📚 IB CIE Biology: End-of-Term Revision Outline | IB CIE 生物期末复习提纲
As the end of term approaches, students following both IB and CIE Biology syllabi need a clear, structured revision plan. This outline summarises the essential topics, key concepts, and practical skills required for exam success. Use it as a checklist to ensure thorough preparation.
期末考试临近，学习IB和CIE生物课程的学生需要一个清晰、系统的复习计划。本提纲总结了必备主题、关键概念和实验技能，帮助你高效备考。可将其作为清单，确保复习全面。
1. Cell Biology | 细胞生物学
Cell theory states that all living organisms are composed of cells, cells are the basic unit of life, and all cells arise from pre-existing cells. Be prepared to discuss how evidence from microscopy supports this theory.
细胞学说指出，所有生物都由细胞构成，细胞是生命的基本单位，且所有细胞都来源于已存在的细胞。准备好讨论显微镜证据如何支持这一理论。
Distinguish between prokaryotic and eukaryotic cells. Prokaryotes (e.g., bacteria) lack a true nucleus and membrane-bound organelles, have 70S ribosomes, and a circular naked DNA molecule called a genophore. Eukaryotes (e.g., animal, plant, fungal cells) possess a nucleus, 80S ribosomes, and compartmentalised organelles.
区分原核细胞与真核细胞。原核细胞（如细菌）没有真正的细胞核和膜包被的细胞器，拥有70S核糖体和称为基因体的环状裸露DNA。真核细胞（如动物、植物、真菌细胞）拥有细胞核、80S核糖体及高度区室化的细胞器。
Know the structure and function of major organelles: nucleus stores genetic information; mitochondria carry out aerobic respiration; rough endoplasmic reticulum (rER) synthesises proteins; smooth endoplasmic reticulum (sER) synthesises lipids; Golgi apparatus modifies and packages proteins; lysosomes digest macromolecules; chloroplasts (in plants) conduct photosynthesis; vacuoles provide storage and turgor pressure; the cell wall gives shape and protection in plants, fungi and prokaryotes.
掌握主要细胞器的结构与功能：细胞核储存遗传信息；线粒体进行有氧呼吸；粗面内质网合成蛋白质；滑面内质网合成脂类；高尔基体修饰和分装蛋白质；溶酶体消化大分子；叶绿体（植物）进行光合作用；液泡提供储存和膨压；细胞壁为植物、真菌和原核细胞提供形态与保护。
Be able to describe the stages of mitosis in order: prophase, metaphase, anaphase, telophase, followed by cytokinesis. Mitosis is essential for growth, tissue repair and asexual reproduction. Recognise cells in various mitotic stages under the microscope.
能够按顺序描述有丝分裂的各阶段：前期、中期、后期、末期，随后是胞质分裂。有丝分裂对生长、组织修复和无性生殖至关重要。在显微镜下识别各分裂期的细胞。
2. Biological Molecules | 生物分子
Water’s properties are central to life. It is an excellent solvent for polar substances, has high specific heat capacity, high latent heat of vaporisation, and strong cohesion and adhesion. These properties support transport in plants (xylem), temperature regulation, and aquatic habitats.
水的特性对生命至关重要。它是极性物质的优良溶剂，具有高比热容、高汽化潜热以及强内聚力和附着力。这些特性支持植物体内的运输（木质部）、体温调节和水生栖息环境。
Carbohydrates are classified as monosaccharides, disaccharides, and polysaccharides. Glucose (C₆H₁₂O₆) is a hexose monosaccharide; ribose is a pentose. Maltose and sucrose are disaccharides formed via condensation reactions that produce glycosidic bonds. Polysaccharides such as starch (amylose and amylopectin), glycogen, and cellulose have distinct structures and roles: energy storage or structural support.
碳水化合物分为单糖、二糖和多糖。葡萄糖（C₆H₁₂O₆）是一种己糖单糖；核糖是戊糖。麦芽糖和蔗糖是通过缩合反应形成糖苷键的二糖。淀粉（直链淀粉与支链淀粉）、糖原和纤维素等多糖具有不同的结构和功能：储能或结构支撑。
Triglycerides consist of one glycerol molecule linked to three fatty acids by ester bonds. Phospholipids have a hydrophilic phosphate head and two hydrophobic fatty acid tails, making them key components of cell membranes. Lipids serve as long-term energy stores, thermal insulators, and protective cushions.
