📚 Core Knowledge for SQA Higher Sciences | SQA 高等级科学核心知识点梳理
For Year 12 learners following Scottish qualifications, the SQA Higher Sciences form a crucial bridge to further study and university entry. This article consolidates the essential concepts across Higher Biology, Higher Chemistry, and Higher Physics, focusing on the underpinning knowledge, key equations, and experimental contexts that examiners expect you to command. Whether you are preparing for assignments, unit assessments, or the final examination, a firm grasp of these cross-subject fundamentals will strengthen your scientific reasoning and problem-solving confidence.
对于学习苏格兰资格证书的 12 年级学生而言，SQA 高等级科学是从中学到大学的重要阶梯。本文整合了高等级生物、高等级化学和高等级物理的核心概念，聚焦于基础理论、关键方程以及考官希望你掌握的实验情境。无论你是在准备作业、单元评估还是期末考试，牢固掌握这些跨学科的基础知识，都会增强你的科学推理能力和解题信心。
1. The Scientific Method and Experimental Design | 科学方法与实验设计
A foundational skill across all SQA Higher Sciences is understanding how scientific knowledge is generated. You must be able to identify independent, dependent, and controlled variables, and explain why only one independent variable should be changed in a fair test. Replication of measurements, use of control groups, and randomisation are essential to increase reliability and validity. When describing an experiment, always link your choice of apparatus to the required precision—for example, using a volumetric pipette in chemistry titrations rather than a measuring cylinder to reduce percentage uncertainty.
所有 SQA 高等级科学学科的一项基础技能，是理解科学知识是如何产生的。你必须能够识别自变量、因变量和受控变量，并解释在一次公平测试中为什么只应改变一个自变量。重复测量、使用对照组和随机化对于提高信度和效度至关重要。在描述实验时，始终将你选择的仪器与所需的精密度联系起来——例如，在化学滴定中使用移液管而非量筒，以降低百分误差。
A key outcome is the ability to evaluate experimental procedures and suggest improvements. Consider sources of random error (e.g., reading a meniscus inconsistently) and systematic error (e.g., a balance that is not zeroed). Discussing how to minimise parallax error, controlling temperature with a water bath, or using data logging to capture rapid changes demonstrates higher-order thinking. The relationship between precision and accuracy must be clear: precise results cluster closely together, while accurate results are close to the true value.
一个关键的能力是能够评价实验步骤并提出改进建议。思考随机误差的来源（如读数时视线不一致）和系统误差的来源（如天平未归零）。讨论如何减小视差、用水浴控制温度，或使用数据记录器捕获快速变化，都能体现高阶思维。精密度与准确度之间的关系必须清晰：精密的结果会紧密聚集在一起，而准确的结果接近真实值。
2. Cells, DNA and Genetic Information | 细胞、DNA 与遗传信息 (Higher Biology)
The cell theory states that all living organisms are composed of cells, and all cells arise from pre-existing cells. You need to compare the structures of prokaryotic and eukaryotic cells, noting the absence of membrane-bound organelles in prokaryotes. Key organelles include mitochondria (site of aerobic respiration), chloroplasts (site of photosynthesis in plants), and ribosomes (site of protein synthesis). The structure of the plasma membrane—a phospholipid bilayer with embedded proteins—controls the movement of substances via diffusion, osmosis, and active transport, the latter requiring ATP.
细胞学说指出，所有生物体都由细胞组成，且所有细胞均来自已存在的细胞。你需要比较原核细胞和真核细胞的结构，注意原核细胞没有膜包被的细胞器。关键的细胞器包括线粒体（有氧呼吸的场所）、叶绿体（植物光合作用的场所）和核糖体（蛋白质合成的场所）。细胞膜的结构——磷脂双分子层镶嵌蛋白质——通过扩散、渗透和主动运输控制着物质的进出，其中主动运输需要消耗 ATP。
The DNA molecule is a double helix composed of nucleotides, each containing deoxyribose sugar, a phosphate group, and a nitrogenous base (adenine, thymine, guanine, cytosine). Base pairing (A–T, C–G) holds the strands together through hydrogen bonds. DNA replication is described as semi-conservative and requires DNA polymerase to add nucleotides in the 5′ to 3′ direction. The Central Dogma of molecular biology explains how the genetic code is expressed: DNA is transcribed into mRNA, which is then translated into a polypeptide chain at the ribosome. A codon of three bases codes for one amino acid, and the process involves tRNA anticodons binding to mRNA codons.
