IGCSE Edexcel Science: End-of-Term Revision Guide | IGCSE Edexcel 科学：期末复习提纲

📚 IGCSE Edexcel Science: End-of-Term Revision Guide | IGCSE Edexcel 科学：期末复习提纲

Mastering IGCSE Edexcel Science means pulling together ideas from Biology, Chemistry and Physics and showing that you can apply them to new situations. This end-of-term revision guide distills the specification into the key principles, equations and practical skills that examiners look for. Work through each section, test yourself on the core definitions, and always link your knowledge back to the command words used in past papers.

掌握 IGCSE Edexcel 科学意味着要将生物、化学和物理的概念融会贯通，并能将其应用于新情境。这份期末复习提纲提炼了考纲中的关键原理、方程式和实验技能，正是阅卷人希望看到的。请逐节复习，自测核心定义，并始终将所学知识与历年真题中的指令词联系起来。

1. Core Principles and Working Scientifically | 核心原则与科学方法

Every IGCSE Edexcel Science paper tests scientific thinking. You must be able to identify independent, dependent and control variables in an investigation. The independent variable is the one you change; the dependent variable is the one you measure; control variables are kept the same to ensure a fair test.

每一份 IGCSE Edexcel 科学试卷都会考查科学思维。你必须能在探究中识别自变量、因变量和控制变量。自变量是你改变的变量；因变量是你测量的变量；控制变量则保持不变，以确保公平测试。

A hypothesis is a testable prediction, often written as ‘If… then… because…’. Results are presented in tables and graphs, and you need to describe patterns (e.g. ‘as X increases, Y decreases’) rather than just reading numbers. Remember to include units in table headings and label axes clearly.

假设是一个可验证的预测，通常写成“如果……那么……因为……”。结果用表格和图表呈现，你需要描述变化趋势（如“随着 X 增大，Y 减小”），而不只是读取数字。记住在表头中注明单位，并清晰地标注坐标轴。

Safety is a key part of experimental design. Common hazards include heating flammable liquids, using corrosive acids, and handling electrical circuits. Always state the specific risk and the precaution (e.g. wear safety goggles to protect eyes from acid splashes).

安全是实验设计的重要部分。常见危险包括加热易燃液体、使用腐蚀性酸和处理电路。要始终说明具体风险和预防措施（如佩戴护目镜以防酸液溅入眼睛）。

2. Biology: Cell Structure and Function | 生物：细胞结构与功能

All living organisms are composed of cells. Eukaryotic cells—found in plants, animals and fungi—contain a true nucleus bounded by a membrane. Prokaryotic cells, such as bacteria, lack a nucleus; their genetic material floats freely in the cytoplasm.

所有生物都由细胞组成。真核细胞（存在于植物、动物和真菌中）具有由膜包裹的真正细胞核。原核细胞，如细菌，没有细胞核；它们的遗传物质游离在细胞质中。

Key organelles include mitochondria, where aerobic respiration releases energy; ribosomes, which carry out protein synthesis; and chloroplasts, present only in plant cells, which absorb light for photosynthesis. The plant cell also has a permanent vacuole filled with cell sap, which maintains turgor pressure.

关键的细胞器包括：线粒体（有氧呼吸释放能量的场所）、核糖体（进行蛋白质合成）以及仅存在于植物细胞中的叶绿体（吸收光能进行光合作用）。植物细胞还有一个充满细胞液的永久液泡，用于维持膨压。

Magnification can be calculated with the formula: Magnification = Size of image ÷ Actual size of object. Always convert all lengths to the same unit before calculating. 1 mm = 1000 µm; 1 µm = 1000 nm.

放大倍数可通过以下公式计算：放大倍数 = 图像大小 ÷ 物体实际大小。计算前务必将所有长度转换为相同单位。1 mm = 1000 µm；1 µm = 1000 nm。

3. Biology: Transport Systems in Plants and Humans | 生物：植物与人类的运输系统

In humans, the heart is a double pump. The right side pumps deoxygenated blood to the lungs via the pulmonary artery; the left side pumps oxygenated blood to the body through the aorta. Valves prevent backflow, and the pacemaker controls the resting heart rate.

