📚 Year 9 OCR Biology: Quick Reference Handbook of Formulas and Theorems | 九年级OCR生物：公式定理速查手册
This quick reference handbook brings together the essential formulas, equations and key theorems you will encounter in the Year 9 OCR Biology course. Whether you are revising photosynthesis, respiration, enzyme action or transport processes, having these relationships at your fingertips will help you tackle exam questions with confidence. Each entry is presented in a clear, bilingual format so you can cross‑reference terminology in English and Chinese as you study.
本速查手册汇总了九年级OCR生物课程中必备的公式、方程和关键定理。无论是复习光合作用、呼吸作用、酶的作用还是物质运输过程，熟记这些关系式都能帮助你自信应对考试题目。每个条目均以清晰的双语形式呈现，便于你在学习过程中随时进行英汉术语对照。
1. Photosynthesis Equation | 光合作用总方程
Photosynthesis is the process by which green plants and some other organisms use light energy to convert carbon dioxide and water into glucose and oxygen. The balanced word and symbol equations are fundamental to understanding energy flow in ecosystems.
光合作用是绿色植物及某些其他生物利用光能，将二氧化碳和水转化为葡萄糖和氧气的过程。掌握配平的文字方程和符号方程对理解生态系统中的能量流动至关重要。
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The reaction requires light energy and chlorophyll; these are shown above the arrow in more detailed versions but are not part of the chemical equation itself. Remember that glucose may be stored as starch.
该反应需要光能和叶绿素，二者通常写在箭头上方，但不属于化学方程式本身。请注意，生成的葡萄糖可能以淀粉的形式储存。
2. Aerobic Respiration Equation | 有氧呼吸方程
Aerobic respiration occurs in the mitochondria of cells when oxygen is plentiful. It releases a large amount of energy from the breakdown of glucose, producing carbon dioxide and water as waste products.
有氧呼吸在氧气充足时发生于细胞的线粒体内。它通过分解葡萄糖释放大量能量，同时产生二氧化碳和水作为代谢废物。
glucose + oxygen → carbon dioxide + water (+ energy)
葡萄糖 + 氧气 → 二氧化碳 + 水 (+ 能量)
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
Energy is shown in parentheses because it is not a chemical substance. This equation is essentially the reverse of photosynthesis in terms of raw materials and products, illustrating the carbon-oxygen cycle.
能量写在括号中，因为它不是化学物质。这个方程在原料和产物上恰与光合作用相反，恰好体现了碳-氧循环。
3. Anaerobic Respiration Equations | 无氧呼吸方程
Anaerobic respiration occurs when oxygen is limited or absent. In animal cells and some bacteria, glucose is converted to lactic acid, while in yeast and plants, glucose is converted to ethanol and carbon dioxide. Both pathways release a small amount of energy.
无氧呼吸发生在氧气不足或缺乏时。在动物细胞和某些细菌中，葡萄糖转化为乳酸；而在酵母和植物细胞中，葡萄糖转化为酒精和二氧化碳。这两种途径都只释放少量能量。
In animals: glucose → lactic acid (+ energy)
动物体内：葡萄糖 → 乳酸 (+ 能量)
C₆H₁₂O₆ → 2C₃H₆O₃
In yeast (fermentation): glucose → ethanol + carbon dioxide (+ energy)
酵母（发酵）：葡萄糖 → 酒精 + 二氧化碳 (+ 能量)
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
Anaerobic respiration yields far fewer molecules of ATP per glucose molecule than aerobic respiration. The lactic acid build‑up in muscles causes fatigue and an oxygen debt.
无氧呼吸每分子葡萄糖产生的ATP数量远少于有氧呼吸。肌肉中乳酸的积累会引起疲劳并产生氧债。
4. Enzyme Activity and Temperature | 酶活性与温度的关系
Enzymes are protein catalysts that speed up biochemical reactions. Each enzyme has an optimum temperature at which the rate of reaction is highest. For many human enzymes this is around 37 °C, while enzymes from thermophilic bacteria may have much higher optima.
酶是加速生化反应的蛋白质催化剂。每种酶都有一个最适温度，此时反应速率最高。许多人体内酶的该温度约为37 °C，而来自嗜热细菌的酶最适温度可能高得多。
reaction rate ∝ 1 / time taken for substrate to disappear
反应速率 ∝ 1 / 底物消失所需时间
As temperature increases, molecules gain kinetic energy, leading to more frequent collisions and more enzyme-substrate complexes. However, beyond the optimum, the active site denatures (permanently changes shape) and activity drops sharply.
