📚 IGCSE CIE Biology: End-of-Term Revision Outline | IGCSE CIE 生物：期末复习提纲
This revision outline summarises the core topics of the IGCSE CIE Biology syllabus, designed to help you focus your exam preparation. Use it as a checklist to ensure you understand the key concepts, definitions, and processes required for the final examination.
本复习提纲总结了 IGCSE CIE 生物学课程的核心主题，旨在帮助你集中精力备考。请将其用作检查清单，确保你掌握了期末考试所需的关键概念、定义和过程。
1. Characteristics and Classification of Living Organisms | 生物的特征与分类
Living organisms share seven characteristics: movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition (MRS GREN). Understanding these helps distinguish living from non-living things.
生物具有七个共同特征：运动、呼吸作用、应激性、生长、生殖、排泄和营养（常缩写为 MRS GREN）。理解这些特征有助于区分生物与非生物。
The binomial system of naming species uses Latin genus and species names, e.g., Homo sapiens. Organisms are classified into the five kingdoms: Animals, Plants, Fungi, Prokaryotes, and Protoctists. Viruses are not placed in any kingdom as they are non-living particles.
物种命名的双名法使用拉丁文属名和种名，例如 Homo sapiens。生物被分为五界：动物界、植物界、真菌界、原核生物界和原生生物界。病毒不被归入任何界，因为它们是非生命颗粒。
Key features used for classification include morphology, anatomy, and, increasingly, DNA sequences. Vertebrates are further divided into five classes: fish, amphibians, reptiles, birds, and mammals, each with distinct characteristics such as body covering, thermoregulation, and reproduction method.
用于分类的关键特征包括形态学、解剖学，以及日益重要的 DNA 序列。脊椎动物进一步分为五个纲：鱼类、两栖类、爬行类、鸟类和哺乳类，各自具有独特的特征，如体表覆盖物、体温调节方式和生殖方法。
Arthropods like insects, crustaceans, arachnids, and myriapods are distinguished by leg number and body segments. Understanding dichotomous keys enables you to identify organisms systematically.
节肢动物如昆虫、甲壳类、蛛形纲和多足纲根据腿的数量和体节来区分。理解二歧检索表能够让你系统地识别生物。
2. Cell Structure and Organisation | 细胞结构与组织层次
Both plant and animal cells share common structures: cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes. Plant cells additionally have a cellulose cell wall, a large permanent vacuole, and chloroplasts for photosynthesis.
植物细胞和动物细胞都有共同的细胞结构：细胞膜、细胞质、细胞核、线粒体和核糖体。植物细胞还多了纤维素细胞壁、一个大的中央液泡和用于光合作用的叶绿体。
Bacterial cells are prokaryotic: they lack a true nucleus and membrane-bound organelles; instead, they have a circular DNA chromosome and plasmids. Cell organelles each have specialised functions: mitochondria for aerobic respiration, ribosomes for protein synthesis, chloroplasts for photosynthesis, and the nucleus controlling cell activities.
细菌细胞是原核细胞：它们没有真正的细胞核和膜结合的细胞器；相反，它们有环状DNA染色体和质粒。每种细胞器都有专门的功能：线粒体进行有氧呼吸，核糖体进行蛋白质合成，叶绿体进行光合作用，细胞核控制细胞活动。
Cells are organised into tissues, tissues into organs, and organs into systems. Examples include the leaf as a plant organ containing palisade mesophyll and spongy mesophyll tissues, and the human digestive system as an organ system.
细胞组织成组织，组织构成器官，器官再构成系统。例如，叶片是包含栅栏组织和海绵组织的植物器官，而人类消化系统则是一个器官系统。
3. Movement Across Membranes | 物质跨膜运输
Substances move in and out of cells by diffusion, osmosis, and active transport. Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, and is a passive process.
物质通过扩散、渗透和主动运输进出细胞。扩散是粒子从高浓度区域向低浓度区域的净移动，顺浓度梯度进行，是一个被动过程。
Osmosis is the diffusion of water molecules through a partially permeable membrane from a region of higher water potential to one of lower water potential. Plant cells in dilute solutions become turgid, while in concentrated solutions they become plasmolysed; animal cells may burst (lysis) or shrink (crenation).
