📚 KS3 Cambridge Biology: Formulas & Theorems Quick Reference | KS3剑桥生物公式定理速查手册
This quick reference guide brings together all the essential formulas, equations, and key principles (theorems) you must know for KS3 Cambridge Biology. Mastering these will help you tackle numerical questions, understand core concepts, and build confidence for your exams.
这本速查手册汇总了KS3剑桥生物所有必背的公式、方程和核心定理。掌握这些内容将帮助你解决计算题、理解关键概念，并为考试做好充分准备。
1. Photosynthesis Equation | 光合作用方程式
Photosynthesis is the process used by plants and algae to convert light energy into chemical energy stored in glucose. It takes place in chloroplasts and requires chlorophyll. The word equation is:
光合作用是植物和藻类将光能转化为化学能（以葡萄糖形式储存）的过程，发生在叶绿体中，需要叶绿素。其词汇方程式为：
carbon dioxide + water → glucose + oxygen
(requires light energy and chlorophyll)
二氧化碳 + 水 → 葡萄糖 + 氧气
（需要光能和叶绿素）
This reaction is endothermic, meaning it absorbs energy from sunlight. Oxygen is released as a by-product, which is essential for the respiration of most living organisms.
该反应是吸热反应，吸收太阳光能。氧气作为副产品释放，这对大多数生物的呼吸至关重要。
2. Aerobic Respiration Equation | 有氧呼吸方程式
Aerobic respiration is the process that releases energy from glucose using oxygen. It occurs continuously in the mitochondria of plant and animal cells. The word equation is:
有氧呼吸是利用氧气从葡萄糖中释放能量的过程，在动植物细胞的线粒体中不断进行。其词汇方程式为：
glucose + oxygen → carbon dioxide + water
(energy is released)
葡萄糖 + 氧气 → 二氧化碳 + 水
（释放能量）
This is an exothermic reaction; the energy released is used for cellular activities such as muscle contraction, active transport, and maintaining body temperature in mammals.
这是一个放热反应；释放的能量用于细胞活动，如肌肉收缩、主动运输以及哺乳动物维持体温。
3. Anaerobic Respiration in Animals | 动物无氧呼吸
When oxygen supply is insufficient, animal cells switch to anaerobic respiration. This produces lactic acid and a small amount of energy. The equation is:
当氧气供应不足时，动物细胞转为无氧呼吸，产生乳酸和少量能量。方程式为：
glucose → lactic acid
(energy is released)
葡萄糖 → 乳酸
（释放能量）
Lactic acid build-up can cause muscle fatigue and cramps. Once oxygen becomes available again, the lactic acid is oxidised back to carbon dioxide and water.
乳酸积累会导致肌肉疲劳和抽筋。一旦氧气重新充足，乳酸会被氧化回二氧化碳和水。
4. Anaerobic Respiration in Yeast and Plants | 酵母和植物的无氧呼吸
In yeast and some plant cells, anaerobic respiration produces ethanol and carbon dioxide instead of lactic acid. This is called fermentation. The word equation is:
在酵母和一些植物细胞中，无氧呼吸产生乙醇和二氧化碳而非乳酸，称为发酵。词汇方程式为：
glucose → ethanol + carbon dioxide
(energy is released)
葡萄糖 → 乙醇 + 二氧化碳
（释放能量）
Fermentation is exploited in the production of bread (CO₂ makes dough rise) and alcoholic drinks (ethanol). It is also an important topic in applied biology.
发酵被用于制作面包（二氧化碳使面团膨胀）和酒精饮料（乙醇）。这也是应用生物学的重要主题。
5. The Magnification Formula | 放大倍数公式
Magnification describes how much larger an image appears compared to the real object. It is calculated using the following equation:
放大倍数描述的是图像相对于实物放大了多少倍，使用以下公式计算：
Magnification = Image size ÷ Actual size
放大倍数 = 图像大小 ÷ 实际大小
Here ‘Image size’ is the size of the specimen measured on a diagram or micrograph, and ‘Actual size’ is its real-life measurement. Both must be in the same units.
“图像大小”是在图或显微照片上测得的尺寸，“实际大小”是它的真实尺寸。两者必须使用相同单位。
The formula can be rearranged to find the actual size or the image size: Image size = Magnification × Actual size and Actual size = Image size ÷ Magnification.
该公式可变形为求实际大小或图像大小：图像大小 = 放大倍数 × 实际大小，实际大小 = 图像大小 ÷ 放大倍数。
6. Using the Magnification Formula | 运用放大倍数公式
eliably, convert all lengths to the same unit, typically millimetres (mm) or micrometres (µm). A common ratio conversion is 1 mm = 1000 µm.
要可靠地运用公式，需将所有长度统一单位，常用毫米 (mm) 或微米 (µm)。常用换算关系是 1 mm = 1000 µm。
nd the actual cell is 0.005 mm, the magnification = 20 ÷ 0.005 = ×4000. Always include the ‘×’ symbol and round sensibly.
