📚 Edexcel Combined Science (088) Revision: Key Concepts | Edexcel 综合科学 (088) 复习：核心概念
Welcome to the ultimate revision guide for Edexcel International GCSE Combined Science (088). This article consolidates the most important ideas across biology, chemistry and physics, helping you master the concepts that frequently appear in Papers 1 and 2. We break down each topic into clear, bilingual explanations so you can strengthen your scientific vocabulary in both English and Chinese while preparing for your exams.
欢迎使用 Edexcel International GCSE 综合科学 (088) 终极复习指南。本文整合了生物、化学和物理中最关键的知识点，帮助你掌握试卷一和试卷二中频繁出现的核心概念。我们将每个主题拆解成清晰的中英双语讲解，让你在备考的同时，巩固中英文科学术语。
1. Cell Structure and Function | 细胞结构与功能
All living organisms are made of cells. Animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes, while plant cells additionally possess a cell wall, a large permanent vacuole and chloroplasts. The nucleus controls cell activities and stores genetic material; mitochondria are the site of aerobic respiration, releasing energy. Ribosomes synthesise proteins, and the cell membrane controls the passage of substances in and out of the cell.
所有生命体都由细胞构成。动物细胞包含细胞核、细胞质、细胞膜、线粒体和核糖体，而植物细胞还拥有细胞壁、一个大液泡和叶绿体。细胞核控制细胞活动并储存遗传物质；线粒体是有氧呼吸的场所，释放能量。核糖体合成蛋白质，细胞膜控制物质进出。
- Plant cells have a cellulose cell wall for support; animal cells do not.
植物细胞有纤维素细胞壁提供支持；动物细胞没有。 - Chloroplasts absorb light energy for photosynthesis.
叶绿体吸收光能进行光合作用。
Key Equation:
magnification = image size ÷ actual size
放大倍数 = 图像大小 ÷ 实际大小
2. Atomic Structure and Bonding | 原子结构与化学键
Atoms consist of protons, neutrons and electrons. Protons carry a positive charge, neutrons are neutral, and electrons are negative. The atomic number equals the number of protons; the mass number is the sum of protons and neutrons. Electrons occupy shells around the nucleus, with the first shell holding up to 2 electrons and the second holding up to 8. Ionic bonding occurs when metals transfer electrons to non‑metals, forming oppositely charged ions that attract. Covalent bonding results from the sharing of electron pairs between non‑metal atoms.
原子由质子、中子和电子组成。质子带正电，中子不带电，电子带负电。原子序数等于质子数；质量数是质子数与中子数之和。电子占据原子核外的壳层，第一层最多容纳2个电子，第二层最多容纳8个。离子键形成于金属把电子转移给非金属时，产生带相反电荷的离子相互吸引。共价键是非金属原子之间共享电子对的结果。
Example: Sodium chloride (NaCl) forms when sodium donates one electron to chlorine, creating Na⁺ and Cl⁻ ions.
例子：氯化钠 (NaCl) 的形成是钠将一个电子给氯，产生 Na⁺ 和 Cl⁻ 离子。
3. Forces and Motion | 力与运动
A force can change an object's speed, direction or shape. Newton' leration: force = mass × acceleration (F = m × a). Weight is the force of gravity on an object, calculated as weight = mass × gravitational field strength (W = m × g). On Earth, g ≈ 10 N/kg.
力可以改变物体的速度、方向或形状。牛顿第一定律指出，除非受到合外力作用，物体将保持静止或匀速直线运动。第二定律把力、质量和加速度联系起来：力 = 质量 × 加速度 (F = m × a)。重力是地球对物体的引力，计算公式为重力 = 质量 × 重力场强度 (W = m × g)。在地球上，g ≈ 10 N/kg。
F = m × a W = m × g
For terminal velocity, when air resistance equals weight, the resultant force is zero and the object falls at constant speed.
当空气阻力等于重力时，达到终极速度，合外力为零，物体匀速下落。
4. States of Matter and Mixtures | 物质状态与混合物
Substances exist as solid, liquid or gas. Solids have a fixed shape and volume because particles vibrate in fixed positions. Liquids have a fixed volume but take the shape of their container; particles can move past each other. Gases have no fixed shape or volume; particles move rapidly in all directions. Changes of state are physical changes: melting, boiling, condensing and freezing. A mixture consists of two or more substances not chemically combined, which can be separated by techniques such as filtration, distillation, chromatography or crystallisation.
