📚 Year 9 Cambridge Biology: Vocabulary & Terminology Quick-Reference Guide | Year 9 剑桥生物：词汇术语速记指南
Mastering biology starts with knowing the language. This quick-reference guide covers the essential terms every Year 9 Cambridge Biology student must memorise, from cell structures and life processes to ecology and genetics. Each term is explained in clear English and Chinese, helping you build a strong bilingual foundation for IGCSE success.
学好生物从掌握专业语言开始。这份速记指南涵盖了 Year 9 剑桥生物课程必须记忆的核心术语，从细胞结构、生命活动到生态和遗传学。每个术语都用清晰的英文和中文解释，帮助你建立扎实的双语基础，为 IGCSE 生物考试做好准备。
1. Cells and Organisation | 细胞与组织层次
A cell is the basic structural and functional unit of all living organisms. Cells can be prokaryotic (without a nucleus) or eukaryotic (with a nucleus). Animal and plant cells are eukaryotic, while bacteria are prokaryotic.
细胞是所有生物体结构和功能的基本单位。细胞分为原核细胞（无细胞核）和真核细胞（有细胞核）。动物和植物细胞属于真核细胞，细菌属于原核细胞。
Key organelles and their functions are crucial for exams. The nucleus controls the cell and contains genetic material (DNA). Mitochondria are the sites of aerobic respiration, releasing energy. Ribosomes carry out protein synthesis. Plant cells also have a cell wall made of cellulose, a large permanent vacuole containing cell sap, and chloroplasts that absorb light energy for photosynthesis.
关键的细胞器及其功能是考试重点。细胞核控制细胞活动并含有遗传物质（DNA）。线粒体是有氧呼吸的场所，释放能量。核糖体进行蛋白质合成。植物细胞还有由纤维素构成的细胞壁、含有细胞液的大液泡，以及吸收光能进行光合作用的叶绿体。
Cells are organised into tissues (groups of similar cells working together), organs (structures made of different tissues), and organ systems (groups of organs performing a major function). For example, the digestive system includes the stomach, intestines, and liver.
细胞组织成组织（相似细胞群共同工作）、器官（由不同组织构成的结构）和器官系统（执行主要功能的器官群）。例如，消化系统包括胃、肠和肝脏。
2. Movement Across Membranes | 跨膜运输
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down the concentration gradient. It is a passive process that does not require energy. Oxygen and carbon dioxide move in and out of cells by diffusion.
扩散是粒子从高浓度区域向低浓度区域的净移动，沿浓度梯度进行。这是一种被动过程，不需要能量。氧气和二氧化碳通过扩散进出细胞。
Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane. In plant cells, osmosis causes turgor pressure, which supports the plant. If a plant cell is placed in pure water, it becomes turgid; in concentrated salt solution, it becomes plasmolysed (the cell membrane pulls away from the cell wall).
渗透是水分子通过部分透性膜从稀释溶液向较浓溶液的扩散。在植物细胞中，渗透产生膨压，为植物提供支持。如果将植物细胞放入纯水中，会变得硬挺；放入浓盐水中，会质壁分离（细胞膜从细胞壁上脱离）。
Active transport moves substances against the concentration gradient, from low to high concentration. It requires energy from respiration (ATP) and involves carrier proteins in the membrane. An example is the uptake of mineral ions by root hair cells from the soil.
主动运输是物质逆浓度梯度移动，从低浓度到高浓度。它需要呼吸作用提供的能量（ATP），并涉及膜上的载体蛋白。一个例子是根毛细胞从土壤中吸收矿质离子。
3. Biological Molecules | 生物分子
The main chemical components of living organisms are carbohydrates, proteins, lipids (fats and oils), and nucleic acids. A balanced diet must include these nutrients, along with vitamins, minerals, water, and dietary fibre.
生物体的主要化学组成是碳水化合物、蛋白质、脂质（脂肪和油）和核酸。均衡饮食必须包含这些营养素，以及维生素、矿物质、水和膳食纤维。
Carbohydrates are made of simple sugars like glucose. Starch and glycogen are polysaccharides used for energy storage in plants and animals, respectively. Proteins are made of amino acids and are needed for growth and repair. Lipids provide insulation, energy storage, and make up cell membranes.
碳水化合物由葡萄糖等单糖组成。淀粉和糖原分别是植物和动物用于能量储存的多糖。蛋白质由氨基酸构成，用于生长和修复。脂质提供绝缘、能量储存，并构成细胞膜。
Food tests help identify biological molecules: iodine solution turns blue-black with starch; Benedict's solution turns brick-red when heated with reducing sugars like glucose; biuret solution turns purple with protein; and the ethanol emulsion test gives a cloudy white layer for lipids.
