📚 Year 7 WJEC Biology: Core Knowledge Summary | Year 7 WJEC 生物：核心知识点梳理
Welcome to your complete Year 7 WJEC Biology revision guide. This article brings together all the essential topics you need to know, from cells and body systems to ecosystems and healthy living. Each section is written in clear English followed by Chinese translation to help you learn and remember the key concepts.
欢迎阅读 Year 7 WJEC 生物完整复习指南。本文汇集了你需要掌握的所有核心主题，从细胞和人体系统到生态系统和健康生活。每个部分先用清晰易懂的英文书写，再配以中文翻译，帮助你学习和记忆关键概念。
1. Introduction to Cells | 细胞入门
All living organisms are made up of cells. A cell is the smallest unit of life that can carry out all life processes. Some organisms, such as bacteria, consist of just a single cell, while others, like humans, are multicellular.
所有生物体都由细胞构成。细胞是能够进行所有生命活动的最小生命单位。有些生物，如细菌，仅由一个细胞构成，而其他生物，如人类，则是多细胞的。
Plant and animal cells have many features in common. Both have a cell membrane, cytoplasm, nucleus and mitochondria. However, plant cells also have a rigid cell wall, a large permanent vacuole and chloroplasts, which are used for photosynthesis.
植物细胞和动物细胞有许多共同特征。两者都有细胞膜、细胞质、细胞核和线粒体。然而，植物细胞还有坚硬的细胞壁、一个大的中央液泡以及用于光合作用的叶绿体。
- Nucleus – controls the cell's activities and contains genetic material (DNA).
细胞核 – 控制细胞的活动并含有遗传物质 (DNA)。 - Cytoplasm – a jelly-like substance where most chemical reactions occur.
细胞质 – 一种胶状物质，是大多数化学反应发生的场所。 - Cell membrane – controls what enters and leaves the cell.
细胞膜 – 控制物质的进出。 - Mitochondria – release energy through aerobic respiration.
线粒体 – 通过有氧呼吸释放能量。 - Chloroplasts (plant cells only) – contain chlorophyll, absorb light energy for photosynthesis.
叶绿体（仅植物细胞）– 含有叶绿素，吸收光能进行光合作用。 - Cell wall (plant cells only) – made of cellulose, provides support and shape.
细胞壁（仅植物细胞）– 由纤维素组成，提供支撑并维持形状。
2. Levels of Organisation | 组织层次
In multicellular organisms, cells are organised into tissues, organs and systems. This hierarchy allows the body to perform complex functions efficiently.
在多细胞生物体内，细胞被组织成组织、器官和系统。这种层次结构使身体能够高效地执行复杂功能。
A group of similar cells working together forms a tissue. For example, muscle tissue is made of muscle cells that contract to produce movement. Different tissues combine to form an organ; the stomach is an organ containing muscle tissue, glandular tissue and epithelial tissue.
一组相似的细胞协同工作形成组织。例如，肌肉组织由能够收缩产生运动的肌细胞构成。不同的组织组合起来形成器官；胃就是一个包含肌肉组织、腺体组织和上皮组织的器官。
Organs work together in organ systems. The digestive system, for instance, includes the mouth, oesophagus, stomach, intestines and liver. All systems work together to keep the organism alive.
器官协同工作在器官系统中。例如，消化系统包括口腔、食道、胃、肠和肝脏。所有系统共同作用以维持生物体的生命。
| Level 层次 | Description 描述 | Example 举例 |
|---|---|---|
| Cell 细胞 | Basic unit of life 生命基本单位 | Muscle cell 肌细胞 |
| Tissue 组织 | Group of similar cells 一组相似细胞 | Muscle tissue 肌肉组织 |
| Organ 器官 | Made of different tissues 由不同组织构成 | Stomach 胃 |
| System 系统 | Group of organs working together 器官协同工作 | Digestive system 消化系统 |
| Organism 生物体 | All systems functioning together 所有系统共同运转 | Human 人 |
3. The Skeletal System | 骨骼系统
The skeletal system provides support, protects internal organs, allows movement and produces blood cells. Your skeleton is made of more than 200 bones connected by ligaments and cartilage.
骨骼系统提供支撑、保护内脏器官、使运动成为可能并制造血细胞。你的骨骼由 200 多块骨头通过韧带和软骨连接而成。
Bones are hard and strong because they contain calcium and phosphorus. The hollow structure of long bones, such as the femur, makes them light yet strong. Bone marrow inside some bones produces red and white blood cells.
骨骼坚硬结实，因为它们含有钙和磷。长骨（如股骨）的中空结构使其既轻又牢固。某些骨骼内部的骨髓能够制造红细胞和白细胞。
Joints are places where two or more bones meet. Freely movable synovial joints, like the knee and shoulder, contain synovial fluid to reduce friction. Ligaments hold bones together, while tendons attach muscle to bone.
