📚 Year 9 SQA Science: Core Knowledge Review | Year 9 SQA 科学：核心知识点梳理
Year 9 in the Scottish Curriculum for Excellence (CfE) sits at the end of the Broad General Education (BGE) phase. It consolidates key scientific ideas across biology, chemistry, and physics, building a solid foundation for National 4/5 qualifications. This article reviews the core concepts every S3/S4 student in Scotland should master.
在苏格兰“卓越课程”（CfE）的框架下，Year 9 正处于广泛普通教育（BGE）阶段的收尾期。它梳理生物、化学和物理的核心科学概念，为升入国家四级/五级课程打下坚实基础。本文梳理了苏格兰中学 S3/S4 阶段学生必须掌握的核心知识点。
1. Cells and Living Organisms | 细胞与生物体
All living things are made of cells. Animal cells contain a nucleus, cytoplasm, cell membrane and mitochondria. Plant cells have the same parts plus a rigid cell wall, a large permanent vacuole and chloroplasts for photosynthesis. Cells are the basic structural and functional units of life.
所有生物都由细胞构成。动物细胞包含细胞核、细胞质、细胞膜和线粒体。植物细胞除此之外还有坚硬的细胞壁、中央大液泡以及进行光合作用的叶绿体。细胞是生命的基本结构与功能单位。
Substances move into and out of cells by diffusion and osmosis. Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. Osmosis is the diffusion of water through a selectively permeable membrane. Both processes are passive and do not require energy.
物质通过扩散和渗透进出细胞。扩散是粒子从高浓度区域向低浓度区域的净移动。渗透是水通过选择透过性膜的扩散。这两个过程都是被动的，不需要消耗能量。
2. Body Systems | 人体系统
The human body is organised into systems that work together. The digestive system breaks down large food molecules into small soluble substances that can be absorbed into the blood. Enzymes are biological catalysts that speed up digestion without being used up.
人体由协同工作的系统构成。消化系统将大分子食物分解为可吸收的小分子可溶物质。酶是生物催化剂，能加速消化而自身不被消耗。
The respiratory system brings oxygen into the body and removes carbon dioxide. Breathing involves the movement of the diaphragm and ribcage to change the volume and pressure inside the chest. Gas exchange happens in the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out.
呼吸系统吸入氧气并排出二氧化碳。呼吸时膈肌和肋骨运动改变胸腔的体积和压力。气体交换在肺泡进行：氧气扩散入血，二氧化碳扩散排出。
The circulatory system carries oxygen, nutrients and waste products around the body. The heart pumps blood through arteries, veins and capillaries. Red blood cells contain haemoglobin, which binds to oxygen for transport.
循环系统负责输送氧气、营养物质和废物。心脏将血液泵入动脉、静脉和毛细血管。红细胞含有血红蛋白，能与氧气结合进行运输。
3. Reproduction and Inheritance | 生殖与遗传
Organisms reproduce either sexually or asexually. Sexual reproduction involves the fusion of male and female gametes (sperm and egg), producing offspring that are genetically different from the parents. Asexual reproduction produces clones – genetically identical offspring – and requires only one parent.
生物通过有性或无性方式繁殖。有性生殖涉及雌雄配子（精子和卵子）融合，后代基因与亲代不同。无性生殖产生克隆――遗传上相同的后代――只需一个亲本。
Inherited characteristics are controlled by genes located on chromosomes in the nucleus. DNA carries the genetic code. Alleles are different versions of a gene, and some are dominant while others are recessive. Simple genetic crosses can be shown using Punnett squares.
遗传特征由位于细胞核染色体上的基因控制。DNA 携带着遗传密码。等位基因是基因的不同版本，有些是显性，有些是隐性。简单的遗传杂交可用庞纳特方格表示。
4. Ecosystems and Energy Flow | 生态系统与能量流动
An ecosystem is a community of living organisms interacting with each other and their non‑living environment. Producers (green plants) make their own food by photosynthesis using sunlight, carbon dioxide and water. Consumers eat other organisms; decomposers break down dead matter and recycle nutrients.
