IB CCEA Science: Last-Minute Revision Notes | IB CCEA 科学：考前冲刺笔记

📚 IB CCEA Science: Last-Minute Revision Notes | IB CCEA 科学：考前冲刺笔记

As the final exams approach, efficient revision becomes paramount. This article consolidates essential concepts, formulas, and practical skills for IB and CCEA Science students. Whether you are tackling Physics, Chemistry, or Biology, use these last-minute notes to reinforce your understanding and boost confidence.

随着期末考试的临近，高效复习至关重要。本文整合了 IB 和 CCEA 科学课程的核心概念、公式与实验技能。无论你应对物理、化学还是生物，均可借助这些考前冲刺笔记巩固理解、增强信心。

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1. Scientific Method and Experimental Design | 科学方法与实验设计

Identify the independent variable (the one you change), dependent variable (the one you measure), and controlled variables (kept constant). A well‑designed experiment changes only one variable at a time.

识别自变量（你改变的变量）、因变量（你测量的变量）和控制变量（保持不变的变量）。精心设计的实验一次只改变一个变量。

Write a clear, testable hypothesis in an ‘If … then … because …’ format. For both IB Internal Assessment and CCEA practical tasks, the hypothesis must link the independent and dependent variables with scientific reasoning.

用“如果……那么……因为……”的格式写出清晰、可验证的假设。无论是 IB 内部评估还是 CCEA 实验任务，假设都必须用科学原理解释自变量与因变量的联系。

Include a control group or control trial where the independent variable is set to a baseline value. This provides a reference to compare the effect of the treatment.

设置对照组或对照实验，将自变量设为基准值。这为比较处理效果提供了参照。

Use systematic and random error terminology. Systematic errors (e.g. poorly calibrated instrument) shift all readings in one direction; random errors fluctuate and can be reduced by repeated measurements.

使用系统误差和随机误差的术语。系统误差（如仪器未校准）使所有读数朝一个方向偏移；随机误差产生波动，可通过重复测量来减小。

Always include detailed method steps that another student could follow to obtain comparable results. Specify equipment with precision (e.g. ‘250 cm³ beaker’ rather than ‘a beaker’).

务必写出详细的实验步骤，让其他同学能够按照你的方法得到可比的结果。精确列出设备（例如“250 cm³ 烧杯”而非“一个烧杯”）。

In IB Biology or CCEA Life Science, note ethical considerations such as maintaining animal welfare or ensuring confidentiality of human participants.

在 IB 生物或 CCEA 生命科学中，要说明伦理考虑，例如保障动物福利或确保人类参与者的隐私。

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2. Data Handling and Uncertainty Analysis | 数据处理与误差分析

Record raw data in clearly labelled tables with appropriate units and consistent decimal places. The column heading should show the quantity and unit divided by a slash, e.g. ‘Length / cm’.

将原始数据记录在标签清晰的表格中，使用适当的单位和小数位数一致。列标题应标明物理量和单位，用斜线分隔，如“长度 / cm”。

Calculate the mean of repeated measurements and the range (max − min) as a quick estimate of precision. In IB, you are also expected to calculate standard deviation where appropriate.

计算重复测量的平均值和极差（最大值 – 最小值）作为精密度的快速估计。在 IB 课程中，还需适时计算标准差。

Determine uncertainty in a single measurement as half the smallest scale division (for analogue instruments) or the smallest digit (for digital instruments). Propagate uncertainties when combining quantities: for addition/subtraction, add absolute uncertainties; for multiplication/division, add percentage uncertainties.

确定单次测量的不确定度：模拟仪表取最小刻度的一半，数字仪表取末位最小读数。合成量时传递不确定度：加减运算用绝对不确定度相加；乘除运算用相对不确定度相加。

When plotting graphs, choose a sensible scale that uses more than half the graph paper. Label axes with quantity and unit, plot data points as small crosses or dots with circles, and draw a best‑fit line or curve.