甘油三酯由一个甘油分子通过酯键与三个脂肪酸相连。磷脂具有亲水的磷酸头部和两条疏水的脂肪酸尾部，是细胞膜的关键组分。脂类用作长期能量储备、保温层和缓冲保护层。
Proteins are polymers of amino acids joined by peptide bonds. The primary structure is the sequence of amino acids; secondary structure includes alpha-helices and beta-pleated sheets; tertiary structure is the overall 3D folding; quaternary structure involves multiple polypeptide subunits. Protein functions include catalysis (enzymes), transport (haemoglobin), and immunity (antibodies).
蛋白质是由肽键连接的氨基酸聚合物。一级结构是氨基酸序列；二级结构包括α螺旋和β折叠；三级结构是整条链的三维折叠；四级结构涉及多条多肽亚基。蛋白质功能包括催化（酶）、运输（血红蛋白）和免疫（抗体）。
DNA and RNA are nucleic acids built from nucleotides (phosphate, pentose sugar, nitrogenous base). DNA stores genetic information as a double helix with complementary base pairing (A-T, C-G) and antiparallel strands. RNA (mRNA, tRNA, rRNA) plays key roles in protein synthesis.
DNA和RNA是由核苷酸（磷酸、五碳糖、含氮碱基）构成的核酸。DNA以双螺旋形式储存遗传信息，碱基互补配对（A-T, C-G），两条链反向平行。RNA（mRNA、tRNA、rRNA）在蛋白质合成中起关键作用。
3. Enzymes and Metabolism | 酶与代谢
Enzymes are globular proteins that lower activation energy and increase the rate of specific biochemical reactions. Their active site is complementary to the substrate. The induced-fit model states that the active site changes shape slightly to bind the substrate, stressing bonds and stabilising the transition state.
酶是球状蛋白质，能降低活化能，提高特定生化反应速率。其活性位点与底物互补。诱导契合模型认为，活性位点会略微改变形状以结合底物，从而拉紧化学键并稳定过渡态。
Enzyme activity is affected by temperature, pH, and substrate concentration. At low temperatures, kinetic energy is low. As temperature rises, activity increases up to an optimum; beyond this, denaturation occurs. Each enzyme has an optimum pH; extremes disrupt ionic and hydrogen bonds, leading to loss of function.
酶活性受温度、pH和底物浓度影响。低温时动能较低；随着温度升高，活性增加直至最适温度；超过最适温度则发生变性。每种酶有其最适pH；极端pH会破坏离子键和氢键，导致功能丧失。
Inhibitors reduce enzyme activity. Competitive inhibitors resemble the substrate and bind reversibly to the active site. Non-competitive inhibitors bind to an allosteric site, changing the enzyme’s shape so the substrate cannot bind effectively. Understand the effects on Vmax and Km values.
抑制剂降低酶活性。竞争性抑制剂结构与底物相似，可逆地与活性位点结合。非竞争性抑制剂结合变构位点，改变酶的形状，使底物无法有效结合。理解其对Vmax和Km值的影响。
4. Cell Membranes and Transport | 细胞膜与运输
The fluid mosaic model describes the membrane as a phospholipid bilayer with embedded proteins (integral and peripheral), cholesterol, and glycoproteins. Phospholipids provide fluidity and a semi-permeable barrier; cholesterol modulates fluidity in animal cells; proteins function as channels, carriers, receptors, and enzymes.
流动镶嵌模型将细胞膜描述为磷脂双分子层，其中嵌有蛋白质（整合蛋白和外周蛋白）、胆固醇和糖蛋白。磷脂提供流动性和半透性屏障；胆固醇调节动物细胞膜的流动性；蛋白质作为通道、载体、受体和酶执行功能。
Passive transport includes simple diffusion, facilitated diffusion (via channel or carrier proteins), and osmosis. These processes move particles down a concentration gradient without energy input. Active transport moves substances against the gradient using ATP, e.g., the sodium-potassium pump. Bulk transport involves endocytosis and exocytosis.
