📚 KS3 AQA Science: Core Knowledge Review | KS3 AQA 科学：核心知识点梳理
KS3 Science under the AQA syllabus builds a strong foundation in biology, chemistry, and physics. Mastering these core concepts prepares you for GCSE and develops scientific thinking and practical skills.
在 AQA 大纲下，KS3 科学为生物学、化学和物理学打下坚实基础。掌握这些核心知识点有助于为 GCSE 做准备，并培养科学思维与实验技能。
1. Cells and Organisation | 细胞与组织
All living organisms are made up of cells. Cells are the basic building blocks of life and carry out all life processes.
所有生物体都由细胞组成。细胞是生命的基本结构单位，进行着一切生命活动。
Animal cells contain a nucleus, cytoplasm, cell membrane, and mitochondria. Plant cells have these plus a cell wall, chloroplasts, and a permanent vacuole.
动物细胞含有细胞核、细胞质、细胞膜和线粒体。植物细胞除了这些，还有细胞壁、叶绿体和中央液泡。
Specialised cells have adaptations that help them perform specific functions. For example, sperm cells have a tail for movement, and root hair cells have a large surface area to absorb water.
特化细胞具有适应其特定功能的特征。例如，精子有一条用于运动的尾巴，根毛细胞有较大的表面积以吸收水分。
Groups of similar cells form tissues, tissues form organs, and organs work together in organ systems. Examples include the digestive system and the circulatory system.
相似细胞构成组织，组织构成器官，器官协同工作构成器官系统。例如消化系统和循环系统。
Substances move in and out of cells by diffusion. Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
物质通过扩散进出细胞。扩散是粒子从高浓度区域向低浓度区域的净移动。
2. Reproduction | 生殖
Reproduction can be sexual (involving two parents and gametes) or asexual (involving one parent and no gametes). Sexual reproduction leads to variation, while asexual reproduction produces genetically identical offspring.
生殖分为有性生殖（涉及双亲和配子）和无性生殖（涉及单一亲本，无配子）。有性生殖导致变异，无性生殖产生遗传上完全相同的后代。
In humans, male gametes (sperm) are produced in the testes and female gametes (eggs) are produced in the ovaries. Fertilisation occurs when a sperm cell fuses with an egg cell.
在人类中，男性配子（精子）在睾丸中产生，女性配子（卵子）在卵巢中产生。当精子与卵细胞融合时，即发生受精。
The menstrual cycle prepares the female body for pregnancy. If fertilisation does not occur, the thickened lining of the uterus is shed during menstruation.
月经周期为女性身体怀孕做准备。如果未发生受精，增厚的子宫内膜会在月经期脱落。
During pregnancy, the embryo develops in the uterus and receives oxygen and nutrients from the mother through the placenta. Birth occurs after about nine months.
怀孕期间，胚胎在子宫内发育，并通过胎盘从母体获得氧气和营养。大约九个月后分娩。
Plants also reproduce sexually, involving pollination and fertilisation. Pollen is transferred from the anther to the stigma, and after fertilisation, seeds and fruits form for dispersal.
植物也进行有性生殖，涉及传粉和受精。花粉从花药传到柱头，受精后形成种子和果实，以便传播。
3. Particles and States of Matter | 粒子与物质状态
All matter is made up of tiny particles. The arrangement and movement of these particles explain the properties of solids, liquids, and gases.
所有物质都由微小粒子构成。这些粒子的排列和运动解释了固体、液体和气体的性质。
In solids, particles are held tightly in fixed positions and only vibrate. In liquids, particles are close together but can move past each other. In gases, particles are far apart and move rapidly in all directions.
在固体中，粒子被紧紧固定在位置上，只能振动。液体中粒子彼此靠近但可以相对滑动。气体中粒子相距很远，朝各个方向快速运动。
Changes of state include melting, freezing, boiling, evaporating, condensing, and sublimation. Mass is conserved during these changes, but energy is transferred.
