📚 Year 9 AQA Biology: Core Knowledge Review | Year 9 AQA 生物：核心知识点梳理
In Year 9 AQA Biology, you begin to explore the living world in a systematic way – from the microscopic building blocks of life to the complex interactions within ecosystems. This article brings together all the essential topics you need to master, helping you build a solid foundation for GCSE. Each section combines clear explanations with practical examples so you can check your understanding and spot any gaps before moving forward.
在 Year 9 AQA 生物课程中，你将开始系统地探索生命世界——从微观的生命基石到生态系统中的复杂相互作用。本文汇总了你需要掌握的所有核心知识，帮助你为 GCSE 打下扎实基础。每个部分都将清晰的概念讲解与贴近生活的实例相结合，方便你检验自己的理解，并在继续学习前发现薄弱环节。
1. The Building Blocks of Life: Cells | 生命的基石：细胞
All living organisms are made up of cells. A cell is the smallest unit of life that can carry out all life functions. There are two main types of cells – prokaryotic cells (like bacteria), which lack a true nucleus, and eukaryotic cells (like those of animals, plants and fungi), which have a distinct nucleus containing DNA.
所有的生物体都由细胞构成。细胞是能够执行所有生命活动的最小生命单位。细胞主要分为两种类型——原核细胞（如细菌），它们没有真正的细胞核；真核细胞（如动物、植物和真菌细胞），它们拥有一个包含 DNA 的明显细胞核。
Animal cells have a cell membrane, cytoplasm, a nucleus and mitochondria. Plant cells have all these parts plus a rigid cell wall, a large permanent vacuole and often chloroplasts, which trap light energy for photosynthesis. Fungal cells also have a cell wall, but it is made of chitin rather than cellulose.
动物细胞具有细胞膜、细胞质、细胞核和线粒体。植物细胞除了这些结构外，还有坚韧的细胞壁、一个大型中央液泡，以及通常含有用于捕获光能以进行光合作用的叶绿体。真菌细胞也有细胞壁，但其成分是几丁质而非纤维素。
opes can magnify up to ×2 000 000 and reveal much finer detail, such as the internal structure of mitochondria.
显微镜让我们能够看到细胞。光学显微镜利用光线和透镜在学校实验室中可将标本放大约 400 倍。电子显微镜可放大至约 200 万倍，能显示出更细微的结构，例如线粒体的内部构造。
2. Cell Organization: Tissues, Organs and Systems | 细胞的层级结构：组织、器官和系统
Cells with a similar structure and function are grouped together to form a tissue. Examples include muscle tissue, which contracts to bring about movement, and xylem tissue in plants, which transports water and mineral ions.
结构和功能相似的细胞聚集在一起形成组织。例如肌肉组织通过收缩产生运动，植物中的木质部组织负责运输水分和矿质离子。
Tissues work together to form an organ. The stomach is an organ containing muscular tissue to churn food, glandular tissue to release enzymes, and epithelial tissue to line its inside. In plants, a leaf is an organ containing mesophyll tissue for photosynthesis, and epidermal tissue to protect the surface.
不同的组织共同构成一个器官。胃是一个器官，它包含用于搅拌食物的肌肉组织、释放酶类的腺体组织，以及内衬表面的上皮组织。在植物中，叶是器官，包含进行光合作用的叶肉组织和起保护作用的表皮组织。
Organs are organized into organ systems that perform a major life function. The digestive system includes the mouth, oesophagus, stomach, intestines and glands like the pancreas. The shoot system of a plant includes leaves, stems and flowers.
器官进一步组成器官系统，负责完成一项主要的生命功能。消化系统包括口腔、食道、胃、肠道以及胰腺等腺体。植物的地上部分系统包括叶、茎和花。
3. Life Processes and Specialized Cells | 生命活动与特化细胞
All living things share seven life processes, often remembered as MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition. Even single-celled organisms like amoeba carry out all these processes within one cell.
所有生物共有的七项生命活动，通常记作 MRS GREN（运动、呼吸、感知、生长、繁殖、排泄和营养）。即使是变形虫这样的单细胞生物，也能在一个细胞内完成所有这些过程。
In multicellular organisms, cells become specialized to perform particular jobs. A sperm cell has a long tail (flagellum) for swimming, many mitochondria for energy, and an acrosome containing enzymes to penetrate the egg. A nerve cell has an elongated axon and branched endings to transmit electrical impulses quickly over long distances.