被动运输包括简单扩散、协助扩散（通过通道蛋白或载体蛋白）和渗透。这些过程顺浓度梯度移动粒子，不消耗能量。主动运输利用ATP逆浓度梯度运送物质，如钠钾泵。批量运输涉及胞吞和胞吐。
Osmosis is the net movement of water from a region of higher water potential to lower water potential across a partially permeable membrane. Animal cells can burst (lysis) in hypotonic solutions; plant cells become turgid, and in hypertonic solutions undergo plasmolysis (cell membrane pulls away from cell wall).
渗透是水分子通过半透膜从高水势区域向低水势区域的净移动。动物细胞在低渗溶液中会胀破（溶血）；植物细胞会变得坚挺，而在高渗溶液中发生质壁分离（细胞膜脱离细胞壁）。
5. Cellular Respiration | 细胞呼吸
Aerobic respiration can be summarised as:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (as ATP)
This process occurs in four stages: glycolysis, link reaction, Krebs cycle, and electron transport chain/oxidative phosphorylation.
有氧呼吸可概括为：
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 能量（以ATP形式）
该过程分四个阶段：糖酵解、连接反应、Krebs循环以及电子传递链/氧化磷酸化。
Glycolysis occurs in the cytoplasm and does not require oxygen. Glucose (6C) is phosphorylated and split into two molecules of pyruvate (3C). This yields a small net gain of 2 ATP (by substrate-level phosphorylation) and 2 reduced NAD.
糖酵解发生在细胞质中，不消耗氧。葡萄糖（6C）被磷酸化并裂解为两分子丙酮酸（3C）。该过程通过底物水平磷酸化净生成2 ATP，并产生2个还原型NAD。
The link reaction and Krebs cycle take place in the mitochondrial matrix. Pyruvate is decarboxylated and converted to acetyl-CoA, which enters the Krebs cycle. Carbon dioxide is released, and reduced coenzymes (NADH and FADH₂) are generated. The electron transport chain on the cristae uses these reduced coenzymes to create a proton gradient, driving ATP synthase (chemiosmosis). Oxygen acts as the final electron acceptor, forming water. Up to 32 ATP can be produced per glucose.
连接反应和Krebs循环发生在线粒体基质中。丙酮酸脱羧并转化为乙酰辅酶A，后者进入Krebs循环。释放出二氧化碳，并产生还原型辅酶（NADH和FADH₂）。嵴上的电子传递链利用这些还原型辅酶建立质子梯度，驱动ATP合酶（化学渗透）。氧气作为最终电子受体生成水。每分子葡萄糖最多可产生32 ATP。
Anaerobic respiration occurs when oxygen is scarce. In animals, pyruvate is converted to lactate; in yeast and plants, pyruvate is decarboxylated to ethanal, then reduced to ethanol. Both pathways regenerate NAD⁺, allowing glycolysis to continue, but yield only 2 ATP per glucose.
无氧呼吸在缺氧条件下进行。动物体内丙酮酸转化为乳酸；酵母和植物中丙酮酸脱羧生成乙醛，再还原为乙醇。两条途径均可再生NAD⁺，使糖酵解继续，但每分子葡萄糖仅产生2 ATP。
6. Photosynthesis | 光合作用
The overall equation for photosynthesis is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Photosynthesis consists of two sets of reactions: the light-dependent reactions and the light-independent (Calvin cycle) reactions.
光合作用总反应式为：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
光合作用包含两类反应：光依赖反应和光不依赖（Calvin循环）反应。
Light-dependent reactions occur on the thylakoid membranes. Chlorophyll absorbs light energy, which is used for photolysis of water (2H₂O → 4H⁺ + 4e⁻ + O₂). Excited electrons pass through electron carriers, generating ATP via non-cyclic photophosphorylation and reducing NADP to NADPH. Cyclic photophosphorylation produces additional ATP.
光依赖反应发生在类囊体膜上。叶绿素吸收光能，用于水的光解（2H₂O → 4H⁺ + 4e⁻ + O₂）。受激电子经电子传递链传递，通过非循环光合磷酸化产生ATP，并将NADP还原为NADPH。循环光合磷酸化可产生额外ATP。
The Calvin cycle occurs in the stroma. Carbon dioxide is fixed to ribulose bisphosphate (RuBP) by the enzyme RuBisCO. The resulting 3-carbon compound glycerate 3-phosphate (GP) is reduced using ATP and NADPH to glyceraldehyde 3-phosphate (G3P). Some G3P is used to regenerate RuBP, and some is used to synthesise glucose and other carbohydrates. Familiarity with limiting factors (light intensity, CO₂ concentration, temperature) is essential.