食物检测有助于鉴别生物分子：碘液遇淀粉变蓝黑色；本尼迪克特溶液与还原糖（如葡萄糖）加热后变砖红色；双缩脲试剂遇蛋白质变紫色；乙醇乳浊液测试遇脂质产生白色云状层。
4. Enzymes | 酶
Enzymes are biological catalysts made of protein. They speed up chemical reactions in living organisms without being used up. Each enzyme is specific to a particular substrate, fitting like a lock and key.
酶是由蛋白质构成的生物催化剂。它们加速生物体内的化学反应而自身不被消耗。每种酶对其特定的底物具有特异性，如同锁和钥匙一样匹配。
The active site is the region on the enzyme where the substrate binds. If the shape of the active site changes, the enzyme is denatured and can no longer function. High temperature and extreme pH can cause denaturation.
活性位点是酶上结合底物的区域。如果活性位点的形状发生变化，酶就会变性，无法再起作用。高温和极端的 pH 值会导致变性。
The optimum temperature for most human enzymes is around 37 °C. At low temperatures, enzyme activity is slow because molecules have less kinetic energy. The optimum pH varies: pepsin in the stomach works best at pH 2, while most other enzymes work best near pH 7.
大多数人体酶的最适温度在 37 °C 左右。在低温下，酶活性缓慢，因为分子动能较低。最适 pH 因酶而异：胃蛋白酶在 pH 2 时活性最佳，而其他大多数酶在 pH 7 左右活性最佳。
5. Photosynthesis and Plant Nutrition | 光合作用与植物营养
Photosynthesis ion is: carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll).
光合作用是植物利用叶绿素吸收的光能，将二氧化碳和水转化为葡萄糖和氧气的过程。文字方程式：二氧化碳 + 水 → 葡萄糖 + 氧气（在光和叶绿素存在下）。
Leaves are adapted for photosynthesis: they are broad and flat to absorb light, have stomata (pores) for gas exchange, and contain chloroplasts packed with chlorophyll in the palisade mesophyll. The xylem brings water, and the phloem transports the produced sugars (translocation).
叶子适应光合作用：它们宽而扁平以吸收光，有气孔进行气体交换，在栅栏组织的叶肉细胞中含有充满叶绿素的叶绿体。木质部运输水分，韧皮部运输生成的糖类（转运作用）。
Plants use glucose for respiration, to make cellulose for cell walls, to produce starch for storage, and to form amino acids (with nitrates) and lipids. A deficiency of nitrate ions causes stunted growth; lack of magnesium ions leads to yellowing leaves (chlorosis) because magnesium is needed to make chlorophyll.
植物利用葡萄糖进行呼吸作用、制造细胞壁所需的纤维素、合成储存用的淀粉，以及（与硝酸盐一起）形成氨基酸和脂质。缺乏硝酸根离子会导致生长迟缓；缺乏镁离子则会导致叶片黄化（缺绿症），因为镁是制造叶绿素所必需的。
6. Respiration and Gas Exchange | 呼吸与气体交换
Respiration is the chemical process that releases energy from glucose in all living cells. It is not the same as breathing. Aerobic respiration gen → carbon dioxide + water (+ large amount of energy). It occurs mainly in mitochondria.
呼吸作用是所有活细胞从葡萄糖释放能量的化学过程。它与呼吸（通气）不是一回事。有氧呼吸利用氧气：葡萄糖 + 氧气 → 二氧化碳 + 水（+ 大量能量）。它主要发生在线粒体中。
Anaerobic respiration occurs when oxygen is insufficient. In yeast, it produces ethanol, carbon dioxide, and a small amount of energy (fermentation). In human muscles during vigorous exercise, it produces lactic acid, causing muscle fatigue. The debt is repaid by breathing deeply after exercise to oxidise the lactic acid.
无氧呼吸在氧气不足时发生。在酵母中，它产生乙醇、二氧化碳和少量能量（发酵）。在人体肌肉剧烈运动时，会产生乳酸，导致肌肉疲劳。运动后通过深呼吸氧化乳酸来偿还氧债。
Gas exchange in humans occurs in the alveoli of the lungs. The alveoli have a large surface area, thin walls, a moist lining, and a rich blood supply, all features that increase the rate of diffusion of oxygen into the blood and carbon dioxide out.
