📚 Cambridge Checkpoint Science 9: Full Revision Guide | 剑桥 Checkpoint 科学 9：完整复习指南
This revision guide summarises the key ideas from Cambridge Checkpoint Science Coursebook 9. It covers biology, chemistry and physics in short, exam-focused sections. Use it alongside your coursebook to test your recall and understanding.
本复习指南总结《Cambridge Checkpoint Science Coursebook 9》的核心知识点，涵盖生物、化学和物理三部分，并以考试重点分节呈现。请结合课本使用，检测自己的记忆与理解。
1. Characteristics of Living Organisms | 生物体的特征
All living organisms carry out seven life processes, often remembered by the letters MRS GREN: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.
所有生物体都进行七种生命活动，常用 MRS GREN 来记忆：运动、呼吸、感应、生长、繁殖、排泄和营养。
Cells are the basic structural and functional units of life. Plant cells have a cellulose cell wall, a large permanent vacuole and chloroplasts, while animal cells do not.
细胞是生命的基本结构和功能单位。植物细胞有纤维素细胞壁、大液泡和叶绿体，而动物细胞没有。
2. Cell Structure and Specialisation | 细胞结构与特化
The main parts of a typical animal cell are the nucleus, cytoplasm and cell membrane. In a plant cell, the cell wall, chloroplasts and vacuole are also present.
典型动物细胞的主要结构包括细胞核、细胞质和细胞膜。植物细胞还含有细胞壁、叶绿体和液泡。
| Feature | Animal cell | Plant cell |
| Cell wall | Absent | Present (cellulose) |
| Chloroplasts | Absent | Present |
| Vacuole | Small or absent | Large permanent vacuole |
Specialised cells are adapted to their functions. A root hair cell has a long extension to absorb water and minerals; a red blood cell has no nucleus to carry more haemoglobin; a sperm cell has a tail for swimming.
特化细胞适应其功能。根毛细胞有长突起以吸收水和矿物质；红细胞无细胞核以携带更多血红蛋白；精子有尾部用于游动。
3. Photosynthesis and Plant Nutrition | 光合作用与植物营养
Photosynthesis is the process by which green plants make glucose from carbon dioxide and water using light energy, absorbed by chlorophyll.
光合作用是绿色植物利用叶绿素吸收的光能，将二氧化碳和水转化为葡萄糖的过程。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The rate of photosynthesis is affected by light intensity, carbon dioxide concentration and temperature. A limiting factor is the one that is in shortest supply.
光合作用速率受光照强度、二氧化碳浓度和温度影响。限制因素是指供应最不足的那个因素。
Plants also need mineral ions: nitrate ions for making amino acids and proteins, and magnesium ions for making chlorophyll.
植物还需要矿质离子：硝酸根离子用于制造氨基酸和蛋白质，镁离子用于制造叶绿素。
4. Human Circulatory and Respiratory Systems | 人体循环与呼吸系统
The circulatory system consists of the heart, blood vessels and blood. The heart pumps blood to the lungs to collect oxygen and to the body to deliver oxygen and nutrients.
循环系统由心脏、血管和血液组成。心脏将血液泵送到肺部获取氧气，并输送到全身提供氧气和营养。
Blood contains red blood cells, white blood cells, platelets and plasma. Red blood cells transport oxygen; white blood cells defend against infection; platelets help blood clot.
血液含有红细胞、白细胞、血小板和血浆。红细胞运输氧气；白细胞抵抗感染；血小板帮助血液凝固。
robic respiration releases energy from glucose: glucose + oxygen → carbon dioxide + water.
在肺部，氧气从肺泡扩散到血液中，二氧化碳从血液扩散到肺泡中。有氧呼吸从葡萄糖中释放能量：葡萄糖 + 氧气 → 二氧化碳 + 水。
5. Variation and Classification | 变异与分类
Variation describes differences between individuals of the same species. Continuous variation shows a range of values, such as height or mass. Discontinuous variation falls into distinct groups, such as blood group or eye colour.
变异描述同种个体之间的差异。连续变异呈现一系列数值，如身高或体重；不连续变异分为不同类别，如血型或眼色。
Living organisms are classified into five kingdoms: animals, plants, fungi, protoctists and bacteria. Vertebrates are divided into fish, amphibians, reptiles, birds and mammals based on features such as body covering and reproduction.
