📚 GCSE CIE Biology: Last-Minute Revision Notes | GCSE CIE 生物：考前冲刺笔记
This comprehensive revision guide covers the core topics of CIE GCSE Biology, presenting key facts and concepts in a clear, concise format. Each section pairs essential English explanations with their Chinese equivalents, helping you reinforce both language and subject knowledge. Use these notes to quickly review cell structure, biomolecules, movement across membranes, plant nutrition, human body systems, genetics, ecology and more before your exam.
这份全面的复习指南涵盖了 CIE GCSE 生物的核心主题，以清晰简洁的形式呈现关键事实和概念。每个部分都将英文解释与中文翻译配对，帮助你巩固语言和学科知识。考前用这些笔记快速回顾细胞结构、生物分子、跨膜运输、植物营养、人体系统、遗传与生态等内容。
1. Cell Structure and Organisation | 细胞结构与组织层次
All living organisms are made of cells. Animal and plant cells share common features – nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cellulose cell wall, a large permanent vacuole and chloroplasts. Eukaryotic cells contain membrane-bound organelles, while prokaryotic cells (bacteria) lack a true nucleus and have a single circular chromosome, plus plasmids.
所有生物都由细胞组成。动物细胞和植物细胞共有细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞还有纤维素细胞壁、大液泡和叶绿体。真核细胞具有膜包被的细胞器，而原核细胞（细菌）没有真正的细胞核，只有一条环状染色体和质粒。
Specialised cells are adapted to their functions. For example, red blood cells have no nucleus to carry more haemoglobin; root hair cells have long extensions to absorb water and minerals. Groups of similar cells form tissues, organs are made of different tissues working together, and organ systems are groups of organs.
特化细胞适应其功能。例如，红细胞无核以携带更多血红蛋白；根毛细胞有长突起以吸收水分和矿物质。相似细胞聚集成组织，不同组织组成器官，多个器官构成系统。
2. Biological Molecules and Enzymes | 生物分子与酶
Carbohydrates, proteins and lipids are the main biological molecules. Starch and glycogen are polysaccharides; glucose is a monosaccharide. Proteins are made of amino acids, while lipids are made of fatty acids and glycerol. The food tests include: iodine test for starch (blue-black), Benedict’s test for reducing sugars (brick-red precipitate on heating), biuret test for protein (purple), and ethanol emulsion test for fats (milky emulsion).
碳水化合物、蛋白质和脂质是主要的生物分子。淀粉和糖原是多糖；葡萄糖是单糖。蛋白质由氨基酸组成，脂质由脂肪酸和甘油组成。食物检测包括：碘液检测淀粉（蓝黑色），本尼迪克特试剂检测还原糖（加热后砖红色沉淀），双缩脲试剂检测蛋白质（紫色），乙醇乳浊液检测脂肪（乳白色）。
Enzymes are biological catalysts that speed up reactions by lowering activation energy. They have an active site complementary to the substrate. Enzyme activity is affected by temperature and pH – extremes denature the enzyme. The lock-and-key model explains specificity. Amylase breaks down starch to maltose, protease breaks down proteins to amino acids, lipase breaks down lipids to fatty acids and glycerol.
酶是生物催化剂，通过降低活化能加速反应。酶的活性位点与底物互补。酶活性受温度和 pH 影响——极端条件使酶变性。锁钥模型解释了专一性。淀粉酶分解淀粉为麦芽糖，蛋白酶分解蛋白质为氨基酸，脂肪酶分解脂质为脂肪酸和甘油。
3. Movement into and out of Cells | 物质进出细胞
Diffusion is the net movement of particles from a region of higher concentration to lower concentration, down a concentration gradient. It is passive and does not require energy. Osmosis is the diffusion of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution. Active transport moves substances against a concentration gradient using energy from respiration and carrier proteins.
