IGCSE CIE Combined Science: End-of-Term Revision Checklist | IGCSE CIE 科学：期末复习提纲

📚 IGCSE CIE Combined Science: End-of-Term Revision Checklist | IGCSE CIE 科学：期末复习提纲

Preparing for the end-of-term IGCSE Combined Science exam requires a structured approach covering Biology, Chemistry and Physics. This checklist highlights the essential topics, key definitions, common equations and typical exam pitfalls to ensure you are fully prepared.

准备IGCSE科学期末考需要系统梳理生物、化学和物理的核心内容。本文复习提纲涵盖必考主题、关键定义、常用方程式及常见失分点，助你全面备考。

1. Cell Structure and Biological Molecules | 细胞结构与生物分子

All living organisms are made of cells. Animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells have these plus a cellulose cell wall, a large permanent vacuole and chloroplasts.

所有生物由细胞构成。动物细胞包含细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞还有纤维素细胞壁、中央大液泡和叶绿体。

The nucleus controls the cell and contains DNA. Mitochondria are the site of aerobic respiration. Ribosomes synthesise proteins. Chloroplasts absorb light for photosynthesis.

细胞核控制细胞活动并含有DNA。线粒体是有氧呼吸的场所。核糖体合成蛋白质。叶绿体吸收光能进行光合作用。

Key biological molecules: carbohydrates provide energy (starch storage in plants, glycogen in animals); proteins are made of amino acids and used for growth and repair; lipids (fats and oils) store energy and form cell membranes. Food tests include Benedict’s solution for reducing sugars (brick-red on heating), iodine solution for starch (blue-black), Biuret reagent for proteins (purple) and ethanol emulsion test for lipids (cloudy white).

关键生物分子：糖类提供能量（植物储存淀粉，动物储存糖原）；蛋白质由氨基酸构成，用于生长和修复；脂质储存能量并组成细胞膜。食物测试：本尼迪克特试剂检测还原糖（加热后砖红），碘液检测淀粉（蓝黑），双缩脲试剂检测蛋白质（紫色），乙醇乳液法检测脂质（乳白色）。

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2. Enzymes and Digestion | 酶与消化系统

Enzymes are biological catalysts made of protein. They speed up reactions without being used up. Each enzyme has a specific active site that fits its substrate like a key in a lock. Enzyme activity is affected by temperature and pH; extremes can denature the enzyme, changing the shape of the active site permanently.

酶是蛋白质生物催化剂。它们加速反应而自身不被消耗。每种酶有特定活性位点，与底物如同锁钥般匹配。酶活性受温度和pH影响；极端条件可使酶变性，永久改变活性位点形状。

Digestive enzymes include amylase (breaks down starch into maltose, produced in salivary glands and pancreas), protease (breaks proteins into amino acids, in stomach and pancreas) and lipase (breaks lipids into fatty acids and glycerol, in pancreas). Bile from the liver neutralises stomach acid and emulsifies fats to increase the surface area for lipase action.

消化酶包括：淀粉酶（分解淀粉为麦芽糖，由唾液腺和胰脏分泌）、蛋白酶（分解蛋白质为氨基酸，胃和胰脏）和脂肪酶（分解脂质为脂肪酸和甘油，胰脏）。肝脏分泌的胆汁中和胃酸、乳化脂肪，增大脂肪酶作用的表面积。

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

Photosynthesis is the process by which plants produce glucose using light energy:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

光合作用是植物利用光能制造葡萄糖的过程：

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

The rate of photosynthesis is limited by light intensity, carbon dioxide concentration and temperature. The leaf is adapted with a broad lamina, stomata for gas exchange, and vascular bundles containing xylem and phloem.

光合作用速率受光照强度、二氧化碳浓度和温度的限制。叶片适应特点包括宽阔叶片、气孔进行气体交换以及包含木质部和韧皮部的维管束。

Xylem transports water and dissolved minerals from roots to leaves; water moves in the transpiration stream, driven by evaporation from stomata. Phloem transports sucrose and amino acids up and down the plant (translocation).

木质部将水和溶解的无机盐从根部运送到叶片；水分在蒸腾流中移动，由气孔蒸发驱动。韧皮部在植物体内双向运输蔗糖和氨基酸（转运）。

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4. Human Circulatory System | 人体循环系统

The heart has four chambers: right atrium, right ventricle, left atrium and left ventricle. Blood returns from the body via the vena cava into the right atrium, then passes to the right ventricle and is pumped to the lungs via the pulmonary artery. Oxygenated blood returns through the pulmonary vein to the left atrium, into the left ventricle, and is pumped to the body through the aorta. Valves prevent backflow.

心脏四腔：右心房、右心室、左心房、左心室。血液从身体经腔静脉回到右心房，流过右心室，通过肺动脉泵入肺内。含氧血液经肺静脉回到左心房，进入左心室，再经主动脉泵至全身。瓣膜防止血液倒流。

Blood components: red blood cells contain haemoglobin for oxygen transport; white blood cells defend against pathogens; platelets aid clotting; plasma transports nutrients, hormones and waste. Coronary heart disease occurs when coronary arteries narrow due to fatty plaques, reducing oxygen supply to the heart muscle.

血液成分：红细胞含血红蛋白运输氧气；白细胞防御病原体；血小板帮助凝血；血浆运输养分、激素和废物。冠状动脉因脂肪斑块狭窄，减少心肌供氧，导致冠心病。

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5. Atoms, Elements and Bonding | 原子、元素与化学键

Atoms are made of protons, neutrons and electrons. Atomic number = number of protons; mass number = protons + neutrons. Isotopes have the same number of protons but different numbers of neutrons.

原子由质子、中子和电子构成。原子序数=质子数；质量数=质子数+中子数。同位素质子数相同而中子数不同。

Ionic bonding involves transfer of electrons from a metal to a non-metal, forming oppositely charged ions held by electrostatic attraction, e.g., NaCl. Covalent bonding involves sharing of electron pairs between non-metals, e.g., H₂O, CO₂. Giant covalent structures such as diamond and silicon dioxide have high melting points because many strong covalent bonds must be broken.

离子键涉及金属与非金属间电子转移，形成带相反电荷的离子，通过静电引力结合，如NaCl。共价键涉及非金属间共享电子对，如H₂O、CO₂。巨型共价结构如金刚石和二氧化硅熔点高，因为需要破坏大量牢固的共价键。

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6. Chemical Reactions, Equations and Stoichiometry | 化学反应、方程式与计量学

All chemical equations must be balanced to obey the law of conservation of mass. State symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous solution.

所有化学方程式必须配平以遵守质量守恒定律。状态符号：(s)固体，(l)液体，(g)气体，(aq)水溶液。

Relative atomic mass (Ar) and relative formula mass (Mr) are used to calculate reacting masses. Moles = mass / Mr. Concentration in mol/dm³ = moles / volume (dm³). Use mole ratios from balanced equations to find masses of reactants or products, and identify limiting reactants.

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