IB & CIE Biology: Last-Minute Revision Notes | IB CIE 生物：考前冲刺笔记

📚 IB & CIE Biology: Last-Minute Revision Notes | IB CIE 生物：考前冲刺笔记

This comprehensive last-minute revision guide covers essential topics for both IB Biology (HL/SL) and CIE A-Level Biology (AS & A2). Use these concise notes to reinforce key concepts, practise data-based questions, and avoid common pitfalls in your final preparations.

本考前冲刺笔记涵盖 IB 生物 (HL/SL) 和 CIE A-Level 生物 (AS & A2) 的核心主题。通过这些精炼的要点，你可以巩固关键概念、练习数据分析题，并规避常见失分点。

1. Cell Structure | 细胞结构

Both IB and CIE require you to know the ultrastructure of prokaryotic and eukaryotic cells. Key organelles: nucleus, mitochondria, rough ER, smooth ER, Golgi apparatus, ribosomes (70S vs 80S), lysosomes, chloroplasts (CIE includes). Remember that prokaryotes lack membrane-bound organelles; their DNA is circular and naked. Contrast plant vs animal cells (cell wall, large central vacuole, chloroplasts). CIE also emphasises the endosymbiotic theory for mitochondria and chloroplasts, while IB includes the Davson-Danielli vs Singer-Nicolson models for membranes. Make sure you can label a diagram of an animal cell and a plant cell.

IB 和 CIE 都要求掌握原核与真核细胞的超微结构。重点细胞器：细胞核、线粒体、粗面内质网、滑面内质网、高尔基体、核糖体（70S 和 80S）、溶酶体、叶绿体（CIE 要求）。记住原核生物没有膜包被的细胞器，其 DNA 为环状、裸露。对比植物细胞与动物细胞（细胞壁、中央大液泡、叶绿体）。CIE 还强调线粒体和叶绿体的内共生学说，IB 则涉及细胞膜的 Davson-Danielli 模型与 Singer-Nicolson 流动镶嵌模型。确保能标注动物细胞和植物细胞的示意图。

2. Biological Molecules | 生物分子

Carbohydrates: monosaccharides (glucose, ribose), disaccharides (sucrose, lactose, maltose), polysaccharides (starch, glycogen, cellulose). Lipids: triglycerides (ester bonds, saturated vs unsaturated), phospholipids, sterols. Proteins: amino acid structure, peptide bonds, four levels of protein structure, denaturation. Nucleic acids: DNA vs RNA (sugar, bases, strands). IB includes the structure of cellulose and its importance in plant cell walls; CIE includes tests for reducing/non-reducing sugars, starch, proteins, lipids (biochemical tests). Know the properties of water (cohesion, adhesion, high specific heat, solvent) for both syllabi.

碳水化合物：单糖（葡萄糖、核糖）、二糖（蔗糖、乳糖、麦芽糖）、多糖（淀粉、糖原、纤维素）。脂质：甘油三酯（酯键、饱和与不饱和）、磷脂、固醇。蛋白质：氨基酸结构、肽键、四级结构、变性。核酸：DNA 与 RNA 的差异（糖、碱基、链数）。IB 要求纤维素结构及其在植物细胞壁中的重要性；CIE 要求还原糖/非还原糖、淀粉、蛋白质、脂质的生化检测。两个大纲均需掌握水的性质（内聚力、附着力、高比热容、优良溶剂）。

3. Enzymes | 酶

Enzymes are globular proteins that act as biological catalysts. Key concepts: activation energy, active site, substrate specificity (lock-and-key vs induced-fit). Factors affecting enzyme activity: temperature, pH, substrate concentration (Vmax and K_m for CIE). IB requires the design of experiments to investigate enzyme activity, while CIE expects calculations of initial rates. Enzyme inhibition: competitive (binds to active site) and non-competitive (binds to allosteric site). CIE extends to reversible vs irreversible inhibition and the effect on K_m and Vmax. The use of immobilised enzymes in industry is common to both (lactose-free milk).

酶是作为生物催化剂的球状蛋白。核心概念：活化能、活性位点、底物特异性（锁钥模型与诱导契合模型）。影响酶活性的因素：温度、pH、底物浓度（CIE 要求 Vmax 和 K_m）。IB 要求设计酶活性探究实验，CIE 则考核初始速率计算。酶抑制：竞争性抑制（结合活性位点）和非竞争性抑制（结合别构位点）。CIE 延伸至可逆与不可逆抑制以及对 K_m 和 Vmax 的影响。固定化酶在工业中的应用为二者共有（无乳糖牛奶）。

4. Cell Membranes & Transport | 细胞膜与运输

The fluid mosaic model: phospholipid bilayer, intrinsic and extrinsic proteins, cholesterol (animals), glycoproteins. Transport mechanisms: simple diffusion, facilitated diffusion (channel and carrier proteins), osmosis (water potential), active transport (Na⁺/K⁺ pump), bulk transport (endocytosis, exocytosis). IB emphasises membrane fluidity and the role of cholesterol; CIE includes co-transport (e.g., glucose-Na⁺ symport). Know how to interpret graphs showing rates of transport and the effects of inhibitors. Water potential calculations (ψ = ψ_s + ψ_p) are required in both courses, but CIE uses water potential in kPa; IB often uses osmolarity.