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，为被动过程，不需要能量。渗透是水分子通过部分透性膜从稀溶液向较浓溶液的扩散。主动运输利用呼吸作用提供的能量和载体蛋白，逆浓度梯度运输物质。
In plant cells, turgor pressure supports the plant. A plant cell in pure water becomes turgid; in a concentrated solution it undergoes plasmolysis. Animal cells may burst (lyse) in pure water due to lack of a cell wall.
在植物细胞中，膨压支持植物体。植物细胞在纯水中变得硬挺；在浓溶液中发生质壁分离。动物细胞在纯水中可能因无细胞壁而破裂（溶胞）。
4. Plant Nutrition and Transport | 植物营养与运输
Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen. The equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Chlorophyll in chloroplasts absorbs light. Factors affecting the rate include light intensity, carbon dioxide concentration and temperature. Glucose is used for respiration or stored as starch.
光合作用利用光能将二氧化碳和水转化为葡萄糖和氧气。方程式：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。叶绿体中的叶绿素吸收光能。影响速率的因素有光照强度、二氧化碳浓度和温度。葡萄糖用于呼吸作用或转化为淀粉储存。
Xylem transports water and mineral ions from roots to leaves. Cohesion-tension theory explains the upward pull driven by transpiration. Phloem translocates sucrose and amino acids from sources to sinks. Transpiration is water loss from leaves via stomata; factors increasing transpiration include higher temperature, wind and low humidity.
木质部将水和无机盐从根部运往叶片。内聚力-拉力学说解释了蒸腾作用产生的向上拉力。韧皮部将蔗糖和氨基酸从源运输到库。蒸腾作用是叶片通过气孔散失水分；温度升高、有风和低湿度会加快蒸腾速率。
5. Human Nutrition and Digestion | 人体营养与消化
A balanced diet includes carbohydrates, proteins, lipids, vitamins, mineral salts, fibre and water. Vitamin C deficiency causes scurvy; vitamin D deficiency causes rickets; iron deficiency leads to anaemia. The digestive system includes the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine, rectum and anus.
均衡膳食包含碳水化合物、蛋白质、脂质、维生素、无机盐、膳食纤维和水。维生素 C 缺乏导致坏血病；维生素 D 缺乏引起佝偻病；缺铁导致贫血。消化系统包括口腔、食道、胃、小肠（十二指肠和回肠）、大肠、直肠和肛门。
Physical digestion breaks food into smaller pieces (chewing, churning). Chemical digestion uses enzymes. In the stomach, pepsin breaks down proteins in acidic conditions. In the small intestine, pancreatic enzymes and bile complete digestion. Bile emulsifies fats, providing a larger surface area for lipase. Absorption of digested food occurs mainly in the villi of the ileum; villi have a large surface area, thin epithelium and a network of capillaries and lacteals.
物理性消化将食物研磨（咀嚼、搅拌）。化学性消化依靠酶。胃中，胃蛋白酶在酸性条件下分解蛋白质。小肠中，胰酶和胆汁完成消化。胆汁乳化脂肪，增大脂肪酶作用的表面积。消化产物的吸收主要在回肠的绒毛进行；绒毛有巨大的表面积、薄的上皮和丰富的毛细血管与乳糜管。
6. Gas Exchange and Respiration | 气体交换与呼吸
The respiratory system includes trachea, bronchi, bronchioles and alveoli. Air enters through the nose or mouth, passes down the trachea, and into the lungs. Alveoli are the site of gas exchange – they have thin walls, a large surface area, and a dense capillary network. Oxygen diffuses into blood and carbon dioxide diffuses out.
呼吸系统包括气管、支气管、细支气管和肺泡。空气经鼻或口进入，沿气管下行入肺。肺泡是气体交换的部位——壁薄、表面积大、毛细血管网丰富。氧气扩散入血，二氧化碳扩散出。
Aerobic respiration requires oxygen and releases a large amount of energy: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ 38 ATP). Anaerobic respiration in humans produces lactic acid and less energy; in yeast, it produces ethanol and carbon dioxide (fermentation). During exercise, breathing rate and depth increase to supply more oxygen and remove excess CO₂.
