IB & AQA Biology Last-Minute Revision Notes | IB 与 AQA 生物考前冲刺笔记

📚 IB & AQA Biology Last-Minute Revision Notes | IB 与 AQA 生物考前冲刺笔记

Mastering biology for IB and AQA exams requires a clear understanding of core concepts, from cell ultrastructure to complex ecological interactions. This revision guide distils essential topics into concise, high-yield notes, helping you recall key facts, compare processes, and apply knowledge to exam-style questions. Whether you are reviewing cell respiration pathways or genetic inheritance patterns, these bilingual notes will reinforce your learning before the big day.

要在 IB 和 AQA 生物考试中取得理想成绩，必须清晰理解从细胞超微结构到复杂生态互动的核心概念。这份复习指南将关键主题浓缩为精简的高分笔记，帮助你回忆重要事实、比较生理过程，并将知识应用于考题。无论你正在复习细胞呼吸途径还是遗传模式，这些中英对照笔记都将在考前强化你的记忆。

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1. Cell Structure & Organelles | 细胞结构与细胞器

Prokaryotic cells: no nucleus, DNA circular and naked in nucleoid, 70S ribosomes, small (1-5 µm), may have plasmids, cell wall contains peptidoglycan.	原核细胞：无细胞核，DNA 为环状且裸露，存在于拟核；70S 核糖体，体积小 (1–5 µm)，可能含有质粒，细胞壁由肽聚糖组成。
Eukaryotic cells: membrane-bound nucleus containing linear DNA associated with histones; 80S ribosomes; larger (10–100 µm); organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and (in plants) chloroplasts and large vacuole.	真核细胞：有膜包被的细胞核，线性 DNA 与组蛋白结合；80S 核糖体；体积较大 (10–100 µm)；含有线粒体、内质网、高尔基体、溶酶体等细胞器，植物细胞还有叶绿体和中央大液泡。

Cell membrane: fluid-mosaic model with phospholipid bilayer, intrinsic/extrinsic proteins, cholesterol (animal cells), and glycocalyx. Controls passage of substances via diffusion, osmosis, active transport, endocytosis/exocytosis.

细胞膜：流动镶嵌模型，由磷脂双分子层、内在/外在蛋白、胆固醇（动物细胞）及糖萼组成，通过扩散、渗透、主动运输、胞吞/胞吐控制物质进出。

Mitochondria: double membrane, inner membrane folded into cristae, matrix contains enzymes for Krebs cycle and link reaction. Site of aerobic respiration; possess own circular DNA and 70S ribosomes.

线粒体：双层膜，内膜向内折叠形成嵴，基质含有克雷布斯循环和连接反应的酶。是有氧呼吸的场所；含有自身环状 DNA 和 70S 核糖体。

Chloroplasts (plant cells): double membrane, internal thylakoid membranes stacked into grana, stroma contains enzymes for Calvin cycle. Thylakoid membranes house chlorophyll and photosystems.

叶绿体（植物细胞）：双层膜，内部类囊体膜堆叠成基粒，基质含有卡尔文循环的酶。类囊体膜上分布着叶绿素和光系统。

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2. Biological Molecules | 生物分子

Carbohydrates: monosaccharides (e.g. glucose, C₆H₁₂O₆) are reducing sugars. Disaccharides: maltose (glucose + glucose), sucrose (glucose + fructose), lactose (glucose + galactose), formed by condensation forming glycosidic bonds. Polysaccharides: starch (amylose & amylopectin) and glycogen are energy stores; cellulose provides structural support (β-glucose, 1,4-glycosidic bonds).

碳水化合物：单糖（如葡萄糖，C₆H₁₂O₆）为还原糖。二糖：麦芽糖（葡萄糖+葡萄糖）、蔗糖（葡萄糖+果糖）、乳糖（葡萄糖+半乳糖），通过缩合反应形成糖苷键。多糖：淀粉（直链淀粉和支链淀粉）和糖原为储能物质；纤维素提供结构支持（β-葡萄糖，1,4-糖苷键）。

Lipids: triglycerides formed from glycerol and three fatty acids via ester bonds; can be saturated or unsaturated. Phospholipids have a phosphate head (hydrophilic) and two fatty acid tails (hydrophobic), forming bilayers.

脂质：甘油三酯由甘油与三个脂肪酸通过酯键结合而成，可分为饱和与不饱和。磷脂具有亲水磷酸头部和两条疏水脂肪酸尾部，构成双分子层。

Proteins: amino acids have amino group, carboxyl group, and variable R group. Peptide bonds formed by condensation. Primary structure: sequence; secondary: α-helix/β-pleated sheet (H-bonds); tertiary: 3D folding (disulfide, ionic, hydrophobic interactions); quaternary: multiple polypeptides.

蛋白质：氨基酸含有氨基、羧基和可变的 R 基团。肽键由缩合反应形成。一级结构：序列；二级结构：α-螺旋/β-折叠（氢键）；三级结构：三维折叠（二硫键、离子键、疏水作用）；四级结构：多条多肽链聚集。

DNA: deoxyribose sugar, bases A, T, C, G; double-stranded anti-parallel double helix; stores genetic information.	DNA：脱氧核糖，碱基 A、T、C、G；双链反平行双螺旋；储存遗传信息。
RNA: ribose sugar, bases A, U, C, G; single-stranded; types: mRNA, tRNA, rRNA; involved in protein synthesis.	RNA：核糖，碱基 A、U、C、G；单链；类型：mRNA、tRNA、rRNA；参与蛋白质合成。

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3. Enzymes & Factors Affecting Activity | 酶及影响活性的因素

Enzymes are biological catalysts that lower activation energy. They have a specific active site complementary to the substrate. The induced-fit model states the active site changes shape slightly to bind the substrate, putting strain on bonds.