在多细胞生物中，细胞会发生特化以执行特定的任务。精子细胞拥有长尾（鞭毛）用于游动、大量线粒体提供能量，以及含有酶的顶体用以穿透卵子。神经细胞拥有细长的轴突和分支状的末梢，能够远距离快速传导电信号。
In plants, root hair cells have a large surface area to absorb water and minerals efficiently. Xylem vessels are dead cells with hollow, lignified walls that form continuous tubes for water transport. Phloem cells are alive and transport sugars made in photosynthesis to other parts of the plant.
在植物中，根毛细胞具有巨大的表面积以高效吸收水分和矿物质。木质部导管是由死细胞构成的、具有中空且木质化管壁的连续管道，用于输导水分。韧皮部细胞是活细胞，负责将光合作用制造的糖类转运到植物的其他部分。
4. The Digestive System | 消化系统
Digestion breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. Mechanical digestion happens when teeth chew food into smaller pieces, increasing the surface area for enzymes to work on. Chemical digestion uses enzymes to break down specific nutrients.
消化作用将大而不可溶的食物分子分解为小而可溶的分子，以便被吸收进入血液。口腔中牙齿将食物咀嚼成更小的碎块属于物理性消化，增大了酶作用的表面积。化学性消化则利用酶来分解特定的营养物质。
Carbohydrates are broken down by amylase into simple sugars like glucose. Amylase is produced in the salivary glands, pancreas and small intestine. Proteins are digested by protease enzymes into amino acids. Proteases work best in the acidic conditions of the stomach and the alkaline conditions of the small intestine. Lipids (fats) are broken down by lipase into fatty acids and glycerol. Bile, made in the liver and stored in the gall bladder, emulsifies fats to increase their surface area for lipase action.
碳水化合物被淀粉酶分解为葡萄糖等单糖。淀粉酶由唾液腺、胰腺和小肠分泌。蛋白质被蛋白酶分解为氨基酸。蛋白酶在胃里的酸性环境和小肠里的碱性环境中活性最佳。脂质（脂肪）则被脂肪酶分解为脂肪酸和甘油。肝脏制造的胆汁储存在胆囊中，它可乳化脂肪，增大表面积以利于脂肪酶发挥作用。
The small intestine is the main site of absorption. Its inner lining is folded into villi, which have a very large surface area, a thin wall (one cell thick) and a good blood supply, allowing efficient diffusion of nutrients into the blood. The large intestine absorbs water and forms faeces.
小肠是吸收的主要场所。其内壁突起形成绒毛，极大地增加了表面积，绒毛壁非常薄（仅一个细胞厚）且血液供应丰富，使营养物质能高效地扩散进入血液。大肠吸收水分并形成粪便。
5. The Respiratory System | 呼吸系统
Respiration releases energy from glucose. It is not the same as breathing. Breathing is the movement of air into and out of the lungs. Respiration is a chemical reaction that happens inside every living cell.
呼吸作用从葡萄糖中释放能量，它与呼吸（换气）是不同的概念。呼吸/换气指的是空气进出肺部的运动，而呼吸作用（细胞呼吸）是发生在每一个活细胞内部的化学反应。
The main organs of the respiratory system are the trachea, bronchi, bronchioles and alveoli. Air passes through the trachea, which is supported by rings of cartilage, into the bronchi and then into smaller bronchioles, finally reaching tiny air sacs called alveoli.
呼吸系统的主要器官包括气管、支气管、细支气管和肺泡。空气经由软骨环支撑的气管进入支气管，再进入更细的细支气管，最终到达称为肺泡的微小气囊。
Gas exchange takes place in the alveoli. Alveoli have a very large surface area, thin walls (one cell thick), a moist lining and a dense network of capillaries. Oxygen diffuses from the air in the alveoli into the blood, while carbon dioxide diffuses in the opposite direction. The overall equation for aerobic respiration is:
glucose + oxygen → carbon dioxide + water (+ energy)
气体交换发生在肺泡中。肺泡具有极大的表面积、极薄的壁（仅一个细胞厚）、湿润的内壁和密集的毛细血管网。氧气从肺泡内的空气扩散进入血液，而二氧化碳则沿相反方向扩散。有氧呼吸的总反应式如下：
葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）
During exercise, muscles need more energy, so breathing rate and depth increase to supply more oxygen and remove extra carbon dioxide. Anaerobic respiration can occur for short periods without oxygen, producing lactic acid in muscles, but it releases far less energy.