状态变化包括熔化、凝固、沸腾、蒸发、冷凝和升华。这些变化中质量守恒，但能量会发生转移。
The particle model explains gas pressure: it is caused by gas particles colliding with the walls of a container. More collisions or faster particles lead to higher pressure.
粒子模型可以解释气体压强：它由气体粒子撞击容器壁造成。碰撞越多或粒子运动越快，压强越大。
Diffusion in liquids and gases provides evidence for the particle model. Heavier particles diffuse more slowly than lighter particles at the same temperature.
液体和气体中的扩散为粒子模型提供了证据。相同温度下，较重的粒子比较轻的粒子扩散得更慢。
4. Atoms, Elements and Compounds | 原子、元素与化合物
An atom is the smallest unit of an element that retains its chemical properties. Elements are listed in the periodic table, each represented by a chemical symbol.
原子是保留元素化学性质的最小单位。元素列于周期表中，每种元素有一个化学符号表示。
Compounds form when two or more different elements chemically combine in fixed proportions. The properties of a compound are often different from those of its constituent elements.
当两种或以上不同元素以固定比例化学结合时，就形成化合物。化合物的性质通常不同于其组成元素的性质。
Mixtures contain two or more substances not chemically combined. They can be separated by physical techniques such as filtration, distillation, chromatography, and evaporation.
混合物包含两种或以上未化学结合的物质。它们可以通过过滤、蒸馏、色谱法和蒸发等物理方法分离。
Atoms have a small central nucleus containing protons and neutrons, surrounded by electrons. Protons carry a positive charge, electrons a negative charge, and neutrons have no charge.
原子有一个包含质子和中子的小原子核，周围有电子。质子带正电，电子带负电，中子不带电。
Chemical formulae use symbols to show the types and numbers of atoms in a compound. For example, H₂O represents water, and CO₂ represents carbon dioxide.
化学式用符号表示化合物中原子的种类和数目。例如，H₂O 代表水，CO₂ 代表二氧化碳。
5. Chemical Reactions | 化学反应
Chemical reactions involve the formation of new substances. Signs of a chemical change include a colour change, temperature change, gas production, or formation of a precipitate.
化学反应涉及新物质的生成。化学变化的迹象包括颜色改变、温度变化、产生气体或形成沉淀。
In a chemical reaction, atoms are rearranged but not created or destroyed. The total mass of reactants equals the total mass of products (conservation of mass).
在化学反应中，原子重新排列，但没有被创造或消灭。反应物的总质量等于生成物的总质量（质量守恒）。
Acids have a pH less than 7, alkalis have a pH greater than 7, and neutral solutions have a pH of 7. A neutralisation reaction occurs between an acid and an alkali, producing a salt and water.
酸的 pH 小于 7，碱的 pH 大于 7，中性溶液的 pH 为 7。酸与碱之间发生中和反应，生成盐和水。
Metals react with acids to produce a salt and hydrogen gas. For example, zinc + hydrochloric acid → zinc chloride + hydrogen (Zn + 2HCl → ZnCl₂ + H₂).
金属与酸反应生成盐和氢气。例如，锌 + 盐酸 → 氯化锌 + 氢气 (Zn + 2HCl → ZnCl₂ + H₂)。
Combustion is a rapid reaction with oxygen that releases heat and light. The complete combustion of a hydrocarbon fuel produces carbon dioxide and water.
燃烧是与氧气的快速反应，释放热和光。碳氢燃料的完全燃烧产生二氧化碳和水。
6. Energy | 能量
Energy can be stored in different forms, including kinetic, thermal, chemical, gravitational potential, elastic potential, and nuclear energy. Energy is measured in joules (J).
能量可以以不同形式储存，包括动能、热能、化学能、重力势能、弹性势能和核能。能量以焦耳 (J) 为单位。
The law of conservation of energy states that energy cannot be created or destroyed; it can only be transferred, stored, or dissipated (spread out wastefully, often as heat).
能量守恒定律指出，能量不能被创造或毁灭，只能被转移、储存或耗散（通常以热的形式浪费性地散开）。
Work is done when a force moves an object. The amount of work done equals the energy transferred. Power is the rate at which energy is transferred or work is done.
