IGCSE Edexcel Science: Last-Minute Revision Notes | IGCSE Edexcel 科学：考前冲刺笔记

📚 IGCSE Edexcel Science: Last-Minute Revision Notes | IGCSE Edexcel 科学：考前冲刺笔记

As the IGCSE Edexcel Science exam approaches, it is crucial to consolidate key concepts from Biology, Chemistry and Physics into concise, memorable revision notes. This article provides a structured last-minute recap covering essential theory, common equations, and exam tips to help you secure top marks.

随着 IGCSE Edexcel 科学考试临近，将生物、化学和物理的关键概念整理成简洁易记的复习笔记至关重要。本文提供了一套结构化的考前冲刺总结，涵盖基本理论、常见方程式以及考试技巧，助你稳获高分。

1. Biology: Cell Structure and Function | 生物：细胞结构与功能

All living organisms are made of cells. Animal cells contain a nucleus, cytoplasm, cell membrane and mitochondria, while plant cells also have a cell wall, chloroplasts and a permanent vacuole.

所有生物均由细胞构成。动物细胞包含细胞核、细胞质、细胞膜和线粒体，而植物细胞还具有细胞壁、叶绿体和中央大液泡。

Key functions: nucleus controls cell activities and stores DNA; cytoplasm is the site of metabolic reactions; cell membrane controls substance movement; mitochondria perform aerobic respiration.

关键功能：细胞核控制细胞活动并储存 DNA；细胞质是代谢反应场所；细胞膜控制物质进出；线粒体进行有氧呼吸。

Plant cells have additional features: cellulose cell wall provides support; chloroplasts contain chlorophyll for photosynthesis; large vacuole maintains turgor pressure.

植物细胞另有：纤维素细胞壁提供支撑；叶绿体含叶绿素进行光合作用；大液泡维持膨压。

Specialised cells: root hair cell (large surface area for water absorption), red blood cell (no nucleus to maximise oxygen capacity), sperm cell (tail for movement).

特化细胞：根毛细胞（大表面积利于吸水）、红细胞（无核以容纳更多氧气）、精细胞（尾部用于运动）。

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2. Biology: Biological Molecules and Enzymes | 生物：生物分子与酶

Carbohydrates, proteins and lipids are essential. Starch and sugars are carbohydrates. The test for starch is iodine solution (turns blue-black). Reducing sugars are tested with Benedict’s solution (heat, forms brick-red precipitate).

碳水化合物、蛋白质和脂质是必需的。淀粉和糖属于碳水化合物。用碘液检测淀粉（变蓝黑色）。还原糖用本尼迪克特溶液检测（加热，形成砖红色沉淀）。

Proteins are tested with Biuret reagent (turns purple). Lipids are tested with ethanol (cloudy emulsion).

蛋白质用双缩脲试剂检测（变紫色）。脂质用乙醇检测（出现乳浊液）。

Enzymes are biological catalysts that speed up reactions without being used up. They have an active site complementary to the substrate “lock and key” model.

酶是生物催化剂，能在不被消耗的情况下加速反应。其活性位点与底物互补，符合“锁钥”模型。

Enzyme activity is affected by temperature and pH. At low temperatures, reactions slow; at the optimum, rate is highest; at high temperatures, enzymes denature (active site shape lost). Denaturation is irreversible. pH also alters enzyme shape; each enzyme has an optimum pH.

酶活性受温度和 pH 影响。低温反应慢；最适温度速率最高；高温使酶变性（活性位点形状改变）。变性不可逆。pH 也会改变酶的形状；每种酶有其最适 pH。

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3. Chemistry: Atomic Structure and Periodic Table | 化学：原子结构与周期表

Atoms consist of protons (positive, mass 1), neutrons (neutral, mass 1) in the nucleus, and electrons (negative, negligible mass) in shells.

原子由核内的质子（正电，质量 1）、中子（中性，质量 1）以及核外电子（负电，可忽略质量）构成。

Atomic number (Z) = number of protons, determines the element. Mass number (A) = protons + neutrons. Isotopes are atoms of the same element with different numbers of neutrons.

原子序数 (Z) = 质子数，决定元素种类。质量数 (A) = 质子数 + 中子数。同位素是质子数相同而中子数不同的同种原子。

Electrons fill shells: 2, 8, 8… The group number equals the number of outer electrons (for main groups). Noble gases (Group 0) have full outer shells, making them unreactive.

电子分层排布：2, 8, 8… 主族元素的族数等于最外层电子数。稀有气体（0 族）最外层已满，性质不活泼。

Ionic bonds form between metals and non‑metals by electron transfer. Covalent bonds form between non‑metals by electron sharing.

离子键由金属与非金属通过电子转移形成。共价键由非金属之间通过共享电子对形成。

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4. Chemistry: Stoichiometry and The Mole | 化学：化学计量与摩尔

The mole is the unit for amount of substance. One mole contains 6.02 × 10²³ particles (Avogadro constant). Molar mass (M) is the mass of one mole in grams per mole (g/mol).

摩尔是物质的量的单位。1 摩尔包含 6.02 × 10²³ 个粒子（阿伏伽德罗常数）。摩尔质量 (M) 是 1 摩尔物质的质量，单位为 g/mol。

number of moles = mass (g) / molar mass (g/mol)   n = m / M

摩尔数 = 质量 (g) / 摩尔质量 (g/mol)   n = m / M

For gases: at room temperature and pressure (RTP), one mole of any gas occupies 24 dm³. Volume (dm³) = moles × 24.

气体：在常温常压 (RTP) 下，1 摩尔任何气体体积为 24 dm³。体积 (dm³) = 摩尔数 × 24。

Concentration: mol/dm³ = moles / volume (dm³). Use formula triangles carefully.

浓度：mol/dm³ = 摩尔数 / 体积 (dm³)。慎用公式三角。

Empirical formula is the simplest whole‑number ratio of atoms, calculated from % or mass data.

经验式是最简整数原子比，可根据质量百分组成计算。

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5. Chemistry: Acids, Bases and Salts | 化学：酸、碱和盐

Acids release H⁺ ions in water. Common strong acids: HCl, H₂SO₄, HNO₃. Alkalis release OH⁻ ions. pH scale: 0–6 acidic, 7 neutral, 8–14 alkaline.

酸在水中释放 H⁺。常见强酸：HCl、H₂SO₄、HNO₃。碱释放 OH⁻。pH 范围：0–6 酸性，7 中性，8–14 碱性。

Neutralisation: acid + base → salt + water. Example: HCl + NaOH → NaCl + H₂O.

中和反应：酸 + 碱 → 盐 + 水。例：HCl + NaOH → NaCl + H₂O。

Acid + metal → salt + hydrogen gas. Acid + carbonate → salt + water + CO₂.

酸 + 金属 → 盐 + 氢气。酸 +

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