运动时，肌肉需要更多能量，因此呼吸频率和深度都会增加，以提供更多氧气并排出多余的二氧化碳。在缺氧情况下，肌肉可短暂进行无氧呼吸，产生乳酸，但这种方式释放的能量要少得多。
6. The Circulatory System | 循环系统
The human circulatory system consists of the heart, blood vessels and blood. It transports oxygen, nutrients, hormones and waste products around the body. The heart is a double pump – the right side pumps deoxygenated blood to the lungs, while the left side pumps oxygenated blood to the rest of the body.
人体的循环系统由心脏、血管和血液组成。它负责将氧气、营养物质、激素和废物运送至全身各处。心脏像是一个双泵——右心将缺氧血泵至肺部，左心则将富氧血泵至身体的其他部分。
The heart has four chambers: two atria (upper) and two ventricles (lower). Valves prevent blood from flowing backwards. The natural pacemaker controls the resting heart rate. Arteries carry blood away from the heart under high pressure; they have thick, elastic muscular walls. Veins carry blood back toward the heart under lower pressure and have valves to prevent backflow. Capillaries are tiny vessels with walls only one cell thick, where exchange of materials with tissues occurs.
心脏有四个腔室：两个心房（上方）和两个心室（下方）。瓣膜可防止血液倒流。心脏的天然起搏器控制着静息心率。动脉在高压下将血液带离心脏，其管壁厚实且富有弹性。静脉在较低的压力下将血液送回心脏，并具有防止血液倒流的瓣膜。毛细血管是极细的血管，管壁仅一个细胞厚，是血液与组织间物质交换的场所。
Blood is a tissue made up of plasma, red blood cells, white blood cells and platelets. Red blood cells contain haemoglobin, a protein that binds oxygen. They have a biconcave shape and no nucleus, which increases the space for haemoglobin. White blood cells are part of the immune system, and platelets help blood to clot.
血液是一种组织，由血浆、红细胞、白细胞和血小板组成。红细胞含有血红蛋白，这种蛋白质能与氧气结合。红细胞呈双凹圆盘状且无细胞核，从而为血红蛋白腾出更多空间。白细胞是免疫系统的一部分，血小板则有助于血液凝固。
7. Plant Structure and Photosynthesis | 植物结构与光合作用
Plants are autotrophs – they make their own food using light energy. The main photosynthetic organ is the leaf. A leaf is broad and flat to capture maximum light. Its internal structure includes a waxy cuticle, upper and lower epidermis, palisade mesophyll packed with chloroplasts, spongy mesophyll with air spaces, and stomata (tiny pores) on the lower surface.
植物是自养生物——它们利用光能制造自己的食物。叶片是进行光合作用的主要器官。叶片宽大而扁平，以最大限度地捕获光线。其内部结构包括蜡质角质层、上下表皮、富含叶绿体的栅栏组织、具有气隙的海绵组织，以及下表皮上的气孔（微小的孔隙）。
Photosynthesis uses carbon dioxide and water, in the presence of light and chlorophyll, to produce glucose and oxygen. The word equation is:
carbon dioxide + water → glucose + oxygen
光合作用利用二氧化碳和水，在光能和叶绿素的参与下，产生葡萄糖和氧气。其文字方程式如下：
二氧化碳 + 水 → 葡萄糖 + 氧气
Glucose is used by the plant for respiration, converted into starch for storage, or used to make cellulose for cell walls and other organic molecules like proteins and lipids. Mineral ions such as nitrates are needed to make amino acids and proteins; magnesium ions are needed to make chlorophyll.
葡萄糖可供植物进行呼吸作用，也可转化为淀粉储存起来，或用于制造细胞壁的纤维素以及其他有机分子（如蛋白质和脂质）。植物需要硝酸盐等矿质离子来合成氨基酸和蛋白质，需要镁离子来合成叶绿素。
8. Reproduction in Humans | 人类的生殖
Reproduction is essential for the survival of a species, though not for the survival of an individual. Humans reproduce sexually, which involves the fusion of male and female gametes to produce genetically unique offspring.
生殖对于物种的延续至关重要，但对个体生存而言并非必需。人类进行有性生殖，即通过雄性和雌性配子的结合，产生遗传上独一无二的后代。
The male reproductive system produces sperm in the testes. Sperm travel through the sperm duct and are mixed with fluids from the prostate gland and seminal vesicles to form semen. The female reproductive system releases eggs from the ovaries. Once every month, an egg is released (ovulation) and travels down the oviduct (fallopian tube) toward the uterus.
