📚 GCSE OCR Combined Science: End-of-Year Revision Guide | GCSE OCR 科学：期末复习提纲
Welcome to your comprehensive end-of-year revision guide for GCSE OCR Combined Science. This article summarises the key concepts from Biology, Chemistry and Physics, helping you focus your revision efficiently. Use the paired notes to review essential knowledge and test yourself as you prepare for the exams.
欢迎阅读 GCSE OCR 科学期末综合复习提纲。本文总结了生物学、化学和物理学的核心概念，旨在帮助你高效复习。在备考过程中，利用中英对照要点来回顾必备知识，并进行自我检测。
1. Cell Biology & Microscopy | 细胞生物学与显微镜
All living organisms are made of cells, the basic structural and functional units of life. Eukaryotic cells, such as animal and plant cells, have a membrane-bound nucleus containing DNA, while prokaryotic cells, like bacteria, lack a true nucleus and have a single circular chromosome.
所有生物体都由细胞构成，细胞是生命的基本结构和功能单位。真核细胞（如动物和植物细胞）具有膜包裹的细胞核，其中含有DNA；而原核细胞（如细菌）没有真正的细胞核，只含有一条环状染色体。
Animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a rigid cell wall, a large permanent vacuole and chloroplasts for photosynthesis.
动物细胞包含细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞还拥有坚硬的细胞壁、一个大型中央液泡以及用于光合作用的叶绿体。
A light microscope uses lenses to magnify specimens. Total magnification = eyepiece lens magnification × objective lens magnification. The formula magnification = image size ÷ actual object size is essential for converting measurements.
光学显微镜利用透镜放大样本。总放大倍数 = 目镜放大倍数 × 物镜放大倍数。公式“放大倍数 = 图像大小 ÷ 实际物体大小”对于单位换算至关重要。
Stem cells are undifferentiated cells that can divide to produce more stem cells or specialised cells. In animals, embryonic and adult stem cells are used in medicine; in plants, meristems enable continuous growth.
干细胞是未分化的细胞，能够分裂产生更多干细胞或特化细胞。在动物中，胚胎干细胞和成体干细胞应用于医学领域；植物中的分生组织则保证了持续生长。
2. Organisation & Enzyme Action | 组织与酶的作用
Living organisms are organised in increasing complexity: cells form tissues, tissues form organs, and organs make up organ systems. The digestive system is an example that breaks down food into absorbable molecules.
生物体按复杂度递增的顺序组织：细胞构成组织，组织构成器官，器官构成器官系统。消化系统就是一个将食物分解为可吸收分子的例子。
Enzymes are biological catalysts that speed up metabolic reactions without being consumed. They are proteins with an active site of a specific shape. The “lock and key” model explains how a substrate fits into the active site.
酶是加快代谢反应速度的生物催化剂，自身不被消耗。它们是由特定形状活性位点的蛋白质。”锁与钥匙”模型解释了底物如何与活性位点契合。
Amylase breaks down starch into maltose in the mouth and small intestine and works best at pH 7. Pepsin digests protein in the acidic stomach (optimum pH 2), while lipase breaks down lipids into glycerol and fatty acids, aided by bile which emulsifies fats.
淀粉酶在口腔和小肠将淀粉分解为麦芽糖，最适pH为7。胃蛋白酶在酸性胃液中消化蛋白质（最适pH 2），而脂肪酶将脂质分解为甘油和脂肪酸，胆汁则通过乳化脂肪辅助其作用。
Factors affecting enzyme activity include temperature and pH. Extremes can denature the enzyme, causing the active site to lose its shape permanently, so the substrate can no longer bind.
影响酶活性的因素包括温度和酸碱度。极端的温度或pH会使酶变性，导致活性位点永久变形，底物便无法结合。
3. Infectious Disease & Immunity | 传染病与免疫
Pathogens, including bacteria, viruses, fungi and protists, cause infectious diseases. They can be spread through direct contact, air, water or vectors. Viral diseases like measles and HIV damage cells, while bacterial diseases like Salmonella and gonorrhoea rely on toxins.
病原体包括细菌、病毒、真菌和原生生物，可引起传染病。它们可通过直接接触、空气、水或媒介生物传播。麻疹和HIV等病毒性疾病会损伤细胞，而沙门氏菌和淋病等细菌性疾病则依赖毒素。
The body’s first lines of defence include skin, nose hairs, mucus and stomach acid. If pathogens enter, the immune system responds: white blood cells engulf pathogens (phagocytosis), produce antitoxins, and generate antibodies specific to antigens on the pathogen.
