📚 Year 9 Cambridge Science: Vocabulary & Terminology Quick Guide | 剑桥九年级科学：词汇术语速记指南
Mastering scientific vocabulary is the key to unlocking Year 9 Cambridge Science. This guide lists essential terms across biology, chemistry, and physics, with clear English definitions followed by Chinese translations. Use it for quick revision, pre‑reading, or building subject‑specific language confidence.
掌握科学词汇是打开九年级剑桥科学大门的钥匙。本指南列出了生物学、化学和物理学中的核心术语，每个术语都先给出清晰的英文定义，再配以中文翻译。可用于快速复习、课前预习，帮助建立学科语言自信。
1. Scientific Inquiry | 科学探究
Hypothesis – A testable prediction, often written as 'If ... then ...' before an experiment begins.
假设 – 一个可检验的预测，通常在实验前写成“如果……那么……”的形式。
Independent variable – The factor deliberately changed by the investigator.
自变量 – 研究者有意改变的因素。
Dependent variable – The factor measured; it responds to changes in the independent variable.
因变量 – 被测量的因素；它随着自变量的变化而变化。
Control variable – A factor kept constant to ensure a fair test.
控制变量 – 保持恒定的因素，以确保实验的公平性。
Fair test – An investigation where only one variable is changed while all others are controlled.
公平测试 – 只改变一个变量而控制所有其他变量的探究方式。
Reliable – Results are reliable if repeated measurements give similar outcomes.
可靠的 – 若重复测量得到相近结果，则数据是可靠的。
2. Cells and Organelles | 细胞与细胞器
Cell membrane – The selectively permeable barrier surrounding the cell, controlling substance entry and exit.
细胞膜 – 包围细胞的选择性渗透屏障，控制物质的进出。
Nucleus – The organelle containing genetic material (DNA) and controlling cell activities.
细胞核 – 含有遗传物质(DNA)并控制细胞活动的细胞器。
Cytoplasm – A jelly‑like substance where most chemical reactions occur.
细胞质 – 一种胶状物质，大部分化学反应在此发生。
Mitochondrion – The site of aerobic respiration, releasing energy from glucose.
线粒体 – 有氧呼吸的场所，从葡萄糖中释放能量。
Ribosome – Tiny structure where proteins are synthesised.
核糖体 – 合成蛋白质的微小结构。
Chloroplast – Found in plant cells; contains chlorophyll for photosynthesis.
叶绿体 – 存在于植物细胞中，含有叶绿素进行光合作用。
Vacuole – A fluid‑filled sac; plant cells often have a large permanent vacuole for support.
液泡 – 充满液体的囊泡；植物细胞常有大型永久液泡起支撑作用。
Cell wall – A rigid outer layer (made of cellulose in plants) that provides structural support.
细胞壁 – 坚硬的外层（植物中由纤维素组成），提供结构支撑。
3. Respiration and Photosynthesis | 呼吸作用与光合作用
Aerobic respiration – es energy from glucose using oxygen: glucose + oxygen → carbon dioxide + water (+ energy).
有氧呼吸 – 使用氧气从葡萄糖中释放能量的化学反应：葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）。
Anaerobic respiration – xygen; in muscle cells glucose → lactic acid; in yeast glucose → ethanol + carbon dioxide.
无氧呼吸 – 无氧条件下的能量释放；肌肉细胞中葡萄糖 → 乳酸；酵母中葡萄糖 → 乙醇 + 二氧化碳。
Photosynthesis – to convert carbon dioxide and water into glucose and oxygen: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
光合作用 – 绿色植物利用光能将二氧化碳和水转化为葡萄糖和氧气的过程：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。
Limiting factor – A factor (light intensity, CO₂ concentration, temperature) that limits the rate of photosynthesis when in short supply.
限制因素 – 当供应不足时限制光合作用速率的因素（光照强度、CO₂浓度、温度）。
Compensation point – The light intensity at which the rate of photosynthesis equals the rate of respiration.
补偿点 – 光合作用速率与呼吸作用速率相等时的光照强度。
4. Atoms and Elements | 原子与元素
Atom – The smallest particle of an element that can take part in a chemical reaction.
原子 – 能参与化学反应的元素的最小粒子。
Element – A pure substance made of only one type of atom.
元素 – 仅由一种原子组成的纯物质。
Compound – A substance formed when two or more elements are chemically bonded together.
化合物 – 两种或多种元素通过化学键结合而成的物质。
Mixture – Two or more substances not chemically combined, which can be separated by physical processes.
混合物 – 两种或多种未通过化学方式结合的物质，可通过物理方法分离。
Proton – Positively charged sub‑atomic particle found in the nucleus.
