Pre-U CAIE Science: Essential Vocabulary & Terminology Quick Guide | Pre-U CAIE 科学：核心词汇术语速记指南

📚 Pre-U CAIE Science: Essential Vocabulary & Terminology Quick Guide | Pre-U CAIE 科学：核心词汇术语速记指南

Mastering scientific terminology is a critical step towards excelling in the Pre-U CAIE Science course. This guide presents high-frequency terms from physics, chemistry, biology, and experimental skills, pairing each English definition with a precise Chinese explanation to accelerate recall and deepen understanding. Work through the sections methodically, and you will build the conceptual vocabulary needed for both structured questions and practical assessments.

掌握科学术语是攻克 Pre-U CAIE 科学课程的关键一步。本指南汇集了物理、化学、生物和实验技巧中的高频词汇，每个英文定义都配有准确的中文解释，帮助你加速记忆并深化理解。按章节有计划地学习，就能为解答结构化试题和实践评估打下扎实的概念词汇基础。

1. Scientific Method & Investigation | 科学方法与探究

A hypothesis is a testable, falsifiable statement that offers a tentative explanation for an observation. It must be framed in a way that allows it to be supported or refuted through experimentation.

假说是一个可检验、可证伪的陈述，为观察到的现象提供试探性解释。它必须以能够通过实验被支持或推翻的方式表述。

The independent variable is the factor deliberately changed or manipulated by the investigator. The dependent variable is the factor measured or observed; its value depends on changes in the independent variable.

自变量是研究者有意改变或操控的因素。因变量是被测量或观察的因素，其数值取决于自变量的变化。

Control variables are quantities kept constant to ensure that any observed effect is due solely to the manipulation of the independent variable, thus establishing a fair test.

控制变量是保持恒定的量，以确保观察到的效应完全由自变量的改变引起，从而保证实验的公平性。

Accuracy describes how close a measured value is to the true value, while precision refers to the consistency of repeated measurements, regardless of their closeness to the true value.

准确度描述测量值与真值的接近程度，而精密度指重复测量结果的一致性，与它们是否接近真值无关。

Systematic error causes readings to deviate from the true value by a consistent amount each time, often due to faulty apparatus or flawed design. Random error produces scatter in readings and can be reduced by taking multiple measurements and calculating a mean.

系统误差使读数每次都以固定量偏离真值，通常由仪器故障或设计缺陷导致。随机误差使读数产生离散性，可通过多次测量取平均值加以减小。

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2. Measurements, Units & Data Handling | 测量、单位与数据处理

All physical quantities in Pre-U Science are expressed in SI units. For instance, length in metres (m), mass in kilograms (kg), time in seconds (s), electric current in amperes (A), and temperature in kelvin (K).

Pre-U 科学中所有物理量都用国际单位制表示。例如，长度用米(m)，质量用千克(kg)，时间用秒(s)，电流用安培(A)，温度用开尔文(K)。

Derived units are combinations of base SI units. For example, the newton (N) is equivalent to kg m s⁻², and the joule (J) is equivalent to kg m² s⁻².

导出单位是基本 SI 单位的组合。例如，牛顿(N)等价于 kg·m·s⁻²，焦耳(J)等价于 kg·m²·s⁻²。

Prefixes simplify very large or very small numbers: mega (M, 10⁶), kilo (k, 10³), centi (c, 10⁻²), milli (m, 10⁻³), micro (μ, 10⁻⁶), nano (n, 10⁻⁹).

词头用于简化极大或极小的数字：兆(M, 10⁶)、千(k, 10³)、厘(c, 10⁻²)、毫(m, 10⁻³)、微(μ, 10⁻⁶)、纳(n, 10⁻⁹)。

Uncertainty in a measurement is half the smallest scale division of the instrument. For a digital instrument, it is ± the least significant digit. The uncertainty tells you the range within which the true value is expected to lie.