温度升高时，分子动能增加，碰撞更频繁，酶-底物复合物形成更快。但超过最适温度后，酶的活性部位会变性（永久改变形状），活性急剧下降。
5. Enzyme Activity and pH | 酶活性与pH的关系
pH is a measure of hydrogen ion concentration. Each enzyme works best at a specific pH, known as its optimum pH. Pepsin in the stomach works best at around pH 2, while trypsin in the small intestine works best at around pH 8.
pH是氢离子浓度的度量。每种酶都在特定的pH值下效率最高，此即最适pH值。胃蛋白酶的最适pH约为2，而小肠中的胰蛋白酶最适pH约为8。
Extreme pH values disrupt the ionic and hydrogen bonds that maintain the enzyme's three-dimensional shape, causing denaturation. The rate of reaction follows a bell‑shaped curve similar to the temperature curve.
过端的pH值会破坏维持酶三维结构的离子键和氢键，导致变性。反应速率随pH变化的曲线与温度曲线类似，呈钟形。
6. Surface Area to Volume Ratio | 表面积与体积之比
As a cell or organism increases in size, its volume increases faster than its surface area. The surface area to volume ratio (SA:V) decreases with increasing size. This limits the maximum size of a single cell and explains why large organisms require transport systems.
随着细胞或生物体体积增大，其体积的增长速度超过表面积。表面积与体积之比（SA:V）随尺寸增大而减小。这限制了单个细胞的最大尺寸，也解释了大型生物为何需要运输系统。
SA:V ratio = surface area ÷ volume
SA:V比 = 表面积 ÷ 体积
- A cube of side 1 cm: SA = 6 cm², V = 1 cm³ → SA:V = 6:1.
- 边长为1 cm的立方体：表面积=6 cm²，体积=1 cm³ → SA:V = 6:1。
- A cube of side 2 cm: SA = 24 cm², V = 8 cm³ → SA:V = 3:1.
- 边长为2 cm的立方体：表面积=24 cm²，体积=8 cm³ → SA:V = 3:1。
A high SA:V ratio allows efficient diffusion of substances across the cell membrane. This is why cells are microscopic and why exchange surfaces such as alveoli and villi have large surface areas.
较高的SA:V比使物质能够高效地扩散穿过细胞膜。这正是细胞体积微小、以及肺泡和绒毛等交换表面具有较大表面积的原因。
7. Nutrient Tests: Key Reagents and Color Changes | 营养素检验：关键试剂与颜色变化
You must be able to recall the tests for starch, reducing sugars, proteins and lipids. These are often presented as 'theorems' of expected results under given conditions.
你需要熟记淀粉、还原糖、蛋白质和脂质的检验方法，这些常被视为给定条件下的‘定理性’实验结果。
| Nutrient / 营养素 | Reagent / 试剂 | Positive result / 阳性结果 |
|---|---|---|
| Starch / 淀粉 | Iodine solution / 碘液 | Blue-black / 蓝黑色 |
| Reducing sugar / 还原糖 | Benedict's solution + heat / 班氏试剂并加热 | Brick-red precipitate / 砖红色沉淀 |
| Protein / 蛋白质 | Biuret reagent / 双缩脲试剂 | Purple / 紫色 |
| Lipids / 脂质 | Ethanol + water / 乙醇+水 | Cloudy white emulsion / 乳白色乳浊液 |
For the ethanol emulsion test, the formation of a cloudy white layer confirms the presence of lipids. The Benedict's test must be carried out in a hot water bath (>80 °C) and the color ranges from green through yellow to brick‑red depending on the concentration of sugar.
进行乙醇乳浊液检验时，出现白色浑浊层即证明脂质存在。班氏试验需在热水浴（>80 °C）中进行，颜色从绿到黄再到砖红，颜色深浅取决于糖的浓度。
8. Food Energy Content Calculation | 食物能量含量计算
The energy content of a food sample can be estimated by burning it and measuring the temperature increase of a known volume of water. This calorimetry method is a common practical skill in Year 9.
食物样品的能量含量可通过燃烧样品，测量已知体积水的温升来估算。该量热法是九年级的一项常见实验技能。
Energy (J) = mass of water (g) × 4.2 × temperature rise (°C)
能量 (J) = 水的质量 (g) × 4.2 × 温度升高值 (°C)
Energy per gram (J/g) = Energy (J) ÷ mass of food burnt (g)
每克能量 (J/g) = 能量 (J) ÷ 燃烧的食物质量 (g)
The specific heat capacity of water, 4.2 J/g°C, is a key constant. In experiments, a lot of energy is lost to the surroundings, so the result is lower than the true energy content shown on food labels.