渗透是水分子通过选择透过性膜从水势较高的区域向水势较低的区域扩散。植物细胞在稀溶液中会变得硬挺，而在浓溶液中会发生质壁分离；动物细胞可能会涨破（细胞溶解）或皱缩。
Active transport uses energy from ATP to move substances against their concentration gradient, e.g., uptake of mineral ions by root hair cells. Factors affecting the rate of movement include surface area, temperature, concentration gradient, and diffusion distance.
主动运输利用 ATP 提供的能量，逆浓度梯度移动物质，例如根毛细胞对矿质离子的吸收。影响运输速率的因素包括表面积、温度、浓度梯度和扩散距离。
4. Biological Molecules and Enzymes | 生物分子与酶
Carbohydrates, proteins, and lipids are the main organic nutrients. The Benedict’s test for reducing sugars (glucose) turns brick-red upon heating; iodine solution tests for starch (blue-black); Biuret reagent turns purple for proteins; and the emulsion test with ethanol produces a cloudy white layer for lipids.
碳水化合物、蛋白质和脂质是主要的有机营养物。本尼迪克特试验检测还原糖（如葡萄糖）加热后产生砖红色沉淀；碘液检测淀粉变蓝黑色；双缩脲试剂检测蛋白质呈紫色；脂质的乙醇乳浊液试验产生白色浑浊。
Enzymes are biological catalysts made of protein that speed up reactions by lowering activation energy. They possess an active site complementary to the substrate, described by the lock-and-key model. Each enzyme operates at an optimum temperature and pH; denaturation occurs at extremes, changing the shape of the active site irreversibly.
酶是由蛋白质构成的生物催化剂，通过降低活化能来加速反应。它们具有与底物互补的活性位点，可用锁钥模型描述。每种酶在最适温度和最适 pH 下发挥作用；极端条件会导致变性，不可逆地改变活性位点的形状。
Enzyme activity is affected by temperature (increase until optimum, then rapid decline), pH (deviation from optimum reduces activity), and substrate concentration (increases until saturation). Remember practical investigations involving catalase and hydrogen peroxide.
酶活性受温度（达到最适温度前升高，随后急剧下降）、pH（偏离最适值则活性降低）和底物浓度（增加直至饱和）的影响。记住涉及过氧化氢酶的探究实验。
5. Plant Nutrition and Photosynthesis | 植物营养与光合作用
Photosynthesis is the process by which plants manufacture glucose from carbon dioxide and water using light energy, absorbed by chlorophyll in chloroplasts. The overall equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Oxygen is released as a by-product.
光合作用是植物利用叶绿体中的叶绿素吸收光能，将二氧化碳和水转化为葡萄糖的过程。总方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。氧气作为副产物释放。
The glucose produced is used for respiration, converted to starch for storage, to cellulose for cell walls, to sucrose for transport, and to amino acids and lipids. The leaf is adapted for photosynthesis: large surface area, thin, transparent epidermis, palisade cells rich in chloroplasts, and stomata for gas exchange.
生成的葡萄糖用于呼吸作用，转化为淀粉储存，转变为纤维素构建细胞壁，转化为蔗糖运输，以及合成氨基酸和脂质。叶片适应光合作用：大的表面积，薄而透明的表皮，富含叶绿体的栅栏组织细胞，以及用于气体交换的气孔。
Limiting factors of photosynthesis include light intensity, carbon dioxide concentration, and temperature. At low light or CO₂, the rate is limited; as temperature rises, enzyme activity increases until denaturation occurs. Glasshouse systems manipulate these factors to maximise crop yield.
光合作用的限制因素包括光照强度、二氧化碳浓度和温度。在低光照或低 CO₂ 时速率受限；温度升高，酶活性增加，直到发生变性。温室系统通过调控这些因素来最大化作物产量。
6. Animal Nutrition and the Human Digestive System | 动物营养与人类消化系统
A balanced diet contains carbohydrates, proteins, lipids, vitamins, minerals, dietary fibre, and water. Each nutrient has a specific role: carbohydrates for energy, proteins for growth and repair, lipids as a long-term energy store and insulation, and vitamins/minerals for body processes (e.g., vitamin C prevents scurvy, calcium strengthens bones).