绘制图表时，选择合理的坐标分度值，使图形占据纸面一半以上。坐标轴标出物理量和单位，数据点用小十字或带圆圈的点标出，然后画出最佳拟合线或曲线。

Find the gradient and intercept from a linear graph. Gradient = Δy / Δx using two well‑separated points on the best‑fit line, not data points. The intercept is where the line crosses the y‑axis.

根据线性图计算斜率和截距。斜率 = Δy / Δx，在最佳拟合线上选取距离较远的两点计算，而非使用数据点。截距为直线与 y 轴的交点。

Use the relationship y = mx + c to derive physical quantities from a linearised graph. For example, plotting T² against L for a pendulum gives a slope of 4π²/g.

利用关系式 y = mx + c，从线性化图中推导物理量。例如，对于单摆，绘制 T² 对 L 的图，斜率为 4π²/g。

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3. Mechanics and Motion | 力学与运动学

Memorise the SUVAT equations for uniformly accelerated motion. They link displacement s, initial velocity u, final velocity v, acceleration a, and time t. Use these equations only when acceleration is constant.

熟记匀加速运动的 SUVAT 方程。这些方程将位移 s、初速度 u、末速度 v、加速度 a 和时间 t 联系起来。仅当加速度恒定时才可使用这些方程。

v = u + a t   s = u t + ½ a t²   v² = u² + 2 a s   s = ½ (u + v) t

Newton’s First Law: an object remains at rest or in uniform motion unless acted upon by a resultant force. Second Law: resultant force = mass × acceleration (F = m a). Third Law: forces occur in action‑reaction pairs, equal in magnitude and opposite in direction, acting on different bodies.

牛顿第一定律：除非受到净外力作用，物体将保持静止或匀速直线运动。第二定律：净外力 = 质量 × 加速度 (F = m a)。第三定律：力成对出现，作用力与反作用力大小相等、方向相反，且作用在不同物体上。

Resolve forces into perpendicular components. For a force F at angle θ to the horizontal, the horizontal component is F cosθ and the vertical component is F sinθ.

将力分解为相互垂直的分量。若力 F 与水平面夹角为 θ，水平分量为 F cosθ，垂直分量为 F sinθ。

Momentum p = m v. The principle of conservation of momentum states that total momentum before a collision equals total momentum after, provided no external resultant force acts. Impulse = change in momentum = F Δt.

动量 p = m v。动量守恒定律指出，只要没有净外力作用，碰撞前的总动量等于碰撞后的总动量。冲量 = 动量变化量 = F Δt。

Work done = force × distance moved in direction of force. Energy is transferred. Kinetic energy Eₖ = ½ m v²; gravitational potential energy Eₚ = m g h. In a closed system, total energy is conserved.

功 = 力 × 沿力方向移动的距离。能量发生转移。动能 Eₖ = ½ m v²；重力势能 Eₚ = m g h。在一个封闭系统中，总能量守恒。

For circular motion, recall that an object moving at constant speed in a circle has a centripetal acceleration a = v²/r = ω² r, directed towards the centre. The centripetal force is F = m v²/r.

对于圆周运动，记住做匀速圆周运动的物体具有向心加速度 a = v²/r = ω² r，方向指向圆心。向心力 F = m v²/r。

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4. Electricity and Circuits | 电学与电路

Ohm’s Law states that the current I through a conductor is directly proportional to the potential difference V across it, provided temperature remains constant: V = I R.

欧姆定律指出，在温度恒定的条件下，通过导体的电流 I 与导体两端的电势差 V 成正比：V = I R。

Resistance R = ρL/A, where ρ is resistivity, L is length, and A is cross‑sectional area. Resistivity depends on the material and temperature.

电阻 R = ρL/A，其中 ρ 为电阻率，L 为长度，A 为横截面积。电阻率取决于材料和温度。

In a series circuit, current is the same everywhere, total resistance R_total = R₁ + R₂ + …, and the supply voltage is divided proportionally. In a parallel circuit, voltage is the same across each branch, and total resistance is given by 1/R_total = 1/R₁ + 1/R₂ + … .