测量的不确定度是仪器最小分度值的一半。对数字仪器，则是最后一位有效数字 ±1。不确定度告诉你真值预期所在的范围。

Significant figures reflect the precision of a measurement. When multiplying or dividing, the result should have the same number of significant figures as the least precise measurement used in the calculation.

有效数字反映测量的精密度。作乘除运算时，结果的有效数字位数应与运算中使用的最不精密测量的位数相同。

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3. Forces, Motion & Mechanics | 力、运动与力学

Displacement (s) is the vector quantity that describes the straight-line distance between an object’s initial and final positions, together with the direction. It differs from distance, which is a scalar and has no direction.

位移(s)是一个矢量，描述物体初位置至末位置的直线距离及其方向。它不同于路程——路程是标量，没有方向。

Velocity (v) is the rate of change of displacement; it is a vector. Speed is the rate of change of distance; it is a scalar. Average speed = total distance / total time.

速度(v)是位移的变化率，为矢量。速率是路程的变化率，为标量。平均速率 = 总路程 / 总时间。

Acceleration (a) is the rate of change of velocity. It can be calculated as a = (v – u) / t, where u is the initial velocity, v is the final velocity, and t is the time taken.

加速度(a)是速度的变化率，可用 a = (v – u)/t 计算，其中 u 为初速度，v 为末速度，t 为所用时间。

Newton’s First Law states that an object remains at rest or in uniform motion in a straight line unless acted upon by a resultant external force. Inertia is the tendency of an object to resist changes in its state of motion.

牛顿第一定律指出，除非受到合外力的作用，否则物体将保持静止或匀速直线运动状态。惯性是物体抗拒运动状态改变的性质。

Newton’s Second Law can be expressed as F = ma, where F is the resultant force, m is the mass, and a is the acceleration. The acceleration is directly proportional to the force and inversely proportional to the mass.

牛顿第二定律可表示为 F = ma，其中 F 为合外力，m 为质量，a 为加速度。加速度与力成正比，与质量成反比。

Momentum (p) is the product of an object’s mass and its velocity: p = mv. In a closed system, the total momentum before a collision equals the total momentum after the collision, provided no external forces act. This is the principle of conservation of momentum.

动量(p)是物体质量与其速度的乘积：p = mv。在不受外力的封闭系统内，碰撞前的总动量等于碰撞后的总动量，这就是动量守恒定律。

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4. Energy, Work & Power | 能量、功与功率

Work (W) is done when a force moves an object in the direction of the force: W = F × d, where d is the distance moved in the direction of the force. Work is a scalar quantity measured in joules (J).

当力使物体沿力的方向移动时，就说力做了功：W = F × d，其中 d 是沿力方向的位移。功是标量，单位为焦耳(J)。

Gravitational potential energy (GPE) gained by an object of mass m raised through a vertical height h is given by ΔEₚ = mgh, where g is the gravitational field strength (9.81 N kg⁻¹ on Earth).

质量为 m 的物体竖直升高 h 时所增加的重力势能为 ΔEₚ = mgh，其中 g 为引力场强度（地球表面约为 9.81 N/kg）。

Kinetic energy (KE) of a moving object is Eₖ = ½mv². The work–energy principle states that the net work done on an object equals its change in kinetic energy.

运动物体的动能为 Eₖ = ½mv²。功能原理指出，合力对物体所做的功等于其动能的变化量。

Power (P) is the rate of doing work or transferring energy: P = W / t or P = ΔE / t. Its SI unit is the watt (W), equivalent to J s⁻¹.

功率(P)是做功或传递能量的速率：P = W/t 或 P = ΔE/t。其 SI 单位是瓦特(W)，等同于 J/s。

Efficiency = (useful output energy / total input energy) × 100%. No practical device can be 100% efficient because some energy is always dissipated as thermal energy to the surroundings.

效率 = （有用输出能量 / 总输入能量）×100%。没有一个实际装置能达到 100% 的效率，因为总有一部分能量以热能形式耗散到环境中。

The principle of conservation of energy asserts that energy cannot be created or destroyed; it can only be transferred or transformed from one form to another. The total energy of an isolated system remains constant.

