Essential IGCSE Science Revision Guide | IGCSE 科学核心复习指南

📚 Essential IGCSE Science Revision Guide | IGCSE 科学核心复习指南

This comprehensive revision guide consolidates the fundamental concepts across Biology, Chemistry, and Physics for the Edexcel IGCSE Science specification. Each section highlights the key principles, equations, and visual representations you need to master for your examinations.

本复习指南系统整合了 Edexcel IGCSE 科学大纲中生物、化学和物理三大学科的核心概念，每个部分都突出讲解了考试中必须掌握的关键原理、公式和图示。

---

1. Biological Molecules | 生物分子

Living organisms are built from four major classes of biological molecules: carbohydrates, proteins, lipids, and nucleic acids. Carbohydrates provide energy, proteins serve structural and enzymatic functions, and lipids form cell membranes and store energy.

生物体由四大类生物分子构成：碳水化合物、蛋白质、脂质和核酸。碳水化合物提供能量，蛋白质承担结构和酶的功能，脂质构成细胞膜并储存能量。

The table below summarises the key tests for identifying these molecules:

下表总结了鉴定这些分子的关键测试方法：

Molecule | 分子	Test | 测试	Positive Result | 阳性结果
Reducing sugars | 还原糖	Benedict’s test | 本尼迪特试剂	Brick-red precipitate | 砖红色沉淀
Starch | 淀粉	Iodine solution | 碘液	Blue-black colour | 蓝黑色
Protein | 蛋白质	Biuret test | 双缩脲试剂	Purple colour | 紫色
Lipids | 脂质	Emulsion test | 乳化测试	White emulsion | 白色乳浊液

Enzymes are biological catalysts that speed up chemical reactions without being consumed. They are specific to their substrate due to the complementary shape of the active site. Temperature and pH affect enzyme activity; extreme conditions cause denaturation, permanently altering the active site’s shape.

酶是生物催化剂，能在不被消耗的情况下加速化学反应。由于活性位点的互补形状，酶对其底物具有专一性。温度和 pH 值会影响酶活性；极端条件会导致变性，永久改变活性位点的形状。

---

2. Cell Structure and Organisation | 细胞结构与组织

Eukaryotic cells contain membrane-bound organelles, including the nucleus, mitochondria, and chloroplasts (in plant cells). Prokaryotic cells, such as bacteria, lack these organelles and have free-floating DNA.

真核细胞含有膜结合细胞器，包括细胞核、线粒体和叶绿体（植物细胞中）。原核细胞（如细菌）缺乏这些细胞器，DNA 游离于细胞质中。

• Animal cells contain: nucleus, cytoplasm, cell membrane, mitochondria, ribosomes | 动物细胞包含：细胞核、细胞质、细胞膜、线粒体、核糖体

• Plant cells additionally contain: cell wall (cellulose), chloroplasts, permanent vacuole | 植物细胞还包含：细胞壁（纤维素）、叶绿体、永久液泡

• Sperm cells have a tail for movement; red blood cells are biconcave discs to maximise surface area for oxygen diffusion | 精子细胞有尾巴用于运动；红细胞呈双凹圆盘状，以最大化氧气扩散的表面积

Diffusion is the net movement of particles from a region of higher concentration to lower concentration. Osmosis is a special case involving water moving across a partially permeable membrane. Active transport moves substances against the concentration gradient, requiring energy from respiration.

扩散是粒子从高浓度区域向低浓度区域的净移动。渗透是水分子穿过部分可渗透膜的特殊扩散。主动运输需要呼吸作用提供能量，逆浓度梯度运输物质。

---

3. Atomic Structure and the Periodic Table | 原子结构与元素周期表

The atom consists of protons, neutrons, and electrons. Protons have a relative charge of +1 and relative mass of 1; neutrons are neutral with relative mass 1; electrons have charge −1 and negligible mass.

原子由质子、中子和电子组成。质子的相对电荷为 +1，相对质量为 1；中子呈电中性，相对质量为 1；电子带 −1 电荷，质量可忽略不计。

Atomic number (Z) = number of protons = number of electrons in a neutral atom
原子序数 = 质子数 = 中性原子中的电子数

Mass number (A) = number of protons + number of neutrons
质量数 = 质子数 + 中子数

The periodic table is arranged in order of increasing atomic number. Elements in the same group have the same number of outer-shell electrons, giving them similar chemical properties. Group 1 elements (alkali metals) are highly reactive and form +1 ions; Group 7 elements (halogens) are reactive non-metals forming −1 ions.

元素周期表按原子序数递增排列。同一族的元素具有相同的最外层电子数，因此化学性质相似。第 1 族元素（碱金属）反应性极强，形成 +1 离子；第 7 族元素（卤素）是活性非金属，形成 −1 离子。

---

4. Chemical Bonding | 化学键

Ionic bonding occurs between metals and non-metals through the transfer of electrons, forming oppositely charged ions held together by electrostatic attraction. Covalent bonding involves the sharing of electron pairs between non-metal atoms. Metallic bonding consists of positive ions in a sea of delocalised electrons.

