📚 IGCSE WJEC Biology: End-of-Year Revision Guide | IGCSE WJEC 生物：期末复习提纲
As the IGCSE Biology examination approaches, a well-structured revision plan is essential. This guide condenses the WJEC specification into key concepts, ensuring you focus on the most critical topics and develop a deep understanding ready for the exam.
随着 IGCSE 生物考试临近，一份结构清晰的复习计划至关重要。本复习提纲浓缩了 WJEC 考纲的核心概念，帮助你锁定最关键的主题，建立起应对考试的深度理解。
1. Cell Structure and Microscopy | 细胞结构与显微镜
All living organisms are composed of cells, which can be categorised as prokaryotic or eukaryotic. Animal and plant cells are eukaryotic and share common organelles, while plant cells possess additional features such as a cellulose cell wall, chloroplasts and a large permanent vacuole.
所有生物都由细胞组成，细胞可分为原核细胞和真核细胞。动物和植物细胞均属于真核细胞，拥有共同的细胞器，但植物细胞还具有纤维素细胞壁、叶绿体和大型永久液泡等特有结构。
The main subcellular structures and their functions include: nucleus (controls cell activities and contains DNA), cytoplasm (site of metabolic reactions), cell membrane (controls substance entry and exit), mitochondria (aerobic respiration), ribosomes (protein synthesis), chloroplasts (photosynthesis), and vacuole (stores cell sap, maintains turgor).
主要亚细胞结构及其功能有：细胞核（控制细胞活动并含有 DNA）、细胞质（代谢反应场所）、细胞膜（控制物质进出）、线粒体（有氧呼吸）、核糖体（蛋白质合成）、叶绿体（光合作用）和液泡（储存细胞液，维持膨压）。
To view cells, light microscopes and electron microscopes are used. Magnification and resolution can be calculated:
观察细胞可使用光学显微镜和电子显微镜。放大倍数和分辨率可通过以下公式计算：
Magnification = Image size ÷ Actual size
Remember to convert all measurements to the same unit (e.g. mm, µm, nm). 1 mm = 1000 µm; 1 µm = 1000 nm.
请记住将所有测量值转换为相同单位（如毫米、微米、纳米）。1 毫米 = 1000 微米；1 微米 = 1000 纳米。
2. Biological Molecules and Food Tests | 生物分子与食物检验
Carbohydrates, proteins and lipids are essential biological molecules. Carbohydrates include simple sugars (e.g. glucose) and complex carbohydrates (e.g. starch, cellulose, glycogen). Proteins are made of amino acids, and lipids are composed of fatty acids and glycerol.
碳水化合物、蛋白质和脂质是必需的生物分子。碳水化合物包括单糖（如葡萄糖）和复杂碳水化合物（如淀粉、纤维素、糖原）。蛋白质由氨基酸构成，脂质由脂肪酸和甘油组成。
Food tests are key practical skills: Benedict' roteins (blue → purple), and the ethanol emulsion test for lipids (cloudy white emulsion).
食物检验是关键实验技能：本尼迪克特试剂检测还原糖（加热后由蓝色变为砖红色），碘液检测淀粉（由黄棕色变为蓝黑色），双缩脲试剂检测蛋白质（蓝色变为紫色），乙醇乳化法检测脂质（出现浑浊白色乳状液）。
WJEC often asks for the variables and controls in these tests. Ensure you can describe the colour change and identify the presence of each nutrient.
WJEC 常考查这些实验的变量和对照设置。请确保能够描述颜色变化，并根据结果判断每种营养物质是否存在。
3. Enzymes | 酶
Enzymes are biological catalysts that speed up metabolic reactions without being used up. They are proteins with a specific active site shape, explained by the lock-and-key model. The substrate fits into the active site to form an enzyme-substrate complex.
