📚 KS3 WJEC Biology: Formula & Theorem Quick Reference Handbook | KS3 WJEC 生物：公式定理速查手册
This quick reference handbook brings together the most important formulas, equations, and key principles from your KS3 WJEC Biology course. Whether you are revising for an exam or completing homework, these bite-sized summaries will help you recall essential facts fast and build a rock-solid foundation for GCSE.
本速查手册汇集了 KS3 WJEC 生物课程中最重要的公式、方程式和关键原理。无论你是在备考还是完成作业，这些简洁的总结都能帮助你快速回忆重要知识点，为 GCSE 打下坚实基础。
1. Total Magnification Equation | 总放大倍数公式
The total magnification of a light microscope tells you how many times larger an object appears compared to its real size. It is found by multiplying the power of the eyepiece lens by the power of the objective lens.
光学显微镜的总放大倍数表示物体被放大的倍数，等于目镜放大倍数乘以物镜放大倍数。
Total Magnification = Eyepiece Magnification × Objective Magnification
For example, if the eyepiece lens is 10× and the objective lens is 40×, the total magnification is 10 × 40 = 400×. This means the image you see is 400 times bigger than the actual specimen.
例如，如果目镜为 10×，物镜为 40×，那么总放大倍数为 10 × 40 = 400×，即你看到的图像比实际标本大 400 倍。
2. Rate of Enzyme-Catalysed Reactions | 酶催化反应速率
The rate of a reaction controlled by an enzyme can be worked out by measuring how quickly a substrate is used up or a product appears. A common method for amylase and starch is to time how long it takes for the iodine test to stop turning blue-black, indicating that all the starch has been broken down.
酶催化反应的速率可以通过测量底物消耗或产物出现的快慢来计算。研究淀粉酶分解淀粉时，常记录碘液不变蓝黑所需的时间，这表明所有淀粉已被分解。
Rate of Reaction (s⁻¹) = 1 ÷ Time taken (s)
If the time taken is 120 seconds, the rate is 1 ÷ 120 = 0.0083 per second. You can also calculate rate as the amount of product formed divided by time, such as volume of oxygen produced per minute in a catalase experiment.
如果用时 120 秒，速率就是 1 ÷ 120 ≈ 0.0083 每秒。你也可以用产物生成量除以时间来计算速率，比如过氧化氢酶实验中每分钟产生氧气的体积。
3. Word Equation for Photosynthesis | 光合作用文字方程式
Photosynthesis is the process plants and algae use to make their own food. It takes place inside chloroplasts and requires light energy captured by chlorophyll.
光合作用是植物和藻类制造自身养料的过程，发生在叶绿体内，需要叶绿素捕获的光能。
carbon dioxide + water → glucose + oxygen
(requires light energy and chlorophyll)
The glucose produced can be used immediately for respiration, stored as starch, or converted into other substances such as cellulose for cell walls. Oxygen is released as a by-product.
生成的葡萄糖可立即用于呼吸作用，以淀粉形式储存，或转化为纤维素等其他物质。氧气作为副产物释放到大气中。
4. Word Equation for Aerobic Respiration | 有氧呼吸文字方程式
Aerobic respiration is the process cells use to release energy from glucose in the presence of oxygen. It happens continuously in most living cells, especially in mitochondria.
有氧呼吸是细胞在有氧条件下从葡萄糖中释放能量的过程，在大多数活细胞中持续进行，尤其在线粒体中活跃。
glucose + oxygen → carbon dioxide + water (+ energy released for cellular work)
The energy released is used for activities such as muscle contraction, growth, cell division, and maintaining a constant body temperature in mammals.
释放的能量用于肌肉收缩、生长、细胞分裂以及哺乳动物的体温维持等生命活动。
5. Anaerobic Respiration Equations | 无氧呼吸方程式
When oxygen is in short supply, cells can respire anaerobically to release a smaller amount of energy quickly. The products depend on the organism.
在氧气不足时，细胞可进行无氧呼吸，快速释放少量能量，产物因生物种类而异。
In animal muscle cells during vigorous exercise:
在剧烈运动时的动物肌肉细胞中：
glucose → lactic acid (+ some energy)
Lactic acid builds up in muscles and causes fatigue and cramps. It is later broken down when oxygen becomes available again.
乳酸积累会导致肌肉疲劳和痉挛，待供氧恢复后会被分解。
In yeast and some plants:
在酵母和一些植物中：
glucose → ethanol + carbon dioxide (+ some energy)
This process is called fermentation and is used to make bread rise and produce alcoholic drinks. The carbon dioxide gas makes dough expand.
这一过程称为发酵，用于制作面包和酒精饮料。二氧化碳气体使面团膨胀。
6. Limiting Factors Law in Photosynthesis | 光合作用限制因素定律
The rate of photosynthesis is governed by the factor that is in shortest supply at any given time. Even if other conditions are ideal, a shortage of light intensity, carbon dioxide concentration, or a too low or too high temperature will limit the rate.