在人体内，心脏是一个双泵。右侧将缺氧血经肺动脉泵送到肺部；左侧通过主动脉将富氧血泵送到全身。瓣膜防止血液倒流，起搏器控制静息心率。

Blood components each have a specialist role: red blood cells (no nucleus, biconcave shape) transport oxygen bound to haemoglobin; white blood cells fight pathogens; platelets trigger clotting; plasma carries dissolved substances like glucose, carbon dioxide and urea.

血液各组分都有专门的作用：红细胞（无核、双凹圆盘状）运输与血红蛋白结合的氧气；白细胞抵抗病原体；血小板触发凝血；血浆运送葡萄糖、二氧化碳和尿素等溶解物质。

In plants, xylem transports water and mineral ions upwards from the roots; phloem translocates sugars (mainly sucrose) from sources to sinks. The transpiration stream is driven by evaporation from leaves and is affected by light intensity, temperature, humidity and wind.

在植物中，木质部将水分和矿质离子从根部向上运输；韧皮部将糖（主要是蔗糖）从源转运到库。蒸腾作用由叶片蒸发驱动，受光照强度、温度、湿度和风速影响。

4. Chemistry: Atoms, Elements and Compounds | 化学：原子、元素与化合物

All matter is built from atoms. An atom consists of a central nucleus containing protons (positive) and neutrons (neutral), surrounded by electrons (negative) in shells. Atomic number = number of protons; mass number = protons + neutrons.

所有物质都由原子构成。原子由包含质子（带正电）和中子（不带电）的原子核，以及核外分层排布的电子（带负电）组成。原子序数 = 质子数；质量数 = 质子数 + 中子数。

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. They have identical chemical properties because their electron arrangement is the same. Relative atomic mass (Aᵣ) is the weighted mean mass of an atom compared to 1/12th of carbon-12.

同位素是质子数相同但中子数不同的同种元素的原子。它们的化学性质相同，因为电子排布相同。相对原子质量（Aᵣ）是一个原子相较于碳-12原子质量的1/12的加权平均质量。

Ionic bonding occurs when a metal transfers electrons to a non-metal, forming oppositely charged ions that attract. Covalent bonding involves the sharing of electron pairs between non-metal atoms. Simple molecular substances have low melting points; giant covalent structures, like diamond, have very high melting points.

离子键是当金属将电子转移给非金属时形成的，产生相互吸引的带相反电荷的离子。共价键涉及非金属原子之间共享电子对。简单分子物质熔点较低；像金刚石这样的巨型共价结构则熔点极高。

5. Chemistry: Reactivity and Acids | 化学：反应活性与酸

The reactivity series orders metals by how vigorously they react. Potassium, sodium and calcium are highly reactive; gold and platinum are unreactive. A more reactive metal can displace a less reactive metal from its compound, e.g. Zn + CuSO₄ → ZnSO₄ + Cu.

反应活性顺序按金属反应的剧烈程度排列。钾、钠和钙反应活性很高；金和铂则很稳定。较活泼的金属能把较不活泼的金属从其化合物中置换出来，例如 Zn + CuSO₄ → ZnSO₄ + Cu。

Acids release H⁺ ions in water. Common laboratory acids are hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The reaction acid + metal → salt + hydrogen is a common way to prepare soluble salts, but only for metals above hydrogen in the reactivity series.

酸在水中释放 H⁺ 离子。常见的实验室酸有盐酸 (HCl)、硫酸 (H₂SO₄) 和硝酸 (HNO₃)。酸 + 金属 → 盐 + 氢气的反应是制备可溶性盐的常用方法，但仅适用于活动性顺序中排在氢之前的金属。

Naming salts follows a pattern: hydrochloric acid produces chlorides; sulfuric acid produces sulfates; nitric acid produces nitrates. Neutralisation (acid + alkali → salt + water) can be followed with pH indicators and titration to find the exact endpoint.

盐的命名遵循规律：盐酸生成氯化物；硫酸生成硫酸盐；硝酸生成硝酸盐。中和反应（酸 + 碱 → 盐 + 水）可用 pH 指示剂和滴定法确定精确终点。

6. Physics: Forces and Motion | 物理：力与运动

Forces are vector quantities, meaning they have both magnitude and direction. When resultant force is zero, an object remains at rest or moves at constant velocity (Newton’s First Law). Acceleration is directly proportional to resultant force and inversely proportional to mass, summarised by:

力是矢量，即既有大小又有方向。当合力为零时，物体保持静止或匀速直线运动（牛顿第一定律）。加速度与合力成正比，与质量成反比，可用下式总结：

F = m × a

Velocity–time graphs provide a direct way to deduce acceleration (gradient) and distance travelled (area under graph). Remember that deceleration is negative acceleration and must be shown with a negative sign in calculations.

