📚 AS CIE Biology: A Complete Syllabus Breakdown | AS CIE 生物：课程大纲全面解析
The Cambridge International AS Level Biology (9700) syllabus builds on key concepts from IGCSE, deepening your understanding of the molecules, cells and systems that make up living organisms. This article provides a thorough overview of the syllabus structure, assessment components and all 11 core topics, helping you plan effective revision and target the highest marks.
剑桥国际AS Level生物学(9700)课程大纲在IGCSE的基础上深化对构成生物体的分子、细胞和系统的理解。本文全面解析课程结构、评估方式和全部11个核心主题，帮助你高效规划复习并冲击最高分。
1. Syllabus Overview and Assessment | 大纲总览与考核
The AS Biology syllabus is divided into 11 topic areas, all of which are examined through three externally assessed papers. Candidates must sit for Paper 1, Paper 2 and Paper 3 (Practical) in a single examination series.
AS生物学大纲分为11个主题领域，全部通过三份外部试卷进行考核。考生必须在同一考试季参加Paper 1、Paper 2和Paper 3（实验卷）的考试。
The table below summarises the structure of the examination components.
下表概括了考试卷的组成结构。
| Paper | Duration | Marks | Question Style |
|---|---|---|---|
| Paper 1 Multiple Choice | 1 hour 15 minutes | 40 | 40 four-option multiple-choice questions |
| Paper 2 Structured Questions | 1 hour 15 minutes | 60 | Structured questions based on the AS core syllabus |
| Paper 3 Advanced Practical Skills | 2 hours | 40 | Practical work and structured questions |
Paper 1 tests breadth of knowledge across all topics, while Paper 2 focuses on deeper understanding, application and data analysis. Paper 3 assesses practical skills, including microscopy, biochemical tests, drawing and planning investigations.
Paper 1考查所有主题知识的广度，而Paper 2侧重于深度理解、应用和数据分析。Paper 3评估实验技能，包括显微镜使用、生化检测、绘图和实验设计。
Mastering the command terms such as ‘describe’, ‘explain’ and ‘suggest’ is essential for accurate responses across all papers.
掌握’describe’, ‘explain’ 和 ‘suggest’等指令词对在所有试卷中准确作答至关重要。
2. Cell Structure | 细胞结构
This topic introduces the ultrastructure of cells as revealed by electron microscopy. Students must be able to compare prokaryotic and eukaryotic cells, recognising key differences in size, nucleus, membrane-bound organelles and ribosomes.
本主题介绍电子显微镜下揭示的细胞超微结构。学生必须能够比较原核细胞和真核细胞，识别大小、细胞核、膜包围的细胞器和核糖体等方面的主要区别。
Important eukaryotic organelles include the nucleus, rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplasts (in plants), lysosomes and ribosomes. The syllabus expects you to link each organelle’s structure to its function.
重要的真核细胞器包括细胞核、粗糙与光滑内质网、高尔基体、线粒体、叶绿体(植物)、溶酶体和核糖体。大纲要求你将每种细胞器的结构与其功能联系起来。
Viruses are acellular, consisting of genetic material (DNA or RNA) enclosed in a protein coat. You should understand why viruses are not considered living cells.
病毒是非细胞的，由遗传物质(DNA或RNA)包裹在蛋白质外壳中组成。你应该理解为什么病毒不被视为活细胞。
- Prokaryotic cells: lack a nucleus; DNA is circular and lies free in cytoplasm; 70S ribosomes; cell wall contains peptidoglycan.
- 原核细胞：无细胞核；DNA呈环状游离于细胞质中；70S核糖体；细胞壁含肽聚糖。
- Eukaryotic cells: membrane-bound nucleus; linear DNA associated with histones; 80S ribosomes; larger and compartmentalised.
- 真核细胞：有膜包围的细胞核；线状DNA与组蛋白结合；80S核糖体；体积较大并且区室化。
3. Biological Molecules | 生物分子
This topic focuses on the structure and roles of carbohydrates, lipids, proteins and water. You need to recognise molecular diagrams and carry out biochemical tests for identifying these molecules.
本主题聚焦于碳水化合物、脂质、蛋白质和水的结构与作用。你需要识别分子结构图，并能进行鉴定这些分子的生化检测。
Carbohydrates include monosaccharides (glucose, fructose), disaccharides (sucrose, maltose) and polysaccharides (starch, glycogen, cellulose). The glycosidic bond is formed via condensation and broken by hydrolysis.