Calvin循环发生在叶绿体基质中。二氧化碳在RuBisCO酶催化下与核酮糖二磷酸（RuBP）结合固定。生成的3-磷酸甘油酸（GP）利用ATP和NADPH还原为3-磷酸甘油醛（G3P）。部分G3P用于再生RuBP，其余用于合成葡萄糖等糖类。熟悉限制因素（光强、CO₂浓度、温度）非常重要。
7. Molecular Genetics | 分子遗传学
DNA replication is semi-conservative: each new DNA molecule consists of one original strand and one newly synthesised strand. Helicase unwinds the double helix; DNA polymerase adds nucleotides complementary to the template strand, working in a 5′ to 3′ direction. The leading strand is synthesised continuously, while the lagging strand is formed as Okazaki fragments, later joined by DNA ligase.
DNA复制是半保留的：每个新DNA分子由一条原始链和一条新合成链组成。解旋酶解开双螺旋；DNA聚合酶按模板链的互补性添加核苷酸，方向为5’→3’。前导链连续合成，而后随链以冈崎片段形式合成，随后由DNA连接酶连接。
Transcription involves RNA polymerase binding to a promoter region, unwinding the DNA, and synthesising a complementary mRNA strand using the template strand. The mRNA is then processed (in eukaryotes) by adding a 5′ cap and poly-A tail and removing introns via splicing.
转录涉及RNA聚合酶与启动子区域结合，解开DNA，以模板链为模板合成互补的mRNA链。随后（真核生物中）mRNA经加工修饰：添加5’帽和poly-A尾，并通过剪接去除内含子。
Translation occurs on ribosomes. The mRNA codon binds to a complementary anticodon on a tRNA molecule carrying a specific amino acid. Peptide bonds form between adjacent amino acids, and the polypeptide chain grows until a stop codon is reached. The ribosome has A, P, and E sites for tRNA binding.
翻译在核糖体上进行。mRNA上的密码子与携带特定氨基酸的tRNA反密码子互补结合。相邻氨基酸之间形成肽键，多肽链不断延伸直至到达终止密码子。核糖体具有A位、P位和E位用于结合tRNA。
Gene expression can be regulated by the environment. In the lac operon model, the presence of lactose inactivates a repressor protein, allowing RNA polymerase to transcribe genes for lactose metabolism. Mutations such as base substitutions (sickle cell anaemia), insertions, or deletions can alter protein structure and function.
基因表达可由环境调控。在乳糖操纵子模型中，乳糖的存在使阻遏蛋白失活，RNA聚合酶得以转录代谢乳糖的基因。碱基置换（镰刀型细胞贫血症）、插入或缺失等突变可改变蛋白质结构与功能。
8. Inheritance and Evolution | 遗传与进化
Mendelian genetics describes the inheritance of traits determined by single genes with dominant and recessive alleles. A monohybrid cross predicts the genotypic and phenotypic ratios of offspring (e.g., 3:1 for two heterozygous parents). Use Punnett squares to illustrate crosses.
孟德尔遗传学描述由具有显性和隐性等位基因的单个基因决定的性状遗传。单基因杂交可预测后代的基因型和表现型比例（如两个杂合亲本产生3:1比例）。使用旁氏表阐明杂交结果。
Sex linkage involves genes located on sex chromosomes. X-linked recessive traits (e.g., colour blindness, haemophilia) are expressed more frequently in males. Pedigree charts help trace inheritance patterns and determine whether a trait is autosomal or sex-linked, dominant or recessive.
性连锁涉及位于性染色体上的基因。X连锁隐性性状（如红绿色盲、血友病）在男性中表达更频繁。系谱图有助于追踪遗传模式，判断某性状是常染色体还是性连锁、显性还是隐性。
Variation within a population may be continuous (polygenic, influenced by environment) or discontinuous (single gene, distinct categories). Natural selection acts on heritable variation: organisms with advantageous alleles are more likely to survive, reproduce, and pass on these alleles. Antibiotic resistance in bacteria is a well-documented example.