酶是生物催化剂，可加速代谢反应而自身不被消耗。酶的本质是蛋白质，具有特定形状的活性位点，可用“锁钥模型”解释。底物进入活性位点形成酶-底物复合物。
Enzyme activity is affected by temperature and pH. Initially, increasing temperature raises kinetic energy and reaction rate, but beyond an optimum, the enzyme denatures – the active site loses its shape permanently. Each enzyme has an optimum pH; extremes of pH also cause denaturation.
酶的活性受温度和 pH 影响。温度升高初期会增加动能和反应速率，但超过最适温度后酶会变性——活性位点永久失去原有形状。每种酶都有最适 pH；极端的 pH 同样会导致变性。
You should be able to interpret graphs showing reaction rate against temperature or pH, and explain the effect of enzyme concentration on the rate of reaction.
你需要能够解读反应速率随温度或 pH 变化的曲线图，并解释酶浓度对反应速率的影响。
4. Transport Across Cell Membranes | 跨膜运输
Substances move across cell membranes by diffusion, osmosis and active transport. Diffusion is the net movement of particles from a region of high concentration to low concentration down a concentration gradient; it is passive and does not require energy.
物质通过扩散、渗透和主动运输进出细胞膜。扩散指微粒沿浓度梯度由高浓度区域向低浓度区域的净移动；该过程为被动运输，不消耗能量。
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water potential (dilute solution) to lower water potential (concentrated solution). Plant cells become turgid in hypotonic solutions and undergo plasmolysis in hypertonic solutions.
渗透是水分子通过部分透性膜从高水势（稀溶液）区域向低水势（浓溶液）区域的净移动。植物细胞在低渗溶液中会变得硬挺，在高渗溶液中会发生质壁分离。
Active transport moves substances against the concentration gradient, requiring energy from respiration. This is vital for the uptake of mineral ions by root hair cells and absorption of glucose in the small intestine.
主动运输使物质逆浓度梯度移动，需要呼吸作用提供的能量。这对于根毛细胞吸收矿物质离子和小肠吸收葡萄糖至关重要。
5. Cell Division and Stem Cells | 细胞分裂与干细胞
Mitosis produces two genetically identical daughter cells for growth and repair. The cell cycle includes interphase (DNA replication) and mitosis (prophase, metaphase, anaphase, telophase) followed by cytokinesis. Cancer results from uncontrolled cell division.
有丝分裂产生两个遗传上完全相同的子细胞，用于生长和修复。细胞周期包括间期（DNA 复制）和有丝分裂（前期、中期、后期、末期），随后是胞质分裂。癌症是细胞分裂失控的结果。
Meiosis produces four genetically different haploid gametes, introducing variation through independent assortment and crossing over. Stem cells are undifferentiated cells that can divide to form more stem cells or differentiate into specialised cells.
减数分裂产生四个遗传上不同的单倍体配子，通过独立分配和交叉互换引入变异。干细胞是未分化的细胞，可以分裂产生更多干细胞，或分化成为特化的细胞。
WJEC may ask about the ethical issues of using embryonic stem cells and the medical potential of adult stem cells.
WJEC 可能会考查使用胚胎干细胞的伦理问题以及成体干细胞的医学潜力。
6. Genetics and Inheritance | 遗传与遗传规律
Genes are sections of DNA coding for proteins. DNA is a double helix made of nucleotides containing a sugar-phosphate backbone and bases A, T, C, G. Alleles are different forms of a gene; dominant alleles mask recessive ones. Genotype describes the alleles present, while phenotype is the expressed characteristic.
基因是编码蛋白质的 DNA 片段。DNA 是双螺旋结构，由核苷酸组成，核苷酸包含糖-磷酸骨架和碱基 A、T、C、G。等位基因是同一基因的不同形式；显性等位基因会掩盖隐性等位基因。基因型描述个体拥有的等位基因，表现型则是表达出来的性状。
Monohybrid crosses can be predicted using Punnett squares. A heterozygous tall plant (Tt) crossed with another heterozygous (Tt) produces offspring in a 3:1 phenotype ratio. Pedigree charts can be used to trace inherited disorders such as cystic fibrosis (recessive) and Huntington's disease (dominant).