人体的第一道防线包括皮肤、鼻毛、黏液和胃酸。若病原体侵入，免疫系统会作出反应：白细胞吞噬病原体、产生抗毒素，并针对病原体表面的抗原制造特异性抗体。
Vaccination introduces a harmless form of the pathogen, triggering antibody production and memory cells. This provides rapid response upon future exposure, preventing illness. Antibiotics kill bacteria but do not work against viruses.
疫苗接种引入无毒害的病原体形式，刺激抗体产生和记忆细胞形成。这使得身体在将来遇到同种病原体时能快速反应，从而预防疾病。抗生素能杀死细菌，但对病毒无效。
Antibiotic resistance arises when bacteria mutate and survive treatment; these resistant strains multiply, making infections harder to treat. Overuse of antibiotics accelerates this problem.
当细菌发生突变并在治疗中存活时，便产生抗生素耐药性；这些耐药菌株会繁殖，使感染更难治疗。抗生素的过度使用加速了这一问题。
4. Bioenergetics: Photosynthesis & Respiration | 生物能量学：光合与呼吸
Photosynthesis is the process by which green plants and algae convert light energy into chemical energy in glucose. The word equation is: carbon dioxide + water → glucose + oxygen, taking place in chloroplasts containing chlorophyll.
光合作用是绿色植物和藻类将光能转变为葡萄糖内化学能的过程。文字方程式为：二氧化碳 + 水 → 葡萄糖 + 氧气，该过程在含有叶绿素的叶绿体中进行。
The balanced symbol equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Light intensity, carbon dioxide concentration and temperature all affect the rate; a limiting factor will restrict photosynthesis until it is increased.
配平的化学方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。光照强度、二氧化碳浓度和温度均影响速率；任何限制因素都会制约光合作用，直到该因素被提高。
Aerobic respiration occurs in mitochondria and releases energy from glucose using oxygen: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy). The energy is used for muscle contraction, active transport and keeping warm.
有氧呼吸发生在线粒体中，利用氧气从葡萄糖中释放能量：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O（+ 能量）。这些能量用于肌肉收缩、主动运输和维持体温。
Anaerobic respiration in animals produces lactic acid, causing muscle fatigue. In plants and yeast, it produces ethanol and carbon dioxide (fermentation). Anaerobic respiration yields much less energy than aerobic respiration.
动物体内的无氧呼吸产生乳酸，导致肌肉疲劳。在植物和酵母中，无氧呼吸产生乙醇和二氧化碳（发酵）。无氧呼吸释放的能量远少于有氧呼吸。
5. Atomic Structure & The Periodic Table | 原子结构与元素周期表
Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. Protons have a positive charge, electrons are negative, and neutrons are neutral. The atomic number equals the number of protons, defining the element.
原子由包含质子和中子的原子核及核外分层排布的电子组成。质子带正电，电子带负电，中子不带电。原子序数等于质子数，决定了元素的种类。
Mass number = protons + neutrons. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Electrons fill shells following the pattern 2, 8, 8, 2 for the first 20 elements.
质量数 = 质子数 + 中子数。同位素是同种元素中质子数相同而中子数不同的原子。前20号元素的电子按2,8,8,2的规律填充各电子层。
The periodic table arranges elements in order of increasing atomic number. Groups (vertical columns) contain elements with similar properties because they have the same number of outer-shell electrons. Periods (horizontal rows) show the number of electron shells.
元素周期表中元素按原子序数递增排列。族（纵列）的元素因最外层电子数相同而具有相似的化学性质。周期（横行）反映了电子层数。
Metals are on the left and centre, losing electrons to form positive ions, while non-metals are on the right, gaining electrons to form negative ions. Transition metals are in the centre and form coloured compounds.
金属位于左侧和中部，失去电子形成阳离子；非金属位于右侧，得到电子形成阴离子。过渡金属处于周期表中部，常形成有色化合物。
6. Structure, Bonding & Properties | 结构、键合与性质
Ionic bonding occurs between a metal and a non-metal, where electrons are transferred. The metal loses electrons to form a positive cation, and the non-metal gains electrons to form a negative anion. Giant ionic lattices have high melting points and conduct electricity when molten or dissolved.
离子键形成于金属与非金属之间，涉及电子转移。金属失去电子形成阳离子，非金属得到电子形成阴离子。巨型离子晶格熔点高，且在熔融或溶于水时能导电。
Covalent bonding involves the sharing of electron pairs between non-metal atoms. Simple molecular substances like water and carbon dioxide have low melting points and do not conduct electricity because they have weak intermolecular forces.
共价键涉及非金属原子间共享电子对。水、二氧化碳等简单分子物质因分子间作用力较弱，熔沸点较低，且不能导电。
Giant covalent structures, such as diamond, graphite and silicon dioxide, have very high melting points. Graphite conducts electricity thanks to delocalised electrons between layers, whereas diamond is hard and an electrical insulator.
