📚 Year 7 SQA Science: Core Concepts Summary | Year 7 SQA 科学：核心知识点梳理
Year 7 science in the Scottish curriculum builds strong foundations in biology, chemistry and physics while developing essential experimental skills. This article pulls together all the key topics, from cells and states of matter to forces, energy and ecosystems, so you can revise confidently and make connections across the sciences.
苏格兰 Year 7 科学课程在生物、化学和物理领域打下坚实基础，同时培养关键的实验技能。本文整理了所有核心主题——从细胞、物质状态到力、能量和生态系统——帮助你自信地复习并建立跨学科的联系。
1. Scientific Inquiry and Lab Safety | 科学探究与实验安全
The scientific method helps us investigate the world. It begins with observations and questions, then moves to forming a testable hypothesis, designing a fair experiment, collecting data and drawing conclusions based on evidence.
科学方法帮助我们探索世界。它从观察和提问开始，然后形成可检验的假设，设计公平实验，收集数据并根据证据得出结论。
In any experiment we identify variables. The independent variable is the factor we change, the dependent variable is what we measure, and control variables are kept constant to make the test fair and reliable.
在任何实验中我们都要确定变量。自变量是我们改变的因素，因变量是我们测量的结果，控制变量则保持不变，以确保测试公平且可靠。
Safety rules protect everyone in the lab. Always wear safety goggles, tie back long hair, tuck in ties, never eat or drink, and know the locations of the fire extinguisher, fire blanket and first aid kit before you start.
安全规则保护实验室的每一个人。始终佩戴护目镜，扎起长发，塞好领带，不要在实验室饮食，并在开始前了解灭火器、灭火毯和急救箱的位置。
2. Cells – The Building Blocks of Life | 细胞——生命的基本单位
All living organisms are made of cells. Animal cells contain a nucleus that stores DNA, cytoplasm where chemical reactions occur, a cell membrane that controls what enters and leaves, and mitochondria that release energy through respiration.
所有生物都由细胞构成。动物细胞包含储存 DNA 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 share these structures but also have three extras: a rigid cell wall made of cellulose for support, chloroplasts that absorb sunlight for photosynthesis, and a large permanent vacuole filled with cell sap that helps keep the cell firm.
植物细胞也拥有这些结构，但还有三个额外的部分：由纤维素组成的刚性细胞壁提供支撑，叶绿体吸收阳光进行光合作用，以及充满细胞液的大液泡，有助于保持细胞坚挺。
| Feature | Plant cell | Animal cell |
|---|---|---|
| Cell wall | Yes | No |
| Chloroplasts | Yes | No |
| Large vacuole | Yes | No |
| Nucleus | Yes | Yes |
To study cells, we use a light microscope. The total magnification is calculated by multiplying the eyepiece lens magnification (usually x10) by the objective lens magnification (e.g. x4, x10 or x40).
我们使用光学显微镜来研究细胞。总放大倍数是目镜放大倍数（通常为 10×）乘以物镜放大倍数（例如 4×、10× 或 40×）。
3. States of Matter and the Particle Model | 物质状态与粒子模型
Matter exists as solid, liquid or gas. In solids, particles are tightly packed in a regular pattern and only vibrate in fixed positions. In liquids, particles are close together but can move past each other. In gases, particles are far apart and move quickly in all directions.
物质以固态、液态或气态存在。在固体中，粒子紧密排列成规则图案，只能在固定位置振动。在液体中，粒子彼此靠近但可以相互滑动。在气体中，粒子相距很远并朝各个方向快速运动。
The particle model explains changes of state. Melting and boiling require energy to overcome forces between particles, while freezing and condensing release energy as particles come closer together.
粒子模型可以解释状态变化。熔化和沸腾需要能量来克服粒子之间的吸引力，而凝固和冷凝则释放能量，因为粒子变得更为靠近。
Sublimation is the change from solid directly to gas, like dry ice. Deposition is the reverse process. The mass stays the same during a change of state because the number of particles does not change.
升华是固体直接变为气体的过程，例如干冰。凝华是相反的过程。在状态变化过程中质量保持不变，因为粒子数目不变。
4. Elements, Compounds and Mixtures | 元素、化合物与混合物
An element is a pure substance made of only one type of atom. The periodic table lists all known elements, arranged in groups and periods according to their atomic number. Common elements include oxygen (O), carbon (C) and iron (Fe).
