystems, ecologists often need to estimate the population size of a species in a large area. Quadrats are square frames placed randomly in the habitat to sample the plants or slow‑moving animals present. A simple formula is then used to estimate the total population.
研究生态系统时，生态学家常需估算大面积区域内某一物种的种群大小。样方是随机放置在栖息地中的方形框，用来抽样调查植物或移动缓慢的动物。然后用一个简单公式估算总群体数量。
Estimated population = (Mean count per quadrat) × (Total area ÷ Area of one quadrat)
估算种群数量 = (每个样方平均计数) × (总面积 ÷ 单个样方面积)
For example, if 10 quadrats (each 0.25 m²) are placed in a 200 m² field, and the mean number of daisies per quadrat is 8, the estimated total is 8 × (200 ÷ 0.25) = 8 × 800 = 6400 daisies. Random sampling avoids bias and allows reliable conclusions to be drawn.
例如，在 200 m² 的田野中放置 10 个 0.25 m² 的样方，每个样方中雏菊的平均数量为 8，则估算总数为 8 × (200 ÷ 0.25) = 8 × 800 = 6400 株雏菊。随机抽样避免了偏差，从而得出可靠的结论。
12. Respiration and Exercise | 呼吸与运动
During exercise, muscles contract more frequently and need more energy. The rate of aerobic respiration increases, so more oxygen is required and more carbon dioxide is produced. This leads to observable changes in breathing rate and heart rate.
运动时肌肉收缩更频繁，需要更多能量。有氧呼吸速率加快，因此需要更多氧气并产生更多二氧化碳。这会导致呼吸频率和心率的可观测变化。
You may use graphs or simple calculations to compare resting and exercising pulse rates. For instance, recovery time is how long it takes for the pulse to return to its resting rate after exercise. Fitter individuals usually have a lower resting heart rate and a shorter recovery time because their circulatory and respiratory systems work more efficiently.
你可以用图表或简单计算来比较静息时和运动时的脉搏率。例如，恢复时间是指运动后脉搏恢复到静息水平所需的时间。身体更健康的人通常静息心率较低、恢复时间也更短，因为他们的循环系统和呼吸系统工作效率更高。
The balanced chemical equation for aerobic respiration (using symbols) appears later in the course, but the principle remains: glucose and oxygen are used, and carbon dioxide plus water are released. Energy is made available for contraction.
有氧呼吸的化学方程式（使用符号）会在后续课程中出现，但其原理不变：消耗葡萄糖和氧气，释放二氧化碳和水，同时为肌肉收缩提供可用能量。
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