男性生殖系统在睾丸中产生精子。精子经过输精管，与前列腺和精囊腺分泌的液体混合形成精液。女性生殖系统从卵巢中排出卵子。每个月会有一枚卵子被释放（排卵），并沿着输卵管向子宫移动。
Fertilization happens when the nucleus of a sperm fuses with the nucleus of an egg in the oviduct. The fertilized egg (zygote) divides to form a ball of cells called an embryo, which implants into the lining of the uterus. The placenta allows exchange of nutrients, oxygen and waste between the mother and the developing embryo, while the amniotic fluid protects it from shocks.
当精子的细胞核与卵子的细胞核在输卵管内融合时，便发生了受精。受精卵（合子）不断分裂形成一个细胞球——胚胎，随后植入子宫内膜。胎盘负责母体与发育中的胚胎之间营养物质、氧气和废物的交换，而羊水则保护胚胎免受振动与冲击。
9. Health and Disease | 健康与疾病
Health is a state of complete physical, mental and social well-being, not just the absence of disease. Diseases can be communicable (caused by pathogens that can spread from person to person) or non-communicable (not passed between individuals, often linked to lifestyle or genetics).
健康不仅是没有疾病，而是一种身体、心理和社会适应方面的完全良好状态。疾病可分为传染性疾病（由可在人与人之间传播的病原体引起）和非传染性疾病（不会在个体间传播，通常与生活方式或遗传因素相关）。
Pathogens include viruses, bacteria, fungi and protists. The body defends itself with physical barriers like skin and mucus, and with the immune system. White blood cells can engulf pathogens (phagocytosis) or produce antibodies that lock onto antigens on the pathogen surface, marking them for destruction. Antibodies are specific to one type of pathogen.
病原体包括病毒、细菌、真菌和原生生物。人体通过皮肤、黏液等物理屏障，以及免疫系统进行自我防御。白细胞能够吞噬病原体（吞噬作用），或产生抗体，抗体会与病原体表面的抗原结合，标记出需要消灭的入侵者。抗体对某种病原体具有高度专一性。
Vaccination introduces a harmless form of a pathogen (or its antigens) to trigger an immune response. Memory cells remain in the blood for a long time, allowing a much faster and stronger response if the real pathogen invades later. This is how we gain immunity to diseases like measles or polio.
疫苗接种是向人体引入一种无害形式的病原体（或其抗原）以触发免疫应答。记忆细胞会长时间存留于血液中，如果日后真正的病原体入侵，就能产生更快、更强的应答。这就是我们获得对麻疹或脊髓灰质炎等疾病免疫力的原理。
Non-communicable diseases include heart disease, type 2 diabetes and some cancers. Risk factors include smoking, obesity, lack of exercise and an unhealthy diet high in saturated fat and sugar. Understanding these risk factors helps us make healthier lifestyle choices.
非传染性疾病包括心脏病、2 型糖尿病和部分癌症。危险因素包括吸烟、肥胖、缺乏运动以及富含饱和脂肪和糖分的不健康饮食。了解这些危险因素有助于我们做出更健康的生活方式选择。
10. Ecosystems and Food Chains | 生态系统与食物链
An ecosystem is a community of living organisms interacting with each other and their physical environment. It includes both biotic factors (living) and abiotic factors (non-living, such as temperature, light and water).
生态系统是由生物群体与其物理环境相互影响、相互作用构成的统一整体。它既包含生物因素（有生命的），也包含非生物因素（无生命的，如温度、光照和水分）。
In any ecosystem, energy enters through photosynthesis in producers (mainly green plants). Feeding relationships can be shown in a food chain.
grass → rabbit → fox
在任何一个生态系统中，能量都经由生产者（主要是绿色植物）的光合作用进入。食物链可以表示生物之间的摄食关系。
草 → 兔 → 狐狸
The arrows in a food chain show the direction of energy transfer. Producers are at the first trophic level, primary consumers at the second, secondary consumers at the third, and so on. Predators kill and eat other animals; prey are the animals that are eaten.
食物链中的箭头表示能量传递的方向。生产者处于第一营养级，初级消费者是第二营养级，次级消费者是第三营养级，依此类推。捕食者猎杀并吃掉其他动物，而被吃掉的动物则为猎物。
Within a community, populations of predators and prey often follow a cyclical pattern: as prey numbers increase, there is more food for predators, so predator numbers also rise; then prey numbers fall due to more predation, causing predator numbers to drop, and the cycle continues.
