📚 Year 8 SQA Science: Core Knowledge Review | Year 8 SQA 科学：核心知识点梳理
This guide covers the essential knowledge for Year 8 SQA Science, aligned with the Curriculum for Excellence. It summarises key concepts across biology, chemistry, physics, and investigative skills to support revision and build a solid foundation for future learning.
本指南涵盖 Year 8 SQA 科学的核心知识，与卓越课程保持一致。它总结了生物学、化学、物理学和探究技能方面的关键概念，以辅助复习并为未来的学习打下坚实的基础。
1. Scientific Inquiry and Skills | 科学探究与技能
Scientists ask questions and design investigations to find answers. A fair test changes only one independent variable while measuring the dependent variable, keeping all other variables controlled.
科学家提出问题并设计探究来寻找答案。公平测试只改变一个自变量，同时测量因变量，保持所有其他变量不变。
An aim describes what you want to investigate, and a hypothesis makes a testable prediction. For example, 'If light intensity increases, the rate of photosynthesis will increase.'
目标描述你想探究的内容，假设则做出可检验的预测。例如，“如果光照强度增加，光合作用速率就会增加。”
Accurate measurements use appropriate units (e.g., cm³ for volume) and repeated readings to calculate an average. A conclusion states what was discovered and whether the hypothesis was supported.
准确的测量要使用适当的单位（例如体积用 cm³），并重复读数以计算平均值。结论要说明发现了什么以及假设是否得到支持。
Safety symbols and risk assessments are essential before any experiment. Always wear goggles, tie back long hair, and listen to the teacher's instructions.
在任何实验之前，安全标志和风险评估都至关重要。始终佩戴护目镜，扎起长发，并听从老师的指示。
2. Cells and Life Processes | 细胞与生命过程
All living organisms carry out seven life processes (MRS GREN): Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.
所有生物体都进行七种生命过程（MRS GREN）：运动、呼吸、感应、生长、繁殖、排泄和营养。
Cells are the basic unit of life. Plant cells have a cell wall, a large permanent vacuole, and chloroplasts, which animal cells lack. Both have a nucleus, cytoplasm, and cell membrane.
细胞是生命的基本单位。植物细胞有细胞壁、大的永久液泡和叶绿体，而动物细胞没有。两者都有细胞核、细胞质和细胞膜。
The nucleus controls the cell and contains DNA. The cell membrane controls what enters and leaves. Mitochondria are where aerobic respiration occurs, releasing energy.
细胞核控制细胞并含有 DNA。细胞膜控制物质的进出。线粒体是有氧呼吸发生的场所，释放能量。
Using a light microscope, we can view cells by preparing a wet mount slide with a drop of water and a coverslip. Stains like iodine make structures like the nucleus visible.
使用光学显微镜，我们可以通过在水滴和盖玻片下制备湿装片来观察细胞。如碘液等染剂能使细胞核等结构可见。
3. Reproduction and Growth | 生殖与生长
Reproduction can be asexual, producing identical offspring from one parent, or sexual, involving two parents and producing genetically varied offspring.
生殖可以是无性的，由一个亲本产生相同的后代；也可以是有性的，涉及两个亲本并产生遗传多样的后代。
In flowering plants, the male sex cell (pollen) is produced by the stamen, and the female sex cell (ovule) is inside the pistil. Pollination followed by fertilisation leads to seed formation.
在开花植物中，雄性生殖细胞（花粉）由雄蕊产生，雌性生殖细胞（胚珠）位于雌蕊内。传粉后受精，形成种子。
In humans, the male gamete is the sperm and the female gamete is the egg. Fertilisation occurs in the oviduct, and the fertilised egg implants in the uterus lining for development.
在人类中，雄配子是精子，雌配子是卵细胞。受精发生在输卵管中，受精卵植入子宫内膜发育。
Adolescence brings physical changes driven by hormones. Puberty includes growth spurts, and the start of menstruation in females, supporting reproductive maturity.
青春期激素驱动带来身体变化。青春期包括快速生长，以及女性月经的开始，这支持生殖成熟。
4. Body Systems and Health | 身体系统与健康
The digestive system breaks down large insoluble food molecules into small soluble ones. Enzymes like amylase speed up breakdown; absorption occurs in the small intestine.
消化系统将大的不溶性食物分子分解成小的可溶性分子。像淀粉酶这样的酶加速分解；吸收在小肠中进行。
The circulatory system transports substances. The heart pumps blood through arteries, veins, and capillaries. Red blood cells carry oxygen bound to haemoglobin.
循环系统运输物质。心脏将血液泵送通过动脉、静脉和毛细血管。红细胞携带与血红蛋白结合的氧气。
The respiratory system brings oxygen into the body and removes carbon dioxide. Breathing involves the diaphragm and rib muscles changing the volume of the chest cavity.
