📚 KS3 WJEC Science: Core Knowledge Organiser | KS3 WJEC 科学：核心知识点梳理
Welcome to your complete KS3 WJEC Science revision guide. This article brings together the most important ideas from Biology, Chemistry and Physics, clearly presented in paired English and Chinese explanations to support deeper understanding. Whether you are preparing for end‑of‑topic tests or building a strong foundation for GCSE, these core knowledge points will help you revise effectively.
欢迎使用 KS3 WJEC 科学复习指南。本文汇集了生物、化学和物理中最关键的知识点，以配对的中英双语讲解帮助你加深理解。无论你是在准备单元测试还是为 GCSE 打下坚实基础，这些核心内容都能让你的复习更高效。
1. Cells – The Building Blocks of Life | 细胞——生命的基石
All living organisms are made of cells. Animal and plant cells share common structures: a nucleus that controls the cell, cytoplasm where chemical reactions happen, a cell membrane that controls what enters and leaves, and mitochondria where respiration releases energy.
所有生物都由细胞构成。动物细胞和植物细胞有共同的结构：控制细胞的细胞核、发生化学反应的细胞质、控制物质进出的细胞膜，以及通过呼吸作用释放能量的线粒体。
Plant cells have three additional parts not found in animal cells: a rigid cell wall made of cellulose that provides support, chloroplasts that absorb light for photosynthesis, and a large permanent vacuole that stores cell sap and helps keep the cell firm.
植物细胞比动物细胞多三个结构：由纤维素组成的坚硬的细胞壁，起支持作用；吸收光能进行光合作用的叶绿体；以及储存细胞液并帮助维持细胞硬挺的大液泡。
Cells are organised in a hierarchy: similar cells form a tissue, tissues work together to form an organ, organs make up an organ system, and several organ systems together create the whole organism.
细胞按照层级组织起来：相似的细胞形成组织，组织协作形成器官，器官构成器官系统，多个器官系统共同组成完整的生物体。
2. Nutrition and Digestion | 营养与消化
A balanced diet provides all the essential nutrients: carbohydrates for energy, proteins for growth and repair, lipids (fats) for insulation and energy storage, vitamins and minerals to keep the body healthy, water for hydration and chemical reactions, and dietary fibre to keep the digestive system moving.
均衡的饮食提供所有必需的营养素：碳水化合物提供能量，蛋白质用于生长和修复，脂类（脂肪）用于保温和储能，维生素和矿物质维持身体健康，水用于补水和化学反应，膳食纤维则保持消化系统通畅。
Digestion breaks large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. In the mouth, teeth physically break down food and salivary amylase begins to digest starch into maltose. In the stomach, hydrochloric acid kills bacteria and protease enzymes start to break down proteins.
消化将大而不溶的食物分子分解为可吸收的小分子。在口腔中，牙齿物理磨碎食物，唾液淀粉酶开始把淀粉消化成麦芽糖。在胃里，盐酸杀死细菌，蛋白酶开始分解蛋白质。
The small intestine is the main site of digestion and absorption. Enzymes from the pancreas complete the breakdown: amylase turns starch into simpler sugars, protease breaks proteins into amino acids, and lipase splits fats into fatty acids and glycerol. The small intestine’s large surface area, created by villi, allows efficient absorption into the bloodstream.
小肠是消化和吸收的主要场所。胰腺分泌的酶完成最终分解：淀粉酶将淀粉转化为单糖，蛋白酶将蛋白质分解为氨基酸，脂肪酶将脂肪分解为脂肪酸和甘油。小肠壁上的绒毛大大增加了表面积，使营养物质能高效地被血液吸收。
3. Reproduction in Humans | 人类的生殖
Puberty is triggered by hormones. In males, the testes start to produce sperm and the hormone testosterone causes changes such as voice deepening, growth of body hair and muscle development. In females, the ovaries release eggs (ova) and the hormones oestrogen and progesterone control the menstrual cycle.
青春期由激素触发。在男性体内，睾丸开始产生精子，睾酮激素引起声音变粗、体毛生长和肌肉发育等变化。在女性体内，卵巢排出卵子，雌激素和孕激素调控月经周期。
Fertilisation occurs when a sperm cell meets an egg cell in the oviduct. The nuclei fuse to form a zygote, which divides many times to become an embryo. Implantation happens when the embryo embeds itself into the lining of the uterus.