在串联电路中，各处电流相等，总电阻 R_total = R₁ + R₂ + …，电源电压按比例分配。在并联电路中，各支路两端电压相等，总电阻满足 1/R_total = 1/R₁ + 1/R₂ + … 。

Electrical power P = V I = I² R = V² / R. Energy transferred E = P t, measured in joules or kilowatt‑hours.

电功率 P = V I = I² R = V² / R。转移的能量 E = P t，单位为焦耳或千瓦时。

Use a voltmeter in parallel to measure potential difference and an ammeter in series to measure current. An ideal voltmeter has infinite resistance; an ideal ammeter has zero resistance.

使用电压表并联测量电势差，使用电流表串联测量电流。理想电压表内阻无穷大；理想电流表内阻为零。

Potential dividers use two resistors in series to provide a fraction of the input voltage. The output voltage V_out = V_in × (R₂ / (R₁ + R₂)), where R₂ is the resistor across which the output is taken.

分压器使用两个串联电阻提供输入电压的一部分。输出电压 V_out = V_in × (R₂ / (R₁ + R₂))，其中 R₂ 是跨接输出端的电阻。

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5. Stoichiometry and the Mole Concept | 化学计量学与摩尔概念

The mole is the SI unit for amount of substance. One mole contains 6.02 × 10²³ particles (Avogadro’s constant). The molar mass M is the mass of one mole of a substance in g mol⁻¹.

摩尔是物质的量的 SI 单位。1 摩尔含有 6.02 × 10²³ 个粒子（阿伏伽德罗常数）。摩尔质量 M 是 1 摩尔物质的质量，单位为 g mol⁻¹。

n = m / M   n = V (gas) / V_m (at RTP, V_m ≈ 24 dm³ mol⁻¹)

Balance chemical equations by ensuring the same number of atoms of each element on both sides. Use state symbols: (s), (l), (g), (aq). A balanced equation provides the mole ratio of reactants and products.

配平化学方程式时，确保每种元素的原子数在反应两边相等。使用状态符号：(s)、(l)、(g)、(aq)。配平后的方程式给出了反应物和生成物的摩尔比。

Empirical formula gives the simplest whole‑number ratio of atoms in a compound. To find it, convert percentage composition to masses, then to moles, and divide by the smallest number of moles.

实验式给出化合物中原子最简单整数比。求实验式时，将各元素的质量百分数转化为质量，再转化为物质的量，并除以最小的物质的量。

In a titration, use the formula c₁V₁/n₁ = c₂V₂/n₂, where c is concentration, V is volume, and n is the mole coefficient from the balanced equation. This helps determine an unknown concentration.

在滴定中，使用公式 c₁V₁/n₁ = c₂V₂/n₂，其中 c 为浓度，V 为体积，n 为平衡方程式中的化学计量数。该式用于求算未知浓度。

Percentage yield = (actual mass / theoretical mass) × 100%. Atom economy = (molar mass of desired product / sum of molar masses of all products) × 100%. Both are crucial for green chemistry evaluation.

产率 = (实际质量 / 理论质量) × 100%。原子经济性 = (目标产物摩尔质量 / 所有产物摩尔质量之和) × 100%。两者对绿色化学评估至关重要。

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6. Chemical Energetics and Rates | 化学反应与能量

Exothermic reactions release energy to the surroundings; the temperature rises and ΔH is negative. Endothermic reactions absorb energy; the temperature falls and ΔH is positive.

放热反应向环境释放能量，温度升高，ΔH 为负值。吸热反应从环境吸收能量，温度降低，ΔH 为正值。

Bond breaking is endothermic (requires energy), and bond making is exothermic (releases energy). ΔH = Σ(bond energies of bonds broken) − Σ(bond energies of bonds formed).

断裂化学键是吸热的（需要能量），形成化学键是放热的（释放能量）。ΔH = Σ(断裂键的键能) − Σ(形成键的键能)。

Calculate enthalpy change using q = m c ΔT, where q is heat energy, m is mass of solution, c is specific heat capacity (usually 4.18 J g⁻¹ °C⁻¹ for water), and ΔT is temperature change. Then ΔH = −q / n.