能量守恒定律断言，能量既不能创生，也不能消灭，只能从一种形式转移或转化为另一种形式。孤立系统的总能量保持恒定。

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5. Waves & Optics | 波与光学

A transverse wave is one in which particles of the medium vibrate perpendicular to the direction of energy transfer. Examples include light, water ripples, and waves on a string.

横波是介质粒子的振动方向与能量传递方向垂直的波。光波、水波涟漪和绳波都是横波的例子。

A longitudinal wave is one in which particles vibrate parallel to the direction of energy transfer. Sound waves in air and seismic P-waves are longitudinal.

纵波是介质粒子的振动方向与能量传递方向平行的波。空气中的声波和地震 P 波都属于纵波。

Amplitude (A) is the maximum displacement of a particle from its equilibrium position. Wavelength (λ) is the distance between two consecutive points in phase, e.g. crest to crest. Frequency (f) is the number of complete oscillations per second, measured in hertz (Hz).

振幅(A)是粒子偏离平衡位置的最大位移。波长(λ)是两个相邻同相点之间的距离，如波峰到波峰。频率(f)是每秒完整振动的次数，单位为赫兹(Hz)。

The wave equation links speed (v), frequency (f), and wavelength (λ): v = f λ. This relationship holds for all types of waves.

波速方程将波速(v)、频率(f)和波长(λ)联系起来：v = f λ。该关系对所有类型的波都成立。

Refraction occurs when a wave changes speed as it crosses a boundary between two media, causing a change in direction unless it hits the boundary normally. Refractive index n = sin i / sin r, where i is the angle of incidence and r is the angle of refraction.

折射发生在波穿过两种介质边界速度改变时，除非垂直入射，否则方向会发生改变。折射率 n = sin i / sin r，其中 i 为入射角，r 为折射角。

Total internal reflection occurs when light travels from a denser to a less dense medium at an angle of incidence greater than the critical angle, so all light is reflected back. The critical angle c is given by sin c = 1 / n.

当光从光密介质射向光疏介质，且入射角大于临界角时，发生全内反射，光全部被反射回原介质。临界角 c 满足 sin c = 1/n。

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6. Electricity & Magnetism | 电与磁

Electric current (I) is the rate of flow of charge: I = ΔQ / Δt. In metals, current is due to the movement of electrons. Conventional current flows from the positive to the negative terminal.

电流(I)是电荷流动的速率：I = ΔQ/Δt。在金属中，电流由电子运动产生。传统电流方向从正极流向负极。

Potential difference (V) between two points is the energy transferred per unit charge: V = W / Q. It is measured in volts (V), where 1 V = 1 J C⁻¹.

电势差(V)是两点间单位电荷转移的能量：V = W/Q。单位为伏特(V)，1 V = 1 J/C。

Resistance (R) is the opposition to current: R = V / I, measured in ohms (Ω). Ohm’s law states that V ∝ I at constant temperature for an ohmic conductor.

电阻(R)是对电流的阻碍作用：R = V/I，单位为欧姆(Ω)。欧姆定律指出，对于欧姆导体，在温度恒定时 V ∝ I。

Resistors in series: total resistance Rₜ = R₁ + R₂ + … The same current flows through each resistor. Resistors in parallel: 1/Rₜ = 1/R₁ + 1/R₂ + … The potential difference across each branch is the same.

串联电阻：总电阻 Rₜ = R₁ + R₂ + …，每个电阻中电流相同。并联电阻：1/Rₜ = 1/R₁ + 1/R₂ + …，各支路两端电压相等。

Electromotive force (emf, ε) is the total energy supplied by a source per unit charge passing through it. The terminal potential difference is less than the emf when current flows because of internal resistance (r): V = ε – Ir.