当精子细胞与卵细胞在输卵管内相遇时发生受精。它们的细胞核融合形成受精卵，受精卵多次分裂发育成胚胎。胚胎植入子宫内膜的过程称为着床。
During pregnancy the placenta allows oxygen and nutrients to pass from the mother’s blood to the baby’s blood, while removing waste products such as carbon dioxide. The amniotic fluid cushions and protects the developing foetus. At birth, the muscular wall of the uterus contracts to push the baby through the birth canal.
怀孕期间胎盘将氧气和营养物质从母体血液输送给胎儿，同时移走二氧化碳等废物。羊水缓冲并保护发育中的胎儿。分娩时子宫肌壁收缩，将婴儿推出产道。
4. Atoms, Elements and Compounds | 原子、元素和化合物
All substances are made of atoms, the smallest particle of an element that can still be recognized as that element. An element is a substance made of only one type of atom and is represented by a chemical symbol, such as O for oxygen or Fe for iron.
所有物质都由原子构成，原子是元素的最小粒子，仍保持该元素的性质。元素是由同一种原子组成的物质，用化学符号表示，例如 O 代表氧，Fe 代表铁。
When two or more different elements chemically combine, they form a compound. The properties of a compound are usually very different from the elements it is made of. For example, sodium is a reactive metal, chlorine is a poisonous gas, but together they form sodium chloride – common table salt.
当两种或以上不同的元素发生化学结合时，就形成化合物。化合物的性质通常与组成它的元素截然不同。例如，钠是活泼金属，氯是有毒气体，但两者结合生成氯化钠——普通的食盐。
Compounds are shown by chemical formulas that tell us the types and ratios of atoms. Word equations show what reacts and what is produced. A simple word equation: magnesium + oxygen → magnesium oxide. The symbol equation is 2Mg + O₂ → 2MgO.
化合物用化学式表示，显示原子的种类和比例。文字方程式表示反应物和生成物。简单的文字方程式：镁 + 氧气 → 氧化镁。其符号方程式为 2Mg + O₂ → 2MgO。
5. The Periodic Table | 元素周期表
The Periodic Table arranges all known elements in order of increasing atomic number. Elements in the same group (vertical column) have the same number of electrons in their outer shell and therefore similar chemical properties.
元素周期表将已知元素按原子序数递增的顺序排列。同一族（纵列）的元素最外层电子数相同，因此化学性质相似。
Group 1 contains the alkali metals, which are very reactive, especially with water, and become more reactive as you go down the group. Group 7 contains the halogens, reactive non‑metals that become less reactive down the group. Group 0 holds the noble gases, which are unreactive because they have full outer electron shells.
第 1 族是碱金属，非常活泼，特别是与水反应，且越往下越活泼。第 7 族是卤素，活泼的非金属，越往下活泼性减弱。第 0 族是稀有气体，因为最外层电子满壳层所以极不活泼。
Metals are found on the left and centre of the table; they are shiny, good conductors of heat and electricity, malleable and ductile. Non‑metals are mostly on the right; they are dull, poor conductors and brittle when solid. The dividing line between metals and non‑metals can be seen around group 4.
金属位于周期表的左侧和中部，它们具有光泽，是良好的热和电的导体，有延展性。非金属大多在右侧，暗淡无光，导热导电性差，固态时较脆。在周期表中大约第 4 族附近可以划出金属与非金属的分界线。
6. Chemical Reactions | 化学反应
Signs that a chemical reaction has taken place include a change in temperature (exothermic or endothermic), a colour change, effervescence (bubbles of gas), formation of a precipitate (an insoluble solid), and an irreversible change.
发生过化学反应的迹象包括温度变化（放热或吸热）、颜色变化、冒泡（产生气体）、生成沉淀（不溶性固体）以及不可逆的变化。
During a chemical reaction, atoms are rearranged to form new substances but no atoms are created or destroyed. This is the law of conservation of mass: the total mass of the products equals the total mass of the reactants.
化学反应中，原子重新排列生成新物质，但原子不会被创造或消灭。这就是质量守恒定律：生成物的总质量等于反应物的总质量。
Reactions can be represented by word equations and symbol equations. For example, calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide. The symbol equation is CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂. Unbalanced equations can be balanced by putting numbers in front of formulas.
