📚 KS3 WJEC Biology: Core Knowledge Summary | KS3 WJEC 生物：核心知识点梳理
This revision guide covers the essential topics in KS3 Biology for the WJEC curriculum. It is designed to help you understand the key concepts, from cells to ecosystems, using clear explanations and bilingual summaries.
本复习指南涵盖 WJEC 课程 KS3 阶段生物学科的核心主题。通过清晰的中英双语解释，帮助你掌握从细胞到生态系统的关键概念。
1. Cells – The Building Blocks of Life | 细胞——生命的基石
All living organisms are made of cells. Cells are the smallest units of life that can carry out all life processes.
所有生物体都由细胞构成。细胞是能进行一切生命活动的最小单位。
Animal cells contain a nucleus, cytoplasm, cell membrane, and mitochondria. Plant cells also have a cell wall, a large central vacuole, and chloroplasts, which contain chlorophyll for photosynthesis.
动物细胞含有细胞核、细胞质、细胞膜和线粒体。植物细胞还具有细胞壁、中央大液泡和含有叶绿素的叶绿体，用于光合作用。
Substances move into and out of cells by diffusion. Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient.
物质通过扩散进出细胞。扩散是指粒子从高浓度区域沿浓度梯度向低浓度区域的净移动。
2. Life Processes (MRS GREN) | 生命过程 (MRS GREN)
All living things share seven life processes, remembered by the acronym MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.
所有生物都具有七大生命过程，可用首字母缩写 MRS GREN 记忆：运动、呼吸、感应、生长、生殖、排泄和营养。
Movement is the ability to change position. Respiration releases energy from food. Sensitivity means detecting and responding to changes in the environment.
运动是指改变位置的能力。呼吸作用从食物中释放能量。感应意味着察觉并响应环境变化。
Growth is a permanent increase in size and mass. Reproduction produces offspring. Excretion removes waste products of metabolism. Nutrition is taking in and using food.
生长是体积和质量的永久性增加。生殖产生后代。排泄清除代谢废物。营养是摄取和利用食物。
3. Human Digestive System | 人体消化系统
Digestion breaks down large, insoluble food molecules into small, soluble molecules that can be absorbed into the blood.
消化将大分子、不溶性食物分解为可被血液吸收的小分子、可溶性物质。
The main organs of the digestive system are the mouth, oesophagus, stomach, small intestine, large intestine, liver, and pancreas.
消化系统的主要器官包括口腔、食道、胃、小肠、大肠、肝脏和胰腺。
Carbohydrates are broken down into simple sugars like glucose by enzymes such as amylase. Proteases break down proteins into amino acids. Lipases break down fats (lipids) into fatty acids and glycerol.
碳水化合物在淀粉酶等酶作用下分解成葡萄糖等单糖。蛋白酶将蛋白质分解为氨基酸。脂肪酶将脂肪（脂类）分解为脂肪酸和甘油。
Absorption of digested food occurs mainly in the small intestine through the walls of villi, which provide a large surface area.
消化后的食物主要在小肠通过绒毛壁被吸收，绒毛提供了很大的表面积。
4. Circulatory System and Blood | 循环系统与血液
The circulatory system transports oxygen, nutrients, hormones, and waste products around the body. It consists of the heart, blood vessels, and blood.
循环系统将氧气、营养物质、激素和废物运输至全身。它由心脏、血管和血液组成。
The heart is a muscular organ that pumps blood. It has four chambers: left atrium, left ventricle, right atrium, and right ventricle.
心脏是一个泵血的肌肉器官。它有四个腔室：左心房、左心室、右心房和右心室。
Arteries carry blood away from the heart at high pressure. Veins return blood to the heart at lower pressure and contain valves to prevent backflow. Capillaries are tiny vessels where exchange of substances occurs.
动脉在高压下将血液从心脏运出。静脉在较低压力下将血液送回心脏，并含有防止回流的瓣膜。毛细血管是进行物质交换的微小血管。
Blood contains red blood cells (carry oxygen using haemoglobin), white blood cells (fight infection), platelets (help clotting), and plasma (liquid that transports dissolved substances).
血液包含红细胞（利用血红蛋白运输氧气）、白细胞（抵抗感染）、血小板（帮助凝血）和血浆（运输溶解物质的液体）。
5. Respiratory System and Gas Exchange | 呼吸系统与气体交换
The respiratory system allows oxygen to enter the blood and carbon dioxide to leave. Breathing involves the movement of the diaphragm and ribs to change the volume of the chest cavity.
呼吸系统使氧气进入血液、二氧化碳排出。呼吸涉及膈肌和肋骨的运动，以改变胸腔容积。
Air enters through the trachea, which splits into two bronchi leading to each lung. The bronchi divide into smaller bronchioles, ending in tiny air sacs called alveoli.
空气通过气管进入，气管分支为两条支气管分别通向两肺。支气管再分成更小的细支气管，末端是微小的气囊——肺泡。
Gas exchange happens in the alveoli. Oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli to be breathed out.
气体交换在肺泡中进行。氧气从肺泡扩散进入血液，二氧化碳从血液扩散进入肺泡被呼出。
Alveoli are adapted for gas exchange by having thin walls, a moist surface, and a rich supply of capillaries, which provide a large surface area and short diffusion distance.
肺泡适应气体交换的特征包括：壁薄、表面湿润、有丰富的毛细血管网，这提供了巨大的表面积和较短的扩散距离。
6. Human Reproduction | 人类的生殖
Human reproduction involves the fusion of a male sex cell (sperm) and a female sex cell (egg) during fertilisation to form a zygote.