人体的气体交换发生在肺部的肺泡中。肺泡具有较大的表面积、薄壁、湿润的内衬和丰富的血液供应，这些特征都提高了氧气进入血液和二氧化碳排出的扩散速率。
7. Circulatory System and Blood | 循环系统与血液
The circulatory system consists of the heart, blood vessels, and blood. It transports oxygen, nutrients, hormones, and waste products. Humans have a double circulatory system: one circuit to the lungs (pulmonary) and one to the rest of the body (systemic).
循环系统由心脏、血管和血液组成。它运输氧气、营养物质、激素和废物。人类拥有双循环系统：一条循环通向肺部（肺循环），另一条通向身体其他部分（体循环）。
The heart has four chambers: right atrium, right ventricle, left atrium, left ventricle. The aorta carries oxygenated blood to the body; the vena cava returns deoxygenated blood. The pulmonary artery takes deoxygenated blood to the lungs; the pulmonary vein brings oxygenated blood back. Remember: arteries carry blood away from the heart (mostly oxygenated, except pulmonary artery); veins carry blood towards the heart (mostly deoxygenated, except pulmonary vein).
心脏有四个腔室：右心房、右心室、左心房、左心室。主动脉将含氧血输送到全身；腔静脉将缺氧血送回心脏。肺动脉将缺氧血送到肺部；肺静脉将含氧血送回心脏。记住：动脉将血液带离心脏（除肺动脉外，大多是含氧血）；静脉将血液带回心脏（除肺静脉外，大多是缺氧血）。
Blood contains red blood cells (carry oxygen with haemoglobin), white blood cells (defend against pathogens, e.g. phagocytes and lymphocytes), platelets (involved in clotting), and plasma (liquid that transports dissolved substances).
血液包含红细胞（通过血红蛋白运输氧气）、白细胞（防御病原体，如吞噬细胞和淋巴细胞）、血小板（参与凝血）和血浆（运输溶解物质的液体）。
8. Disease and Immunity | 疾病与免疫
A pathogen is a microorganism that causes disease, such as bacteria, viruses, fungi, and protists. The body has physical barriers (skin, mucus in airways), chemical defences (stomach acid, tears with lysozyme), and white blood cells.
病原体是引起疾病的微生物，如细菌、病毒、真菌和原生生物。身体具有物理屏障（皮肤、呼吸道粘液）、化学防御（胃酸、含溶菌酶的眼泪）以及白细胞。
Phagocytosis is when a phagocyte engulfs and digests pathogens. Lymphocytes produce antibodies that are specific to antigens on the pathogen's surface. This is part of the specific immune response. Memory cells remain in the body to provide long-term immunity.
吞噬作用指吞噬细胞吞噬并消化病原体。淋巴细胞产生针对病原体表面抗原的特异性抗体。这是特异性免疫应答的一部分。记忆细胞留在体内提供长期免疫。
Vaccination involves introducing a harmless form of the pathogen (containing antigens) to stimulate the production of memory cells. This means the body can respond quickly if it encounters the real pathogen later. Antibiotics only kill bacteria; they are ineffective against viruses.
接种疫苗涉及引入无害形式的病原体（含有抗原），刺激记忆细胞的产生。这意味着如果以后遇到真正的病原体，身体能快速作出反应。抗生素只能杀灭细菌，对病毒无效。
9. Ecology and Ecosystems | 生态与生态系统
An ecosystem is a unit containing all the living organisms (the community) and their non-living environment. The habitat is the place where an organism lives. A population is all members of a single species in a habitat; a community is all populations of different species living together.
生态系统是一个包含所有生物（群落）及其非生物环境的单位。栖息地是生物居住的地方。种群是栖息地中一个物种的所有成员；群落是共同生活的所有不同物种种群。
he flow of energy: producer → primary consumer → secondary consumer → tertiary consumer. A food web is a network of interconnected food chains. Organisms can be classified as producers (plants, which photosynthesise), consumers (herbivores, carnivores, omnivores), and decomposers (bacteria and fungi that break down dead matter).
食物链显示能量流动：生产者 → 初级消费者 → 次级消费者 → 三级消费者。食物网是相互连接的食物链网络。生物可分为生产者（植物，光合作用）、消费者（食草动物、食肉动物、杂食动物）和分解者（分解死物质的细菌和真菌）。
Energy is lost at each trophic level through respiration, movement, and undigested waste, which limits the length of food chains. Pyramids of numbers and biomass represent the number or mass of organisms at each level.