反应可以用文字方程式和符号方程式表示。例如，碳酸钙 + 盐酸 → 氯化钙 + 水 + 二氧化碳。符号方程式为 CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂。可以通过在化学式前添加数字来配平未平衡的方程式。
7. Forces and Motion | 力与运动
A force is a push or a pull measured in newtons (N). Contact forces include friction and air resistance, which act when objects touch. Non‑contact forces act over a distance and include gravity, magnetic force and electrostatic force.
力是推力或拉力，单位是牛顿（N）。接触力包括摩擦力和空气阻力，物体接触时产生。非接触力能从远处作用，包括重力、磁力和静电力。
When forces on an object are balanced, the object remains stationary or moves at a constant speed in a straight line. When forces are unbalanced, the object accelerates (speeds up), decelerates (slows down) or changes direction.
当作用在物体上的力平衡时，物体会保持静止或沿直线匀速运动。当力不平衡时，物体会加速、减速或改变方向。
speed = distance ÷ time
The speed equation allows you to calculate the average speed of an object. Distance–time graphs show journey details: a horizontal line means the object is stationary, a straight sloping line shows constant speed, and a steeper slope indicates a higher speed.
速度公式可用来计算物体的平均速度。距离 — 时间图展示运动过程：水平线代表物体静止，倾斜直线代表匀速运动，斜率越陡速度越快。
8. Energy Stores and Transfers | 能量的储存与转移
Energy can be stored in different ways: kinetic energy (moving objects), thermal energy (heat), chemical energy (fuels, food, batteries), gravitational potential energy (position in a gravitational field), elastic potential energy (stretched or compressed objects) and nuclear energy (nucleus of atoms).
能量可以多种形式储存：动能（运动的物体）、热能（热量）、化学能（燃料、食物、电池）、重力势能（在引力场中的位置）、弹性势能（拉伸或压缩的物体）和核能（原子核中）。
Energy can be transferred from one store to another by four main pathways: mechanically (by a force doing work), electrically (by an electric current), by heating (from a hotter to a cooler object) or by radiation (as light or sound waves). The total amount of energy before and after a transfer remains the same – energy cannot be created or destroyed.
能量可以通过四种主要途径从一个储存处转移到另一个：机械做功（通过力）、电流做功、加热（从高温物体到低温物体）或辐射（如光波或声波）。转移前后能量的总量保持不变——能量无法被创造或消灭。
Sankey diagrams illustrate energy transfers using arrows. The thickness of each arrow represents the amount of energy. They make it easy to see how much useful energy is transferred and how much is wasted, often as heat.
桑基图用箭头展示能量转移，箭头的粗细代表能量的大小。它能直观显示有多少能量被有效转移、多少被浪费，通常以热的形式散失。
9. Waves: Light and Sound | 波：光与声
Light travels in straight lines. When it hits a smooth surface it obeys the law of reflection: the angle of incidence equals the angle of reflection. Rough surfaces scatter light, causing diffuse reflection. Refraction happens when light passes from one medium to another and changes speed, causing it to bend.
光沿直线传播。当光照到光滑表面时遵循反射定律：入射角等于反射角。粗糙表面使光散射，形成漫反射。光从一种介质进入另一种介质时速度改变而发生偏折，称为折射。
Sound is produced by vibrations. It travels as a longitudinal wave, meaning the particles vibrate back and forth along the direction the wave travels. Sound cannot travel through a vacuum because there are no particles to carry the vibration. In air at room temperature, sound travels at about 330 m/s.
声音由振动产生。它以纵波的形式传播，即质点沿波传播方向前后振动。声音不能在真空中传播，因为真空中没有粒子传递振动。在室温下，声音在空气中的传播速度约为 330 米/秒。
The human ear detects sound: the eardrum vibrates, tiny bones (ossicles) amplify the vibrations and send them to the cochlea, where they are turned into electrical signals for the brain. Frequency determines pitch (higher frequency = higher pitch) and amplitude determines loudness (greater amplitude = louder sound). Human hearing range is around 20 Hz to 20 000 Hz.
人耳探测声音：鼓膜振动，小骨（听小骨）放大振动并传至耳蜗，在那里振动转化为电信号传给大脑。频率决定音调（频率越高音调越高），振幅决定响度（振幅越大声音越响）。人类的听觉范围大约在 20 赫兹到 20 000 赫兹之间。
10. Electricity and Magnetism | 电与磁
An electric circuit must be complete for current to flow. Current (I) is a flow of electric charge measured in amperes (A). Potential difference (voltage, V) is measured in volts (V) and pushes the current around. Resistance (R) measured in ohms (Ω) opposes the flow of current. Ohm’s law links these quantities: V = I × R.