生态系统是生物群落与环境中非生物成分相互作用的系统。生产者（绿色植物）利用阳光、二氧化碳和水通过光合作用制造食物。消费者取食其他生物；分解者分解死物并循环养分。
Energy flows through an ecosystem in a food chain or food web. At each trophic level, energy is lost as heat and through movement, so only about 10% of the energy is passed on to the next level. Pyramids of numbers and biomass represent these relationships.
能量通过食物链或食物网在生态系统中流动。每经过一个营养级，能量都以热和运动等形式损耗，只有约 10% 传给下一个层级。数量金字塔和生物量金字塔表示了这些关系。
5. States of Matter and Particle Theory | 物质状态与粒子理论
Matter exists as solid, liquid or gas. The particle model explains the properties of each state: in solids, particles are closely packed in a regular pattern and vibrate in fixed positions; in liquids, particles are close but can move past each other; in gases, particles are far apart and move randomly at high speed.
物质以固态、液态或气态存在。粒子模型解释各状态的性质：固体中粒子紧密排列并原地振动；液体中粒子较近但能互相滑动；气体中粒子相距很远且高速随机运动。
Changes of state include melting, freezing, boiling, condensation and sublimation. Adding heat gives particles more kinetic energy, causing a change to a more energetic state. Mass is conserved during a change of state because the number of particles stays the same.
物态变化包括熔化、凝固、沸腾、凝结和升华。加热使粒子动能增加，促使向更高能态变化。物态变化过程中质量守恒，因为粒子总数不变。
6. Atoms, Elements and the Periodic Table | 原子、元素与周期表
All substances are made of atoms. An atom has a tiny central nucleus containing protons and neutrons, surrounded by electrons in shells. The atomic number is the number of protons, which determines the element. An element is a substance made of only one type of atom.
所有物质由原子构成。原子中心有极小的原子核，内含质子和中子，核外有电子排布在电子层中。原子序数即质子数，决定了元素的种类。元素是仅由一种原子组成的物质。
The periodic table arranges elements in order of increasing atomic number. Groups are vertical columns; elements in the same group have similar chemical properties because they have the same number of outer electrons. Metals are on the left, non‑metals on the right.
周期表按原子序数递增的顺序排列元素。族是竖列；同族元素因最外层电子数相同而化学性质相似。金属位于左侧，非金属位于右侧。
7. Chemical Reactions and Equations | 化学反应与方程式
In a chemical reaction, reactants are converted into new products. Signs of a reaction include colour change, temperature change, gas production and precipitate formation. Chemical equations use symbols and formulae to show what happens. Word equations and balanced symbol equations are both used at this level.
在化学反应中，反应物转化为新的生成物。反应现象包括颜色变化、温度变化、产生气体和生成沉淀。化学方程式用符号和化学式表示反应过程。本级需掌握文字方程式和配平的符号方程式。
products. For example: 2Mg + O₂ → 2MgO. The numbers of each type of atom balance on both sides.
质量守恒定律表明原子不可凭空创造或消灭。因此反应物总质量等于生成物总质量。例如：2Mg + O₂ → 2MgO，两边每种原子的数目相等。
8. Acids and Alkalis | 酸与碱
Acids have a pH less than 7; alkalis have a pH greater than 7. The pH scale measures how acidic or alkaline a solution is. Neutral solutions, like pure water, have a pH of 7. Indicators such as litmus and universal indicator show the pH by colour change.
酸溶液的 pH 小于 7；碱溶液的 pH 大于 7。pH 标度衡量溶液的酸碱度。中性溶液（如纯水）的 pH 为 7。石蕊和通用指示剂等指示剂通过颜色变化显示 pH。
⁺ + OH⁻ → H₂O. The name of the salt comes from the acid and the metal in the alkali. For example, hydrochloric acid + sodium hydroxide → sodium chloride + water.