在每一营养级，能量通过呼吸作用、运动和未消化的废物而损失，这限制了食物链的长度。数量金字塔和生物量金字塔表示每一营养级的生物数量或质量。
10. Inheritance and Variation | 遗传与变异
DNA is the molecule that carries genetic information. A gene is a section of DNA that codes for a specific protein. Chromosomes are long, coiled molecules of DNA found in the nucleus. In humans, body cells are diploid (46 chromosomes, 23 pairs), while gametes are haploid (23 chromosomes).
DNA 是携带遗传信息的分子。基因是编码特定蛋白质的 DNA 片段。染色体是位于细胞核中的长链、盘绕的 DNA 分子。人类体细胞为二倍体（46 条染色体，23 对），而配子为单倍体（23 条染色体）。
Alleles are different versions of the same gene. A dominant allele is expressed even if only one copy is present; a recessive allele is only expressed if two copies are present. Genotype is the genetic makeup; phenotype is the observable characteristic.
等位基因是同一基因的不同版本。显性等位基因只要有一个拷贝就能表达；隐性等位基因只在有两个拷贝时才表达。基因型是遗传组成；表型是可观察的特征。
Variation can be continuous (e.g., height, where there is a range) or discontinuous (e.g., blood group, where there are distinct categories). Variation arises from genetic differences and environmental influences. Mutations are changes in DNA that can create new alleles.
变异可以是连续的（如身高，有范围）或不连续的（如血型，有明确类别）。变异源于遗传差异和环境的影响。突变是 DNA 的改变，可能产生新的等位基因。
11. Reproduction | 生殖
Asexual reproduction involves one parent and produces genetically identical offspring (clones). Examples include binary fission in bacteria, budding in yeast, and runners in plants. Sexual reproduction involves the fusion of male and female gametes to form a zygote, creating genetic variation.
无性生殖涉及一个亲本，产生遗传上相同的后代（克隆）。例子包括细菌的二分裂、酵母的出芽和植物的匍匐茎。有性生殖涉及雄配子和雌配子融合形成合子，产生遗传变异。
In flowering plants, the male gametes are in pollen grains produced by the anther. The female gametes are ovules inside the ovary. Pollination is the transfer of pollen from anther to stigma. Fertilisation occurs when the pollen nucleus fuses with the ovule nucleus; after fertilisation, the ovule becomes a seed and the ovary becomes a fruit.
在开花植物中，雄配子位于花药产生的花粉粒中。雌配子是子房内的胚珠。传粉是花粉从花药传到柱头。受精发生在花粉核与胚珠核融合时；受精后，胚珠发育成种子，子房发育成果实。
In humans, the female produces eggs in the ovaries; the male produces sperm in the testes. Fertilisation normally occurs in the oviduct (fallopian tube). The placenta allows exchange of nutrients, oxygen, and waste between mother and fetus without mixing their blood.
在人类中，女性在卵巢中产生卵子；男性在睾丸中产生精子。受精通常发生在输卵管中。胎盘允许母体和胎儿之间交换营养、氧气和废物，但二者的血液不混合。
12. Coordination and Response | 协调与反应
The nervous system coordinates responses using electrical impulses along neurones. A reflex arc nsory neurone → relay neurone in spinal cord → motor neurone → effector (muscle or gland).
神经系统通过沿神经元传导的电脉冲来协调反应。反射弧是一种快速、自动的反应，绕过意识思考：刺激 → 感受器 → 感觉神经元 → 脊髓中的联络神经元 → 运动神经元 → 效应器（肌肉或腺体）。
Hormones are chemical messengers produced by endocrine glands and transported in the blood. They have slower but longer-lasting effects. For example, adrenaline prepares the body for 'fight or flight' by increasing heart rate and blood flow to muscles. Insulin lowers blood glucose levels by converting glucose to glycogen in the liver.
激素是由内分泌腺产生并通过血液运输的化学信使。它们作用较慢但持续时间较长。例如，肾上腺素通过提高心率和肌肉血流为身体“战斗或逃跑”做准备。胰岛素通过将葡萄糖转化为肝糖原来降低血糖水平。
Homeostasis is the maintenance of a constant internal environment. Examples include regulation of body temperature (sweating, shivering), blood glucose, and water levels. Negative feedback loops reverse any change away from the set point.
稳态是维持恒定内环境。例子包括调节体温（出汗、颤抖）、血糖和水分水平。负反馈回路可以逆转任何偏离设定点的变化。
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