碳水化合物包括单糖(葡萄糖、果糖)、二糖(蔗糖、麦芽糖)和多糖(淀粉、糖原、纤维素)。糖苷键通过缩合形成，水解断裂。
Lipids, particularly triglycerides, are composed of glycerol and three fatty acid chains joined by ester bonds. Phospholipids form the bilayer of cell membranes.
脂质，特别是甘油三酯，由甘油和三条脂肪酸链通过酯键连接组成。磷脂构成细胞膜的双分子层。
Proteins demonstrate four levels of structure: primary (amino acid sequence), secondary (α-helix and β-pleated sheet), tertiary (3D folding) and quaternary (multiple polypeptides). The shape determines function.
蛋白质展示四级结构：一级(氨基酸序列)、二级(α-螺旋和β-折叠)、三级(三维折叠)和四级(多条多肽)。形状决定功能。
Water’s properties — high specific heat capacity, high latent heat of vaporisation, cohesion and solvent ability — are all linked to its hydrogen bonding and are crucial to life.
水的特性——高比热容、高蒸发潜热、内聚力和溶剂能力——都与其氢键有关，对生命至关重要。
4. Enzymes | 酶
Enzymes are globular proteins acting as biological catalysts. The lock-and-key hypothesis and the induced-fit model explain enzyme specificity and the formation of enzyme-substrate complexes.
酶是球状蛋白，起生物催化剂作用。锁钥假说和诱导契合模型解释酶的专一性以及酶-底物复合物的形成。
You need to describe how temperature, pH, enzyme concentration and substrate concentration affect the rate of an enzyme-catalysed reaction. Use the term Vmax to denote the maximum rate at saturating substrate concentration.
你需要描述温度、pH、酶浓度和底物浓度如何影响酶促反应速率。用术语Vmax表示底物饱和时的最大速率。
Effect of substrate concentration: initial rate increases until active sites are saturated, approaching Vmax.
底物浓度影响：初始速率增加直到活性位点饱和，趋近Vmax。
Competitive inhibitors resemble the substrate and bind to the active site; non-competitive inhibitors bind to an allosteric site, changing the enzyme’s shape. Immobilised enzymes, such as lactase in alginate beads, are used in industry to produce lactose-free milk.
竞争性抑制剂与底物结构相似，结合于活性位点；非竞争性抑制剂结合到别构位点，改变酶的形状。固定化酶，如海藻酸钠珠中的乳糖酶，被用于工业生产无乳糖牛奶。
5. Cell Membranes and Transport | 细胞膜与运输
The cell membrane is described by the fluid mosaic model, consisting of a phospholipid bilayer with embedded proteins, cholesterol (in animal cells), glycoproteins and glycolipids.
细胞膜由流动镶嵌模型描述，由磷脂双分子层和嵌入其中的蛋白质、胆固醇(动物细胞)、糖蛋白和糖脂组成。
You should relate membrane structure to its functions: selective permeability, cell signalling and cell recognition. Cholesterol regulates membrane fluidity and stability.
你应能将膜结构与其功能联系起来：选择透过性、细胞信号传导和细胞识别。胆固醇调节膜的流动性和稳定性。
Transport mechanisms include simple diffusion, facilitated diffusion via channel and carrier proteins, osmosis, active transport (e.g. sodium-potassium pump) and bulk transport (endocytosis and exocytosis).
运输机制包括简单扩散、通过通道蛋白和载体蛋白的易化扩散、渗透作用、主动运输(如钠钾泵)以及批量运输(胞吞和胞吐)。
Osmosis is the net movement of water from a region of higher water potential to a region of lower water potential through a partially permeable membrane. Water potential (Ψ) of pure water is 0 kPa; adding solute lowers Ψ.
渗透是水通过部分透性膜从水势较高的区域向水势较低的区域的净移动。纯水的水势(Ψ)为0 kPa；加入溶质会降低水势。
6. The Mitotic Cell Cycle | 有丝分裂细胞周期
The cell cycle consists of interphase (G1, S, G2) and mitotic phase. DNA is replicated during S phase, and proteins are synthesised throughout interphase. Mitosis produces two genetically identical daughter cells for growth and repair.
细胞周期由间期(G1、S、G2)和有丝分裂期组成。DNA在S期复制，蛋白质在整个间期合成。有丝分裂产生两个遗传上相同的子细胞，用于生长和修复。
Mitosis is divided into prophase, metaphase, anaphase and telophase. You must be able to recognise these stages in diagrams and micrographs, and describe the behaviour of chromosomes and the spindle apparatus.