均衡膳食包含碳水化合物、蛋白质、脂质、维生素、矿物质、膳食纤维和水。每种营养素都有特定功能：碳水化合物提供能量，蛋白质用于生长和修复，脂质作为长期能量储存和绝缘体，维生素和矿物质维持生理过程（例如维生素 C 预防坏血病，钙强化骨骼）。
Digestion involves mechanical breakdown (chewing, stomach churning) and chemical breakdown by enzymes. Amylase in saliva and pancreatic juice digests starch to maltose; proteases (pepsin in stomach, trypsin from pancreas) digest proteins to amino acids; lipase digests lipids to fatty acids and glycerol, aided by bile salts that emulsify fats.
消化包括物理性破碎（咀嚼、胃的搅拌）和酶的化学分解。唾液和胰液中的淀粉酶将淀粉消化为麦芽糖；蛋白酶（胃蛋白酶、胰蛋白酶）将蛋白质消化为氨基酸；脂肪酶在胆汁盐的帮助下将脂质消化为脂肪酸和甘油，胆汁盐使脂肪乳化。
The alimentary canal is adapted for absorption: the small intestine has villi with microvilli to increase surface area, a dense capillary network, and a lacteal for lipid absorption. The large intestine absorbs water. Peristalsis moves food along the gut.
消化道适应吸收：小肠有绒毛和微绒毛增大表面积，密集的毛细血管网，以及用于吸收脂质的乳糜管。大肠吸收水分。蠕动推动食物沿肠道移动。
7. Transport in Plants and Animals | 植物与动物的运输
In flowering plants, xylem transports water and mineral ions from roots to leaves, supported by transpiration pull, cohesion, and adhesion. Phloem transports sucrose and amino acids in both directions (translocation). Xylem vessels are dead, hollow tubes reinforced with lignin; phloem consists of living sieve tubes and companion cells.
在有花植物中，木质部将水和矿质离子从根运输到叶，依靠蒸腾拉力、内聚力和附着力。韧皮部双向运输蔗糖和氨基酸（转运）。木质部导管是无生命的、中空的、木质素加固的管；韧皮部由活筛管和伴胞组成。
Factors increasing transpiration rate include higher temperature, lower humidity, greater air movement (wind), and increased light intensity (stomata open). Wilting occurs when water loss exceeds uptake.
提高蒸腾速率的因素包括较高的温度、较低的湿度、较大的空气运动（风）和较强的光照强度（气孔张开）。当失水超过吸水时发生萎蔫。
In humans, the circulatory system consists of the heart (a double pump), blood vessels (arteries, veins, capillaries), and blood. Blood carries oxygen (on haemoglobin in red cells), carbon dioxide, nutrients, hormones, and wastes. The heart structure: atria collect blood, ventricles pump blood out; valves prevent backflow.
在人体中，循环系统由心脏（双泵）、血管（动脉、静脉、毛细血管）和血液组成。血液运输氧气（由红细胞中的血红蛋白携带）、二氧化碳、营养物质、激素和废物。心脏结构：心房收集血液，心室泵出血液；瓣膜防止倒流。
Double circulation: pulmonary circuit to the lungs and systemic circuit to the body. Coronary heart disease is associated with risk factors like smoking, high-fat diet, stress, and lack of exercise. Lymphatic system returns tissue fluid.
双循环：肺循环到肺，体循环到全身。冠心病与吸烟、高脂饮食、压力和缺乏运动等危险因素有关。淋巴系统回收组织液。
8. Respiration and Gas Exchange | 呼吸作用与气体交换
Aerobic respiration uses oxygen to completely break down glucose: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP). It occurs in mitochondria. Anaerobic respiration occurs without oxygen: in animals it produces lactic acid (causing muscle fatigue and oxygen debt); in yeast it produces ethanol and CO₂ (fermentation).
有氧呼吸利用氧气彻底分解葡萄糖：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 能量（ATP）。它发生在线粒体中。无氧呼吸在没有氧气的情况下进行：在动物中产生乳酸（导致肌肉疲劳和氧债）；在酵母中产生乙醇和 CO₂（发酵）。
The human gas exchange system includes the trachea, bronchi, bronchioles, and alveoli. Alveoli are adapted for diffusion: large surface area, thin walls (one cell thick), moist surface, and rich blood supply. Breathing movements (inspiration and expiration) are caused by the diaphragm and intercostal muscles.