使用公式 q = m c ΔT 计算焓变，其中 q 为热量，m 为溶液质量，c 为比热容（水通常取 4.18 J g⁻¹ °C⁻¹），ΔT 为温度变化。然后 ΔH = −q / n。

Rate of reaction can be measured by monitoring change in mass of a gas released, volume of gas produced, turbidity, or colour change. Average rate = Δ(quantity) / Δt.

反应速率可通过监测释放气体的质量变化、气体体积、浑浊度或颜色变化来衡量。平均速率 = Δ(量) / Δt。

Collision theory states that for a reaction to occur, particles must collide with sufficient energy (at least the activation energy Eₐ) and with correct orientation. Increasing temperature, concentration, surface area, or using a catalyst all increase the rate.

碰撞理论指出，发生反应需要粒子以足够的能量（至少达到活化能 Eₐ）和正确的取向发生碰撞。升高温度、增大浓度、增加表面积或使用催化剂均可提高反应速率。

Catalysts provide an alternative reaction pathway with lower activation energy. They are not consumed. Enzymes are biological catalysts that exhibit specificity and optimal pH/temperature ranges.

催化剂提供一条活化能较低的反应途径，自身不被消耗。酶是生物催化剂，具有专一性以及最适 pH/温度范围。

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7. Cell Biology and Biochemistry | 细胞生物学与生化

All living organisms are composed of cells. Prokaryotic cells (bacteria) lack a nucleus and membrane‑bound organelles; eukaryotic cells (animals, plants, fungi) have a true nucleus.

所有生物体均由细胞构成。原核细胞（细菌）没有细胞核和膜包被的细胞器；真核细胞（动物、植物、真菌）具有真正的细胞核。

Key organelles and their functions: nucleus (stores DNA), mitochondria (aerobic respiration), ribosomes (protein synthesis), chloroplasts (photosynthesis), vacuole (storage, turgor), cell membrane (selective permeability).

关键细胞器及其功能：细胞核（储存 DNA）、线粒体（有氧呼吸）、核糖体（蛋白质合成）、叶绿体（光合作用）、液泡（储存、维持膨胀压）、细胞膜（选择透过性）。

Four major biomolecules: carbohydrates (energy source and structural, e.g. glucose, starch), lipids (long‑term energy storage, insulation, membrane structure), proteins (enzymes, structural components, transport), and nucleic acids (DNA, RNA).

四大类生物分子：碳水化合物（能量来源和结构物质，如葡萄糖、淀粉）、脂类（长期储能、保温、膜结构）、蛋白质（酶、结构组分、运输）和核酸（DNA、RNA）。

Enzyme activity depends on the active site’s shape. The lock‑and‑key and induced‑fit models explain substrate specificity. Denaturation (by high temperature or extreme pH) permanently alters the active site, stopping enzyme function.

酶活性取决于活性部位的形状。锁钥模型和诱导契合模型解释了底物专一性。变性（由高温或极端 pH 引起）永久性地改变活性部位，使酶失活。

Photosynthesis overall equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Light‑dependent reactions occur in thylakoid membranes; light‑independent reactions (Calvin cycle) occur in the stroma. Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy).

光合作用总反应式：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。光反应发生在类囊体薄膜上；暗反应（卡尔文循环）发生在基质中。呼吸作用：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O（+能量）。

DNA structure: double helix of nucleotides, each consisting of deoxyribose sugar, phosphate, and a nitrogenous base (A,T,C,G). Complementary base pairing: A–T and C–G. RNA replaces thymine with uracil (U) and uses ribose sugar.

DNA 结构：由核苷酸组成的双螺旋，每个核苷酸包含脱氧核糖、磷酸和含氮碱基（A、T、C、G）。互补碱基配对：A–T，C–G。RNA 用尿嘧啶 (U) 替代胸腺嘧啶，并使用核糖。

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8. Genetics and Evolution | 遗传与进化

Genes are segments of DNA that code for a polypeptide. An allele is a variant form of a gene. Genotype is the combination of alleles; phenotype is the observable characteristic.