DNA 分子是由核苷酸组成的双螺旋，每个核苷酸包含脱氧核糖、一个磷酸基团和一个含氮碱基（腺嘌呤、胸腺嘧啶、鸟嘌呤、胞嘧啶）。碱基配对（A–T、C–G）依靠氢键连接两条链。DNA 复制被描述为半保留复制，需要 DNA 聚合酶按 5′ 到 3′ 方向添加核苷酸。分子生物学的中心法则解释了遗传信息如何表达：DNA 转录为 mRNA，mRNA 再在核糖体处翻译为多肽链。三个碱基的密码子对应一个氨基酸，该过程涉及 tRNA 反密码子与 mRNA 密码子的结合。
3. Metabolic Pathways and Respiration | 代谢途径与呼吸作用 (Higher Biology)
Metabolic pathways consist of a series of enzyme-controlled reactions. Anabolic pathways build up complex molecules and require energy, while catabolic pathways break down substrates and release energy. Enzymes are biological catalysts that lower the activation energy. Their activity is influenced by temperature and pH; at extreme values, denaturation causes a permanent change to the active site. Substrate concentration, competitive inhibitors, and non-competitive inhibitors alter the rate of reaction. The induced-fit model describes how the active site changes shape to bind the substrate more tightly.
代谢途径由一系列酶控反应组成。合成代谢途径构建复杂分子并消耗能量，而分解代谢途径分解底物并释放能量。酶是降低活化能的生物催化剂。其活性受温度和 pH 影响；在极端条件下，变性会导致活性位点发生不可逆改变。底物浓度、竞争性抑制剂和非竞争性抑制剂都会改变反应速率。诱导契合模型描述了活性位点如何改变形状以更紧密地结合底物。
Aerobic respiration involves glycolysis, the citric acid cycle, and the electron transport chain. Glycolysis takes place in the cytoplasm and converts glucose into pyruvate, yielding a small net gain of ATP and NADH. In the presence of oxygen, pyruvate enters the mitochondria and is converted to acetyl CoA, which feeds into the citric acid cycle. NADH and FADH₂ donate electrons to the electron transport chain on the inner mitochondrial membrane, driving the synthesis of a large amount of ATP by ATP synthase. Without oxygen, animal cells undergo lactate fermentation, regenerating NAD⁺ for glycolysis.
有氧呼吸包括糖酵解、柠檬酸循环和电子传递链。糖酵解发生在细胞质中，将葡萄糖转化为丙酮酸，产生少量 ATP 净得和 NADH。在氧气存在的情况下，丙酮酸进入线粒体并转化为乙酰辅酶 A，后者进入柠檬酸循环。NADH 和 FADH₂ 将电子传递给位于线粒体内膜上的电子传递链，驱动 ATP 合酶合成大量 ATP。没有氧气时，动物细胞进行乳酸发酵，为糖酵解再生 NAD⁺。
4. Chemical Bonding and Intermolecular Forces | 化学键与分子间作用力 (Higher Chemistry)
Understanding how atoms bond is central to explaining the properties of substances. Ionic bonding involves the transfer of electrons from a metal to a non-metal, forming a lattice of oppositely charged ions. Ionic compounds have high melting and boiling points and conduct electricity when molten or dissolved. Covalent bonding occurs when non-metal atoms share pairs of electrons. Covalent molecular substances like water and carbon dioxide have low melting points, while covalent network structures such as diamond and silicon dioxide are extremely hard and have very high sublimation points.
理解原子的键合方式是解释物质性质的核心。离子键涉及电子从金属转移到非金属，形成由带相反电荷离子构成的晶格。离子化合物具有较高的熔点和沸点，并在熔融或溶解时导电。共价键发生在非金属原子之间共用电子对时。共价分子物质如水和二氧化碳，熔点较低；而共价网络结构如金刚石和二氧化硅则极其坚硬，升华点非常高。
Intermolecular forces determine physical properties. London dispersion forces exist between all atoms and molecules and increase with molecular size. Permanent dipole–permanent dipole interactions arise in polar molecules, leading to higher boiling points. Hydrogen bonding, the strongest type of intermolecular force, occurs when hydrogen is bonded to nitrogen, oxygen, or fluorine. This force explains the anomalously high boiling point of water and the stability of DNA. The polarity of bonds is predicted by electronegativity differences, and molecules can be non-polar overall if dipoles cancel due to symmetry.