物质以固态、液态或气态存在。固体有固定的形状和体积，因为粒子在固定位置振动。液体有固定体积但形状随容器而变；粒子可以相互滑动。气体没有固定形状或体积；粒子向各个方向快速运动。状态变化是物理变化：熔化、沸腾、冷凝和凝固。混合物由两种或以上未发生化学结合的物质组成，可通过过滤、蒸馏、色谱法或结晶等方法分离。
| Separation Technique | 分离方法 | Used for |
|---|---|---|
| Filtration | 过滤 | Insoluble solid from liquid |
| Simple distillation | 简单蒸馏 | Liquid from a solution |
| Chromatography | 色谱法 | Separating dissolved substances |
5. Photosynthesis and Respiration | 光合作用与呼吸作用
ophyll. The word equation is: carbon dioxide + water → glucose + oxygen. This endothermic reaction stores energy in glucose. Aerobic respiration releases energy from glucose using oxygen: glucose + oxygen → carbon dioxide + water (+ energy). Anaerobic respiration in animals produces lactic acid, while in yeast it produces ethanol and carbon dioxide.
光合作用是绿色植物利用叶绿素吸收的光能，从二氧化碳和水制造葡萄糖和氧气的过程。文字方程式：二氧化碳 + 水 → 葡萄糖 + 氧气。该吸热反应将能量储存在葡萄糖中。有氧呼吸利用氧气从葡萄糖中释放能量：葡萄糖 + 氧气 → 二氧化碳 + 水 (+ 能量)。动物体内的无氧呼吸产生乳酸，而酵母则产生乙醇和二氧化碳。
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂ (photosynthesis)
Factors affecting photosynthesis: light intensity, carbon dioxide concentration and temperature.
影响光合作用的因素：光照强度、二氧化碳浓度和温度。
6. Chemical Reactions and Energy Changes | 化学反应与能量变化
During a chemical reaction, atoms are rearranged to form new substances. The total mass is conserved. Exothermic reactions transfer energy to the surroundings, causing a rise in temperature, e.g. combustion and neutralisation. Endothermic reactions absorb energy from the surroundings, causing a temperature drop, e.g. thermal decomposition and photosynthesis. Reaction profiles show the energy changes, with activation energy being the minimum energy required to start a reaction.
在化学反应中，原子重新排列生成新的物质。总质量守恒。放热反应将能量传递给周围环境，使温度升高，如燃烧和中和反应。吸热反应从周围环境吸收能量，使温度降低，如热分解和光合作用。反应剖面图展示能量变化，活化能是启动反应所需的最低能量。
Bond breaking is endothermic; bond making is exothermic.
断裂化学键是吸热过程；形成化学键是放热过程。
7. Waves and the Electromagnetic Spectrum | 波与电磁波谱
ion of energy transfer. Longitudinal waves (e.g. sound) have oscillations parallel to the direction of energy transfer. The wave equation links speed (v), frequency (f) and wavelength (λ): v = f × λ. The electromagnetic spectrum, in order of decreasing wavelength, includes radio waves, microwaves, infrared, visible light, ultraviolet, X‑rays and gamma rays. All travel at 3 × 10⁸ m/s in a vacuum.
波传递能量而不传递物质。横波（如光、水波）的振动方向与能量传递方向垂直。纵波（如声波）的振动方向与能量传递方向平行。波速公式将速度 (v)、频率 (f) 和波长 (λ) 联系起来：v = f × λ。电磁波谱按波长递减排列，包括无线电波、微波、红外线、可见光、紫外线、X射线和伽马射线。所有电磁波在真空中传播速度均为 3 × 10⁸ m/s。
v = f × λ
All electromagnetic waves can be reflected and refracted.
所有电磁波都能被反射和折射。
8. Genetics and Evolution | 遗传与进化
Genes are segments of DNA that code for specific proteins. Each gene occupies a particular locus on a chromosome. Humans have 23 pairs of chromosomes in body cells; gametes contain 23 single chromosomes. Alleles are different forms of the same gene. A dominant allele masks the effect of a recessive allele. Natural selection explains how organisms with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation. Over time, this can lead to evolution of new species.
基因是编码特定蛋白质的 DNA 片段。每个基因位于染色体的特定位置上。人体细胞有23对染色体；配子含有23条单条染色体。等位基因是同一基因的不同形式。显性等位基因掩盖隐性等位基因的效应。自然选择解释了具有有利性状的生物更可能生存繁衍，并将这些性状传递给下一代。久而久之，这可能导致新物种的进化。
Monohybrid cross: crossing two heterozygous parents (Tt × Tt) gives a 3:1 phenotype ratio.
