📚 Year 8 CCEA Biology Formula & Theorem Quick Reference | Year 8 CCEA 生物：公式定理速查手册
This quick reference guide collects all the essential formulas, equations and key theorems you will meet in Year 8 CCEA Biology. Use it to strengthen your understanding of photosynthesis, respiration, magnification, enzyme action and more. Each entry includes the core concept in both English and Chinese, with a clear explanation and the formula or statement you need to memorise.
本速查手册汇集了 Year 8 CCEA 生物学中的核心公式、方程和重要定理。用它来巩固你对光合作用、呼吸作用、放大倍率、酶作用等重要内容的理解。每个条目同时提供英文和中文解释，并清晰列出你需要记住的公式和定理陈述。
1. Photosynthesis Word Equation | 光合作用文字方程式
Photosynthesis is the chemical process in which green plants use light energy, absorbed by chlorophyll, to convert carbon dioxide and water into glucose and oxygen. This reaction takes place in the chloroplasts of plant cells.
光合作用是绿色植物利用叶绿素吸收的光能，将二氧化碳和水转化为葡萄糖和氧气的化学过程。该反应发生在植物细胞的叶绿体中。
The word equation for photosynthesis is easy to memorise and tells you exactly what goes in and what comes out:
光合作用的文字方程式容易记忆，它准确地说明了反应物和生成物：
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The arrow means 'gives' or 'produces' reaction to happen. In symbol form, the balanced equation is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
箭头表示“生成”，同时也提醒我们光能和叶绿素是反应发生的必要条件。用符号表示，配平后的方程式为 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。
Remember: glucose is a sugar the plant uses for energy and growth, and oxygen is released as a waste product or used in respiration.
记住：葡萄糖是植物用于提供能量和生长的糖，氧气作为废物释放，或用于呼吸作用。
2. Aerobic Respiration Equation | 有氧呼吸方程式
Aerobic respiration is the process that releases energy from glucose using oxygen. It happens continuously in the mitochondria of nearly all living cells and is the most efficient way to make energy.
有氧呼吸是利用氧气从葡萄糖中释放能量的过程。它几乎在所有活细胞的线粒体中持续进行，是产生能量最高效的方式。
The word equation summarises the overall reaction:
文字方程式总结了整个反应：
glucose + oxygen → carbon dioxide + water (+ energy)
葡萄糖 + 氧气 → 二氧化碳 + 水 (+ 能量)
the reactants of the other. The balanced chemical equation is C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.
将其与光合作用相比较：二者基本上互为逆过程，一个过程的产物正好成为另一个过程的反应物。配平后的化学方程式是 C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O。
Energy is not a chemical substance, so it is shown in brackets or simply stated as 'energy is released'. This energy is used for movement, growth, keeping warm and all other life processes.
能量不是化学物质，因此用括号表示，或直接说明“释放能量”。这些能量用于运动、生长、保温以及所有其他生命活动。
3. Anaerobic Respiration in Yeast | 酵母无氧呼吸
When oxygen is absent, yeast cells switch to anaerobic respiration. This process produces ethanol, carbon dioxide and a small amount of energy. It is a form of fermentation used in baking and brewing.
当缺乏氧气时，酵母细胞转而进行无氧呼吸。这一过程生成乙醇、二氧化碳和少量能量。这是一种用于烘焙和酿造的发酵形式。
The word equation for anaerobic respiration in yeast is different from aerobic respiration:
酵母无氧呼吸的文字方程式与有氧呼吸不同：
glucose → ethanol + carbon dioxide (+ energy)
葡萄糖 → 乙醇 + 二氧化碳 (+ 能量)
Notice that oxygen is not used, and ethanol (alcohol) is produced instead of water. The energy yield is much lower than in aerobic respiration, which is why organisms prefer oxygen when it is available.
注意此过程不使用氧气，产生的不是水而是乙醇（酒精）。其能量产量远低于有氧呼吸，这就是生物在有氧气时优先选择有氧呼吸的原因。
4. Magnification Formula (Microscope) | 放大倍率公式（显微镜）
When you look at a specimen under a microscope, the image you see is much larger than the real object. Magnification tells you how many times larger the image is compared to the actual size.
当你通过显微镜观察标本时，看到的图像比实际物体大得多。放大倍率反映的是图像尺寸相比于实际尺寸放大了多少倍。
The formula you must know is:
你必须掌握的公式是：
Magnification = Image size ÷ Actual size
放大倍率 = 图像尺寸 ÷ 实际尺寸
ze ÷ Magnification. Always make sure both sizes are in the same unit before you calculate.
你可以利用三角形法对公式进行变形：遮住你想求的项，然后将另外两项相乘或相除。例如，实际尺寸 = 图像尺寸 ÷ 放大倍率。计算前务必确保两个尺寸的单位一致。
This formula is used frequently when drawing biological diagrams, calculating cell sizes and interpreting scale bars.
这一公式在绘制生物图、计算细胞大小和解读比例尺时频繁使用。
5. Percentage Change | 百分比变化
In many experiments, such as osmosis in potato cylinders, you need to calculate a percentage change in mass or length. This allows you to compare results fairly even when starting values are different.