电路必须闭合才能有电流通过。电流（I）是电荷的流动，单位是安培（A）。电位差（电压，V）的单位是伏特（V），它推动电荷流动。电阻（R）的单位是欧姆（Ω），阻碍电流流动。欧姆定律将三者联系起来：V = I × R。
In a series circuit there is only one loop. The current is the same everywhere, but the total potential difference is shared across the components. In a parallel circuit there are branches. The current splits along each branch, but the potential difference across each branch is the same.
串联电路中只有一个回路，各处电流相等，但总电压被各个元件分摊。并联电路有支路，电流在支路中分流，但各支路两端的电压相同。
Magnets have north and south poles. Like poles repel and unlike poles attract. An electromagnet is made by passing an electric current through a coil of wire. Its strength can be increased by adding more turns to the coil, increasing the current, or placing an iron core inside the coil.
磁铁具有北极和南极，同名磁极相互排斥，异名磁极相互吸引。电磁铁是让电流通过线圈制成的。增加线圈匝数、增大电流或在线圈内放置铁芯都可以增强电磁铁的磁力。
11. Earth and Atmosphere | 地球与大气
The Earth has a layered structure: a thin solid crust, a mantle of semi‑solid rock that flows very slowly, a liquid outer core made of iron and nickel, and a solid inner core where temperature and pressure are extremely high.
地球具有层状结构：薄薄的固体地壳，由缓慢流动的半固态岩石组成的地幔，由铁、镍组成的液态外核，以及温度和压力极高的固态内核。
Rocks are constantly recycled in the rock cycle. Igneous rocks form from cooled magma or lava; sedimentary rocks form from compressed layers of sediment; metamorphic rocks form when existing rocks are changed by heat and pressure. Weathering, erosion, melting and cooling drive this cycle.
岩石在岩石循环中不断被重塑。岩浆或熔岩冷却后形成火成岩；沉积物被压实成层形成沉积岩；已有岩石在高温高压下变质形成变质岩。风化、侵蚀、熔融和冷却驱动着这一循环。
The Earth’s atmosphere is roughly 78% nitrogen (N₂), 21% oxygen (O₂), 0.04% carbon dioxide (CO₂), with small amounts of noble gases and water vapour. Photosynthesis by plants and algae maintains oxygen levels, while respiration, combustion and decomposition return carbon dioxide.
地球大气中约 78% 是氮气（N₂），21% 是氧气（O₂），0.04% 是二氧化碳（CO₂），还有少量的稀有气体和水蒸气。植物和藻类的光合作用维持氧气水平，而呼吸作用、燃烧和分解则把二氧化碳送回大气。
12. Working Scientifically | 科学探究方法
A scientific investigation usually follows a logical order: start with a question, then propose a hypothesis – a possible explanation that can be tested. Make a prediction based on the hypothesis, design a fair test, carry out the experiment, collect and record data, then draw a conclusion. Finally, evaluate the method and results, suggesting improvements.
科学探究通常遵循逻辑顺序：首先提出问题，然后提出假设——一种可检验的可能解释。基于假设进行预测，设计公平测试，进行实验，收集和记录数据，然后得出结论。最后评估方法和结果，提出改进建议。
In any experiment it is essential to identify variables. The independent variable is the one you change, the dependent variable is the one you measure, and control variables are all the factors you keep the same to ensure a fair test.
在任何实验中，识别变量至关重要。自变量是你改变的变量，因变量是你测量的变量，控制变量是你为了确保公平测试而保持不变的各项因素。
Data should be presented clearly, often in tables and graphs. A bar chart is used when the independent variable is categoric, while a line graph is used when both variables are continuous. It is important to label axes with units, use a sensible scale, and plot points accurately.
数据应当清晰呈现，通常使用表格和图表。当自变量是类别变量时使用条形图，当两个变量都是连续变量时使用折线图。重要的是要标注轴的单位，采用合宜的刻度，并准确描点。
Health and safety are a priority in the lab. Always carry out a risk assessment before starting an experiment and know the meanings of common hazard symbols, such as flammable, corrosive and toxic. Reliability can be improved by repeating measurements and accuracy by using instruments with finer scales.
实验室里的健康与安全是头等大事。实验前务必进行风险评估，并了解常见危险符号的含义，如易燃、腐蚀性和有毒。通过重复测量可以提高可靠性，使用刻度更精细的仪器能够提高准确性。
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