种群内的变异可以是连续变异（多基因遗传，受环境影响）或不连续变异（单基因，表型类别分明）。自然选择作用于可遗传的变异：具有有利等位基因的个体更可能存活、繁殖并传递这些等位基因。细菌的抗生素抗性是一个充分证实的实例。
Speciation occurs when populations become reproductively isolated. Allopatric speciation involves a geographical barrier; sympatric speciation occurs without geographical separation, often through polyploidy or behavioural changes. Evidence for evolution includes the fossil record, comparative anatomy, and molecular biology.
物种种群一旦形成生殖隔离，物种形成便发生。异域物种形成涉及地理屏障；同域物种形成无地理隔离，常通过多倍体化或行为改变发生。进化证据包括化石记录、比较解剖学和分子生物学。
9. Ecology | 生态学
Understand key ecological terms: species (group of organisms that can interbreed to produce fertile offspring), population, community, ecosystem, habitat, and niche (the role of an organism in its environment).
理解关键生态学术语：物种（能相互交配并产生可育后代的生物群体）、种群、群落、生态系统、栖息地和生态位（生物在其环境中的角色）。
Energy flows through ecosystems via food chains and food webs. Only about 10% of energy is transferred from one trophic level to the next; the rest is lost as heat or used in respiration. Pyramids of energy always have an upright shape. Biomass pyramids can be inverted in some aquatic ecosystems.
能量通过食物链和食物网在生态系统中流动。仅约10%的能量从一个营养级传递至下一营养级；其余以热量形式散失或用于呼吸作用。能量金字塔始终呈正立形态。生物量金字塔在某些水生生态系统中可以倒置。
The carbon cycle involves photosynthesis (CO₂ fixation), respiration (CO₂ release), decomposition, and combustion of fossil fuels. The nitrogen cycle includes nitrogen fixation (by bacteria, lightning), nitrification, assimilation, ammonification, and denitrification. Be able to label diagrams of these cycles.
碳循环涉及光合作用（固定CO₂）、呼吸作用（释放CO₂）、分解以及化石燃料燃烧。氮循环包括固氮作用（由细菌、闪电完成）、硝化作用、同化作用、氨化作用和反硝化作用。应能标示这些循环的示意图。
Biodiversity can be measured using Simpson’s diversity index, which accounts for species richness and evenness. Biotic factors (predation, competition) and abiotic factors (temperature, water availability, pH) determine the distribution and abundance of organisms. Climate change, driven by enhanced greenhouse effect, impacts ecosystems by altering temperatures and sea levels.
生物多样性可通过Simpson多样性指数衡量，该指数综合考虑物种丰富度和均匀度。生物因素（捕食、竞争）和非生物因素（温度、水供应、pH值）决定生物的分布与丰度。由增强的温室效应驱动的气候变化通过改变温度和海拔影响生态系统。
10. Physiology and Homeostasis | 生理学与稳态
Homeostasis is the maintenance of a stable internal environment. The nervous system uses action potentials and synapses to transmit rapid signals. The resting potential is around -70 mV; depolarisation triggers an action potential. Neurotransmitters diffuse across synaptic clefts to relay signals between neurones.
稳态是指维持内环境稳定。神经系统利用动作电位和突触传递快速信号。静息电位约为-70 mV；去极化触发动作电位。神经递质通过扩散穿越突触间隙，在神经元之间传递信号。
The endocrine system regulates processes via hormones released into the blood. Insulin and glucagon control blood glucose through negative feedback. Thyroxin regulates metabolic rate, and ADH (antidiuretic hormone) controls water reabsorption in the kidney. Appreciate the principle of negative feedback.
内分泌系统通过释放入血的激素调节生理过程。胰岛素和胰高血糖素通过负反馈调控血糖。甲状腺素调节代谢率，抗利尿激素（ADH）控制肾脏对水的重吸收。领会负反馈原理。
The immune system protects against pathogens. Phagocytes engulf non-self material. B lymphocytes produce specific antibodies that destroy antigens; memory cells provide long-term immunity. Vaccination involves exposure to an antigenic material to stimulate an immune response without causing disease. Monoclonal antibodies are identical antibodies produced from a single
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