有丝分裂分为前期、中期、后期和末期。你必须能够在图谱和显微照片中识别这些阶段，并描述染色体和纺锤体的行为。
Cancer results from uncontrolled cell division due to mutations in genes that regulate the cell cycle. Telomeres and stem cells are also mentioned in the context of cell division and differentiation.
癌症是由于调控细胞周期的基因发生突变导致细胞分裂失控引起的。端粒和干细胞也在细胞分裂和分化的背景下提及。
7. Nucleic Acids and Protein Synthesis | 核酸与蛋白质合成
DNA is a double helix composed of nucleotides (deoxyribose, phosphate, nitrogenous base: adenine, thymine, cytosine, guanine). Base pairing is specific: A-T and C-G, held by hydrogen bonds. RNA contains ribose and uracil instead of thymine.
DNA是由核苷酸(脱氧核糖、磷酸、含氮碱基：腺嘌呤、胸腺嘧啶、胞嘧啶、鸟嘌呤)组成的双螺旋。碱基配对特异：A-T和C-G，由氢键连接。RNA含核糖，且尿嘧啶代替胸腺嘧啶。
DNA replication is semi-conservative, using each strand as a template. The enzymes DNA helicase and DNA polymerase are essential; you should also mention the formation of Okazaki fragments on the lagging strand.
DNA复制是半保留的，以每一条链为模板。DNA解旋酶和DNA聚合酶是关键酶；你还应提及后随链上冈崎片段的形成。
Protein synthesis involves transcription (in the nucleus) and translation (at ribosomes). mRNA carries the genetic code; tRNA brings specific amino acids. A gene is a sequence of DNA that codes for a polypeptide.
蛋白质合成包括转录(在细胞核)和翻译(在核糖体)。mRNA携带遗传密码；tRNA带来特定氨基酸。基因是编码一个多肽的DNA序列。
Mutations such as base substitution and insertion/deletion can alter the amino acid sequence, affecting protein structure and function. Sickle cell anaemia is a key example of a substitution mutation.
碱基替换和插入/缺失等突变可改变氨基酸序列，影响蛋白质的结构和功能。镰刀型细胞贫血是碱基替换突变的一个重要实例。
8. Transport in Plants | 植物体内的运输
Xylem tissue transports water and mineral ions from roots to leaves, whereas phloem transports sucrose and amino acids (assimilates) from sources to sinks. You should be able to identify these tissues in stem and root cross-sections.
木质部组织将水和无机离子从根运输到叶，而韧皮部将蔗糖和氨基酸(同化物)从源运输到库。你应能在茎和根的横截面中识别这些组织。
Water movement in xylem is explained by the cohesion-tension theory: transpiration from leaves generates tension, pulling a continuous column of water under cohesion. The transpiration stream is driven by evaporation.
木质部中的水分运动由内聚力-张力理论解释：叶片的蒸腾作用产生张力，通过内聚力拉动连续水柱。蒸腾流由蒸发驱动。
Translocation in phloem is described by the mass flow hypothesis. Sucrose is actively loaded into sieve tubes at the source, lowering water potential; water enters by osmosis, creating high hydrostatic pressure that drives flow toward the sink.
韧皮部的运输由集流假说描述。蔗糖在源处被主动装载进筛管，降低水势；水通过渗透进入，产生高静水压推动液流向库移动。
Factors affecting transpiration rate include light intensity, temperature, humidity and air movement. You should be able to design and explain potometer experiments.
影响蒸腾速率的因素包括光照强度、温度、湿度和空气流动。你应该能够设计并解释蒸腾计实验。
9. Transport in Mammals | 哺乳动物体内的运输
The mammalian circulatory system is a closed double circuit: pulmonary (to lungs) and systemic (to body tissues). Arteries, veins and capillaries have structures adapted to their functions.
哺乳动物的循环系统是封闭的双循环系统：肺循环(到肺)和体循环(到身体组织)。动脉、静脉和毛细血管的结构适应其功能。
The heart is a muscular organ with four chambers: right atrium, right ventricle, left atrium and left ventricle. The septum separates oxygenated and deoxygenated blood. The cardiac cycle is coordinated by the sinoatrial node (SAN) as pacemaker.
心脏是一个肌性器官，有四个腔室：右心房、右心室、左心房和左心室。室间隔分开充氧血和去氧血。心动周期由作为起搏器的窦房结(SAN)协调。
Blood consists of plasma, red blood cells (biconcave, no nucleus, contain haemoglobin), white blood cells (immune defence) and platelets (clotting). The role of haemoglobin in oxygen transport and the dissociation curve are important.