离子键发生在金属和非金属之间，通过电子转移形成带相反电荷的离子，由静电引力维系。共价键是非金属原子之间共享电子对。金属键由沉浸在自由电子海中的正离子构成。

Ionic compounds have high melting points due to strong electrostatic forces and conduct electricity when molten or in solution. Covalent substances, like carbon dioxide, often have low melting points and do not conduct electricity. Diamond and graphite are both giant covalent structures of carbon but differ in arrangement and properties.

离子化合物由于强静电作用力而熔点高，在熔融或溶液中能导电。共价物质（如二氧化碳）通常熔点低且不导电。金刚石和石墨都是碳的巨型共价结构，但排列方式和性质不同。

---

5. Forces and Motion | 力与运动

Speed is the distance travelled per unit time, while velocity includes direction. Acceleration is the rate of change of velocity. Newton’s laws of motion govern the behaviour of objects under forces.

速度是单位时间内移动的距离，而速率还包含方向。加速度是速度的变化率。牛顿运动定律支配物体在力作用下的行为。

v = u + at    s = ut + ½at²    F = ma    W = mg

v² = u² + 2as    KE = ½mv²    PE = mgh

• Newton’s First Law: an object remains at rest or constant velocity unless acted on by a resultant force | 牛顿第一定律：物体在不受合外力作用时保持静止或匀速直线运动状态

• Newton’s Second Law: force = mass × acceleration (F = ma) | 牛顿第二定律：力 = 质量 × 加速度

• Newton’s Third Law: every action has an equal and opposite reaction | 牛顿第三定律：每一个作用力都有一个大小相等、方向相反的反作用力

---

6. Energy Transfers and Resources | 能量转化与资源

Energy is measured in joules (J). The principal of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed. Common energy stores include kinetic, gravitational potential, elastic potential, chemical, and thermal.

能量以焦耳（J）为单位。能量守恒定律指出：能量不能被创造或消灭，只能被转移或转化。常见的能量储存形式包括动能、重力势能、弹性势能、化学能和热能。

Non-renewable energy resources (coal, oil, natural gas, nuclear) are finite and release pollutants. Renewable resources (solar, wind, hydroelectric, geothermal, tidal) are sustainable and produce minimal pollution. Each has advantages and disadvantages regarding cost, reliability, and environmental impact.

不可再生能源（煤炭、石油、天然气、核能）是有限资源且会释放污染物。可再生能源（太阳能、风能、水力发电、地热能、潮汐能）可持续利用且污染极少。每种能源在成本、可靠性和环境影响方面各有优缺点。

Efficiency is the ratio of useful output energy to total input energy, usually expressed as a percentage. Reducing unwanted energy transfers, such as through insulation, improves efficiency.

效率是有用输出能量与总输入能量的比值，通常以百分比表示。减少不必要的能量转化（如通过隔热保温）可以提高效率。

---

7. Electricity and Circuits | 电与电路

Electric current (I) is the rate of flow of charge, measured in amperes (A). Potential difference (V) is the energy transferred per unit charge, measured in volts (V). Resistance (R) opposes current flow and is measured in ohms (Ω).

电流（I）是电荷流动的速率，单位为安培（A）。电势差（V）是单位电荷传递的能量，单位为伏特（V）。电阻（R）阻碍电流流动，单位为欧姆（Ω）。

V = I × R    P = V × I    E = P × t

In a series circuit, the same current flows through all components, and the total resistance is the sum of individual resistances. In a parallel circuit, the voltage across each branch is the same, and the total current is the sum of branch currents.

在串联电路中，所有元件通过相同的电流，总电阻是各电阻之和。在并联电路中，每个支路两端的电压相同，总电流是各支路电流之和。

---

8. Plant Nutrition and Transport | 植物营养与运输

Photosynthesis converts carbon dioxide and water into glucose and oxygen using light energy. The word equation is:

光合作用利用光能将二氧化碳和水转化为葡萄糖和氧气。化学方程式为：

Carbon dioxide + Water → Glucose + Oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气

Chlorophyll in chloroplasts absorbs light energy. Factors limiting the rate of photosynthesis include light intensity, carbon dioxide concentration, and temperature. Increasing any limiting factor will increase the rate until another factor becomes limiting.

叶绿体中的叶绿素吸收光能。限制光合作用速率的因素包括光照强度、二氧化碳浓度和温度。增加任一限制因素都会提高速率，直到另一个因素成为新的限制因子。

In the xylem, water and mineral ions are transported upward from roots to leaves. In the phloem, sucrose and amino acids are transported bidirectionally between sources and sinks. Transpiration is the loss of water vapour from leaves through stomata.

木质部将水和矿质离子从根部向上运输到叶片。韧皮部在源和库之间双向运输蔗糖和氨基酸。蒸腾作用是水分以水蒸气形式通过气孔从叶片散失的过程。

---

9. Rates of Reaction | 化学反应速率

The rate of a chemical reaction can be measured by the change in concentration, mass, or volume of reactants or products per unit time. Factors affecting reaction rate include temperature, concentration, surface area, pressure, and the presence of catalysts.