电动势(emf, ε)是电源每输送单位电荷所提供的总能量。当有电流通过时，因内阻(r)的存在，路端电压小于电动势：V = ε – Ir。

A magnetic field is a region where a magnetic force is experienced. Field lines show the direction of the force on a north pole. A current-carrying wire produces a circular magnetic field; a solenoid produces a field similar to that of a bar magnet.

磁场是存在磁力作用的区域。磁感线显示北极受力方向。载流导线产生环绕导线的磁场；螺线管产生的磁场与条形磁铁相似。

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7. Atomic Structure & Periodicity | 原子结构与周期性

The atom consists of a nucleus containing protons (positive charge, relative mass 1) and neutrons (neutral, relative mass 1), surrounded by electrons (negative charge, relative mass 1/1840) arranged in energy levels or shells.

原子由原子核和核外电子构成。核内包含质子（带正电，相对质量 1）和中子（不带电，相对质量 1），电子（带负电，相对质量 1/1840）分层排布在能量层中。

Atomic number (Z) is the number of protons in the nucleus, which determines the element. Mass number (A) is the total number of protons plus neutrons. Isotopes are atoms of the same element with the same Z but different A.

原子序数(Z)是核内质子数，决定了元素的种类。质量数(A)是质子数与中子数的总和。同位素是相同原子序数、不同质量数的同种元素的原子。

Electrons fill orbitals in a specific order: 1s, 2s, 2p, 3s, 3p, 4s, 3d. The electron configuration of an element describes this arrangement and underpins its chemical properties.

电子按特定顺序填充原子轨道：1s, 2s, 2p, 3s, 3p, 4s, 3d。电子排布式描述这种排布方式，并决定了元素的化学性质。

Ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous ions with a single positive charge. It shows periodic trends and provides evidence for electron shell structure.

电离能是从一摩尔气态原子中移去一摩尔电子、形成一摩尔气态正一价离子所需的能量。它呈现周期性的变化趋势，为电子层结构提供了证据。

Electronegativity is the ability of an atom to attract the bonding pair of electrons in a covalent bond. It increases across a period and decreases down a group.

电负性是原子在共价键中吸引成键电子对的能力。在同一周期中从左至右递增，在同一族中自上而下递减。

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8. Chemical Bonding & Reactions | 化学键与化学反应

An ionic bond is the electrostatic attraction between oppositely charged ions. It typically forms between metals and non‑metals when electrons are transferred from the metal to the non‑metal.

离子键是带相反电荷离子之间的静电吸引力。通常形成于金属与非金属之间，电子从金属转移到非金属。

A covalent bond is formed when two atoms share one or more pairs of electrons. Dative covalent (coordinate) bonds occur when both electrons in the shared pair come from the same atom.

共价键由两个原子共用一对或多对电子形成。配位共价键是指共用电子对完全由其中一个原子提供。

Metallic bonding is the electrostatic attraction between a lattice of positive metal ions and a ‘sea’ of delocalised electrons, which explains electrical conductivity and malleability.

金属键是正金属离子晶格与离域电子“海”之间的静电吸引，这解释了金属的导电性和延展性。

The mole is the amount of substance that contains 6.02 × 10²³ specified particles (Avogadro constant). The molar mass (M) is the mass of one mole of that substance, expressed in g mol⁻¹.

摩尔是包含 6.02×10²³ 个指定微粒的物质的量（阿伏伽德罗常数）。摩尔质量(M)是一摩尔该物质的质量，单位为 g/mol。

Rate of reaction is the change in concentration of a reactant or product per unit time. It can be affected by temperature, concentration (or pressure for gases), surface area of solids, and catalysts.

反应速率是单位时间内反应物或生成物浓度的变化。温度、浓度（气体的压强）、固体表面积和催化剂都会影响反应速率。

Dynamic equilibrium occurs in a reversible reaction when the forward and backward rates are equal, and the concentrations of reactants and products remain constant. Le Chatelier’s principle predicts how the position of equilibrium shifts when conditions are changed.