质子 – 原子核中带正电的亚原子粒子。
Neutron – Neutral particle in the nucleus, with mass similar to a proton.
中子 – 原子核中的中性粒子，质量与质子相近。
Electron – Negatively charged particle that orbits the nucleus in shells.
电子 – 带负电的粒子，分层绕核运动。
Atomic number – The number of protons in the nucleus; defines the element.
原子序数 – 原子核中的质子数，决定了元素的种类。
Mass number – The total number of protons and neutrons in the nucleus.
质量数 – 原子核中质子与中子的总数。
5. Chemical Reactions | 化学反应
Reactant – A starting substance in a chemical reaction.
反应物 – 化学反应中的起始物质。
Product – A substance formed as a result of a chemical reaction.
生成物 – 化学反应产生的物质。
Exothermic – A reaction that transfers thermal energy to the surroundings, causing a temperature rise.
放热 – 向周围转移热能的反应，导致温度升高。
Endothermic – A reaction that absorbs thermal energy from the surroundings, leading to a temperature drop.
吸热 – 从周围吸收热能的反应，导致温度下降。
Activation energy – The minimum energy needed for particles to collide successfully and react.
活化能 – 粒子成功碰撞并发生反应所需的最低能量。
Catalyst – A substance that speeds up a reaction without being used up itself.
催化剂 – 加速反应而自身不被消耗的物质。
Conservation of mass – In a chemical reaction, the total mass of reactants equals the total mass of products.
质量守恒 – 在化学反应中，反应物的总质量等于生成物的总质量。
Oxidation – A reaction where a substance gains oxygen; in terms of electrons, oxidation is loss of electrons.
氧化 – 物质获得氧的反应；从电子角度看，氧化是失电子。
Reduction – A reaction where a substance loses oxygen; or gains electrons.
还原 – 物质失去氧的反应；或得到电子。
6. Forces and Motion | 力与运动
Force – A push or pull that can change an object's speed, direction, or shape; measured in newtons (N).
力 – 能改变物体速度、方向或形状的推或拉；单位为牛顿(N)。
Resultant force – The single force that has the same effect as all forces acting on an object combined.
合力 – 与作用在物体上的所有力联合效果相同的单个力。
Balanced forces – When resultant force is zero, the object remains at rest or moves at constant velocity.
平衡力 – 合力为零时，物体保持静止或匀速直线运动。
Friction – A force opposing motion between two surfaces in contact.
摩擦力 – 阻碍两接触表面相对运动的力。
Weight – The force of gravity on a mass: weight = mass × gravitational field strength (W = m × g).
重量 – 质量受到的重力：重量 = 质量 × 重力场强度 (W = m × g)。
Mass – The quantity of matter in an object; measured in kilograms (kg).
质量 – 物体所含物质的多少；单位为千克(kg)。
Speed – The rate of change of distance: speed = distance / time.
速率 – 距离随时间的变化率：速率 = 距离 / 时间。
Velocity – Speed in a given direction.
速度 – 给定方向上的速率。
Acceleration – The rate of change of velocity: acceleration = change in velocity / time.
加速度 – 速度的变化率：加速度 = 速度变化量 / 时间。
7. Energy Forms and Transfers | 能量形式与转移
Kinetic energy – Energy possessed by moving objects.
动能 – 运动物体具有的能量。
Potential energy – Energy stored due to position (gravitational) or shape (elastic).
势能 – 由于位置（重力）或形状（弹性）而储存的能量。
Thermal energy – Energy transferred due to temperature difference; often called heat.
热能 – 因温度差而转移的能量；常称为热。
Conduction – Transfer of thermal energy through a material without bulk movement of the material itself.
传导 – 热能通过物质传递而无宏观物质运动的转移方式。
Convection – Transfer of thermal energy through fluids (liquids or gases) by the movement of the fluid.
对流 – 流体（液体或气体）中通过流体运动进行的热能传递。
Radiation – Transfer of energy by electromagnetic waves, e.g. infrared radiation; does not require a medium.
辐射 – 通过电磁波（如红外线）进行的能量传递；无需介质。
Insulator – A material that is poor at conducting thermal energy.
绝缘体 – 导热性能差的材料。
Efficiency – at is transferred usefully: efficiency = (useful output energy / total input energy) × 100%.
效率 – 输入能量中有用输出所占的比例：效率 = (有用输出能量 / 总输入能量) × 100%。
Renewable energy – Energy from sources that are not depleted when used, e.g. solar, wind, tidal.
可再生能源 – 使用后不会枯竭的能源，如太阳能、风能、潮汐能。
8. Waves and Sound | 波与声
Wave – A disturbance that transfers energy from one point to another without transferring matter.