化学反应速率可通过单位时间内反应物或产物的浓度、质量或体积变化来测量。影响反应速率的因素包括温度、浓度、表面积、压力和催化剂的存在。

Increasing temperature gives particles more kinetic energy, leading to more frequent and more energetic collisions. Increasing concentration or pressure increases the frequency of collisions. Increasing surface area exposes more particles to collisions. Catalysts provide an alternative pathway with lower activation energy.

升高温度使粒子获得更多动能，导致碰撞更频繁、更有力。增加浓度或压力会提高碰撞频率。增加表面积使更多粒子暴露于碰撞中。催化剂提供了活化能更低的替代反应路径。

---

10. Human Reproduction and Inheritance | 人类生殖与遗传

The male gamete (sperm) fuses with the female gamete (egg) during fertilisation, restoring the full chromosome number. Human body cells contain 46 chromosomes (23 pairs); sex cells contain 23 chromosomes. The sex of a child is determined by the X and Y chromosomes from the father.

受精过程中，雄性配子（精子）与雌性配子（卵细胞）融合，恢复完整的染色体数目。人体体细胞含 46 条染色体（23 对）；生殖细胞含 23 条染色体。胎儿性别由父亲的 X 和 Y 染色体决定。

Inheritance follows Mendel’s laws. Homozygous individuals carry two identical alleles; heterozygous individuals carry two different alleles. A dominant allele masks the expression of a recessive allele in the heterozygous state. Punnett squares are used to predict the probability of offspring genotypes and phenotypes.

遗传遵循孟德尔定律。纯合个体携带两个相同的等位基因；杂合个体携带两个不同的等位基因。显性等位基因在杂合状态下掩盖隐性等位基因的表达。庞尼特方格用于预测后代的基因型和表型概率。

---

11. Acids, Bases and Salts | 酸、碱与盐

Acids produce hydrogen ions (H⁺) in aqueous solution; bases produce hydroxide ions (OH⁻). The pH scale ranges from 0 (strongly acidic) to 14 (strongly alkaline), with pH 7 being neutral. Universal indicator or pH probes are used to measure pH.

酸在水溶液中产生氢离子（H⁺）；碱产生氢氧根离子（OH⁻）。pH 标度范围从 0（强酸性）到 14（强碱性），pH 7 为中性。使用万能指示剂或 pH 计测量 pH 值。

Neutralisation reactions between acids and bases produce salt and water. General equations include:

酸碱中和反应生成盐和水。通式包括：

Acid + Base → Salt + Water
H⁺(aq) + OH⁻(aq) → H₂O(l)

Acid reactions with metals produce salt and hydrogen gas; acid reactions with carbonates produce salt, water, and carbon dioxide. Soluble salts can be prepared by titration, while insoluble salts are made by precipitation.

酸与金属反应生成盐和氢气；酸与碳酸盐反应生成盐、水和二氧化碳。可溶性盐可通过滴定法制备，不可溶性盐则通过沉淀反应制备。

---

12. Radioactivity and Particles | 放射性与粒子

Radioactive decay occurs when an unstable nucleus emits radiation to become more stable. The three main types of radiation are alpha (α), beta (β), and gamma (γ) rays. Alpha particles are helium nuclei (2 protons, 2 neutrons); beta particles are fast-moving electrons; gamma rays are high-energy electromagnetic waves.

放射性衰变发生在不稳定原子核释放辐射以变得更加稳定时。三种主要辐射类型是α射线、β射线和γ射线。α粒子是氦核（2个质子、2个中子）；β粒子是快速运动的电子；γ射线是高能电磁波。

Alpha particles are stopped by paper, beta by thin aluminium, and gamma requires thick lead or concrete. The half-life is the time taken for half of the radioactive nuclei in a sample to decay. Carbon-14 dating uses the known half-life of carbon-14 to determine the age of organic materials.

α粒子可被纸张阻挡，β粒子可被薄铝阻挡，γ射线则需要厚铅或混凝土。半衰期是指样品中一半放射性原子核发生衰变所需的时间。碳-14 测年法利用碳-14 的已知半衰期来确定有机材料的大致年代。

Activity (Bq) = number of decays per second
放射性活度（贝克勒尔）= 每秒衰变次数

Understanding radioactive decay, background radiation, and safety precautions is essential. Radiation is used in medicine for imaging (X-rays, gamma cameras) and cancer treatment (radiotherapy), as well as in industry for thickness measurement and sterilisation.

理解放射性衰变、本底辐射和安全防护措施至关重要。辐射在医学中用于成像（X射线、γ相机）和癌症治疗（放疗），在工业中用于厚度测量和灭菌。

---

Mastering these twelve core areas will build a solid foundation for success in your Edexcel IGCSE Science examinations. Practise past papers, create summary diagrams, and revisit topics where you feel less confident. Good luck!

掌握这十二个核心领域将为你在 Edexcel IGCSE 科学考试中取得成功奠定坚实基础。多做历年真题，制作知识总结图，并定期复习薄弱环节。祝你考试顺利！

Published by TutorHao | Science Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）