速度-时间图可直接得出加速度（斜率）和行驶距离（图像下方面积）。记住，减速度是负加速度，计算中需标明负号。

Several equations of motion are used when acceleration is constant. The most common ones are:

v = u + at

s = ut + ½at²

where u = initial velocity, v = final velocity, a = acceleration, t = time, s = displacement. Always state the direction when giving final answers to vector quantities.

当加速度恒定时，会用到几个运动方程。最常用的是：v = u + at 和 s = ut + ½at²，其中 u 为初速度，v 为末速度，a 为加速度，t 为时间，s 为位移。给出矢量量的最终答案时，务必表明方向。

7. Physics: Electricity and Magnetism | 物理：电与磁

Current (I) is the rate of flow of charge and is measured in amperes (A). In a series circuit, current is the same at all points; in a parallel circuit, the current splits across branches. Voltage (V) is the energy transferred per unit charge; it is shared in series circuits and equal in parallel branches.

电流 (I) 是电荷流动的速率，以安培 (A) 为单位。串联电路中，电流处处相等；并联电路中，电流在分支中分配。电压 (V) 是每单位电荷所传递的能量；在串联电路中分配，在并联支路中相等。

Resistance (R) is measured in ohms (Ω). Ohm’s Law links these quantities for a metallic conductor at constant temperature:

电阻 (R) 以欧姆 (Ω) 为单位。对于温度恒定的金属导体，欧姆定律将这些量联系起来：

V = I × R

Electrical power (P) can be calculated using P = I × V or P = I² × R. Energy transferred is power × time, so E = P × t. Remember to convert time to seconds and power to watts before multiplying.

电功率 (P) 可用 P = I × V 或 P = I² × R 计算。能量传递 = 功率 × 时间，因此 E = P × t。计算前务必将时间换算为秒，将功率换算为瓦特。

Electromagnets are produced when a current flows through a coil of wire wound around a soft iron core. The magnetic field can be switched on and off, and made stronger by increasing current, adding more turns, or using an iron core. Permanent magnets always produce a magnetic field without needing a current.

当电流流过绕在软铁芯上的导线线圈时，就产生了电磁体。磁场可以接通和断开，通过增大电流、增加线圈匝数或使用铁芯可以增强磁场。永磁体无需电流就可一直产生磁场。

8. Physics: Waves and Energy Transfer | 物理：波与能量传输

Waves transfer energy without transferring matter. Transverse waves (e.g. light, water ripples) have oscillations perpendicular to the direction of energy transfer. Longitudinal waves (e.g. sound) have oscillations parallel to the transfer direction, consisting of compressions and rarefactions.

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递方向垂直。纵波（如声波）的振动方向与传递方向平行，由疏部和密部组成。

The wave equation links speed (v), frequency (f) and wavelength (λ):

波速方程将波速 (v)、频率 (f) 和波长 (λ) 联系起来：

v = f × λ

For electromagnetic waves, all types travel at the same speed in a vacuum (3.0 × 10⁸ m/s) but have different wavelengths and frequencies. The electromagnetic spectrum, in order of increasing frequency (decreasing wavelength), is: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. Each region has its own uses and dangers; for instance, gamma rays sterilise medical equipment but are highly ionising.

对于电磁波，所有类型在真空中传播速度相同（3.0 × 10⁸ m/s），但波长和频率不同。电磁波谱按频率递增（波长递减）顺序为：无线电波、微波、红外线、可见光、紫外线、X射线、伽马射线。每个波段都有其用途和危险；例如伽马射线可用于医疗器械消毒，但电离能力很强。

Be able to interpret ray diagrams for reflection and refraction. The law of reflection states that the angle of incidence equals the angle of reflection. Refraction occurs because waves change speed when they enter a different medium; when light slows down (e.g. entering glass from air), it bends towards the normal.