金刚石、石墨和二氧化硅等巨型共价结构熔沸点极高。石墨因层间有离域电子而能导电，而金刚石坚硬且不导电。
Metallic bonding consists of positive metal ions surrounded by a “sea” of delocalised electrons. This structure allows metals to be malleable, ductile, and good conductors of heat and electricity.
金属键由正金属离子和包围它们的离域电子”海”构成。这种结构赋予金属延展性、可塑性以及良好的导热和导电性。
7. Quantitative Chemistry & Moles | 定量化学与摩尔
The relative atomic mass (Aᵣ) is the average mass of an atom of an element compared to 1/12 of the mass of a carbon‑12 atom. Relative formula mass (Mᵣ) is the sum of Aᵣ values for all atoms in a formula unit.
相对原子质量（Aᵣ）是一个元素的原子平均质量相对于碳-12原子质量的1/12的比值。相对式量（Mᵣ）是化学式单元中所有原子Aᵣ值的总和。
One mole of a substance contains 6.02 × 10²³ particles and has a mass equal to its Mᵣ in grams. The number of moles = mass (g) ÷ Mᵣ. This relationship is fundamental to balanced equations and reacting mass calculations.
一摩尔物质含有6.02×10²³个微粒，其质量以克为单位等于其Mᵣ值。摩尔数 = 质量(g) ÷ Mᵣ。这一关系是配平方程式及反应质量计算的基础。
In a balanced chemical equation, the ratios of moles give the proportions of reactants and products. Limiting reactants control the maximum amount of product. Concentration in mol/dm³ = amount of solute (mol) ÷ volume (dm³).
配平的化学方程式中，摩尔比例表示了反应物与生成物的数量关系。限量反应物决定了产物的最大量。浓度( mol/dm³ ) = 溶质的摩尔数 ÷ 溶液的体积( dm³ )。
Percentage yield = (actual mass of product ÷ theoretical mass) × 100. Atom economy = (Mᵣ of desired product ÷ sum of Mᵣ of all reactants) × 100, assessing the efficiency of a reaction.
产率 = (实际产量 ÷ 理论产量) × 100。原子经济性 = (目标产物的Mᵣ ÷ 所有反应物Mᵣ之和) × 100，用于评估反应的效率。
8. Energy Changes & Reaction Rates | 能量变化与反应速率
Exothermic reactions transfer energy to the surroundings, typically raising the temperature, e.g. combustion and neutralisation. Endothermic reactions absorb energy, e.g. thermal decomposition and photosynthesis.
放热反应向环境释放能量，通常使温度升高，如燃烧和中和反应。吸热反应从环境吸收能量，如热分解和光合作用。
Reaction profiles show the energy of reactants and products. The activation energy (Eₐ) is the minimum energy particles need to collide successfully. Catalysts provide an alternative pathway with a lower Eₐ, increasing the rate without being used up.
反应剖面图展示了反应物和生成物的能量。活化能（Eₐ）是粒子发生有效碰撞所需的最低能量。催化剂提供一条活化能较低的替代路径，从而提高反应速率，而自身不被消耗。
Rate of reaction = quantity of reactant used or product formed ÷ time. According to collision theory, reactions occur when particles collide with sufficient energy and correct orientation. Increasing concentration, pressure, surface area or temperature increases collision frequency or energy.
反应速率 = 反应物消耗量或生成物产生量 ÷ 时间。根据碰撞理论，反应发生时粒子必须以足够的能量和正确的取向发生碰撞。增大浓度、压强、表面积或温度可提高碰撞频率或能量。
The mean rate can be deduced from the gradient of a graph of amount against time. A steeper gradient indicates a faster rate; the curve flattens when the limiting reactant is used up.
平均速率可由反应量-时间曲线的斜率求得。斜率越大，速率越快；当限量反应物耗尽时，曲线趋于平缓。
9. Motion & Forces | 运动与力
Scalar quantities have magnitude only, e.g. speed, distance, mass. Vector quantities have both magnitude and direction, e.g. velocity, displacement, force. Speed = distance ÷ time; velocity is speed in a stated direction.
标量只有大小，如速率、距离、质量。矢量既有大小又有方向，如速度、位移、力。速率 = 距离 ÷ 时间；速度是带有方向的速率。
Acceleration is the rate of change of velocity: a = (v – u) ÷ t, where v is final velocity, u is initial velocity, and t is time. On a distance–time graph, the gradient represents speed; on a velocity–time graph, the gradient gives acceleration and the area under the graph gives displacement.