单基因杂交：两个杂合亲本 (Tt × Tt) 杂交，表型比例为3:1。
9. Acids, Bases and Salts | 酸、碱与盐
; alkalis are soluble bases that release OH⁻ ions in water. The pH scale measures acidity: values less than 7 are acidic, 7 is neutral, greater than 7 are alkaline. When an acid reacts with a base, a salt and water are formed (neutralisation). For example: hydrochloric acid + sodium hydroxide → sodium chloride + water.
酸是质子 (H⁺) 给予体。常见酸包括盐酸 (HCl)、硫酸 (H₂SO₄) 和硝酸 (HNO₃)。碱能中和酸；可溶性碱在水中释放 OH⁻ 离子，称为碱溶液。pH 标度衡量酸碱度：小于7为酸性，等于7为中性，大于7为碱性。酸与碱反应生成盐和水（中和反应）。例如：盐酸 + 氢氧化钠 → 氯化钠 + 水。
HCl + NaOH → NaCl + H₂O
Metal carbonates react with acids to produce a salt, water and carbon dioxide gas.
金属碳酸盐与酸反应生成盐、水和二氧化碳气体。
10. Electricity and Magnetism | 电与磁
e. In a metallic conductor, free electrons move. Current (I) is measured in amperes (A), voltage (V) in volts (V), resistance (R) in ohms (Ω). Ohm' s, current is the same everywhere; in parallel circuits, the voltage across each branch is equal. Electromagnets are created when an electric current flows through a coil of wire, producing a magnetic field. The motor effect explains how a current‑carrying wire experiences a force in a magnetic field.
电流是电荷的流动。在金属导体中，自由电子移动。电流 (I) 以安培 (A) 为单位，电压 (V) 以伏特 (V) 为单位，电阻 (R) 以欧姆 (Ω) 为单位。欧姆定律指出 V = I × R。串联电路中电流处处相等；并联电路中各支路电压相等。当电流通过线圈时会产生电磁铁，形成磁场。电动机效应解释了通电导线在磁场中受到力的原理。
V = I × R
Power (P) is the rate of energy transfer: P = I × V.
功率 (P) 是能量传递的速率：P = I × V。
11. Homeostasis and Coordination | 稳态与协调
Homeostasis maintains a constant internal environment. The body regulates temperature through sweating, shivering and altering blood flow to the skin. Blood glucose is controlled by insulin (lowers glucose) and glucagon (raises glucose). The nervous system uses electrical impulses along neurones; at synapses, chemicals transmit signals. Hormones are chemical messengers transported in the blood, producing slower but longer‑lasting responses. The eye focuses light by changing the shape of the lens (accommodation).
稳态维持内环境的稳定。身体通过出汗、发抖和改变皮肤血流量来调节体温。血糖由胰岛素（降低血糖）和胰高血糖素（升高血糖）调控。神经系统通过神经元传导电冲动；在突触处，化学物质传递信号。激素是通过血液运输的化学信使，产生的反应较慢但持续时间更长。眼睛通过改变晶状体形状（调节）对焦。
Negative feedback reverses a change to return to the set point.
负反馈逆转变化以恢复到设定值。
12. Rate of Reaction and Equilibria | 反应速率与平衡
The rate of a chemical reaction depends on the frequency of successful collisions between reactant particles. Increasing temperature, concentration, pressure (for gases) or surface area increases the rate. Catalysts lower activation energy and provide an alternative pathway, remaining chemically unchanged. Reversible reactions can reach dynamic equilibrium when the forward and reverse rates are equal. Le Chatelier's principle states that if a system at equilibrium is disturbed, the position shifts to counteract the change.
化学反应速率取决于反应物粒子之间成功碰撞的频率。升高温度、增加浓度、压强（对气体）或增大表面积都能加快反应速率。催化剂降低活化能并提供替代路径，自身化学性质保持不变。可逆反应在正逆反应速率相等时可达到动态平衡。勒夏特列原理指出，如果平衡体系受到干扰，平衡位置会向抵消该变化的方向移动。
N₂ + 3 H₂ ⇌ 2 NH₃ (Haber process)
For the Haber process, high pressure favours ammonia production, but too high a temperature shifts equilibrium to the left.
在哈伯法中，高压有利于氨的生成，但过高的温度会使平衡向左移动。
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