📚 Year 9 WJEC Science: Core Knowledge Organiser | Year 9 WJEC 科学：核心知识点梳理
Welcome to your Year 9 WJEC Science revision guide. This article summarises the essential knowledge you need to master key concepts in biology, chemistry, and physics. Use it to reinforce your learning and build confidence before assessments.
欢迎来到 Year 9 WJEC 科学复习指南。本文梳理了生物、化学和物理中必须掌握的核心知识点，帮助你巩固所学，在考试前建立信心。
1. Cells and Organisation | 细胞与组织
All living organisms are made up of cells. Animal and plant cells share common features such as a nucleus, cytoplasm, cell membrane, and mitochondria, but plant cells also have a cell wall, chloroplasts, and a permanent vacuole.
所有生物都由细胞组成。动物细胞和植物细胞都有细胞核、细胞质、细胞膜和线粒体，但植物细胞还具有细胞壁、叶绿体和中央大液泡。
Cells group together to form tissues, organs, and organ systems. For example, muscle tissue contracts to produce movement, and the digestive system breaks down food and absorbs nutrients.
细胞聚集形成组织、器官和器官系统。例如，肌肉组织收缩产生运动，消化系统分解食物并吸收营养。
Specialised cells have adaptations suited to their functions. Red blood cells have no nucleus and contain haemoglobin to carry oxygen; sperm cells have a tail for swimming; root hair cells increase surface area for water absorption.
特化细胞具有适应其功能的结构。红细胞没有细胞核且含有血红蛋白以携带氧气；精子有尾部用于游动；根毛细胞增大表面积以利于吸水。
2. Particles and States of Matter | 粒子与物质状态
The particle model describes how particles are arranged and move in solids, liquids, and gases. In solids, particles vibrate in fixed positions; in liquids, they move past each other; in gases, they move rapidly in all directions.
粒子模型描述了固体、液体和气体中粒子的排列方式和运动方式。固体中粒子在固定位置振动；液体中粒子相互滑过；气体中粒子朝各个方向快速运动。
Changes of state, such as melting, boiling, condensing, and freezing, happen at specific temperatures and involve energy transfer without a change in temperature during the process.
状态变化，如熔化、沸腾、冷凝和凝固，都在特定温度下发生，并伴随能量转移，但在变化过程中温度保持不变。
The amount of energy required to change state can be represented by the equation:
改变状态所需能量可用以下方程式表示：
Energy = mass × specific latent heat (E = m L)
3. Atoms, Elements and Compounds | 原子、元素和化合物
An element is a substance made of only one type of atom. A compound contains atoms of two or more elements chemically bonded together. The Periodic Table arranges all known elements in order of increasing atomic number.
元素是由一种原子组成的物质。化合物由两种或两种以上不同元素的原子通过化学键结合而成。元素周期表按原子序数递增的顺序排列所有已知元素。
Atoms consist of a nucleus containing protons and neutrons, with electrons orbiting in shells. The number of protons determines the element, while electrons are arranged in shells (2,8,8 pattern for the first twenty elements).
原子由含质子和中子的原子核及绕核运动的电子组成。质子数决定了元素种类，电子排列在第一到第四电子层（前20个元素遵循2,8,8的排布规律）。
Chemical formulae show the types and ratios of atoms in a compound, for example H₂O for water and CO₂ for carbon dioxide. Subscripts indicate the number of atoms.
化学式表示化合物中原子的种类和比例，例如 H₂O 表示水，CO₂ 表示二氧化碳。下标数字表示原子个数。
Balancing equations ensures mass is conserved. For example:
配平方程式可以保证质量守恒。例如：
2H₂ + O₂ → 2H₂O
4. Chemical Reactions | 化学反应
Chemical reactions involve the rearrangement of atoms to form new substances. Signs of a reaction include colour change, gas production, precipitate formation, and energy change.
化学反应涉及原子重新排列形成新物质。反应的迹象包括颜色变化、气体放出、沉淀生成和能量变化。
Common reaction types include combustion, neutralisation, oxidation, and thermal decomposition. The combustion of a hydrocarbon fuel produces carbon dioxide and water.