分子间作用力决定了物理性质。伦敦色散力存在于所有原子和分子之间，并随分子大小而增强。永久偶极-永久偶极相互作用存在于极性分子中，导致沸点升高。氢键是最强的分子间作用力，当氢与氮、氧或氟成键时产生。这种力解释了水沸点的异常升高以及 DNA 的稳定性。键的极性通过电负性差异来预测，若因分子对称而偶极抵消，分子总体上可以是非极性的。
5. The Mole, Concentration and Volumetric Analysis | 摩尔、浓度与容量分析 (Higher Chemistry)
The mole is the amount of substance containing the same number of elementary entities as there are atoms in 12 g of carbon-12. Quantitative calculations are essential: n = m ÷ M, n = C × V, n = V(gas) ÷ Vₘ, where Vₘ is the molar volume (taken as 24.0 L mol⁻¹ at room temperature and pressure for SQA). You must be confident converting mass, moles, concentration, and gas volume. Reacting mole ratios from a balanced equation allow you to determine the mass or concentration of an unknown reactant.
摩尔是物质的量，其包含的基本单元数与 12 克碳-12 中的原子数相等。定量计算至关重要：n = m ÷ M，n = C × V，n = V(气体) ÷ Vₘ，其中 Vₘ 是摩尔体积（在 SQA 中，常温常压下取 24.0 L mol⁻¹）。你必须熟练掌握质量、摩尔、浓度和气体体积之间的转换。根据配平方程式中的摩尔比，可以求出未知反应物的质量或浓度。
Volumetric analysis, particularly acid–base titration, is a core practical skill. A standard solution of known concentration is prepared by dissolving a primary standard (e.g., anhydrous sodium carbonate) in a volumetric flask. An appropriate indicator such as phenolphthalein or methyl orange is chosen based on the strength of the acid and alkali. Titre volumes should be concordant within 0.1 cm³. From the titre and known concentration, you calculate the unknown concentration, then scale up or down to determine purity or mass of analyte in the original sample.
容量分析，特别是酸碱滴定，是一项核心实验技能。将基准物质（如无水碳酸钠）溶解于容量瓶来配制已知浓度的标准溶液。根据酸和碱的强度，选择合适的指示剂如酚酞或甲基橙。滴定管读数应达到 0.1 cm³ 的精度内一致。根据滴定体积和已知浓度，计算未知浓度，然后按比例放大或缩小，以确定原始样品中待分析物的纯度或质量。
6. Enthalpy, Hess’s Law and Reaction Feasibility | 焓变、赫斯定律与反应可行性 (Higher Chemistry)
The enthalpy change, ΔH, is the heat energy change at constant pressure. Exothermic reactions (negative ΔH) release energy to the surroundings, while endothermic reactions (positive ΔH) absorb energy. You need to write thermochemical equations showing the state symbols and the ΔH value. Calculations typically use the relationship q = c m ΔT, where c is the specific heat capacity of the solution (often taken as 4.18 J g⁻¹ °C⁻¹), m is the mass of the solution, and ΔT is the temperature change. From q and the number of moles you find ΔH in kJ mol⁻¹.
焓变 ΔH 是指恒压下的热能量变化。放热反应（ΔH 为负）向环境释放能量，吸热反应（ΔH 为正）则吸收能量。你需要书写包含状态符号和 ΔH 值的热化学方程式。计算通常使用关系式 q = c m ΔT，其中 c 是溶液的比热容（常取 4.18 J g⁻¹ °C⁻¹），m 为溶液质量，ΔT 为温度变化。由 q 和摩尔数可求得 ΔH，单位为 kJ mol⁻¹。
Hess’s Law states that the enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same. This allows you to calculate an unknown enthalpy change from a combination of known enthalpies of formation or combustion. Bond enthalpies can also be used to estimate ΔH: ΔH = Σ(bond enthalpies broken) – Σ(bond enthalpies made). However, bond enthalpy values are averages and do not apply exactly to specific compounds. The feasibility of a reaction is judged using free energy: ΔG = ΔH – TΔS. A reaction is feasible at a given temperature when ΔG < 0.