流动镶嵌模型：磷脂双分子层、内在蛋白和外在蛋白、胆固醇（动物细胞）、糖蛋白。运输机制：简单扩散、协助扩散（通道蛋白和载体蛋白）、渗透（水势）、主动运输（钠钾泵）、批量运输（胞吞、胞吐）。IB 强调膜流动性和胆固醇的作用；CIE 包含协同转运（如葡萄糖-钠离子同向转运）。需掌握如何解读运输速率图以及抑制剂的影响。水势计算（ψ = ψ_s + ψ_p）两个课程均有要求，但 CIE 采用 kPa 表示水势，IB 常用摩尔渗透浓度。

5. Cell Division | 细胞分裂

Mitosis: stages (prophase, metaphase, anaphase, telophase), result (two genetically identical diploid cells). Meiosis: stages I and II, crossing over, independent assortment, result (four genetically diverse haploid cells). Both IB and CIE require identification of stages from micrographs and diagrams. CIE includes the life cycle of flowering plants (alternation of generations, gametophyte/sporophyte). IB focuses on mitotic index and cancer (role of cyclins). Don’t forget non-disjunction leading to aneuploidy (Down syndrome, Turner syndrome).

有丝分裂：分期（前期、中期、后期、末期），结果（两个遗传相同的二倍体细胞）。减数分裂：第一、二次分裂，交叉互换，自由组合，结果（四个遗传多样性的单倍体细胞）。IB 和 CIE 均要求根据显微照片和示意图识别分裂各期。CIE 包含开花植物的生活史（世代交替，配子体/孢子体）。IB 强调有丝分裂指数与癌症（周期蛋白的作用）。不要忘记染色体不分离导致的非整倍体（唐氏综合征、特纳综合征）。

6. DNA Replication & Protein Synthesis | DNA 复制与蛋白质合成

DNA replication is semi-conservative (Meselson-Stahl experiment). Enzymes: helicase, DNA polymerase (III and I in CIE), ligase, primase. Leading vs lagging strand, Okazaki fragments. Transcription: RNA polymerase, promoter, template strand, mRNA. Translation: ribosomes (A, P, E sites in CIE), tRNA with anticodon, codon-anticodon pairing. Genetic code is degenerate and universal. IB introduces nucleosome structure and DNA supercoiling; CIE delves into gene mutations (point mutations, frameshift) and their effects on protein structure.

DNA 复制为半保留复制（Meselson-Stahl 实验）。酶：解旋酶、DNA 聚合酶（CIE 中需区分 III 和 I）、连接酶、引物酶。前导链与后随链，冈崎片段。转录：RNA 聚合酶、启动子、模板链、mRNA。翻译：核糖体（CIE 要求 A、P、E 位点）、带有反密码子的 tRNA，密码子-反密码子配对。遗传密码具有简并性和通用性。IB 引入核小体结构和 DNA 超螺旋；CIE 深入探讨基因突变（点突变、移码突变）及其对蛋白质结构的影响。

7. Genetics & Inheritance | 遗传与遗传学

Mendel’s laws: segregation and independent assortment. Monohybrid and dihybrid crosses (Punnett squares), test cross. Codominance, incomplete dominance, multiple alleles (ABO blood group), sex-linkage (haemophilia, colour blindness). Pedigree analysis to determine pattern of inheritance. IB requires understanding of gene pools and Hardy-Weinberg equilibrium (p² + 2pq + q² = 1) when there is no selection, no mutation, large population, random mating, no migration. CIE also covers autosomal linkage and recombination frequencies (chi-squared test). Epistasis and polygenic inheritance might appear in both.

孟德尔定律：分离定律和自由组合定律。单因子杂交和双因子杂交（庞纳特方格），测交。共显性、不完全显性、复等位基因（ABO 血型）、伴性遗传（血友病、红绿色盲）。通过系谱分析推断遗传方式。IB 要求理解基因库和哈代-温伯格平衡（p² + 2pq + q² = 1），适用条件无选择、无突变、大群体、随机交配、无迁移。CIE 还涵盖常染色体连锁和重组频率（卡方检验）。上位效应和多基因遗传可能在两者均有出现。

8. Evolution & Natural Selection | 进化与自然选择

Darwin’s theory of natural selection: variation, overproduction, struggle for existence, survival of the fittest, inheritance. Speciation: allopatric (geographical isolation) and sympatric (reproductive isolation). Evidence for evolution: fossil record, comparative anatomy (homologous vs analogous structures), molecular biology. Antibiotic resistance as an example of natural selection. CIE expects description of the processes of stabilising, directional, and disruptive selection. IB includes taxonomy and cladistics (clades, parsimony). Note the difference between gradualism and punctu

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