有氧呼吸需要氧气并释放大量能量：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ 38 ATP)。人体无氧呼吸产生乳酸，能量较少；酵母的无氧呼吸产生乙醇和二氧化碳（发酵）。运动时，呼吸频率和深度增加，以供应更多氧气并排除多余的二氧化碳。
7. Circulatory System | 循环系统
Mammals have a double circulatory system. The heart has four chambers: right atrium, right ventricle, left atrium, left ventricle. Deoxygenated blood flows from the body into the right side, is pumped to the lungs, returns oxygenated to the left side, and is pumped to the rest of the body. Arteries carry blood away from the heart, have thick muscular walls; veins carry blood back, have valves; capillaries are one-cell thick for exchange.
哺乳动物具有双循环系统。心脏有四腔：右心房、右心室、左心房、左心室。缺氧血从身体流入右侧，泵至肺部，携带氧后回到左侧，再泵至全身。动脉将血液带离心脏，管壁厚且有肌肉；静脉将血液带回，有瓣膜；毛细血管仅一层细胞厚，便于交换。
Blood contains red blood cells (transport oxygen via haemoglobin), white blood cells (defence), platelets (clotting) and plasma (transports dissolved substances). The lymphatic system drains excess tissue fluid and returns it to the blood.
血液包含红细胞（通过血红蛋白运氧）、白细胞（防御）、血小板（凝血）和血浆（运输溶解物质）。淋巴系统将多余的组织液送回血液。
8. Coordination and Response | 协调与反应
The nervous system uses electrical impulses. A reflex arc involves receptor → sensory neurone → relay neurone (in CNS) → motor neurone → effector. Synapses use neurotransmitters to pass signals. The endocrine system uses hormones, which travel in the blood and have slower, longer-lasting effects. Adrenaline prepares the body for ‘fight or flight’; insulin lowers blood glucose by converting glucose to glycogen in the liver.
神经系统利用电冲动。反射弧包括感受器 → 感觉神经元 → 中间神经元（中枢神经系统） → 运动神经元 → 效应器。突触利用神经递质传递信号。内分泌系统使用激素，经血液运输，作用较慢但持久。肾上腺素使身体做好“战斗或逃跑”准备；胰岛素通过促进肝脏将葡萄糖转化为糖原来降低血糖。
The eye focuses light on the retina. In dim light, the pupil dilates; in bright light, it constricts. Accommodation for near objects involves contraction of ciliary muscles and relaxation of suspensory ligaments, making the lens more convex. Long-sightedness (hyperopia) is corrected with converging lenses; short-sightedness (myopia) with diverging lenses.
眼睛将光线聚焦于视网膜。弱光下瞳孔扩大；强光下瞳孔收缩。看近物时，睫状肌收缩、悬韧带松弛，晶状体变凸。远视用凸透镜矫正；近视用凹透镜矫正。
9. Homeostasis and Excretion | 稳态与排泄
Homeostasis is the maintenance of a constant internal environment. The kidney regulates water content and excretes urea. The nephron filters blood in the glomerulus, reabsorbs glucose, some water and ions selectively, and secretes unwanted substances. ADH controls the amount of water reabsorbed in the collecting ducts.
稳态指维持恒定的内环境。肾脏调节水含量并排出尿素。肾单位在肾小球过滤血液，选择性重吸收葡萄糖、部分水和离子，并分泌不需要的物质。抗利尿激素（ADH）控制集合管对水的重吸收量。
Temperature regulation involves the skin. When hot, vasodilation and sweating increase heat loss; when cold, vasoconstriction and shivering generate heat. The liver plays a central role in metabolism and deamination of excess amino acids to form urea.