加速度是速度变化的快慢：a = (v – u) ÷ t，其中v为末速度，u为初速度，t为时间。在距离-时间图上，斜率代表速率；在速度-时间图上，斜率代表加速度，曲线下的面积代表位移。
Newton’s Second Law states F = ma (resultant force = mass × acceleration). Inertia is the tendency of an object to resist changes in motion. Stopping distance = thinking distance + braking distance, affected by speed, mass, road conditions and driver distractions.
牛顿第二定律指出F = ma（合力 = 质量 × 加速度）。惯性是物体抵抗运动状态改变的性质。停车距离 = 反应距离 + 制动距离，受车速、质量、路况和驾驶员注意力等因素影响。
Work done = force × distance moved in the direction of the force. Energy transferred is equal to work done. Springs obey Hooke’s Law: extension is proportional to applied force, F = kx, up to the limit of proportionality.
功 = 力 × 沿力方向移动的距离。能量转移量等于做功大小。弹簧遵循胡克定律：在弹性限度内，伸长量与施加的力成正比，F = kx。
10. Energy & Electricity | 能量与电学
Energy is stored in various forms including kinetic, gravitational potential, thermal, chemical and nuclear. The law of conservation of energy states that energy cannot be created or destroyed, only transferred between stores.
能量可以储存为多种形式，如动能、重力势能、热能、化学能和核能。能量守恒定律指出，能量不能被创造或消灭，只能在不同的储能库之间转移。
In electrical circuits, current (I) is the flow of charge, measured in amperes; potential difference (V) drives the current, measured in volts; resistance (R) opposes the current, measured in ohms. Ohm’s Law: V = IR.
在电路中，电流（I）是电荷的流动，单位为安培；电势差（V）驱动电流，单位为伏特；电阻（R）阻碍电流，单位为欧姆。欧姆定律：V = IR。
Series circuits have a single path; total resistance is the sum of individual resistances. Parallel circuits offer multiple branches, and the total resistance is less than the smallest individual resistance. Components like LDRs and thermistors alter resistance with light intensity and temperature.
串联电路只有一条回路，总电阻为各电阻之和。并联电路有多条支路，总电阻小于最小分支电阻。光敏电阻和热敏电阻等元件的阻值随光照强度或温度变化而变化。
Power (P) = IV = I²R = V²/R. Energy transferred (E) = P × t = IV × t. In the home, mains electricity is alternating current (a.c.) at 230 V, and safety features include fuses, circuit breakers and earthing.
电功率 P = IV = I²R = V²/R。转移能量 E = P × t = IV × t。家庭电路使用230V交流电，安全设施包括保险丝、断路器和接地保护。
11. Waves & Electromagnetism | 波与电磁
Waves transfer energy without transferring matter. Transverse waves (e.g. light, water waves) have oscillations perpendicular to the direction of energy transfer; longitudinal waves (e.g. sound) have oscillations parallel to the direction.
波传递能量而不传递物质。横波（如光波、水波）的振动方向与能量传播方向垂直；纵波（如声波）的振动方向与能量传播方向平行。
Key wave parameters: amplitude (maximum displacement from rest), wavelength (λ, distance between adjacent peaks), frequency (f, number of waves per second) and period (T = 1/f). The wave equation is v = f λ.
波的关键参数：振幅（偏离平衡位置的最大位移）、波长（λ，相邻波峰间的距离）、频率（f，每秒的波数）以及周期（T = 1/f）。波速公式为 v = f λ。
The electromagnetic spectrum is a continuum of transverse waves, in order of increasing frequency/decreasing wavelength: radio, microwaves, infrared, visible light, ultraviolet, X‑rays and gamma rays. All travel at the same speed in a vacuum (3 × 10⁸ m/s).
电磁波谱是一系列连续的横波，按频率递增、波长递减的顺序排列：无线电波、微波、红外线、可见光、紫外线、X射线和伽马射线。它们在真空中的传播速度相同，均为3×10⁸米/秒。
Different EM waves have different uses based on their penetrating power and energy. Radio waves are used for broadcasting, X‑rays for medical imaging, and gamma rays for sterilising and cancer treatment. Over‑exposure to ionising radiation can damage cells and cause mutations.
不同波段的电磁波因其穿透能力和能量而被用于不同用途：无线电波用于广播，X射线用于医学成像，伽马射线用于灭菌和癌症治疗。过度暴露于电离辐射会损伤细胞并诱发突变。
12. Radioactivity & Nuclear Physics | 放射性衰变与核物理
Some atomic nuclei are unstable and emit radiation to become more stable. Alpha particles (α) are helium nuclei (2 protons + 2 neutrons), beta particles (β) are high‑speed electrons, and gamma rays (γ) are electromagnetic waves.
某些原子核不稳定，通过发射辐射变得更稳定。α粒子是氦核（2个质子+2个中子），β粒子是
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