在群落内部，捕食者和猎物的种群数量常常呈周期性变化：猎物数量增多，捕食者获得更多食物，其数量随之增加；随后由于捕食压力加大，猎物数量下降，捕食者数量也随之减少，如此形成循环。
All organisms take in materials from their environment and return them through processes such as decay. Microorganisms like bacteria and fungi are decomposers – they break down dead organic matter, returning important nutrients to the soil for producers to use again.
所有生物都从环境中摄取物质，又通过腐烂等过程将其归还。细菌和真菌等微生物属于分解者——它们将死亡的有机物质分解，使重要的营养元素回归土壤，供生产者再次利用。
11. Inheritance and Variation | 遗传与变异
Offspring inherit characteristics from their parents through genes, which are sections of DNA found on chromosomes in the nucleus. Humans have 23 pairs of chromosomes (46 in total) in most body cells. Gametes (sperm and egg) contain only one set of 23 chromosomes, so that at fertilization the normal number is restored.
子女通过基因从父母那里获得性状，基因是位于细胞核中染色体上的 DNA 片段。人类的多数体细胞含有 23 对染色体（共 46 条）。配子（精子和卵子）中只含一套 23 条染色体，以便在受精时恢复正常的染色体数目。
Some characteristics are determined by a single gene, but most are influenced by several genes working together, often along with environmental factors. Variations within a species can be genetic (inherited), environmental (caused by surroundings) or a combination of both.
部分性状由单个基因决定，但大多数性状是由多个基因共同作用，并且常与环境因素共同影响的结果。物种内的变异可以是遗传的（可遗传）、环境的（由生活环境造成）或两者共同导致的。
Mutations are random changes in the DNA sequence. They can have no effect, be harmful, or very occasionally give an advantage in a particular environment. This is the basis of natural selection: individuals with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation.
基因突变是 DNA 序列中随机发生的改变。它们可能没有影响，也可能有害，在极少情况下还能为特定环境下的个体提供优势。这便是自然选择的基础：具有有利性状的个体更可能生存和繁殖，并将这些性状传给后代。
12. Key Practical Skills and Scientific Thinking | 核心实验技能与科学思维
Throughout Year 9, you will develop practical skills that are central to biology. This includes using a light microscope correctly – starting with the lowest power objective lens, turning the coarse focusing knob first, then using the fine focus – and being able to draw and label cell diagrams accurately.
在整个 Year 9 阶段，你将培养对生物学至关重要的实验技能。这包括正确使用光学显微镜——先从低倍物镜开始，先用粗准焦螺旋，再用细准焦螺旋调焦——以及能够准确绘制并标注细胞图。
You will also design investigations to test how a factor affects a biological process. For example, you might investigate how temperature influences the activity of amylase on starch, using iodine solution to monitor the reaction. A fair test requires you to change only one independent variable, keep all other variables constant, and measure the dependent variable accurately.
你还将设计实验来探究某一因素如何影响生物过程。例如，你可能会探究温度如何影响淀粉酶对淀粉的作用，并使用碘液来监测反应进程。公平测试要求你只改变一个自变量，让所有其他变量保持不变，并准确测量因变量。
Presenting results in tables and graphs is essential. Line graphs are used for continuous data (e.g., time, temperature), while bar charts are for categoric data (e.g., different types of sugar). You should be able to describe patterns, identify anomalous results and draw conclusions supported by evidence. Evaluating the method and suggesting improvements are also key parts of the practical cycle.
用表格和图表呈现结果是基本能力。线形图适用于连续型数据（如时间、温度），柱形图则适用于分类型数据（如不同种类的糖）。你应当能够描述规律、识别异常数据，并基于证据得出结论。对实验方法进行评估并提出改进建议，也是实验循环中的重要环节。
Safety is paramount. Always wear eye protection when using solutions like iodine or when heating substances. Know the hazard symbols and follow your teacher’s instructions. Good scientific thinking means being curious, critical and careful with evidence.
安全永远是第一位的。在使用碘液等溶液或加热物质时，务必佩戴护目镜。认识各种危险品标志并听从老师的指导。好的科学思维意味着保持好奇心、批判精神和对证据的严谨态度。
Published by TutorHao | Biology Revision Series | aleveler.com
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