生物分为五个界：动物、植物、真菌、原生生物和细菌。脊椎动物根据体表覆盖物和繁殖方式等特征分为鱼类、两栖类、爬行类、鸟类和哺乳类。
6. Particle Theory and States of Matter | 粒子理论与物质状态
All matter is made of tiny particles that move constantly. In solids, particles are closely packed in a regular arrangement and vibrate in fixed positions. In liquids, particles are close but can move past each other. In gases, particles are far apart and move rapidly.
所有物质由不断运动的小粒子组成。固体中，粒子紧密排列且规则，只能在固定位置振动；液体中，粒子靠近但能相互滑动；气体中，粒子相距很远并快速运动。
Changes of state include melting, freezing, boiling, condensation and sublimation. During a change of state, temperature stays constant while energy is transferred.
物态变化包括熔化、凝固、沸腾、凝结和升华。在物态变化过程中，温度保持不变，同时发生能量传递。
Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. It occurs faster in gases than in liquids and increases with temperature.
扩散是粒子从高浓度区域向低浓度区域的运动。气体中的扩散比液体中快，并随温度升高而加快。
7. Elements, Compounds and Mixtures | 元素、化合物与混合物
An element is a substance made of only one type of atom and cannot be broken down into simpler substances. The periodic table lists all known elements, each with a chemical symbol.
元素是只由一种原子组成的物质，不能分解为更简单的物质。周期表列出所有已知元素，每种元素有化学符号。
A compound is formed when two or more elements chemically combine in fixed proportions. A mixture contains substances that are not chemically combined and can be separated by physical methods such as filtration, evaporation and distillation.
化合物是由两种或多种元素以固定比例化学结合而成。混合物中的物质没有化学结合，可通过过滤、蒸发和蒸馏等物理方法分离。
8. Chemical Reactions, Acids and Bases | 化学反应、酸和碱
Signs of a chemical reaction include colour change, gas production, temperature change or formation of a precipitate. Word equations show reactants on the left and products on the right.
化学反应的迹象包括颜色变化、产生气体、温度变化或生成沉淀。文字方程式将反应物写在左边，生成物写在右边。
The pH scale measures how acidic or alkaline a solution is. Values below 7 are acidic, 7 is neutral, and values above 7 are alkaline. Indicators such as litmus change colour in acids and alkalis.
pH 标度衡量溶液的酸碱性。pH 小于 7 为酸性，等于 7 为中性，大于 7 为碱性。石蕊等指示剂在酸和碱中会变色。
HCl + NaOH → NaCl + H₂O
Neutralisation is the reaction between an acid and a base to form a salt and water.
中和反应是酸与碱反应生成盐和水的过程。
9. Forces and Motion | 力与运动
A force is a push or a pull, measured in newtons (N). Forces can change the speed, direction or shape of an object. Friction is a force that opposes motion.
力是推或拉，单位为牛顿 (N)。力可以改变物体的速度、方向或形状。摩擦力是阻碍运动的力。
Balanced forces keep an object at rest or moving at constant speed. Unbalanced forces cause acceleration or deceleration.
平衡力使物体保持静止或匀速运动。非平衡力导致加速或减速。
speed = distance ÷ time
Speed is calculated by dividing distance travelled by time taken. On a distance-time graph, the slope represents speed, and a horizontal line means the object is stationary.
速度由行驶距离除以时间计算。在距离-时间图像中，斜率表示速度，水平线表示物体静止。
10. Energy Transfers and Resources | 能量传递与资源
Energy exists in many forms, including kinetic, potential, thermal, chemical, electrical and light energy. Energy cannot be created or destroyed, only transferred or stored.
能量有多种形式，包括动能、势能、热能、化学能、电能和光能。能量不能被创造或消灭，只能被传递或储存。
Heat energy can be transferred by conduction, convection and radiation. Conduction occurs mainly in solids; convection occurs in liquids and gases; radiation can travel through a vacuum.
热能可以通过传导、对流和辐射传递。传导主要发生在固体中；对流发生在液体和气体中；辐射可以在真空中传播。
Energy resources include renewable sources such as solar, wind, hydroelectric and biomass, and non-renewable sources such as coal, oil and natural gas.
能源包括可再生能源，如太阳能、风能、水能和生物质能，以及不可再生能源，如煤、石油和天然气。
11. Electricity and Magnetism | 电与磁
An electric circuit needs a complete loop with a power supply, connecting wires and components such as bulbs or resistors. Current is
Published by TutorHao | IB Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图