水的比热容4.2 J/g°C是一个关键常数。实验中大量能量散失到环境中，因此测得的能量值通常低于食品标签上的真实值。
9. Osmosis and Turgor Pressure | 渗透与膨压
Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. Water potential is affected by solute concentration and pressure.
渗透是指水分子通过部分通透膜，从水势较高的区域向水势较低的区域净移动。水势受溶质浓度和压力的影响。
When a plant cell is placed in a dilute solution, water enters by osmosis, the vacuole swells and the cytoplasm pushes against the cell wall. This turgor pressure supports the plant. In a concentrated solution, water leaves the cell, the membrane pulls away from the wall (plasmolysis) and the plant wilts.
当植物细胞置于稀溶液中时，水分通过渗透进入，液泡膨胀，细胞质挤压细胞壁。这种膨压支撑了植物。在浓溶液中，水分离开细胞，质膜与细胞壁分离（质壁分离），植物发生萎蔫。
10. Diffusion and Factors Affecting Rate | 扩散及其影响因素
Diffusion is the passive net movement of particles from a region of higher concentration to a region of lower concentration. The rate of diffusion is given by Fick's law, which relates rate to surface area, concentration gradient and diffusion distance.
扩散是粒子从高浓度区域向低浓度区域的被动净移动。扩散速率可通过菲克定律描述，该定律将速率与表面积、浓度梯度和扩散距离联系起来。
Rate of diffusion ∝ (surface area × concentration difference) ÷ thickness of membrane
扩散速率 ∝ (表面积 × 浓度差) ÷ 膜厚度
- Larger surface area → faster diffusion / 表面积越大，扩散越快
- Greater concentration difference → faster diffusion / 浓度差越大，扩散越快
- Thinner exchange surface → faster diffusion / 交换面越薄，扩散越快
- Higher temperature → faster diffusion / 温度越高，扩散越快 (增加动能)
These principles explain the adaptations of alveoli, villi and gill filaments for efficient gas and nutrient exchange.
这些原理阐释了肺泡、绒毛和鳃丝为高效气体与养分交换而形成的适应性结构。
11. Active Transport | 主动运输
Active transport is the movement of molecules or ions from a region of lower concentration to a region of higher concentration (against the concentration gradient) using energy from respiration. It requires carrier proteins in the cell membrane.
主动运输是指利用呼吸作用释放的能量，将分子或离子从低浓度区域移向高浓度区域（逆浓度梯度）的过程。该过程需要细胞膜上的载体蛋白参与。
Examples include the uptake of mineral ions by root hair cells from the soil (where ion concentration is lower) and the absorption of glucose by the villi in the small intestine when the gut lumen concentration is lower than the blood.
例子包括根毛细胞从土壤中吸收矿物离子（土壤离子浓度较低），以及当肠腔葡萄糖浓度低于血液时，小肠绒毛对其的吸收。
12. Key Definitions and Theorems | 关键定义与定理
Here is a compact summary of the 'laws' and definitions that underpin the topics above. Knowing these exactly will help in command‑word questions.
以下是支撑上述主题的‘定律’与定义的简明汇总。精确掌握它们有助于解答指令词类问题。
- Enzyme specificity: The active site of an enzyme is complementary in shape to a specific substrate. / 酶的专一性：酶的活性部位在形状上与特定底物互补。
- Lock and key hypothesis: The substrate fits into the active site like a key fitting a lock. / 锁钥假说：底物嵌入活性部位，如同钥匙插入锁具。
- Denaturation: Permanent change in the shape of an enzyme's active site caused by extreme temperature or pH, leading to loss of function. / 变性：因极端温度或pH引起酶活性部位形状的永久改变，导致功能丧失。
- Limiting factor in photosynthesis: The factor (light intensity, carbon dioxide concentration or temperature) that is at the lowest level relative to the plant's needs and therefore restricts the rate. / 光合作用的限制因子：相对于植物需求处于最低水平的因子（光照强度、二氧化碳浓度或温度），因此制约着光合速率。
- Metabolism: The sum of all chemical reactions occurring in an organism. / 新陈代谢：生物体内发生的所有化学反应的总和。
Review these definitions regularly, and practice writing them out in full sentences. Linking the Chinese and English terms will deepen your understanding and prepare you for bilingual or international assessments.
定期复习这些定义，并练习用完整的句子书写。将中英文术语联系起来能加深理解，帮助你为双语或国际测评做好准备。
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