基因是编码多肽的 DNA 片段。等位基因是基因的变体形式。基因型是等位基因的组合；表型是可见的特征。

Monohybrid inheritance follows Mendel’s laws. In a cross between two heterozygous individuals (Aa × Aa), the expected phenotypic ratio in offspring is 3:1 for a dominant‑recessive trait.

单基因遗传遵循孟德尔定律。在两个杂合子 (Aa × Aa) 的杂交中，若为显隐性性状，后代预期表型比例为 3:1。

Sex determination: in humans, females are XX and males are XY. Sex‑linked disorders, such as haemophilia and colour blindness, are more common in males because they have only one X chromosome.

性别决定：人类女性为 XX，男性为 XY。伴性遗传病，如血友病和色盲，在男性中更常见，因为他们只有一条 X 染色体。

Mutations are changes in the DNA sequence. They can be spontaneous or induced by mutagens (radiation, chemicals). Some mutations are neutral, harmful, or rarely beneficial.

突变是 DNA 序列的改变。突变可自然发生或由诱变剂（辐射、化学物质）诱发。有些突变是中性的，有的有害，极少情况下有利。

Natural selection acts on variation within a population. Individuals with advantageous traits are more likely to survive and reproduce, increasing the frequency of those alleles over generations. This is the basis of evolution.

自然选择作用于种群内的变异。具有有利性状的个体更可能存活和繁殖，从而在世代过程中增加这些等位基因的频率。这是进化的基础。

Speciation occurs when populations become reproductively isolated. Geographic isolation followed by genetic divergence can lead to the formation of new species.

当种群发生生殖隔离时，就会产生物种形成。地理隔离后的遗传分化可导致新物种的出现。

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9. Ecology and Energy Flow | 生态学与能量流

Ecosystems consist of a community of living organisms (biotic) interacting with their non‑living environment (abiotic). Habitat is the place where an organism lives; niche is its role in the ecosystem.

生态系统由生物群落（生物因子）与其非生物环境（非生物因子）相互作用构成。栖息地是生物生活的地方；生态位是其在生态系统中的角色。

Food chains and food webs represent feeding relationships. Producers (plants) convert light energy to chemical energy. Consumers eat other organisms. Decomposers break down dead matter, recycling nutrients.

食物链和食物网代表了摄食关系。生产者（植物）将光能转化为化学能。消费者取食其他生物。分解者分解死亡有机体，循环养分。

Energy flows through ecosystems and is lost as heat at each trophic level. Typically, only about 10% of energy is transferred to the next level. This limits the length of food chains.

能量流经生态系统，在每一营养级都会以热能形式散失。通常仅有约 10% 的能量传递到下一营养级，这限制了食物链的长度。

Carbon cycle: CO₂ is removed from the atmosphere by photosynthesis and returned through respiration, combustion, and decomposition. The greenhouse effect results from increased CO₂ and methane trapping infrared radiation.

碳循环：CO₂ 通过光合作用从大气中被移除，又通过呼吸作用、燃烧和分解返回到大气中。温室效应源于 CO₂ 和甲烷增多，截留红外辐射。

Nitrogen cycle involves nitrogen fixation (N₂ → NH₃/NH₄⁺), nitrification (NH₄⁺ → NO₂⁻ → NO₃⁻), assimilation by plants, and denitrification (NO₃⁻ → N₂). Bacteria play vital roles at each stage.

氮循环包括固氮 (N₂ → NH₃/NH₄⁺)、硝化 (NH₄⁺ → NO₂⁻ → NO₃⁻)、植物同化以及反硝化 (NO₃⁻ → N₂)。细菌在每个阶段都发挥着关键作用。

Biodiversity can be measured using species richness (number of species) and evenness. Deforestation, pollution, and climate change are major threats. Conservation methods include habitat protection and captive breeding.