人类生殖涉及男性性细胞（精子）与女性性细胞（卵子）在受精过程中融合，形成受精卵。
The male reproductive system includes the testes (produce sperm and testosterone), sperm ducts, prostate gland, and penis. The female system includes the ovaries (produce eggs, oestrogen, and progesterone), oviducts, uterus, cervix, and vagina.
男性生殖系统包括睾丸（产生精子和睾酮）、输精管、前列腺和阴茎。女性系统包括卵巢（产生卵子、雌激素和孕激素）、输卵管、子宫、宫颈和阴道。
The menstrual cycle prepares the uterus lining for possible pregnancy. If fertilisation does not occur, the thickened lining is shed during menstruation.
月经周期为子宫内膜增厚做准备，以备可能怀孕。若未发生受精，增厚的内膜在月经期间脱落。
After fertilisation, the zygote divides and implants in the uterus. The placenta forms, allowing exchange of oxygen, nutrients, and waste between mother and baby without mixing their blood.
受精后，受精卵分裂并植入子宫。胎盘形成，可在母体和胎儿之间交换氧气、营养物质和废物，但两者的血液不会混合。
7. Plants – Photosynthesis and Reproduction | 植物——光合作用与生殖
Photosynthesis is the process by which green plants produce glucose and oxygen from carbon dioxide and water using light energy, captured by chlorophyll.
光合作用是绿色植物利用被叶绿素捕获的光能，将二氧化碳和水转化为葡萄糖和氧气的过程。
+ water → glucose + oxygen. The balanced symbol equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
文字方程式为：二氧化碳 + 水 → 葡萄糖 + 氧气。配平的化学方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。
Plants also respire, breaking down glucose to release energy for growth and other life processes. Photosynthesis only occurs in the presence of light, while respiration occurs continuously.
植物也进行呼吸作用，分解葡萄糖以释放能量，供给生长和其他生命过程。光合作用只在有光时进行，而呼吸作用持续进行。
Plants can reproduce sexually through flowers. Pollination transfers pollen from an anther to a stigma. Fertilisation leads to seed and fruit formation. Seeds are dispersed by wind, water, animals, or explosion.
植物可通过花进行有性生殖。授粉将花粉从花药传到柱头。受精后形成种子和果实。种子通过风、水、动物或弹射传播。
8. Ecosystems and Food Chains | 生态系统与食物链
An ecosystem consists of a community of living organisms interacting with each other and their non-living (abiotic) environment.
生态系统由相互作用的生物群落及其非生物环境组成。
Food chains show the feeding relationships and energy flow in an ecosystem. Producers (green plants) convert light energy into chemical energy via photosynthesis.
食物链显示了生态系统中的捕食关系和能量流动。生产者（绿色植物）通过光合作用将光能转化为化学能。
Primary consumers (herbivores) eat producers. Secondary consumers (carnivores) eat primary consumers. Tertiary consumers eat secondary consumers. Decomposers break down dead organisms, recycling nutrients.
初级消费者（草食动物）吃生产者。次级消费者（肉食动物）吃初级消费者。三级消费者吃次级消费者。分解者分解死去的生物，使营养循环利用。
Energy is lost at each trophic level through heat, movement, and waste, which limits the length of food chains. Pyramids of number and biomass represent the structure of feeding relationships.
能量在每一营养级因热量、运动、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可以表示食物链的结构。
9. Variation and Classification | 变异与分类
Variation refers to the differences between individuals of the same species. It can be caused by genetic factors, environmental factors, or a combination of both.
变异是指同种个体之间的差异。变异可由遗传因素、环境因素或两者共同引起。
Continuous variation shows a full range of differences (e.g., height), while discontinuous variation has clear, distinct groups (e.g., blood type).
连续变异呈现完整的差异范围（如身高），而非连续变异表现为明显的、截然不同的类别（如血型）。
Organisms are classified into groups based on similar characteristics. The main kingdoms are Animals, Plants, Fungi, Prokaryotes (bacteria), and Protoctists.
生物根据相似的特征被分类。主要界包括动物界、植物界、真菌界、原核生物界（细菌）和原生生物界。
Within the animal kingdom, vertebrates are classified into five groups: mammals, birds, reptiles, amphibians, and fish. They share features like a backbone and internal skeleton.
在动物界中，脊椎动物分为五类：哺乳动物、鸟类、爬行动物、两栖动物和鱼类。它们共同拥有脊柱和内骨骼等特征。
10. Microorganisms and Health | 微生物与健康
Microorganisms (microbes) are tiny living things that can only be seen under a microscope. They include bacteria, viruses, and some fungi and protoctists.
微生物是只能在显微镜下看到的微小生物。它们包括细菌、病毒以及部分真菌和原生生物。
Some microbes are harmful and cause infectious diseases. Pathogens can enter the body through cuts, the air, contaminated food or water, or direct contact.
有些微生物是有害的，会引起传染病。病原体可通过伤口、空气、受污染的食物或水或直接接触进入人体。
The human body has several defence mechanisms: the skin, mucus in airways, stomach acid, and white blood cells that engulf pathogens or produce antibodies.
人体有多种防御机制：皮肤、气道中的黏液、胃酸，以及能吞噬病原体或产生抗体的白细胞。
Vaccination involves introducing a weakened or inactive form of a pathogen to stimulate the body's immune system to produce memory cells, providing long-term protection.
疫苗接种通过引入减毒或灭活的病原体，刺激人体免疫系统产生记忆细胞，从而提供长期保护。
Good hygiene, cooking food thoroughly, and safe water help prevent the spread of harmful microorganisms.
良好的卫生习惯、彻底煮熟食物以及确保饮水安全有助于防止有害微生物的传播。
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