常见的反应类型包括燃烧、中和、氧化和热分解。碳氢燃料燃烧生成二氧化碳和水。
The rate of a reaction can be affected by temperature, concentration, surface area, and the presence of a catalyst. Collision theory explains these effects: particles must collide with sufficient energy for a reaction to occur.
反应速率受温度、浓度、表面积和催化剂的影响。碰撞理论解释这些影响：粒子必须以足够的能量发生碰撞才能引起反应。
Exothermic reactions transfer energy to the surroundings (e.g. combustion), whereas endothermic reactions absorb energy (e.g. thermal decomposition of calcium carbonate).
放热反应向环境释放能量（如燃烧），吸热反应则吸收能量（如碳酸钙热分解）。
5. Energy Transfers and Stores | 能量转移与储存
Energy can be stored in various forms: kinetic, gravitational potential, chemical, elastic potential, thermal, and nuclear. The principle of conservation of energy states that energy cannot be created or destroyed, only transferred or converted.
能量可以储存在不同形式中：动能、重力势能、化学能、弹性势能、热能和核能。能量守恒定律指出能量既不能创造也不能消灭，只能转移或转化。
Energy transfers can be represented using Sankey diagrams. Useful energy is transferred to where it is wanted, but some energy is always dissipated (often as heat) due to friction and resistance.
能量转移可以用桑基图表示。有用的能量被转移到需要的地方，但由于摩擦和阻力，总有一些能量耗散（通常以热的形式）。
Work done is equal to the energy transferred when a force moves an object through a distance:
当力使物体移动一段距离时，所做的功等于转移的能量：
Work done = force × distance (W = F d)
Power is the rate of doing work: P = W / t, where t is time.
功率是做功的快慢：P = W / t，其中 t 为时间。
6. Forces and Motion | 力与运动
Forces can change the speed, direction, or shape of an object. Forces are measured in newtons (N). Contact forces include friction, tension, and air resistance; non-contact forces include gravity, magnetism, and electrostatic forces.
力可以改变物体的速度、方向或形状。力的单位是牛顿（N）。接触力包括摩擦力、张力和空气阻力；非接触力包括引力、磁力和静电力。
Newton’s First Law states that an object will remain at rest or in uniform motion unless acted on by a resultant force. Newton’s Second Law links force, mass, and acceleration:
牛顿第一定律指出，除非受到合外力作用，物体将保持静止或匀速直线运动状态。牛顿第二定律将力、质量和加速度联系起来：
Force = mass × acceleration (F = m a)
The weight of an object is the gravitational force acting on its mass: Weight = mass × gravitational field strength (g). On Earth, g ≈ 10 N/kg.
物体的重量是作用在其质量上的引力：重量 = 质量 × 引力场强度（g）。在地球上，g ≈ 10 N/kg。
Speed is calculated as distance ÷ time. A distance-time graph shows motion; the gradient represents speed. A steeper gradient indicates a higher speed.
速度的计算公式为距离 ÷ 时间。距离-时间图能反映运动情况；斜率表示速度，斜率越大速度越快。
7. Electricity and Circuits | 电与电路
Electric current is the flow of electric charge. In metals, current consists of delocalised electrons moving. Current (I) is measured in amperes (A), potential difference (V) in volts (V), and resistance (R) in ohms (Ω).
电流是电荷的流动。在金属中，电流由自由电子的移动形成。电流（I）的单位是安培（A），电压（V）的单位是伏特（V），电阻（R）的单位是欧姆（Ω）。
Ohm’s law relates these quantities:
欧姆定律将这三个量联系起来：
V = I × R
In series circuits, the current is the same at all points, and the total potential difference is shared across components. In parallel circuits, the total current splits between branches, and the potential difference across each branch is equal.
在串联电路中，各处电流相等，总电压分给各个元件。在并联电路中，干路电流等于各支路电流之和，各支路两端电压相等。
Components such as resistors, lamps, diodes, and thermistors affect current in different ways. LDRs (light-dependent resistors) change resistance with light level; thermistors change with temperature.