波 – 将能量从一点传递到另一点而不传递物质的扰动。
Transverse wave – A wave where oscillations are perpendicular to the direction of energy transfer, e.g. light.
横波 – 振动方向与能量传递方向垂直的波，如光。
Longitudinal wave – A wave where oscillations are parallel to the direction of energy transfer, e.g. sound.
纵波 – 振动方向与能量传递方向平行的波，如声音。
Amplitude – The maximum displacement of a wave from its rest position; related to loudness in sound.
振幅 – 波离开平衡位置的最大位移；与声音的响度相关。
Frequency – The number of complete waves passing a point per second; measured in hertz (Hz).
频率 – 每秒通过某点的完整波数；单位为赫兹(Hz)。
Wavelength – The distance between two corresponding points on adjacent waves, e.g. crest to crest.
波长 – 相邻两个波上对应点之间的距离，如波峰到波峰。
Reflection – The bouncing back of a wave when it hits a surface; echoes are sound reflections.
反射 – 波碰到表面时反弹的现象；回声是声音的反射。
Refraction – The change in direction of a wave when it enters a new medium at an angle due to speed change.
折射 – 波因速度改变而以一定角度进入新介质时发生的方向变化。
Electromagnetic spectrum – The range of all electromagnetic waves: radio, microwave, infrared, visible light, ultraviolet, X‑ray, gamma ray.
电磁波谱 – 所有电磁波的范围：无线电波、微波、红外线、可见光、紫外线、X射线、伽马射线。
9. Ecosystems and Adaptations | 生态系统与适应
Ecosystem – A community of living organisms interacting with their non‑living environment.
生态系统 – 生物群落与其非生物环境相互作用的整体。
Habitat – The place where an organism lives.
栖息地 – 生物居住的地方。
Population – All individuals of the same species living in a particular area.
种群 – 生活在特定区域的同种全部个体。
Community – All populations of different species living and interacting in an area.
群落 – 一个区域内所有不同物种的种群及其相互作用。
Producer – An organism that makes its own food via photosynthesis; the first trophic level.
生产者 – 通过光合作用自己制造食物的生物；第一营养级。
Consumer – An organism that feeds on other organisms; primary, secondary, tertiary consumers.
消费者 – 以其他生物为食的生物；可分为初级、次级、三级消费者。
Decomposer – Organisms (bacteria, fungi) that break down dead material and recycle nutrients.
分解者 – 分解死物质、循环养分的生物（细菌、真菌）。
Food web – A network of interconnected food chains, showing feeding relationships.
食物网 – 相互关联的食物链网络，展示捕食关系。
Adaptation – A feature that helps an organism survive and reproduce in its environment.
适应 – 帮助生物在环境中生存和繁殖的特征。
Natural selection – The process by which better‑adapted individuals survive and pass on their traits.
自然选择 – 适应更好的个体存活并传递性状的过程。
10. Reproduction and Inheritance | 生殖与遗传
Asexual reproduction – Reproduction involving one parent, producing genetically identical offspring (clones).
无性生殖 – 仅涉及一个亲本，产生遗传上相同的后代（克隆）。
Sexual reproduction – Reproduction involving two parents; gametes fuse to produce genetically varied offspring.
有性生殖 – 涉及两个亲本；配子融合产生遗传变异的后代。
Gamete – A sex cell (sperm in males, egg/ovum in females) with half the normal chromosome number.
配子 – 性细胞（雄性为精子，雌性为卵子），染色体数目为正常体细胞的一半。
Fertilisation – The fusion of a male gamete and a female gamete to form a zygote.
受精 – 雄配子与雌配子融合形成合子的过程。
Chromosome – A thread‑like structure of DNA carrying genetic information; humans have 46 (23 pairs).
染色体 – 携带遗传信息的DNA线状结构；人类有46条（23对）。
Gene – A section of DNA that codes for a particular protein or trait.
基因 – 编码特定蛋白质或性状的DNA片段。
Allele – A different version of the same gene.
等位基因 – 同一基因的不同形式。
Dominant – An allele that is expressed even if only one copy is present.
显性 – 即使只存在一个拷贝也会表现出来的等位基因。
Recessive – An allele that is only expressed when two copies are present.
隐性 – 只有两个拷贝都存在时才表现出来的等位基因。
Genotype – The genetic make‑up of an organism (e.g. BB, Bb, bb).
基因型 – 生物的遗传组成（如 BB, Bb, bb）。
Phenotype – The observable characteristics resulting from the genotype and environment.
表现型 – 由基因型和环境共同决定的可见性状。
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