在任何时刻，光合作用速率都受供应最少的因素制约。即便其他条件理想，只要光照强度、二氧化碳浓度不足，或温度过低过高，都会限制速率。
As light intensity increases, the rate of photosynthesis rises until another factor becomes limiting. Similarly, raising CO₂ levels only boosts the rate up to the point where the next factor runs short. Temperature affects enzyme activity; the rate peaks at an optimum and then falls steeply as enzymes denature.
光照增强时，光合速率上升，直到另一个因素成为限制。增加 CO₂ 浓度也只能将速率提高到下个因素不足为止。温度影响酶活性，速率在最适温度达到峰值，之后酶变性导致速率急剧下降。
You can use a graph with the limiting factor on the x‑axis; the plateau indicates that another factor has become the limiting one.
你可绘制横轴为限制因素的曲线图，平台上平表明另一因素已成为限制因素。
7. 10% Energy Transfer Rule in Food Chains | 食物链中的 10% 能量传递规则
At each trophic level in a food chain, only about 10% of the energy is passed on to the next level. The rest is lost mainly through movement, heat, and undigested waste.
在食物链的每一营养级中，只有约 10% 的能量传递到下一级，其余大部分通过运动、热和未消化废物等形式散失。
Energy available at next trophic level ≈ 10% × Energy in previous level
For example, if a plant captures 10 000 kJ of light energy, a herbivore eating the plant may only gain about 1 000 kJ, and a carnivore eating the herbivore might receive around 100 kJ. This explains why food chains rarely exceed four or five links.
例如，一株植物固定了 10 000 kJ 的光能，食草动物只能获取约 1 000 kJ，而捕食该食草动物的肉食动物仅获得约 100 kJ。这就是食物链很少超过四到五级的原因。
8. Population Density Equation | 种群密度公式
Ecologists estimate population size by sampling with quadrats. The average number of individuals per quadrat is multiplied up to estimate the population per square metre or per hectare.
生态学家用样方法估计种群大小，将每个样方的平均个体数换算成每平方米或每公顷的种群密度。
Population Density (individuals/m²) = Total individuals counted ÷ (Number of quadrats × Area of one quadrat in m²)
For instance, if you throw a 1 m² quadrat 10 times and count a total of 50 daisies, the density is 50 ÷ (10 × 1) = 5 daisies per m². To estimate the total population in a field, multiply density by the field area.
例如，你抛掷 10 次 1 m² 的样方，共数到 50 株雏菊，密度为 50 ÷ (10 × 1) = 5 株/m²。要估算整片田地的种群总数，将密度乘以田地面积即可。
9. Punnett Square Probability | 庞纳特方格概率
Genetic crosses can be predicted using a Punnett square. When you cross two heterozygous parents (e.g., Bb × Bb) for a trait controlled by a single gene with dominant and recessive alleles, the offspring genotype ratios follow a predictable pattern.
遗传杂交结果可用庞纳特方格预测。若一对等位基因控制某一性状，显性杂合子（Bb × Bb）交配时，后代基因型比例遵循可预测的模式。
The dominant allele is shown with a capital letter (B = brown eyes) and the recessive with a lower-case letter (b = blue eyes).
显性等位基因用大写字母表示（如 B = 棕色眼），隐性用小写（b = 蓝色眼）。
| Gametes | B (from father) | b (from father) |
|---|---|---|
| B (from mother) | BB | Bb |
| b (from mother) | Bb | bb |
The possible offspring genotypes are BB, Bb, Bb and bb. This gives a genotypic ratio of 1 BB : 2 Bb : 1 bb. Since BB and Bb both show the dominant brown-eye phenotype, the phenotypic ratio is 3 brown : 1 blue (3/4 dominant, 1/4 recessive).
后代可能的基因型为 BB、Bb、Bb 和 bb，基因型比为 1 BB : 2 Bb : 1 bb。由于 BB 和 Bb 均表现为显性棕色眼，表现型比为 3 棕色 : 1 蓝色（显性概率 3/4，隐性概率 1/4）。
10. Key Principles: Diffusion, Osmosis and Active Transport | 扩散、渗透与主动运输的关键原理
Substances move in and out of cells by three main processes. Understanding their differences is essential for explaining everything from gas exchange to nutrient absorption.
物质出入细胞主要通过三种过程，理解它们的区别对于解释气体交换、营养吸收等现象至关重要。
| Process | Direction of Movement | Energy Required? | Membrane Needed? |
|---|---|---|---|
| Diffusion | High to low concentration | No (passive) | No (can happen in gases or liquids) |
| Osmosis | High water potential to low water potential (dilute to concentrated) | No (passive) | Partially permeable membrane required |
| Active Transport | Low to high concentration | Yes (uses ATP from respiration) | Carrier proteins in cell membrane needed |
In animals, oxygen and carbon dioxide move by diffusion in the lungs. Water enters plant roots by osmosis, and mineral ions are often taken up by active transport even when their concentration is higher inside the root cells.
动物体内，氧气和二氧化碳在肺部通过扩散移动。水分通过
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