赫斯定律指出，只要初态和终态条件相同，反应焓变与路径无关。这使得你可以通过组合已知的生成焓或燃烧焓来计算未知焓变。键焓也可以用来估算 ΔH：ΔH = Σ（断裂键的键焓）– Σ（形成键的键焓）。然而，键焓值是平均值，并不精确适用于特定化合物。反应的可行性通过自由能来判定：ΔG = ΔH – TΔS。在给定温度下，当 ΔG < 0 时反应是可行的。
7. Kinematics and Newton’s Laws | 运动学与牛顿定律 (Higher Physics)
Kinematics deals with the description of motion using displacement, velocity, and acceleration. The three equations of motion for constant acceleration in a straight line are fundamental. You must be able to apply these to objects moving vertically under gravity, on slopes, and in projectile motion (treating horizontal and vertical components independently). In higher physics, vector resolution is essential: any vector can be resolved into two perpendicular components, usually horizontal and vertical. The equations of motion are:
运动学涉及用位移、速度和加速度来描述运动。这三个匀加速直线运动的方程是基础。你必须能够将这些方程应用于在重力作用下垂直运动的物体、斜面运动以及抛体运动（独立处理水平方向和竖直方向分运动）。在高等级物理中，矢量分解至关重要：任何矢量都可以分解为两个垂直的分量，通常是水平和竖直方向。运动学方程为：
v = u + at
s = ut + ½at²
v² = u² + 2as
Where u is initial velocity, v final velocity, a acceleration, s displacement, and t time. Sign conventions are critical: you must assign a positive direction and keep acceleration signs consistent.
其中 u 为初速度，v 为末速度，a 为加速度，s 为位移，t 为时间。正负号约定至关重要：你必须指定一个正方向，并保持加速度的正负一致。
Newton’s laws of motion link force and motion. The first law introduces inertia; balanced forces mean constant velocity or rest. The second law, F = ma, is used extensively—unbalanced force causes acceleration. The third law explains that forces occur in pairs, acting on different objects. Combining Newton’s second law with vector resolution allows analysis of objects on inclined planes, connected systems (e.g., two masses over a light frictionless pulley), and lift problems. Free-body diagrams are the best tool for identifying all forces acting on an object.
牛顿运动定律将力与运动联系起来。第一定律引入了惯性；平衡力意味着速度恒定或静止。第二定律 F = ma 被广泛使用——不平衡力产生加速度。第三定律解释了力是成对出现的，作用在不同物体上。将牛顿第二定律与矢量分解结合，可以分析斜面上的物体、连接体系统（例如轻质无摩擦滑轮上的两个质量）和电梯问题。受力分析图是识别物体所受全部力的最佳工具。
8. Energy, Power and Momentum | 能量、功率与动量 (Higher Physics)
The principle of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed. Kinetic energy Eₖ = ½mv² and gravitational potential energy Eₚ = mgh are the two mechanical forms you manipulate most. In perfect collisions or conserved systems, loss in potential energy equals gain in kinetic energy. However, work done against friction converts mechanical energy into heat. The work–energy theorem states that the total work done by the external forces equals the change in kinetic energy. Power is the rate of doing work: P = E / t = Fv.
能量守恒定律指出，能量不能被创造或消灭，只能被转移或转化。动能 Eₖ = ½mv² 和重力势能 Eₚ = mgh 是你最常处理的两个机械能形式。在理想碰撞或守恒系统中，势能的减少等于动能的增加。然而，克服摩擦力做功会将机械能转化为热能。功能定理表明，外力做的总功等于动能的变化量。功率是做功的速率：P = E / t = Fv。
Momentum is a vector quantity given by p = mv. The law of conservation of momentum states that, in the absence of external forces, the total momentum of a system remains constant. This principle underpins collision and explosion calculations. Collisions are classified as elastic (kinetic energy conserved) or inelastic (kinetic energy is lost, often as heat and sound). In perfectly inelastic collisions, objects stick together. Impulse is the change in momentum and equals the area under a force–time graph: FΔt = Δp = mv – mu. This explains how airbags and crumple zones reduce force by increasing impact time.
动量是矢量，由 p = mv 给出。动量守恒定律指出，在没有外力作用的情况下，系统的总动量保持不变。这一原理是碰撞和爆炸计算的基础。碰撞分为弹性碰撞（动能守恒）和非弹性碰撞（动能损失，常转化为热和声）。在完全非弹性碰撞中，物体会粘在一起。冲量是动量的变化，等于力-时间图下的面积：FΔt = Δp = mv – mu。这解释了气囊和溃缩区域如何通过延长碰撞时间来减小作用力。
9. Waves, Refraction and the Electromagnetic Spectrum | 波、折射与电磁波谱 (Higher Physics)
Waves transfer energy without transferring matter. Transverse waves (e.g., light, EM waves) oscillate perpendicular to the direction of energy transfer; longitudinal waves (e.g., sound) oscillate parallel. Key parameters include frequency f, wavelength λ, amplitude, and period T, linked by v = f λ and f = 1/T. Diffraction is the spreading of a wave into a region of geometrical shadow when it passes through a gap or around an obstacle; the effect is most pronounced when the gap width is comparable to the wavelength.