元素是由一种原子组成的纯净物。周期表列出了所有已知元素，按原子序数排列成族和周期。常见的元素包括氧（O）、碳（C）和铁（Fe）。
A compound forms when two or more different elements chemically bond together. The properties of a compound are different from its elements. For example, water (H₂O) is a liquid, while hydrogen and oxygen are gases.
当两种或多种不同元素通过化学键结合在一起时，就形成了化合物。化合物的性质不同于其组成元素。例如水（H₂O）是液体，而氢和氧是气体。
A mixture contains two or more substances not chemically joined. Mixtures can be separated by physical methods: filtration for insoluble solids, distillation for liquids with different boiling points, and chromatography for dissolved colours.
混合物含有两种或多种未发生化学结合的物质。混合物可以通过物理方法分离：过滤用于不溶性固体，蒸馏用于沸点不同的液体，色谱法用于分离溶解的颜色。
5. Introduction to Chemical Reactions | 化学反应简介
A chemical reaction creates new substances with different properties. Signs of a reaction include a colour change, temperature change, gas production (bubbles or fizzing) or formation of a precipitate (solid from solutions).
化学反应生成具有不同性质的新物质。反应的迹象包括颜色变化、温度变化、产生气体（气泡或嘶嘶声）或形成沉淀（从溶液中析出的固体）。
products. A word equation shows the transformation: magnesium + oxygen → magnesium oxide.
在反应中，起始物质称为反应物，生成的物质称为产物。文字方程式展示这一转变：镁 + 氧气 → 氧化镁。
Some reactions are exothermic (give out heat), such as burning. Others are endothermic (take in heat), such as sherbet dissolving on your tongue. Energy is always conserved and transferred between the system and its surroundings.
有些反应是放热的（释放热量），比如燃烧。另一些是吸热的（吸收热量），例如雪酪在舌头上溶解。能量总是守恒的，并在系统与周围环境之间传递。
6. Forces and Motion | 力与运动
A force is a push or pull that can change an object's speed, direction or shape. Common forces include gravity, friction, air resistance, tension, magnetic force and upthrust. Force is measured in newtons (N).
力是一种推或拉，可以改变物体的速度、方向或形状。常见的力包括重力、摩擦力、空气阻力、张力、磁力和上推力。力的单位是牛顿（N）。
Balanced forces (equal in size, opposite in direction) mean an object stays at rest or moves at a steady speed. Unbalanced forces cause acceleration, deceleration or change in direction.
平衡力（大小相等、方向相反）意味着物体保持静止或匀速运动。非平衡力则导致加速、减速或方向改变。
Average speed can be calculated using the formula:
speed = distance ÷ time
平均速度可以用以下公式计算：
速度 = 距离 ÷ 时间
On a distance–time graph, a straight sloping line shows constant speed; a horizontal line shows the object is stationary. The steeper the line, the higher the speed.
在距离–时间图中，倾斜的直线表示匀速运动；水平线表示物体静止。线越陡，速度越大。
7. Energy Forms and Transfers | 能量形式与转化
Energy comes in many forms: kinetic (movement), thermal (heat), light, sound, electrical, chemical (stored in fuels and food), elastic potential (stretched spring) and gravitational potential (high position).
能量有多种形式：动能（运动）、热能（热）、光能、声能、电能、化学能（储存在燃料和食物中）、弹性势能（拉伸的弹簧）和重力势能（处于高处）。
The law of conservation of energy states that energy cannot be created or destroyed, only transferred from one form to another. In a light bulb, electrical energy is transferred into light and thermal energy.
能量守恒定律指出，能量不能凭空产生或消失，只能从一种形式转化为另一种形式。在灯泡中，电能转化为光能和热能。
Sankey diagrams show energy transfers. The arrow width represents the amount of energy. The useful energy is shown as a straight thick arrow, while wasted energy branches off.
桑基图展示能量传递。箭头的宽度代表能量的多少。有用的能量用直而粗的箭头表示，而浪费的能量则以分支箭头表示。
8. Electricity and Circuits | 电与电路
Electric current is the flow of charged particles. For a circuit to work, it must be a closed loop containing a source of voltage (cell or battery), conducting wires and a load such as a bulb or motor.