呼吸系统将氧气带入体内并排出二氧化碳。呼吸涉及膈肌和肋骨肌肉改变胸腔的容积。
A balanced diet includes carbohydrates, proteins, lipids, vitamins, minerals, fibre, and water. Smoking and alcohol can damage these systems, increasing disease risk.
均衡饮食包括碳水化合物、蛋白质、脂类、维生素、矿物质、纤维和水。吸烟和酒精会损害这些系统，增加患病风险。
5. States of Matter | 物质的状态
Matter exists as solid, liquid, or gas. The particle model explains that all substances are made of tiny particles that move differently in each state.
物质以固态、液态或气态存在。粒子模型解释所有物质由微小的粒子组成，这些粒子在不同状态下的运动方式不同。
In solids, particles are tightly packed in a regular arrangement, vibrating in fixed positions. In liquids, particles are close but can move past each other.
在固体中，粒子紧密排列成规则的结构，在固定的位置上振动。在液体中，粒子距离很近但可以相互滑过。
In gases, particles are far apart and move quickly in all directions. Diffusion is the movement of particles from a high concentration area to a low one.
在气体中，粒子相距很远，朝各个方向快速运动。扩散是粒子从高浓度区域向低浓度区域的运动。
Changes of state – melting, freezing, boiling, evaporation, condensation, and sublimation – involve adding or removing energy, not creating new substances.
状态变化——熔化、凝固、沸腾、蒸发、冷凝和升华——涉及能量的增加或减少，而不产生新物质。
6. Atoms, Elements and Compounds | 原子、元素与化合物
All substances are made of atoms. An element is a substance made of only one type of atom, listed on the Periodic Table (e.g., oxygen O, iron Fe).
所有物质由原子组成。元素是仅由一种原子组成的物质，列在元素周期表中（例如氧 O，铁 Fe）。
A compound is formed when two or more different elements chemically join together. The compound has properties different from its elements (e.g., water H₂O).
化合物是两种或多种不同元素化学结合时形成的。化合物的性质与其组成元素不同（例如水 H₂O）。
Chemical symbols and formulas show the type and number of atoms. Subscripts indicate atom count: CO₂ has one carbon atom and two oxygen atoms.
化学符号和化学式显示了原子的种类和数量。下标表示原子数：CO₂ 有一个碳原子和两个氧原子。
Mixtures contain different substances not chemically joined, and they can be separated by physical methods like filtration, distillation, or chromatography.
混合物包含未化学结合的不同物质，可以通过过滤、蒸馏或色谱法等物理方法进行分离。
7. Chemical Reactions | 化学反应
A chemical reaction makes new substances. Signs include colour change, gas production (bubbles), temperature change, or a precipitate forming.
化学反应产生新物质。迹象包括颜色变化、产生气体（气泡）、温度变化或形成沉淀。
Word equation: methane + oxygen → carbon dioxide + water
文字方程式：甲烷 + 氧气 → 二氧化碳 + 水
In a chemical reaction, atoms are rearranged; no atoms are created or destroyed. This is the law of conservation of mass.
在化学反应中，原子重新排列；没有原子被创造或消灭。这就是质量守恒定律。
Reaction rate depends on temperature, concentration, particle size (surface area), and the presence of a catalyst. Acids react with alkalis in neutralisation to make salt and water.
反应速率取决于温度、浓度、颗粒大小（表面积）以及催化剂的存在。酸与碱在中和反应中生成盐和水。
Common indicators like litmus turn red in acid and blue in alkali. The pH scale measures acidity from 0 (strongly acidic) to 14 (strongly alkaline), with 7 neutral.
常见的指示剂如石蕊在酸中变红，在碱中变蓝。pH 值衡量酸碱度，从 0（强酸性）到 14（强碱性），7 为中性。
8. Forces and Motion | 力与运动
A force is a push or pull measured in newtons (N). Forces can change an object's speed, direction, or shape. Friction opposes motion and often produces heat.
力是推或拉，以牛顿 (N) 为单位测量。力可以改变物体的速度、方向或形状。摩擦力阻碍运动，经常产生热。
Balanced forces cause no change in motion (constant speed or stationary). Unbalanced forces cause acceleration, deceleration, or change in direction.
平衡力不引起运动变化（匀速或静止）。不平衡力引起加速、减速或方向改变。
nal field strength, W = mg). Mass stays constant, but weight changes on different planets.
重力是质量之间的吸引力。在地球上，它产生重量（重量 = 质量 × 重力场强度，W = mg）。质量保持不变，但在不同行星上重量会变化。
Speed is calculated as distance divided by time. A distance-time graph shows motion: a horizontal line means stationary, a straight sloping line means constant speed.