要能够解读反射和折射的光线图。反射定律指出，入射角等于反射角。折射的发生是由于波进入不同介质时速度改变；当光速减慢时（如从空气进入玻璃），光线向法线偏折。

9. Mastering Practical Investigations | 掌握实验探究

IGCSE Edexcel Science places a strong emphasis on practical skills. When describing an investigation, start with a testable question, state the variables clearly, and list the apparatus. You must always repeat readings and calculate a mean to improve reliability, excluding any anomalous results identified by sudden deviations.

IGCSE Edexcel 科学非常重视实验技能。描述一项探究时，先提出一个可检验的问题，清晰说明变量，并列出仪器。你必须始终重复读取数据并计算平均值以提高可靠性，同时剔除任何有明显偏差的异常值。

Drawing graphs: use a sharp pencil, label axes with quantity and unit, and choose sensible scales that use more than half the grid. Data points should be plotted with small crosses, and a line of best fit (smooth curve or straight line) should be drawn to show the trend. Do not ‘join the dots’ unless the question explicitly asks for it.

绘制图表：使用削尖的铅笔，标注坐标轴并附上物理量和单位，选择合适的标度使图形占据网格一半以上。数据点用小叉号标记，绘制最佳拟合线（平滑曲线或直线）以显示趋势。除非题目明确要求，否则不要简单地将点连起来。

Be prepared to describe methods for topics such as: investigating how temperature affects enzyme activity (using amylase and starch); measuring the specific heat capacity of a metal block; and preparing a pure, dry sample of a soluble salt via neutralisation and crystallisation. In each case, focus on precision—e.g. using a water bath to control temperature—and on safety measures.

要准备好描述以下主题的实验方法：探究温度如何影响酶活性（用淀粉酶和淀粉）；测量金属块的比热容；以及通过中和反应和结晶制备纯净、干燥的可溶性盐样品。每个实验都要关注精确性——例如使用水浴控制温度——以及安全措施。

10. Exam Technique and Common Pitfalls | 应试技巧与常见误区

Command words determine how much detail you need to give. ‘State’ requires a short factual answer; ‘Describe’ asks you to say what you see or what happens; ‘Explain’ demands linking scientific ideas to the observation, often using ‘because’. ‘Evaluate’ means you must discuss advantages and disadvantages and give a justified conclusion.

指令词决定了你需要给出多少细节。“State”要求简短的事实回答；“Describe”要求说出你看到或发生了什么；“Explain”要求将科学概念与观察结果联系起来，通常使用“因为”；“Evaluate”则意味着你必须讨论优缺点并给出有理有据的结论。

Unit conversions are a perennial trap. Always write down the conversion step before doing a calculation: for example, 25 cm = 0.25 m. When using prefixes like kilo (× 1000), mega (× 10⁶), and milli (× 10⁻³), double-check your powers of ten. In electricity questions, check whether components are in series or parallel before applying rules for current and voltage.

单位换算是一个常见的陷阱。计算前务必先写出换算步骤：例如 25 cm = 0.25 m。当使用千 (× 1000)、兆 (× 10⁶) 和毫 (× 10⁻³) 等词头时，仔细核对 10 的幂次。在电学问题中，先确认元件是串联还是并联，再应用电流和电压的规则。

Many students lose marks by not reading the question fully. Underline key information such as ‘not to scale’, ‘in terms of particles’, or ‘name the independent variable’. In 6-mark extended-response questions, structure your answer logically; a bullet-point plan on the question paper can save you from rambling.

许多学生因没有完整审题而丢分。圈出关键信息，如“未按比例”、“从粒子角度”或“写出自变量名称”。在 6 分扩展作答题中，有逻辑地组织答案；在问卷上列一个要点式提纲可以避免漫无边际地作答。

Finally, time management is critical. Allocate time based on marks—roughly 1 minute per mark—and leave five minutes at the end to check calculations and ensure you have filled in all the answer lines. Confidence comes from thorough revision, so keep revisiting these key concepts right up to the morning of the exam.

最后，时间管理至关重要。根据分值分配时间——大致每 1 分 1 分钟——并留出 5 分钟在最后检查计算，确保所有答题线都填满。信心来自扎实的复习，因此要反复回顾这些关键概念，直到考试当天早晨。

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IGCSE Edexcel Science: End-of-Term Revision Guide | IGCSE Edexcel 科学：期末复习提纲