在许多实验中，例如土豆圆柱体的渗透实验，你需要计算质量或长度的百分比变化。这样即使初始值不同，也能公平地比较结果。
The standard formula is:
标准公式为：
Percentage Change = (Final value − Initial value) ÷ Initial value × 100%
百分比变化 =（最终值 − 初始值）÷ 初始值 × 100%
A positive answer means there was an increase; a negative answer shows a decrease. For instance, if a potato strip gains mass in water, the percentage change is positive, indicating water moved into the cells by osmosis.
正值表示增加，负值表示减少。例如，若土豆条在水中质量增加，百分比变化为正，表明水通过渗透作用进入细胞。
6. Rate of Reaction | 反应速率
When investigating how fast an enzyme works or how quickly a substance is used up, you often calculate the rate of reaction. This is particularly useful in experiments with catalase, amylase or other enzymes.
在研究酶的工作速度或物质消耗快慢时，经常需要计算反应速率。这在过氧化氢酶、淀粉酶等酶实验中尤其有用。
A simple and widely used rate formula is:
一种简单且广泛使用的速率公式是：
Rate = 1 ÷ time (in seconds)
速率 = 1 ÷ 时间（以秒为单位）
This gives a rate in 'per second' quantity ÷ time. The key point is that a steeper gradient on a graph means a faster rate.
这样得到的速率单位是“每秒”（s⁻¹）。有时你可能测量每分钟产生的气体体积或每分钟减少的质量；此时速率 = 量 ÷ 时间。关键点是，图上斜率越大，表示速率越快。
7. Enzyme Specificity – Lock and Key Model | 酶特异性——锁钥模型
Enzymes are biological catalysts that speed up reactions without being used up. The lock and key model explains why each enzyme only works on one particular substrate.
酶是生物催化剂，能加快反应速度而自身不被消耗。锁钥模型解释了为什么每种酶只作用于特定的底物。
In this model, the enzyme's active site has a specific shape. Only a substrate with a complementary shape can fit into it, just as a key fits into a specific lock. Once the substrate is bound, the reaction takes place and products are released, leaving the enzyme unchanged.
该模型中，酶的活性部位具有特定形状。只有形状互补的底物才能嵌入，正如一把钥匙只能插入特定的锁。底物结合后，反应发生并释放产物，酶本身保持不变。
This theorem is crucial for understanding factors that affect enzyme activity, such as temperature and pH. If the active site changes shape (denatures), the key no longer fits and the reaction stops.
这一理论对于理解影响酶活性的因素（如温度和 pH）至关重要。如果活性部位形状改变（变性），钥匙就不再匹配，反应随之停止。
8. Surface Area to Volume Ratio and Diffusion | 表面积与体积比及扩散
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration. The rate of diffusion is strongly affected by the surface area to volume ratio (SA:V).
扩散是粒子从高浓度区域向低浓度区域的净移动。扩散速率受表面积与体积比 (SA:V) 的强烈影响。
The relationship can be expressed as:
该关系可表示为：
SA:V ratio = Surface area ÷ Volume
表面积与体积比 = 表面积 ÷ 体积
Small objects, such as bacteria or small cubes, have a large SA:V ratio, which means they can exchange materials with their surroundings very efficiently. As an organism gets larger, its SA:V ratio decreases, making simple diffusion too slow to meet its needs.
小物体，例如细菌或小立方体，具有大的 SA:V 比，这意味着它们能非常高效地与周围环境交换物质。随着生物体积增大，其 SA:V 比下降，使得简单扩散太慢，无法满足需求。
This principle explains why large multicellular organisms need specialised exchange surfaces like lungs, gills and transport systems.
这一原理解释了为什么大型多细胞生物需要专门的交换表面，例如肺、鳃和运输系统。
9. Cell Theory | 细胞学说
Cell theory is one of the foundation stones of biology. It states three fundamental truths about living things:
细胞学说是生物学的基石之一。它提出了有关生物的三条基本论断：
1. All living organisms are composed of one or more cells.
2. The cell is the basic unit of structure and function in living things.
3. All cells arise from pre-existing cells.
1. 所有生物体都由一个或多个细胞组成。
2. 细胞是生物体结构与功能的基本单位。
3. 所有细胞都来自原先已存在的细胞。
This theorem emerged from the work of scientists like Schwann, Schleiden and Virchow. It helps you understand why we study cells so intensively – everything that makes an organism alive happens inside its cells.
这一学说是基于施万、施莱登和微尔肖等科学家的研究而形成的。它帮你理解为什么我们要如此深入地研究细胞——使生物具有生命力的一切过程都发生在细胞内部。
10. Food Chain Energy Transfer Rule | 食物链能量传递规则
Energy is transferred along food chains from producers to consumers, but not all of the energy is passed on. A widely used rule of thumb is the 10% rule.
能量沿着食物链从生产者传递到消费者，但并非所有能量都传递下去。一个广泛使用的经验法则是 10% 规则。
Only about 10% of the energy in one trophic level is converted into biomass in the next level. The rest is lost through movement, heat, respiration, undigested material and waste.
一个营养级中只有大约 10% 的能量转化为下一级的生物量。其余能量因运动、散热、呼吸、未消化物质和废物而损失。
This principle explains why food chains rarely have more than four or five trophic levels and why there are far fewer top predators than producers in an ecosystem.
这一原理说明了为什么食物链很少超过四到五个营养级，以及为什么生态系统中顶级捕食者的数量远少于生产者。
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