电流是带电粒子的流动。要使电路工作，必须形成一个闭合回路，包含电压源（电池或电池组）、导线以及灯泡或电动机等负载。
In a series circuit, components are connected one after another. If one bulb breaks, the whole circuit stops. In a parallel circuit, each component has its own loop, so removing one component does not stop the others.
在串联电路中，元件一个接一个地连接。如果一个灯泡损坏，整个电路就会中断。在并联电路中，每个元件有自己的回路，因此移除一个元件不会影响其他元件的工作。
Current (I) is measured in amperes (A) using an ammeter connected in series. Voltage (V) is measured in volts (V) with a voltmeter connected in parallel across a component.
电流（I）用串联接入的安培计测量，单位是安培（A）。电压（V）用并联在元件两端的伏特计测量，单位是伏特（V）。
9. Human Body Systems | 人体系统概述
The digestive system breaks down large food molecules into small, soluble ones that can be absorbed into the blood. Food travels from the mouth through the oesophagus to the stomach, then into the small intestine where most absorption occurs.
消化系统将大的食物分子分解成小的可溶性分子，以便被吸收到血液中。食物从口腔经食管进入胃，然后进入小肠，大部分吸收在这儿发生。
The respiratory system brings oxygen into the body and removes carbon dioxide. Air enters through the trachea, travels through bronchi and bronchioles, and reaches alveoli where gas exchange happens with the blood.
呼吸系统将氧气带入体内并排出二氧化碳。空气通过气管进入，经过支气管和细支气管，到达肺泡，在那里与血液进行气体交换。
The circulatory system consists of the heart, blood vessels and blood. The heart pumps blood around the body; arteries carry blood away, veins carry it back, and capillaries allow exchange of gases and nutrients at tissues.
循环系统由心脏、血管和血液组成。心脏将血液泵送到全身；动脉将血液送出，静脉将血液送回，毛细血管则负责在组织处交换气体和营养物质。
10. Ecosystems and Food Chains | 生态系统与食物链
An ecosystem includes all the living organisms in an area interacting with each other and the non‑living environment. Producers (green plants) make their own food through photosynthesis using sunlight, CO₂ and water.
生态系统包括一个区域中所有相互作用的生物以及它们与非生物环境之间的互动。生产者（绿色植物）利用阳光、二氧化碳和水通过光合作用制造自己的食物。
Consumers eat other organisms. Primary consumers eat producers, secondary consumers eat primary consumers, and so on. Decomposers like bacteria and fungi break down dead material, returning nutrients to the soil.
消费者以其他生物为食。初级消费者吃生产者，次级消费者吃初级消费者，依此类推。分解者如细菌和真菌分解死去的生物，将养分归还土壤。
A food chain shows the feeding relationship and energy flow. Arrows point from the food to the eater. A food web is a network of interconnected food chains, showing a more realistic picture of an ecosystem.
食物链展示取食关系和能量流动。箭头从被吃的生物指向取食者。食物网是由多条相互连接的食物链组成的网络，能更真实地反映生态系统。
11. The Solar System and Earth's Place | 太阳系与地球的位置
The Solar System consists of the Sun, eight planets, their moons, dwarf planets like Pluto, and countless asteroids and comets. The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
太阳系由太阳、八大行星、它们的卫星、像冥王星这样的矮行星以及无数的小行星和彗星组成。按离太阳由近到远的顺序，行星是水星、金星、地球、火星、木星、土星、天王星和海王星。
Gravity keeps the planets in orbit around the Sun. The greater the mass of an object, the stronger its gravitational pull. Earth spins on its axis once every 24 hours, causing day and night, and orbits the Sun once a year.
引力使行星绕太阳运行。物体的质量越大，其引力就越强。地球每 24 小时自转一周，形成昼夜；每年绕太阳公转一周。
The Moon orbits Earth roughly every 28 days. Its phases change as we see different amounts of its illuminated half. A solar eclipse occurs when the Moon passes between the Sun and Earth, a lunar eclipse when Earth is between the Sun and Moon.
月球大约每 28 天绕地球一周。由于我们看到其被照亮半球的比例不同，月相会发生变化。当月球运行到太阳和地球之间时发生日食，当地球位于太阳和月球之间时发生月食。
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