生物多样性可通过物种丰富度（物种数目）和均匀度来衡量。森林砍伐、污染和气候变化是主要威胁。保护方法包括栖息地保护和圈养繁殖。

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10. Practical Skills and Safety | 实验技能与安全

Always wear safety goggles, a lab coat, and tie back long hair. Know the location of eye‑wash stations, fire extinguishers, and fire blankets. Handle all chemicals as if they are hazardous.

始终佩戴护目镜和实验服，扎起长发。了解洗眼器、灭火器和灭火毯的位置。处理所有化学试剂时均应视其具有危险性。

When heating, use a Bunsen burner with safety flame or a water bath. Never point the mouth of a test tube at yourself or others. Use thermal gloves when handling hot objects.

加热时，使用本生灯的安全火焰或水浴加热。切勿将试管口朝向自己或他人。拿取热物体时使用耐热手套。

Use measuring instruments correctly: read the bottom of the meniscus for liquids, avoid parallax error by aligning your eye level, and record measurements to the appropriate number of significant figures.

正确使用测量仪器：读取液体凹液面底部，视线与之平齐以避免视差，并以适当有效数字记录测量值。

When drawing biological specimens, use a sharp pencil, continuous lines, and do not shade. Include a title, magnification, and labels with straight, non‑crossing label lines.

绘制生物标本图时，使用锋利的铅笔和连续线条，不要涂阴影。添加标题、放大倍数，并用平直且不交叉的引线标注。

For chemistry practicals, always carry out a risk assessment. Use a fume cupboard when dealing with toxic or volatile substances. Dispose of waste in the correct containers.

化学实验中，始终进行风险评估。处理有毒或挥发性物质时，应在通风橱内操作。废弃物要分类投放至正确的收集容器。

IB students must maintain a complete lab portfolio with detailed reflections; CCEA students should be familiar with the practical assessment criteria. Practice writing conclusions that refer back to the initial hypothesis and evaluate limitations.

IB 学生必须维护一套完整的实验档案并附上详细反思；CCEA 学生应熟悉实验评价标准。练习撰写能回扣初始假设并评估实验局限性的结论。

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11. Exam-Day Checklist | 考前检查清单

Prepare your equipment the night before: transparent pencil case, pens, pencils (HB and 2B for graphs), ruler, calculator with fresh batteries, and a clear water bottle. Check you have any required data booklet or formula sheet.

前一天晚上准备好考试用品：透明笔袋、笔、铅笔（HB 和用于绘图的 2B）、直尺、装有新电池的计算器、透明水瓶。检查是否携带了所需的数据手册或公式表。

Read the paper instructions and all questions carefully. Highlight command terms such as ‘explain’, ‘describe’, ‘calculate’, and ‘evaluate’, and tailor your answer accordingly.

仔细阅读试卷说明和所有题目。用荧光笔标出“解释”、“描述”、“计算”、“评价”等指令词，并据此调整作答方式。

Manage your time: allocate roughly one minute per mark. If stuck on a question, mark it and move on; return to it after completing the rest of the paper.

管理好时间：大致按每分一分钟的方式分配。若被某题卡住，先做标记并继续答题，完成其余部分后再返回答题。

For calculation questions, show every step of the working, state the formula, substitute values with units, and give the final answer to the correct number of significant figures. A correct answer without working may lose marks.

计算题要展示每一步过程：列出公式，代入数值并带单位，最后结果取正确有效数字。没有过程仅有答案可能无法得到全部分数。

In longer written responses (especially IB extended response or CCEA quality of written communication questions), structure your answer with a brief introduction, logical paragraphs for each key point, and a concluding sentence. Use scientific terminology accurately.

在较长的文字回答中（尤其是 IB 拓展回答或 CCEA 书面表达品质题），用简短的引言、每个要点一个逻辑段落以及结论句来组织答案。准确使用科学术语。

Finally, stay calm and positive. If you feel anxious, take three slow breaths and refocus. You have prepared thoroughly – trust your revision notes and your ability to apply what you know.

Published by TutorHao | IB Science Revision Series | aleveler.com

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