单基因杂交可用庞纳特方格预测。杂合高茎植物 (Tt) 与杂合高茎 (Tt) 杂交，后代表现型比例为 3:1。系谱图可用于追踪遗传疾病，如囊性纤维化（隐性遗传）和亨廷顿舞蹈症（显性遗传）。
Understand the terms homozygous, heterozygous, phenotype ratio, and be able to interpret family pedigree diagrams.
请理解纯合子、杂合子、表现型比例等术语，并能够解释家族系谱图。
7. Evolution and Natural Selection | 进化与自然选择
Charles Darwin proposed the theory of evolution by natural selection. Individuals with advantageous alleles are more likely to survive, reproduce and pass on these traits to their offspring. Over generations, the frequency of these alleles increases in the population.
查尔斯·达尔文提出了自然选择进化论。拥有有利等位基因的个体更有可能存活、繁殖并将这些性状传递给后代。经过许多代后，这些等位基因在种群中的频率会上升。
Antibiotic resistance in bacteria is a clear example: mutations produce resistant strains; when antibiotics are used, sensitive bacteria die, leaving resistant ones to multiply – a selection pressure. Speciation occurs when populations become reproductively isolated and evolve into separate species.
细菌的抗生素耐药性是典型例子：突变产生耐药菌株；使用抗生素后，敏感菌死亡，耐药菌存活繁殖——这就是选择压力。当种群变得生殖隔离并演化成不同的物种时，物种形成就发生了。
8. Ecology and Nutrient Cycles | 生态学与养分循环
An ecosystem includes all biotic and abiotic factors in an area. Energy flows through food chains and food webs, beginning with producers (plants) that trap light energy via photosynthesis. At each trophic level, only about 10% of energy is passed on; the rest is lost as heat, respiration and waste.
生态系统包括区域内所有生物和非生物因子。能量通过食物链和食物网流动，始于通过光合作用捕获光能的生产者（植物）。每一营养级大约只有 10% 的能量传递到下一级，其余以热能、呼吸和对排泄物的形式散失。
The carbon cycle and nitrogen cycle are crucial for recycling materials. Carbon is recycled via photosynthesis, respiration, combustion and decomposition. Nitrogen is fixed by bacteria, nitrified, taken up by plants, and eventually returned by denitrification. Deforestation and burning fossil fuels disrupt these cycles.
碳循环和氮循环对物质循环至关重要。碳通过光合作用、呼吸、燃烧和分解被循环利用。氮由细菌固氮、硝化后被植物吸收，最终通过反硝化作用返回大气。森林砍伐和燃烧化石燃料会扰乱这些循环。
Human impacts such as eutrophication (excess fertiliser runoff causing algal blooms) and global warming are common exam topics.
富营养化（过量肥料流入水体导致藻华）和全球变暖等人类影响是常见的考题。
9. Human Digestive System | 人体消化系统
Major organs: mouth (mechanical digestion, salivary amylase breaks down starch to maltose), oesophagus (peristalsis), stomach (protease pepsin, acidic pH), small intestine (digestion completed; villi absorb products), large intestine (water absorption).
主要器官：口腔（机械消化，唾液淀粉酶将淀粉分解为麦芽糖）、食道（蠕动）、胃（蛋白酶胃蛋白酶，酸性环境）、小肠（消化完成；绒毛吸收产物）、大肠（吸收水分）。
Enzymes break down large insoluble molecules: amylase digests starch to maltose; proteases digest proteins to amino acids; lipases digest lipids to fatty acids and glycerol. Bile emulsifies fats, increasing surface area for lipase action.
酶将大分子不溶性物质分解：淀粉酶将淀粉分解为麦芽糖；蛋白酶将蛋白质分解为氨基酸；脂肪酶将脂质分解为脂肪酸和甘油。胆汁可乳化脂肪，增加脂肪酶的作用表面积。
Villi in the small intestine increase surface area, have thin walls (one cell thick), a good blood supply and lacteals for absorption of nutrients.