电阻器、灯泡、二极管和热敏电阻等元件对电流的影响各不相同。光敏电阻（LDR）的阻值随光照变化；热敏电阻随温度变化。
Electrical energy transferred is given by E = V × I × t or E = P × t, where power P = V × I.
电能转移的计算公式为 E = V × I × t 或 E = P × t，其中电功率 P = V × I。
8. Waves: Light and Sound | 波：光与声
Waves transfer energy without transferring matter. Transverse waves (e.g. light, water waves) have oscillations perpendicular to energy transfer; longitudinal waves (e.g. sound) have oscillations parallel to energy transfer.
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递方向垂直；纵波（如声波）的振动方向与能量传递方向平行。
The amplitude, wavelength, frequency, and wave speed are key properties. The wave equation is:
振幅、波长、频率和波速是关键属性。波动方程为：
Wave speed = frequency × wavelength (v = f λ)
Light travels in straight lines and can be reflected and refracted. The law of reflection states that the angle of incidence equals the angle of reflection. Refraction occurs when light passes from one medium to another, causing a change in speed and direction.
光沿直线传播，可发生反射和折射。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时，速度改变并发生折射。
Sound waves are produced by vibrations and require a medium to travel. The speed of sound in air is about 340 m/s. Loudness relates to amplitude, and pitch relates to frequency.
声波由振动产生，需要介质传播。空气中声速约为 340 m/s。响度与振幅有关，音调与频率有关。
9. Ecosystems and Interdependence | 生态系统与相互依存
An ecosystem comprises a community of organisms interacting with their abiotic environment. Producers (such as plants) photosynthesise, converting light energy into chemical energy. Consumers obtain energy by eating other organisms.
生态系统由生物群落及其与非生物环境相互作用组成。生产者（如植物）通过光合作用将光能转变为化学能。消费者通过捕食其他生物获取能量。
Food chains and food webs show feeding relationships. Arrows represent the flow of energy. Decomposers break down dead material, recycling nutrients.
食物链和食物网展示取食关系。箭头表示能量流动方向。分解者分解死体，使营养得以循环。
The equation for aerobic respiration releases energy for cells: glucose + oxygen → carbon dioxide + water (+ energy). Photosynthesis is the reverse process in plants: carbon dioxide + water → glucose + oxygen, in the presence of light and chlorophyll.
有氧呼吸方程式为细胞释放能量：葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）。光合作用是植物中的逆过程：二氧化碳 + 水 → 葡萄糖 + 氧气，需要光照和叶绿素。
Human influences such as pollution, deforestation, and habitat destruction can disrupt ecosystems. Conservation helps maintain biodiversity.
污染、砍伐森林和栖息地破坏等人类活动会扰乱生态系统。保护自然有助于维持生物多样性。
10. The Periodic Table and Patterns | 元素周期表与规律
The modern Periodic Table arranges elements by increasing atomic number. Vertical columns are called groups; elements in the same group have similar chemical properties due to the same number of outer electrons.
现代元素周期表按原子序数递增顺序排列元素。纵列称为族；同族元素化学性质相似，因为它们的最外层电子数相同。
Group 1 contains the alkali metals, which are highly reactive and react vigorously with water. Group 7 contains the halogens, reactive non-metals. Group 0 (or 8) consists of the noble gases, which are unreactive because they have full outer shells.
第1族为碱金属，非常活泼，能与水剧烈反应。第7族为卤素，是活泼的非金属。第0族（或第8族）是稀有气体，由于最外层电子已满，化学性质不活泼。
Metals are generally found on the left and centre, non-metals on the right. Transition metals form coloured compounds and are often catalysts.
金属通常位于表的左侧和中部，非金属位于右侧。过渡金属能形成有色化合物，常用作催化剂。
The electronic structure of atoms determines their position in the table. Trends in reactivity exist down groups, such as alkali metals becoming more reactive down the group.
原子的电子排布决定了其在表中的位置。同一族从上到下，反应活性呈现一定趋势，例如碱金属从上到下逐渐增强。
Published by TutorHao | Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导