酸含氢离子（H⁺），碱含氢氧根离子（OH⁻）。中和反应中，酸与碱反应生成盐和水：H⁺ + OH⁻ → H₂O。盐的名称来自酸和碱中的金属。例如：盐酸 + 氢氧化钠 → 氯化钠 + 水。
9. Forces and Motion | 力与运动
converts kinetic energy into thermal energy. Weight is the force of gravity on a mass: W = m × g, where g = 10 N/kg on Earth.
力是推或拉，单位为牛顿（N）。不平衡的力导致速度或方向的变化。摩擦力阻碍运动，并将动能转化为热能。重量是作用在质量上的重力：W = m × g，地球上 g = 10 N/kg。
er unit time: speed = distance ÷ time. Acceleration is the rate of change of speed: a = (v – nal speed, u is initial speed, and t is time. Balanced forces mean constant speed or rest.
速度是单位时间内走过的距离：速度 = 距离 ÷ 时间。加速度是速度的变化率：a = (v – u) ÷ t，其中 v 为末速度，u 为初速度，t 为时间。平衡力意味着速度不变或静止。
10. Energy Forms and Transfers | 能量形式与转移
Energy exists in many forms: kinetic, potential (gravitational, elastic, chemical), thermal, light, electrical and sound. Energy can be stored or transferred from one store to another through forces, heating or electrical work.
能量存在多种形式：动能、势能（重力势能、弹性势能、化学能）、热能、光能、电能和声能。能量可被储存，或通过力、加热或电做功在不同储存方式间转移。
seful. Efficiency = useful output energy ÷ total input energy, often expressed as a percentage. For example, gravitational potential energy gained = m × g × h.
封闭系统中的总能量守恒。在能量转移中，部分能量通常以热的形式耗散（散开），变得无用。效率 = 有用输出能 ÷ 总输入能，常以百分比表示。例如，增加的重力势能 = m × g × h。
11. Electricity and Circuits | 电与电路
Current is the flow of electric charge. It is measured in amperes (A) with an ammeter connected in series. Voltage (potential difference) is the energy transferred per unit charge, measured in volts (V) using a voltmeter in parallel. Resistance, measured in ohms (Ω), opposes the flow of current.
电流是电荷的流动，单位为安培（A），用电流表串联测量。电压（电位差）是单位电荷转移的能量，单位为伏特（V），用电压表并联测量。电阻以欧姆（Ω）为单位，阻碍电流流动。
Ohm' urrent is the same everywhere and voltages add up. In parallel circuits, the voltage across each branch is the same and currents split. Household wiring uses parallel circuits so each appliance works independently.
欧姆定律联系电压、电流和电阻：V = I × R。串联电路中电流处处相等，电压相加。并联电路中各支路电压相等，电流分流。家庭供电使用并联电路，使得每个电器独立工作。
12. Waves and Sound | 波与声音
light, water ripples). In longitudinal waves, vibrations are parallel to the direction of energy transfer (e.g. sound). The wave equation is v = fλ, where v is speed, f is frequency and λ is wavelength.
波传递能量而不传递物质。横波的振动方向与能量传递方向垂直（如光波、水波）。纵波的振动方向与能量传递方向平行（如声波）。波速公式为 v = fλ，其中 v 为波速，f 为频率，λ 为波长。
Sound is caused by vibrating objects and travels fastest in solids, slower in liquids and slowest in gases. The ear detects sound waves that are channelled to the eardrum, causing it to vibrate. Echoes are reflected sound waves; sonar uses echoes to determine distances. Pitch is related to frequency, and loudness to amplitude.
声音由物体振动产生，在固体中传播最快，液体中次之，气体中最慢。耳朵接收声波，声波使鼓膜振动。回声是反射的声波；声纳利用回声测量距离。音调与频率相关，响度与振幅相关。
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