体温调节涉及皮肤。热时，血管舒张和出汗增加散热；冷时，血管收缩和战栗产生热量。肝脏在代谢和脱氨基作用中起核心作用，将多余氨基酸转化为尿素。
10. Reproduction and Inheritance | 生殖与遗传
Sexual reproduction involves gametes (sperm and egg) and produces genetically varied offspring. In humans, fertilisation occurs in the oviduct; the embryo implants in the uterus. The placenta allows exchange of nutrients, gases and wastes between mother and foetus. The menstrual cycle is controlled by hormones (FSH, LH, oestrogen, progesterone).
有性生殖涉及配子（精子和卵细胞），产生遗传变异的后代。人类受精发生在输卵管；胚胎植入子宫。胎盘允许母亲与胎儿之间进行营养物质、气体和废物的交换。月经周期受激素调控（促卵泡激素、黄体生成素、雌激素、孕激素）。
Genes are sections of DNA. Alleles are different forms of a gene. Monohybrid inheritance can be shown with genetic diagrams. Dominant alleles mask recessive ones. Sex determination: XX female, XY male. Codominance occurs when both alleles are expressed (e.g., AB blood group). Some disorders are inherited, like sickle cell anaemia (recessive) and Huntington’s disease (dominant).
基因是 DNA 片段。等位基因是同一基因的不同形式。单基因遗传可用遗传图解表示。显性等位基因遮盖隐性等位基因。性别决定：XX 为女性，XY 为男性。共显性时两个等位基因均表达（如 AB 血型）。某些疾病是遗传的，如镰状细胞贫血（隐性）和亨廷顿病（显性）。
11. Variation, Selection and Evolution | 变异、选择与进化
Variation can be continuous (e.g., height) or discontinuous (e.g., blood group). Mutations are random changes in DNA; they can be neutral, harmful or occasionally beneficial. Natural selection occurs when individuals with advantageous characteristics are more likely to survive and reproduce, passing on the alleles. This leads to adaptation over generations.
变异可以是连续的（如身高）或不连续的（如血型）。突变是 DNA 的随机变化；可能中性、有害或偶尔有益。自然选择指具有有利特征的个体更可能存活繁殖并传递等位基因，经过多代导致适应。
Selective breeding involves humans choosing parents with desired traits to produce offspring with enhanced characteristics, but it can reduce genetic diversity. Evolution by natural selection explains the diversity of life; evidence includes fossils and antibiotic resistance in bacteria.
选择性育种指人类选择具有理想性状的亲本繁殖，以强化特征，但可能降低遗传多样性。通过自然选择的进化解释了生命的多样性；证据包括化石和细菌的抗生素耐药性。
12. Ecology and Ecosystems | 生态学与生态系统
An ecosystem includes a community of living organisms interacting with their physical environment. Food chains and food webs show feeding relationships. Energy flows from producers (plants) through consumers (herbivores, carnivores, decomposers); energy is lost at each trophic level through respiration, heat and waste, so chains are rarely more than 4–5 levels.
生态系统包括生物群落与其物理环境的相互作用。食物链和食物网展示了摄食关系。能量从生产者（植物）流向消费者（草食动物、肉食动物、分解者）；每一营养级通过呼吸、热量和废物损失能量，因此食物链很少超过 4–5 个营养级。
Carbon cycle and nitrogen cycle recycle essential nutrients. Human activities like deforestation, burning fossil fuels and intensive farming increase atmospheric CO₂ and cause pollution. Conservation and sustainability help maintain biodiversity. Sampling techniques (quadrats, transects, mark-release-recapture) are used to estimate population sizes.
碳循环和氮循环回收必需营养。人类活动如砍伐森林、燃烧化石燃料和集约化农业增加了大气 CO₂ 并引起污染。保护与可持续发展有助于维持生物多样性。取样技术（样方、样带、标记-放回-重捕）用于估算种群大小。
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