血液由血浆、红细胞(双凹圆盘状、无核、含血红蛋白)、白细胞(免疫防御)和血小板(凝血)组成。血红蛋白在氧气运输中的作用和氧解离曲线很重要。
Tissue fluid forms by filtration of blood plasma at the arterial end of capillaries, driven by hydrostatic pressure. Reabsorption occurs at the venous end due to osmotic effects; the lymphatic system collects excess tissue fluid.
组织液在毛细血管动脉端由血浆滤过形成，由静水压驱动。在静脉端由于渗透效应发生重吸收；淋巴系统收集多余的组织液。
10. Gas Exchange and Smoking | 气体交换与吸烟
The human gas exchange system includes the trachea, bronchi, bronchioles and alveoli. Goblet cells and ciliated epithelium in the airways trap and remove pathogens and particles.
人体气体交换系统包括气管、支气管、细支气管和肺泡。气道中的杯状细胞和纤毛上皮捕获并清除病原体和颗粒。
Alveoli are adapted for efficient gas exchange: large surface area, thin walls (one cell thick), good blood supply and ventilation. The partial pressure gradients of oxygen and carbon dioxide drive diffusion.
肺泡适应高效气体交换：表面积大、壁薄(一个细胞厚)、血液供应充分和通风。氧气和二氧化碳的分压梯度驱动扩散。
Smoking damages the gas exchange system. Main diseases are chronic obstructive pulmonary disease (COPD), chronic bronchitis, emphysema and lung cancer. Nicotine causes addiction, and carbon monoxide reduces the oxygen-carrying capacity of haemoglobin.
吸烟损害气体交换系统。主要疾病包括慢性阻塞性肺疾病(COPD)、慢性支气管炎、肺气肿和肺癌。尼古丁导致成瘾，一氧化碳降低血红蛋白的携氧能力。
Tar accumulates in the airways, paralysing cilia and stimulating excessive mucus production, leading to ‘smoker’s cough’. The syllabus expects you to explain the links between smoking and specific diseases using epidemiological evidence.
焦油在气道中积聚，麻痹纤毛并刺激过量黏液分泌，导致’吸烟者咳嗽’。大纲要求你利用流行病学证据解释吸烟与特定疾病之间的联系。
11. Infectious Diseases and Immunity | 传染病与免疫
Infectious diseases are caused by pathogens: bacteria, viruses, fungi and protists. Key AS examples include cholera (Vibrio cholerae), tuberculosis (Mycobacterium tuberculosis), malaria (Plasmodium) and HIV/AIDS.
传染病由病原体引起：细菌、病毒、真菌和原生生物。AS的关键实例包括霍乱(霍乱弧菌)、结核病(结核分枝杆菌)、疟疾(疟原虫)和艾滋病(HIV)。
Antibiotics, such as penicillin, inhibit bacterial cell processes without harming host cells. Antiviral drugs are less common because viruses use host cell machinery. Antibiotic resistance arises through natural selection; misuse accelerates this process.
抗生素如青霉素抑制细菌细胞过程而不伤害宿主细胞。抗病毒药物较少，因为病毒利用宿主细胞机制。抗生素抗性通过自然选择产生；滥用加速了这一过程。
The immune system distinguishes self from non-self. Phagocytes carry out non-specific engulfment, while lymphocytes mount specific responses. B lymphocytes produce antibodies (humoral immunity); T lymphocytes destroy infected cells (cell-mediated immunity).
免疫系统区分自身和非自身。吞噬细胞进行非特异性吞噬，而淋巴细胞发动物特异性应答。B淋巴细胞产生抗体(体液免疫)；T淋巴细胞破坏感染细胞(细胞介导免疫)。
Active immunity results from natural infection or vaccination; passive immunity is conferred by transfer of antibodies (e.g. from mother to baby across placenta, or breast milk). Memory cells provide long-term protection and form the basis of vaccination programmes.
主动免疫由自然感染或疫苗接种产生；被动免疫通过抗体转移获得(如通过胎盘或母乳从母体到婴儿)。记忆细胞提供长期保护，是疫苗接种计划的基础。
Monoclonal antibodies are produced from a clone of hybridoma cells and are used in pregnancy testing, cancer treatment and disease diagnosis.
单克隆抗体由杂交瘤细胞克隆产生，用于妊娠检测、癌症治疗和疾病诊断。
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