人体气体交换系统包括气管、支气管、细支气管和肺泡。肺泡适应扩散：表面积大、壁薄（一层细胞）、表面湿润、血液供应丰富。呼吸运动（吸气和呼气）由膈肌和肋间肌引起。
Effects of smoking include nicotine (addiction), carbon monoxide (reduces oxygen-carrying capacity), tar (causes cancer and chronic bronchitis), and damage to cilia leading to increased infections.
吸烟的影响包括尼古丁（上瘾）、一氧化碳（降低携氧能力）、焦油（导致癌症和慢性支气管炎），以及纤毛受损导致感染增多。
9. Coordination, Response, and Homeostasis | 协调、反应与稳态
The nervous system uses electrical impulses along neurones. A reflex arc involves a receptor, sensory neurone, relay neurone in the CNS, motor neurone, and effector (muscle or gland), allowing rapid involuntary responses. The synapse is a junction where neurotransmitters diffuse across to trigger a new impulse.
神经系统利用电冲动沿神经元传递。反射弧包括感受器、感觉神经元、中枢神经系统中的联络神经元、运动神经元和效应器（肌肉或腺体），实现快速的不随意反应。突触是一个连接点，神经递质在此扩散并触发新的冲动。
The endocrine system uses hormones, chemical messengers carried in the blood. Key examples: adrenaline for ‘fight or flight’ (increases heart rate, blood glucose), insulin (lowers blood glucose by converting glucose to glycogen), and glucagon (raises blood glucose). Diabetes (Type 1) results from insufficient insulin.
内分泌系统利用激素，即由血液携带的化学信使。关键实例：肾上腺素负责“战斗或逃跑”反应（增加心率、血糖），胰岛素（通过将葡萄糖转化为糖原降低血糖），胰高血糖素（升高血糖）。1 型糖尿病是由胰岛素不足引起的。
Homeostasis maintains a constant internal environment. The skin controls temperature via sweating, vasodilation, and vasoconstriction. Blood glucose regulation is a negative feedback loop. The kidney removes urea and regulates water content; ADH controls water reabsorption.
稳态维持恒定的内环境。皮肤通过出汗、血管舒张和血管收缩调节温度。血糖调节是一个负反馈回路。肾脏排出尿素并调节水分平衡；抗利尿激素（ADH）控制水的重吸收。
The eye accommodates by changing the lens shape (ciliary muscles and suspensory ligaments). Focusing on near objects requires a thicker lens; on distant objects, a thinner lens. The pupil reflex regulates light entry via the iris.
眼睛通过改变晶状体形状（睫状肌和悬韧带）进行调节。聚焦近物需要较厚的晶状体；远物则需要较薄的晶状体。瞳孔反射通过虹膜调节光线进入。
10. Reproduction and Inheritance | 生殖与遗传
Asexual reproduction produces genetically identical offspring (clones) via mitosis, found in plants (runners, bulbs) and some animals. Sexual reproduction involves the fusion of gametes (sperm and egg) produced by meiosis, giving genetic variation.
无性生殖通过有丝分裂产生基因相同的后代（克隆），见于植物（匍匐茎、鳞茎）和一些动物。有性生殖涉及由减数分裂产生的配子（精子和卵子）融合，产生遗传变异。
In humans, the male reproductive system includes testes, sperm ducts, prostate gland, and penis. The female system includes ovaries, oviducts, uterus, and vagina. Fertilisation occurs in the oviduct, and the zygote implants in the uterus. The placenta allows exchange of nutrients, gases, and wastes between mother and foetus.
在人体中，男性生殖系统包括睾丸、输精管、前列腺和阴茎。女性系统包括卵巢、输卵管、子宫和阴道。受精发生在输卵管，受精卵植入子宫。胎盘允许母体和胎儿之间进行营养物质、气体和废物的交换。
Chromosomes contain DNA, which is a double helix carrying genes. A gene is a section of DNA coding for a protein. Alleles are different forms of a gene. Monohybrid crosses follow 3:1 and 1:1 ratios for complete dominance. Co-dominance (e.g., AB blood group) and sex-linked traits (e.g., colour blindness) are also tested.