酶是降低活化能的生物催化剂。它们具有与底物互补的特定活性位点。诱导契合模型认为活性位点略变形以结合底物，使化学键受力。

Temperature & pH: increase kinetic energy raises activity to an optimum; beyond, denaturation occurs (breaking of hydrogen/ionic bonds). pH changes alter charges at active site, reducing binding.

温度与 pH：升高动能可提高活性直至最适值；超过最适则导致变性（氢键/离子键断裂）。pH 变化改变活性位点电荷，降低结合能力。

Competitive inhibition – inhibitor resembles substrate, binds active site; overcome by increasing [S]; Vmax unchanged, Km increases.	竞争性抑制 – 抑制剂类似底物，结合活性位点；可提高底物浓度克服；Vmax 不变，Km 增大。
Non-competitive inhibition – inhibitor binds allosteric site, changes active site shape; cannot be overcome by [S]; Vmax decreases, Km unchanged.	非竞争性抑制 – 抑制剂结合别构位点，改变活性位点形状；无法通过增加底物浓度克服；Vmax 降低，Km 不变。

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4. DNA Replication, Transcription & Translation | DNA 复制、转录与翻译

DNA replication (semi-conservative): Helicase unwinds double helix; DNA polymerase synthesises new strand in 5′→3′ direction using parent strands as templates; leading strand continuous, lagging strand forms Okazaki fragments joined by DNA ligase. Meselson-Stahl experiment proved semi-conservative model.

DNA 复制（半保留）：解旋酶解开双螺旋；DNA 聚合酶以亲链为模板沿 5′→3′ 方向合成新链；前导链连续合成，后随链形成冈崎片段，由 DNA 连接酶连接。Meselson-Stahl 实验证明了半保留模型。

Transcription: RNA polymerase binds to promoter, unwinds DNA; synthesises mRNA complementary to template strand (A-U, T-A, C-G, G-C). In eukaryotes, pre-mRNA is spliced (introns removed).

转录：RNA 聚合酶与启动子结合，解开 DNA；合成与模板链互补的 mRNA（A-U、T-A、C-G、G-C）。在真核细胞中，前体 mRNA 经剪接去除内含子。

Translation: mRNA attaches to ribosome; tRNA with anticodon brings specific amino acid; codon-anticodon pairing; peptide bonds form between amino acids. Process continues until stop codon.

翻译：mRNA 附着于核糖体；tRNA 携带特定氨基酸并通过反密码子与密码子配对；氨基酸间形成肽键。持续至终止密码子。

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5. Cell Cycle & Mitosis | 细胞周期与有丝分裂

Cell cycle: G₁ (growth, protein synthesis), S (DNA replication), G₂ (preparation for division), M phase (mitosis and cytokinesis). Checkpoints ensure accuracy.

细胞周期：G₁ 期（生长、蛋白质合成）、S 期（DNA 复制）、G₂ 期（准备分裂）、M 期（有丝分裂与胞质分裂）。检查点确保精确性。

Mitosis: Prophase (chromosomes condense, spindle forms, nuclear envelope breaks down), Metaphase (chromosomes align at equator), Anaphase (sister chromatids pulled to poles), Telophase (nuclear envelopes reform). Cytokinesis follows. Produces two genetically identical diploid daughter cells.

有丝分裂：前期（染色体凝聚、纺锤体形成、核膜解体）、中期（染色体排列在赤道面）、后期（姐妹染色单体拉向两极）、末期（核膜重新形成）。随后发生胞质分裂，产生两个遗传相同的二倍体子细胞。

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6. Cellular Respiration & ATP | 细胞呼吸与 ATP

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 能量 (ATP)

Glycolysis (cytoplasm): glucose → 2 pyruvate; net 2 ATP, 2 NADH.

糖酵解（细胞质）：葡萄糖 → 2 丙酮酸；净得 2 ATP、2 NADH。

Link reaction (mitochondrial matrix): pyruvate → acetyl-CoA, releasing CO₂ and reducing NAD⁺ to NADH.

连接反应（线粒体基质）：丙酮酸 → 乙酰辅酶 A，释放 CO₂，NAD⁺ 还原为 NADH。

Krebs cycle (matrix): acetyl-CoA enters cycle, produces 2 CO₂, 1 ATP (GTP), 3 NADH, 1 FADH₂ per turn (×2 per glucose).

克雷布斯循环（基质）：乙酰辅酶 A 进入循环，每圈产生 2 CO₂、1 ATP (GTP)、3 NADH、1 FADH₂（每分子葡萄糖循环两次）。

Oxidative phosphorylation (inner mitochondrial membrane): electrons from NADH/FADH₂ pass through electron transport chain; proton gradient drives ATP synthase (chemiosmosis). O₂ final electron acceptor → H₂O. Total ~32 ATP per glucose.

氧化磷酸化（线粒体内膜）：NADH/FADH₂ 的电子经电子传递链传递；质子梯度驱动 ATP 合酶（化学渗透）。O₂ 为最终电子受体形成 H₂O。每分子葡萄糖总共产生约 32 ATP。

Anaerobic respiration: animals – lactate fermentation (pyruvate → lactate, regenerates NAD⁺); yeast/plants – ethanol fermentation (pyruvate → ethanal → ethanol + CO₂).

无氧呼吸：动物——乳酸发酵（丙酮酸 → 乳酸，再生 NAD⁺）；酵母/植物——酒精发酵（丙酮酸 → 乙醛 → 乙醇 + CO₂）。

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7. Photosynthesis | 光合作用

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Light-dependent reactions (thylakoid membrane): light energy excites chlorophyll; photolysis of water produces H⁺, electrons, O₂; electrons pass through electron transport chain

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