当一个力使物体移动时，就做了功。所做的功等于转移的能量。功率是能量转移或做功的速率。
Energy can be transferred by heating through conduction, convection, and radiation. Conduction occurs mainly in solids, convection in fluids, and radiation does not require a medium.
能量可以通过热传导、对流和辐射进行传递。传导主要发生在固体中，对流在流体中，辐射不需要介质。
Our bodies obtain energy from food. Food energy is also measured in joules, and different foods provide different amounts of energy per gram.
我们的身体从食物中获取能量。食物能量也用焦耳计量，不同食物每克提供的能量不同。
7. Forces and Motion | 力与运动
A force is a push or a pull, measured in newtons (N). Forces can be contact forces (e.g., friction) or non-contact forces (e.g., gravity, magnetism).
力是推力或拉力，以牛顿 (N) 为单位测量。力可以是接触力（如摩擦力）或非接触力（如重力、磁力）。
When multiple forces act on an object, the resultant force determines the motion. If the resultant force is zero, the object is in equilibrium and its motion does not change.
当多个力作用在物体上时，合力决定其运动。如果合力为零，物体处于平衡状态，其运动状态不变。
Speed is calculated as distance divided by time (speed = distance ÷ time, in m/s or km/h). A distance–time graph shows how far an object has travelled over time; a steeper slope indicates a higher speed.
速度的计算方式为距离除以时间（速度 = 距离 ÷ 时间，单位为 m/s 或 km/h）。距离-时间图显示物体随时间移动的距离；斜率越大表示速度越快。
Friction is a force that opposes motion between two surfaces. It can be reduced by lubrication or streamlining. Air resistance is a type of friction acting on objects moving through air.
摩擦力是阻碍两表面相对运动的力，可以通过润滑或流线型设计减小。空气阻力是作用在空气中运动物体上的一种摩擦力。
Stretching a spring demonstrates Hooke’s law: the extension of a spring is directly proportional to the applied force, provided the elastic limit is not exceeded.
拉伸弹簧可验证胡克定律：在不超过弹性限度的条件下，弹簧的伸长量与施加的力成正比。
8. Electricity | 电
An electric circuit needs a complete path for current to flow. Current is the flow of electric charge, measured in amperes (A).
电路需要完整的回路才能使电流流动。电流是电荷的流动，以安培 (A) 为单位。
Voltage (potential difference) is the ‘push’ that drives current around a circuit, measured in volts (V). Resistance opposes the flow of current and is measured in ohms (Ω).
电压（电势差）是推动电流在电路中流动的“推力”，以伏特 (V) 为单位。电阻阻碍电流流动，以欧姆 (Ω) 为单位。
Ohm’s law relates voltage, current, and resistance: V = I × R (voltage equals current multiplied by resistance).
欧姆定律将电压、电流和电阻联系起来：V = I × R（电压等于电流乘以电阻）。
In a series circuit, the current is the same everywhere, but the voltage is divided across components. In a parallel circuit, the voltage across each branch is the same but the current splits.
在串联电路中，各处电流相等，但电压在各元件间分配。在并联电路中，各支路两端电压相同，但电流分流。
Circuit diagrams use standard symbols to represent components such as cells, batteries, lamps, switches, and motors. Wires are shown as straight lines.
电路图用标准符号表示元件，如电池、电池组、灯泡、开关和电动机。导线用直线表示。
9. Waves: Sound and Light | 波：声音与光
Waves transfer energy without transferring matter. Transverse waves (e.g., light, water waves) have oscillations perpendicular to the direction of energy move; longitudinal waves (e.g., sound) have oscillations parallel to it.
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播方向垂直；纵波（如声波）的振动方向与传播方向平行。
Sound is produced by vibrations and travels as a longitudinal wave through a medium such as air, liquid, or solid. It cannot travel through a vacuum.