例如，一个细胞的图像长 20 mm，实际细胞长 0.005 mm，放大倍数 = 20 ÷ 0.005 = ×4000。务必带“×”符号并合理取整。
Remember the ‘ ou get Magnification × Actual size; cover Magnification, you get Image size ÷ Actual size.
记住“I AM”三角形：遮住要求的量，按显示运算。遮住图像大小得放大倍数 × 实际大小；遮住放大倍数得图像大小 ÷ 实际大小。
7. Estimating Population Size Using Quadrats | 样方法估计种群数量
To estimate the population size of stationary organisms like plants, ecologists use quadrats. The basic estimation formula is:
为了估算植物等静止生物的种群大小，生态学家使用样方。基本估算公式是：
Estimated population = (Mean number per quadrat) × (Total area ÷ Area of one quadrat)
估计种群数量 = （每样方平均个体数）×（总面积 ÷ 单个样方面积）
Random sampling and a sufficient number of quadrats improve accuracy. The mean per quadrat is obtained by counting organisms in multiple randomly placed quadrats and dividing by the number of quadrats.
随机取样并放置足够多样方可提高准确性。每样方平均个体数通过统计多个随机样方中的个体数并除以样方数量获得。
8. Capture-Recapture Method | 标记重捕法
For mobile animals, quadrats are impractical. Instead, the capture-recapture method estimates population size (N) using this formula:
对于活动性动物，样方法不适用。标记重捕法使用以下公式估计种群数量 (N)：
N = (M × C) ÷ R
种群数量 = （首次标记数 × 第二次捕获总数）÷ 第二次捕获中的标记个体数
M is the number initially caught and marked; C is the total number caught in the second sample; R is the number of marked individuals recaptured in the second sample. Assumptions include that marks are not lost and mixing is even.
M 为首次捕获并标记的个体数；C 为第二次捕获的总个体数；R 为第二次捕获中带有标记的个体数。前提假设包括标记不丢失、种群充分混合等。
9. Energy Transfer in Food Chains | 食物链中的能量传递
Energy flows through food chains from producers to consumers. At each trophic level, a large proportion of energy is lost as heat through respiration, excretion and uneaten parts. As a rule of thumb, only about 10% of energy is transferred to the next level.
能量沿着食物链从生产者流向消费者。每个营养级都有大量能量通过呼吸作用、排泄和未食部分以热能形式散失。粗略估计只有约10%的能量传递到下一级。
The efficiency of energy transfer can be expressed as:
能量传递效率可表示为：
Efficiency (%) = (Energy available to next level ÷ Energy available at current level) × 100
传递效率 (%) = （下一营养级可用能量 ÷ 当前营养级可用能量）× 100
This is why food chains rarely exceed five trophic levels and why biomass pyramids take their characteristic shape.
这就是食物链很少超过五个营养级以及生物量金字塔呈现典型形状的原因。
10. The Cell Theory | 细胞学说
The cell theory is a fundamental principle of biology. It states three key points:
细胞学说是生物学的基本原理，包含三个要点：
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 by cell division.
1. 所有生物体都由一个或多个细胞组成。
2. 细胞是生物体结构和功能的基本单位。
3. 一切细胞都通过细胞分裂来自已有的细胞。
This theory unifies the study of biology and was developed by scientists such as Schleiden, Schwann and Virchow.
该学说统一了生物学研究，由施莱登、施万和菲尔肖等科学家共同奠定。
11. Enzyme Action: Lock and Key Model | 酶作用：锁钥模型
Enzymes are biological catalysts that speed up reactions. The lock and key model explains their specificity: the active site of an enzyme has a complementary shape to its substrate, like a key fitting a lock.
酶是加速反应的生物催化剂。锁钥模型解释了其专一性：酶的活性位点具有与底物互补的形状，就像钥匙配锁。
When the substrate binds, an enzyme-substrate complex forms. The reaction occurs, products are released, and the enzyme is unchanged and can be reused.
底物结合时形成酶-底物复合物。反应发生，产物释放，酶本身不变并可再次使用。
Temperature and pH affect enzyme activity by changing the shape of the active site. If the shape is altered beyond a certain point, the enzyme denatures and loses function.
温度和 pH 通过改变活性位点的形状来影响酶活性。若形状改变过度，酶会变性失活。
12. Diffusion and Osmosis Key Principles | 扩散与渗透核心原理
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. The rate of diffusion is increased by a steeper concentration gradient, higher temperature, and larger surface area of the membrane.
扩散是粒子从高浓度区域向低浓度区域的净运动。扩散速率随浓度梯度增大、温度升高以及膜表面积增大而加快。
Osmosis is the net diffusion of water molecules across a partially permeable membrane from a region of higher water potential to a region of lower water potential (i.e. from a dilute to a more concentrated solution).
渗透是水分子通过部分透性膜从水势较高区域（稀溶液）向水势较低区域（浓溶液）的净扩散。
In plant cells, osmosis causes turgor pressure when water enters, making the cell firm. If a plant cell loses too much water, it becomes plasmolysed and wilts.
在植物细胞中，水分进入引起膨压，使细胞坚挺。如果失水过多，植物细胞发生质壁分离并萎蔫。
Published by TutorHao | Biology Revision Series | aleveler.com
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