可逆反应中，当正、逆反应速率相等且各物质浓度保持恒定时，即达到动态平衡。勒夏特列原理可预测条件改变时平衡移动的方向。

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9. Cell Structure & Biological Molecules | 细胞结构与生物分子

The cell is the basic structural and functional unit of all living organisms. Prokaryotic cells lack a membrane‑bound nucleus; eukaryotic cells have a true nucleus and membrane‑bound organelles.

细胞是所有生物体结构和功能的基本单位。原核细胞没有膜包被的细胞核；真核细胞具有真正的细胞核和膜性细胞器。

Mitochondria are the sites of aerobic respiration, producing ATP. Ribosomes are the sites of protein synthesis. Chloroplasts (in plant cells) carry out photosynthesis.

线粒体是有氧呼吸的场所，产生 ATP。核糖体是蛋白质合成的场所。叶绿体（存在于植物细胞）进行光合作用。

The cell membrane is a phospholipid bilayer with embedded proteins. It controls the movement of substances into and out of the cell via diffusion, osmosis, and active transport.

细胞膜是磷脂双分子层并镶嵌有蛋白质。它通过扩散、渗透和主动运输控制物质进出细胞。

Carbohydrates are composed of carbon, hydrogen, and oxygen. Monosaccharides (e.g. glucose, C₆H₁₂O₆) are simple sugars. Polysaccharides such as starch, glycogen, and cellulose are polymers of glucose.

碳水化合物由碳、氢、氧组成。单糖（如葡萄糖 C₆H₁₂O₆）是简单糖类。多糖如淀粉、糖原和纤维素是葡萄糖的聚合物。

Proteins are polymers of amino acids joined by peptide bonds. The sequence of amino acids (primary structure) determines the protein’s three‑dimensional shape and its function. Enzymes are biological catalysts that lower activation energy.

蛋白质是通过肽键连接的氨基酸聚合物。氨基酸序列（一级结构）决定蛋白质的三维构象和功能。酶是降低活化能的生物催化剂。

Lipids include fats and oils, made of glycerol and three fatty acids (triglycerides). They are hydrophobic, provide energy storage, thermal insulation, and form cell membranes (phospholipids).

脂质包括脂肪和油，由甘油和三个脂肪酸（甘油三酯）组成。它们疏水，具有能量储存、隔热以及构成细胞膜（磷脂）等功能。

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10. Genetics, Inheritance & Evolution | 遗传、变异与进化

DNA (deoxyribonucleic acid) is a double‑stranded helix that carries genetic information. Its building blocks are nucleotides, each consisting of a deoxyribose sugar, a phosphate group, and a nitrogenous base (A, T, C, G).

DNA（脱氧核糖核酸）是携带遗传信息的双螺旋结构。其基本单位是核苷酸，每个核苷酸由脱氧核糖、磷酸基团和含氮碱基（A, T, C, G）组成。

A gene is a sequence of DNA that codes for a specific polypeptide. An allele is an alternative version of a gene. Genotype is the combination of alleles an organism possesses; phenotype is the observable characteristic.

基因是编码特定多肽的 DNA 序列。等位基因是基因的不同版本。基因型是一个生物体拥有的等位基因组合；表现型是可观察到的特征。

Mitosis produces two genetically identical diploid daughter cells, used for growth and repair. Meiosis produces four genetically different haploid gametes, introducing variation through independent assortment and crossing over.

有丝分裂产生两个遗传上相同的二倍体子细胞，用于生长和修复。减数分裂产生四个遗传上不同的单倍体配子，通过独立分配和交叉互换引入变异。

Natural selection is the process by which individuals with heritable traits better suited to their environment tend to survive and reproduce more successfully, passing those advantageous alleles to the next generation.

自然选择是指具有更适应环境的可遗传性状的个体，往往能更好地存活和繁殖，并将那些有利等位基因传递给下一代的过程。

Genetic engineering involves modifying an organism’s genome by inserting a foreign gene. Polymerase chain reaction (PCR) is used to amplify small samples of DNA, and gel electrophoresis separates DNA fragments by size.