声音由振动产生，以纵波形式通过空气、液体或固体等介质传播。它不能在真空中传播。
The pitch of a sound depends on its frequency (measured in hertz, Hz); a higher frequency gives a higher pitch. The loudness depends on the amplitude of the wave; a larger amplitude produces a louder sound.
声音的音调取决于其频率（以赫兹 Hz 为单位）；频率越高，音调越高。响度取决于波的振幅；振幅越大，声音越响。
Light travels in straight lines at a very high speed (about 300 000 000 m/s in a vacuum). We see objects because they emit light or reflect light into our eyes.
光沿直线传播，速度极快（真空中约 3×10⁸ m/s）。我们看见物体是因为它们发光或将光反射到我们眼中。
The law of reflection states that the angle of incidence equals the angle of reflection. Refraction occurs when light changes speed as it passes from one medium to another, causing it to change direction.
反射定律指出，入射角等于反射角。当光从一种介质进入另一种介质速度改变时，会发生折射，导致光改变方向。
10. Ecosystems and Interdependence | 生态系统与相互依存
An ecosystem consists of a community of living organisms interacting with each other and with the non-living parts of their environment. Producers, consumers, and decomposers play key roles.
生态系统由生物群落与其环境中非生物部分相互作用而构成。生产者、消费者和分解者扮演着关键角色。
Food chains and food webs show feeding relationships and energy flow. Producers (mainly green plants) make food by photosynthesis, using sunlight to convert carbon dioxide and water into glucose and oxygen.
食物链和食物网展示捕食关系与能量流动。生产者（主要是绿色植物）通过光合作用制造食物，利用阳光将二氧化碳和水转化为葡萄糖和氧气。
Photosynthesis can be summarised as: carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll). The glucose is used for energy and growth, or stored as starch.
光合作用可概括为：二氧化碳 + 水 → 葡萄糖 + 氧气（在光和叶绿体存在下）。葡萄糖用于能量和生长，或储存为淀粉。
Predators and prey have a cyclical relationship: as prey numbers increase, predators have more food and their numbers rise, which then reduces prey numbers, and the cycle continues.
捕食者和猎物有循环关系：猎物数量增加时，捕食者食物充足，数量上升，进而导致猎物数量减少，这一循环不断持续。
Organisms compete for resources such as food, water, light, and space. Adaptations help them survive in their habitats. Biodiversity is vital for a stable ecosystem.
生物为食物、水、光和空间等资源竞争。适应性帮助它们在其栖息地生存。生物多样性对稳定的生态系统至关重要。
11. Earth Science | 地球科学
The Earth has a layered structure: a solid inner core, a liquid outer core, a mantle, and a thin crust. Convection currents in the mantle drive plate tectonics.
地球具有层状结构：固态内核、液态外核、地幔以及薄的地壳。地幔中的对流驱动了板块构造。
Rocks are classified into three main types: igneous (formed from cooling magma or lava), sedimentary (formed from compressed layers of sediment), and metamorphic (formed by heat and pressure changing existing rocks).
岩石分为三大类：火成岩（由岩浆或熔岩冷却形成）、沉积岩（由沉积物压紧成层形成）和变质岩（由热和压力改变原有岩石形成）。
The rock cycle describes how rocks change from one type to another over geological time through processes such as weathering, erosion, melting, and metamorphism.
岩石循环描述了岩石如何通过风化、侵蚀、熔融和变质等过程，在地质时间尺度上由一种类型变为另一种类型。
Earth’s atmosphere is composed mainly of nitrogen (about 78%) and oxygen (about 21%), with small amounts of argon, carbon dioxide, and water vapour. Human activities can change its composition.
地球大气层主要由氮气（约 78%）和氧气（约 21%）组成，还有少量的氩、二氧化碳和水蒸气。人类活动可能改变其成分。
The carbon cycle shows how carbon is recycled naturally, but burning fossil fuels and deforestation increase atmospheric CO₂, contributing to the enhanced greenhouse effect and global warming.
碳循环显示了碳如何自然循环，但燃烧化石燃料和砍伐森林增加了大气中的 CO₂，导致增强的温室效应和全球变暖。
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