小肠的绒毛增大了表面积，壁薄（仅一层细胞），有丰富的血液供应和乳糜管用于营养物质吸收。
10. Gas Exchange and Circulatory System | 气体交换与循环系统
In humans, gas exchange occurs in the alveoli of the lungs. Alveoli are adapted by having a large surface area, thin moist walls and dense capillary network. Breathing involves the diaphragm and intercostal muscles changing thoracic volume and pressure.
人体气体交换在肺部肺泡进行。肺泡的适应特征包括巨大表面积、薄而湿润的壁和丰富的毛细血管网。呼吸作用涉及膈肌和肋间肌改变胸腔容积与压力。
Inhaled air: 21% O₂, 0.04% CO₂; exhaled air: 16% O₂, 4% CO₂, more water vapour. The double circulatory system consists of the heart (right side pumps to lungs, left side to body), arteries (thick muscular walls), veins (valves, wider lumen) and capillaries (one-cell thick for exchange).
吸入空气：21% 氧气，0.04% 二氧化碳；呼出空气：16% 氧气，4% 二氧化碳，更多水蒸气。双循环系统包括心脏（右侧泵血至肺，左侧泵向全身）、动脉（肌肉壁厚）、静脉（有瓣膜，管腔较宽）和毛细血管（单细胞厚度，利于交换）。
Red blood cells contain haemoglobin for oxygen transport; white blood cells defend against pathogens; plasma transports CO₂, nutrients, hormones and wastes.
红细胞含血红蛋白运输氧气；白细胞防御病原体；血浆运输二氧化碳、营养物质、激素和废物。
11. Coordination: Nervous and Hormonal Systems | 协调：神经系统和激素系统
or) produces rapid, involuntary responses. Synapses allow communication between neurons via neurotransmitters.
神经系统通过神经元传导电脉冲进行控制。反射弧（刺激 → 感受器 → 感觉神经元 → 中间神经元 → 运动神经元 → 效应器）产生快速、非自主的反应。突触通过神经递质在神经元之间传递信息。
Hormones are chemical messengers carried in blood. Important hormones include insulin (lowers blood glucose, produced by pancreas), glucagon (raises blood glucose), adrenaline (fight-or-flight response), and ADH (controls water reabsorption in kidneys).
激素是通过血液运输的化学信使。重要的激素有胰岛素（降低血糖，由胰腺产生）、胰高血糖素（升高血糖）、肾上腺素（“战或逃”反应）以及抗利尿激素 ADH（控制肾脏对水的重吸收）。
WJEC often compares nervous and hormonal control: nervous is fast, short-term, electrical; hormonal is slower, longer-lasting, chemical.
WJEC 常比较神经控制和激素控制：神经控制快速、短期、电信号；激素控制较慢、作用持久、化学信号。
12. Homeostasis and Excretion | 稳态与排泄
Homeostasis maintains a constant internal environment. Key examples: thermoregulation (skin – vasodilation, sweating, shivering), osmoregulation (kidneys control water balance via ADH), and blood glucose regulation (insulin and glucagon).
稳态维持稳定的内环境。关键实例：体温调节（皮肤——血管舒张、排汗、战栗）、渗透调节（肾脏通过 ADH 控制水平衡）和血糖调节（胰岛素和胰高血糖素）。
The kidneys excrete urea and regulate water and ion levels. Ultrafiltration occurs in the Bowman's capsule, followed by selective reabsorption of all glucose, some ions and water in the proximal convoluted tubule. The loop of Henle and collecting duct control water reabsorption under ADH influence.
肾脏排泄尿素并调节水和离子水平。超滤作用发生在肾小囊，随后近曲小管重吸收所有的葡萄糖、部分离子和水。髓袢和集合管在 ADH 影响下调控水的重吸收。
Dialysis can replace kidney function; a kidney transplant is a long-term treatment. Urine composition is often tested in exam questions.
透析可替代肾功能；肾移植是长期疗法。尿液成分是考试中常见的考查点。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图