染色体含有DNA，DNA是携带基因的双螺旋结构。基因是编码蛋白质的一段DNA。等位基因是同一基因的不同形式。单基因杂合交配遵循完全显性的3:1和1:1比例。共显性（如AB血型）和伴性遗传（如色盲）也是考查内容。
Mutations are changes in DNA that can be neutral, harmful, or beneficial. Natural selection acts on variation, leading to evolution. Antibiotic resistance in bacteria is a classic example of evolution by natural selection.
突变是DNA的变化，可能是中性、有害或有利的。自然选择作用于变异，导致进化。细菌的抗生素耐药性是通过自然选择进化的典型例子。
11. Organisms and Their Environment | 生物与环境
Ecosystems comprise populations, communities, and the physical environment. Energy flows from the Sun through producers (plants) to consumers (herbivores, carnivores) and decomposers, forming food chains and webs. Energy is lost at each trophic level as heat and through respiration, so chains rarely exceed 4-5 levels.
生态系统由种群、群落和物理环境组成。能量从太阳流过生产者（植物）到消费者（食草动物、食肉动物）和分解者，形成食物链和食物网。能量在每一营养级以热能和呼吸作用的形式损失，因此食物链很少超过4-5级。
The carbon cycle shows how carbon moves between the atmosphere, organisms, and fossil fuels via photosynthesis, respiration, feeding, decomposition, and combustion. The nitrogen cycle involves nitrogen fixation, nitrification, assimilation, and denitrification, driven by bacteria in soil and root nodules of legumes.
碳循环显示碳如何通过光合作用、呼吸作用、进食、分解和燃烧在大气、生物和化石燃料之间移动。氮循环包括固氮作用、硝化作用、同化作用和反硝化作用，由土壤中的细菌和豆科植物根瘤中的细菌驱动。
Population size is affected by food supply, predation, disease, and competition. Sigmoid population growth curves show lag, exponential, stationary, and decline phases. Deforestation, pollution (global warming, eutrophication), and loss of biodiversity are major human influences.
种群大小受食物供应、捕食、疾病和竞争的影响。S型种群增长曲线表现出调整期、指数期、稳定期和衰落期。森林砍伐、污染（全球变暖、富营养化）和生物多样性丧失是主要的人类影响。
Conservation and sustainable development aim to protect habitats and species for future generations. Key methods include captive breeding, seed banks, and legislation.
保护与可持续发展旨在为后代保护栖息地和物种。关键方法包括圈养繁殖、种子库和立法。
12. Biotechnology and Genetic Engineering | 生物技术与基因工程
Biotechnology uses living organisms for useful products. Yeast is used in bread-making (CO₂ raises dough, ethanol evaporates) and in brewing (ethanol production). Bacteria are used to make yoghurt by fermenting lactose into lactic acid. The fermenter is controlled for temperature, pH, oxygen, and nutrient supply.
生物技术利用生物制造有用产品。酵母用于制作面包（CO₂使面团蓬松，乙醇蒸发）和酿酒（生成乙醇）。细菌用于制作酸奶，通过将乳糖发酵为乳酸。发酵罐的温度、pH、氧气和营养供应受到控制。
Genetic engineering involves transferring a gene from one organism to another. Insulin production uses human insulin gene inserted into bacteria; GM crops may be herbicide-resistant or produce insecticide (Bt toxin). The process involves restriction enzymes to cut DNA, and ligase to join it into a plasmid vector.
基因工程涉及将基因从一个生物转移到另一个生物。胰岛素生产利用插入人类胰岛素基因的细菌；转基因作物可能具有抗除草剂性或产生杀虫剂（Bt 毒素）。该过程使用限制酶切割 DNA，连接酶将其连接到质粒载体中。
Benefits include increased yield, disease resistance, and medical products. Risks involve potential gene flow to wild relatives, effects on non-target species, and unknown long-term health impacts. Ethical considerations are debated.
益处包括提高产量、抗病性和医药产品。风险涉及向野生近缘种的基因漂移、对非靶标物种的影响以及未知的长期健康影响。伦理问题仍在争论中。
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