波传递能量而不传递物质。横波（如光、电磁波）的振动方向垂直于能量传递方向；纵波（如声波）的振动方向则平行于传递方向。关键参数包括频率 f、波长 λ、振幅和周期 T，它们之间的关系为 v = f λ 并且 f = 1/T。衍射是指波在穿过狭缝或绕过障碍物时扩散到几何阴影区域的现象；当狭缝宽度与波长相近时，衍射效应最为明显。
Refraction is the change in direction of a wave as it passes from one medium into another due to a change in its speed. Snell’s law describes the relationship: n₁ sin θ₁ = n₂ sin θ₂, where n is the refractive index. The refractive index of a material is defined as the ratio of the speed of light in vacuum to the speed in the medium: n = c / v. A higher refractive index means a greater bending of light toward the normal. Total internal reflection occurs when light travels from a high-index medium to a lower-index one at an angle of incidence greater than the critical angle θ꜀. This principle is exploited in optical fibres for communication.
折射是指波从一种介质进入另一种介质时，由于速度改变而发生的方向变化。斯涅尔定律描述了这一关系：n₁ sin θ₁ = n₂ sin θ₂，其中 n 为折射率。材料的折射率定义为光在真空中的速度与在介质中速度之比：n = c / v。折射率越高，代表光线向法线偏折越大。当光从高折射率介质射向低折射率介质，且入射角大于临界角 θ꜀ 时，会发生全内反射。这一原理被应用于通信用的光纤中。
10. Electrical Circuits and Internal Resistance | 电路与内电阻 (Higher Physics)
Understanding the flow of charge is fundamental. Current I is the rate of flow of charge; potential difference V is the energy transferred per unit charge. Ohm’s law at constant temperature gives V = IR for ohmic conductors. Resistance depends on temperature; for most metals, resistance increases as temperature rises, but for negative temperature coefficient thermistors, resistance falls. In series circuits, current is the same and the supply voltage splits across resistors; in parallel, the voltage is the same and the current divides. The combined resistance rules are: series R_total = R₁ + R₂ + … and parallel 1/R_total = 1/R₁ + 1/R₂ + …
理解电荷的流动是基础。电流 I 是电荷流动的速率；电势差 V 是转移单位电荷所消耗的能量。欧姆定律在恒温条件下给出 V = IR，适用于欧姆导体。电阻取决于温度；对大多数金属而言，电阻随温度升高而增大，但对负温度系数热敏电阻来说，电阻是下降的。在串联电路中，电流相同，电源电压分配在各个电阻上；在并联电路中，电压相同，电流分流。电阻组合的规则是：串联 R_总 = R₁ + R₂ + …；并联 1/R_总 = 1/R₁ + 1/R₂ + …
A real source of emf (electromotive force) has internal resistance r. The terminal potential difference V across the cell is less than the emf when current flows: V = E – Ir. The lost volts Ir inside the cell heat the battery. This is often explored through a circuit where a variable resistor is used to collect pairs of V and I readings. Plotting V against I yields a straight-line graph with gradient –r and y-intercept E. Short-circuit current occurs when V = 0 giving I_max = E / r. Capacitors in DC circuits store charge on two parallel plates; for a given capacitor, Q = CV, and the energy stored is E = ½QV = ½CV².