速度计算为距离除以时间。距离-时间图显示运动情况：水平线表示静止，倾斜直线表示匀速运动。
9. Energy Forms and Transfers | 能量形式与转换
Energy exists in different stores: kinetic, gravitational potential, thermal, chemical, elastic potential, and nuclear. Energy is never created or destroyed – it is conserved.
能量以不同的形式存在：动能、重力势能、热能、化学能、弹性势能和核能。能量既不会被创造也不会被消灭——它守恒。
Energy can be transferred between stores by forces, heating, or electric currents. For example, a lamp transfers electrical energy into light and thermal energy.
能量可以通过力、加热或电流在不同存储之间转移。例如，灯将电能转化为光能和热能。
Renewable energy resources include solar, wind, tidal, and hydroelectric power. Non-renewable resources like coal, oil, and gas are finite and produce carbon dioxide.
可再生能源包括太阳能、风能、潮汐能和水力发电。不可再生能源如煤、石油和天然气是有限的，并产生二氧化碳。
Power is the rate of energy transfer, measured in watts (W). One watt equals one joule per second. More powerful appliances transfer more energy in a given time.
功率是能量转移的速率，以瓦特 (W) 为单位。一瓦特等于每秒一焦耳。功率更大的电器在给定时间内转移更多的能量。
10. Electricity and Magnetism | 电与磁
An electric circuit needs a complete loop of conductors for current to flow. Components include cells, bulbs, switches, and resistors. Current is measured in amperes (A) using an ammeter.
电路需要完整的导体回路才能有电流流动。元件包括电池、灯泡、开关和电阻器。电流使用电流表以安培 (A) 为单位测量。
Voltage (potential difference) is the 'push' of electrons around a circuit, measured in volts (V) using a voltmeter. Resistance opposes current and is measured in ohms (Ω).
电压（电势差）是驱动电子绕电路流动的“推力”，使用电压表以伏特 (V) 为单位测量。电阻阻碍电流，以欧姆 (Ω) 为单位测量。
Series circuits have one loop; current is the same everywhere, but voltage is shared. Parallel circuits have branches; total current splits, but voltage is the same across each branch.
串联电路只有一个回路；各处电流相同，但电压被分配。并联电路有分支；总电流分流，但每个分支的电压相同。
Magnets have north and south poles. Like poles repel, unlike poles attract. An electromagnet is made by passing a current through a coil of wire around an iron core.
磁铁有北极和南极。同极相斥，异极相吸。电磁体是通过在铁芯周围的线圈中通电流制成的。
11. Waves: Sound and Light | 波：声与光
Waves transfer energy without transferring matter. In transverse waves (light), vibrations are perpendicular to wave direction; in longitudinal waves (sound), vibrations are parallel.
波传递能量而不传递物质。在横波（光）中，振动与波的传播方向垂直；在纵波（声）中，振动与传播方向平行。
Sound travels fastest in solids, slower in liquids, and slowest in gases. It cannot travel through a vacuum. Loudness relates to amplitude, pitch to frequency.
声音在固体中传播最快，液体中较慢，气体中最慢。它不能在真空中传播。响度与振幅有关，音调与频率有关。
smooth surface, it reflects at the same angle (angle of incidence = angle of reflection).
光沿直线传播。当光线照射到光滑表面时，它以相同的角度反射（入射角 = 反射角）。
Refraction occurs when light passes from one transparent medium to another, changing speed and bending. A prism splits white light into the colours of the visible spectrum (ROYGBIV).
当光从一种透明介质进入另一种时发生折射，速度改变并发生弯曲。棱镜将白光分解成可见光谱的颜色（红橙黄绿蓝靛紫）。
12. Earth and Space | 地球与太空
Earth's structure includes the crust, mantle, outer core, and inner core. The rock cycle describes how igneous, sedimentary, and metamorphic rocks transform through processes like weathering, melting, and pressure.
地球结构包括地壳、地幔、外核和内核。岩石循环描述了火成岩、沉积岩和变质岩如何通过风化、熔融和压力等过程相互转化。
The Solar System consists of the Sun, eight planets, and other objects like asteroids and comets. The inner planets are rocky; the outer planets are gas giants.
太阳系由太阳、八颗行星以及小行星和彗星等其他天体组成。内行星是岩石行星；外行星是气态巨行星。
Earth spins on its axis, giving us day and night. It orbits the Sun, causing seasons due to the tilt of its axis. A year is one full orbit (365.25 days).
地球绕轴自转，产生了昼夜。它围绕太阳公转，由于地轴倾斜而产生季节。一年是一次完整的公转（365.25 天）。
The Moon orbits Earth roughly every 28 days, showing phases from new moon to full moon. Tides are caused by the gravitational pull of the Moon and Sun.
月球大约每 28 天绕地球一圈，展现从新月到满月的月相。潮汐是由月球和太阳的引力引起的。
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