基因工程通过插入外源基因来修饰生物体的基因组。聚合酶链式反应(PCR)用于扩增微量 DNA 样本，凝胶电泳则根据分子大小分离 DNA 片段。

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11. Ecology & Ecosystems | 生态与生态系统

An ecosystem is a community of living organisms (biotic factors) interacting with their non‑living (abiotic) environment. Habitat is the place where an organism lives; niche describes its role and position within the ecosystem.

生态系统是生物群落（生物因素）与其非生物环境相互作用的整体。栖息地是生物生存的地方；生态位描述它在生态系统中的角色和地位。

Producers (autotrophs) make their own food via photosynthesis. Consumers (heterotrophs) feed on other organisms. Decomposers break down dead organic matter, recycling nutrients.

生产者（自养生物）通过光合作用制造食物。消费者（异养生物）以其他生物为食。分解者分解死去的有机物质，使营养物质再循环。

A food chain shows a single linear pathway of energy transfer, while a food web comprises interconnected food chains. Energy is lost at each trophic level, which is why food chains rarely exceed five levels.

食物链显示单一的能量传递线性路径，而食物网由相互关联的多条食物链组成。能量在每一营养级都会损失，故食物链一般不超过五级。

The carbon cycle describes how carbon is exchanged between the atmosphere, organisms, oceans, and rocks through processes such as photosynthesis, respiration, combustion, and decomposition.

碳循环描述碳通过光合作用、呼吸作用、燃烧和分解等过程，在大气、生物体、海洋和岩石之间进行交换的路径。

Biodiversity is the variety of species and genetic diversity within an ecosystem. High biodiversity often indicates a stable, resilient ecosystem. Human activities such as deforestation and pollution threaten biodiversity.

生物多样性指生态系统中物种和遗传多样性的丰富程度。高生物多样性往往意味着生态系统的稳定和恢复力强。砍伐森林和污染等人类活动威胁着生物多样性。

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12. Experimental Skills & Safety | 实验技能与安全

Always perform a risk assessment before starting an experiment: identify hazards (e.g., corrosive chemicals, hot surfaces), evaluate risks, and specify control measures such as wearing eye protection, using fume cupboards, or tying back long hair.

实验前务必进行风险评估：识别危险源（如腐蚀性化学品、烫热表面），评价风险，并规定控制措施，如佩戴护目镜、使用通风橱或扎起长发。

When drawing a graph, label axes with the quantity and unit, use sensible linear scales, plot points with small crosses or circled dots, and draw a line of best fit (straight or smooth curve) that passes through as many points as possible with a roughly equal scatter of points on either side.

绘制图表时，坐标轴要标注物理量和单位，采用合理的线性刻度，用细“×”或圆圈标出数据点，并画出最佳拟合线（直线或光滑曲线），使其尽可能通过更多点，并使两侧散点大致均衡。

A control experiment is set up to verify that the observed effect is due to the independent variable and not to some other factor. It is identical to the main experiment except that the independent variable is omitted or set to a standard value.

对照实验用于确认观察到的效应是由自变量而非其他因素引起的。它与主实验完全相同，只是省略了自变量或将其设定为标准值。

Reliability of data is improved by repeating measurements and calculating an average. Outliers should be identified and, where appropriate, excluded with justification.

通过重复测量并计算平均值，可以提高数据的可靠性。应识别异常值，并在有充分理由时予以剔除。

When recording observations, use clear, objective language. For example, note colour changes, formation of a precipitate (state its colour), effervescence (gas bubbles), and temperature changes. Tabulate results neatly with headings and units in the header row.

记录观察时，使用清晰、客观的语言。例如，注意颜色变化、沉淀生成（记下颜色）、冒泡（气体逸出）和温度变化。用表格整齐地记录数据，表头行需注明名称和单位。

Published by TutorHao | Science Revision Series | aleveler.com

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