真实的电动势源具有内电阻 r。当有电流流过时，电池的端电压 V 低于电动势：V = E – Ir。电池内部的损耗电压 Ir 会使电池发热。这通常通过一个可变电阻电路来探究，收集对应的 V 和 I 数据点。画出 V–I 图，得到一条直线，其斜率为 –r，y 轴截距为 E。短路电流发生在 V = 0 时，此时 I_最大值 = E / r。直流电路中的电容器可在两个平行板上储存电荷；对于一个给定的电容器，Q = CV，储存的能量为 E = ½QV = ½CV²。
11. Spectroscopy and Chemical Analysis | 光谱与化学分析 (Higher Chemistry / Physics overlap)
Spectroscopic techniques are used to identify elements and compounds. Atomic emission spectroscopy produces line spectra from excited atoms. Each element has a unique fingerprint because electrons fall from higher to lower energy levels, emitting photons of specific energies. The relationship between photon energy and frequency is E = hf, where h is Planck’s constant. Absorption spectra appear as dark lines on a continuous background and are equally useful for identification. In infrared spectroscopy, bonds vibrate at characteristic frequencies, absorbing IR radiation; functional groups such as O–H, C=O, and C–H show characteristic absorption bands, enabling identification of organic molecules.
光谱技术用于鉴定元素和化合物。原子发射光谱由激发态原子产生线状光谱。每种元素都有独特的指纹，这是因为电子从高能级回落到低能级时，会发射特定能量的光子。光子能量与频率的关系为 E = hf，其中 h 是普朗克常数。吸收光谱表现为连续谱背景上的暗线，同样可用于鉴定。在红外光谱中，化学键以其特征频率振动，吸收红外辐射；O–H、C=O、C–H 等官能团显示出特征吸收峰，从而能够鉴别有机分子。
Chemical testing in Higher Chemistry includes distinguishing between aldehydes and ketones using Tollen’s reagent (silver mirror with aldehydes) or Fehling’s solution (brick-red precipitate). The iodoform test indicates methyl ketone groups or ethanol. Chromatography separates mixtures based on relative solubility and adsorption. The Rf value (distance moved by spot divided by distance moved by solvent front) aids identification. In a biological context, the Bradford assay determines protein concentration using a spectrophotometer by measuring absorbance at 595 nm.
高等级化学中的化学测试包括：使用托伦试剂（醛类产生银镜）或斐林试剂（砖红色沉淀）区分醛和酮；碘仿试验指示甲基酮基团或乙醇。色谱法基于相对溶解度和吸附作用分离混合物。Rf 值（斑点移动距离除以溶剂前沿移动距离）有助于鉴定。在生物情境中，布拉德福测定法利用分光光度计在 595 nm 处测量吸光度以测定蛋白质浓度。
12. Integrating Across the Sciences | 跨科学整合
SQA Higher Sciences reward the ability to make connections. For example, the concept of energy transfer links cellular respiration in biology, enthalpy in chemistry, and conservation of energy in physics. The action spectrum of photosynthesis aligns with the electromagnetic spectrum and the inverse relationship between wavelength and photon energy. Chemical bonding explains the properties of biomolecules such as proteins and DNA. The principles of forces and equilibrium are applied when analysing the biomechanics of joints and muscle levers. Practicing questions that blend physics with biological systems—such as fluid flow, gas laws in respiration, or the optics of the eye—deepens understanding and prepares you for the problem-solving nature of the examinations.
SQA 高等级科学鼓励建立联系的能力。例如，能量转移的概念联系了生物学中的细胞呼吸、化学中的焓变和物理学中的能量守恒。光合作用的作用光谱与电磁波谱以及波长和光子能量之间的反比关系相契合。化学键解释了蛋白质和 DNA 等生物分子的性质。力和平衡原理被应用于分析关节和肌肉杠杆的生物力学中。练习那些将物理学与生物系统结合起来的题目——如流体流动、呼吸中的气体定律或眼睛的光学——可以加深理解，并为考试的解题特性做好准备。
Finally, keep the SQA question words central to your revision. ‘Describe’ requires stating the facts; ‘Explain’ demands a reason or mechanism; ‘Calculate’ expects a precise numeric answer with appropriate units; and ‘Evaluate’ involves a balanced judgement. Time management, correct unit conversions, and significant figures (typically two or three in final answers) are cross-subject skills that can easily gain or lose marks. Return frequently to data book values—SQA provides a data booklet for each science that holds constants, equations, and spectra you must be able to locate and apply quickly.
最后，在复习中要始终围绕 SQA 的指令词。“描述”要求陈述事实；“解释”要求给出原因或机理；“计算”要求得出精确的数字答案并带适当单位；“评价”则涉及做出权衡性的判断。时间管理、正确的单位换算以及有效数字（最终答案通常取两位或三位）是跨学科技能，很容易因此得分或失分。要反复回顾数据手册中的数值——SQA 为每门科学提供了数据小册子，内含常数、方程和光谱，你必须能够快速查找和应用它们。
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