关节是两块或多块骨头相遇的地方。可自由活动的滑液关节，如膝关节和肩关节，含有滑液以减少摩擦。韧带将骨与骨连接，而肌腱将肌肉连接到骨骼上。
4. Muscles and Movement | 肌肉与运动
Muscles produce movement by contracting and relaxing. They work in antagonistic pairs: when one muscle contracts, the other relaxes. The biceps and triceps in the upper arm are a classic example.
肌肉通过收缩和舒张产生运动。它们以拮抗肌对的形式工作：当一块肌肉收缩时，另一块舒张。上臂的肱二头肌和肱三头肌就是一个典型例子。
To bend your arm at the elbow, the biceps contracts and pulls on the radius bone; at the same time the triceps relaxes. To straighten the arm, the triceps contracts and the biceps relaxes. This coordinated control is managed by the nervous system.
弯曲手臂时，肱二头肌收缩并拉动桡骨；同时肱三头肌舒张。伸直手臂时，肱三头肌收缩而肱二头肌舒张。这种协调控制是由神经系统管理的。
Muscles need energy to contract. This energy is released by respiration in the mitochondria. During intense exercise, muscles may respire anaerobically, producing lactic acid which causes fatigue.
肌肉收缩需要能量。这种能量通过线粒体中的呼吸作用释放。剧烈运动时，肌肉可能进行无氧呼吸，产生乳酸，从而引起疲劳。
5. The Digestive System | 消化系统
The digestive system breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the bloodstream. Digestion involves both physical breakdown (chewing, churning) and chemical breakdown by enzymes.
消化系统将大的、不溶的食物分子分解成可以吸收进入血液的小的可溶分子。消化包括物理性分解（咀嚼、搅拌）和酶促化学分解。
Enzymes are biological catalysts that speed up digestion without being used up. Each enzyme is specific to one type of food: amylase breaks down starch into glucose, protease breaks down proteins into amino acids, and lipase works on fats.
酶是生物催化剂，能加速消化而自身不被消耗。每种酶只作用于一种食物：淀粉酶将淀粉分解为葡萄糖，蛋白酶将蛋白质分解为氨基酸，脂肪酶作用于脂肪。
The main organs of the digestive system are the mouth, oesophagus, stomach, small intestine, large intestine, and anus. Accessory organs include the salivary glands, liver and pancreas, which produce digestive juices.
消化系统的主要器官有口腔、食道、胃、小肠、大肠和肛门。附属器官包括唾液腺、肝脏和胰腺，它们产生消化液。
Absorption of digested food occurs mostly in the small intestine, whose lining is folded into villi to increase surface area. Water is absorbed in the large intestine, forming faeces.
消化后食物的吸收主要在小肠中进行，小肠内壁折叠成绒毛以增加表面积。大肠吸收水分，形成粪便。
6. The Respiratory System | 呼吸系统
The respiratory system brings oxygen into the body and removes carbon dioxide. Breathing in is called inhalation (or inspiration), and breathing out is exhalation (or expiration).
呼吸系统将氧气带入体内并排出二氧化碳。吸气称为吸入（或吸气），呼气称为呼出（或呼气）。
Air enters through the nose or mouth, passes down the trachea (windpipe), which branches into two bronchi, each leading to a lung. Inside the lungs, the bronchi divide into smaller bronchioles ending in tiny air sacs called alveoli.
空气通过鼻或口进入，沿气管向下，气管分成两支支气管，各自通向一个肺。在肺内，支气管再分为更细的细支气管，末端是被称为肺泡的微小气囊。
Gas exchange occurs in the alveoli: oxygen diffuses into the blood, and carbon dioxide diffuses out. Alveoli have thin walls, a large surface area and a rich blood supply to maximise diffusion efficiency.
气体交换在肺泡中进行：氧气扩散进入血液，二氧化碳扩散出去。肺泡壁薄、表面积大且有丰富的血液供应，以达到最大的扩散效率。
The diaphragm and intercostal muscles work together to change the volume of the chest cavity. When you inhale, the diaphragm contracts and flattens, and the ribcage expands; when you exhale, the diaphragm relaxes and the ribcage returns.
膈肌和肋间肌协同工作以改变胸腔容量。吸气时，膈肌收缩变平，胸腔扩张；呼气时，膈肌放松，胸腔恢复原位。
7. The Circulatory System | 循环系统
The circulatory system transports substances such as oxygen, nutrients, hormones and waste products around the body. It consists of the heart, blood vessels and blood.
循环系统在全身运输氧气、营养物质、激素和废物等物质。它由心脏、血管和血液组成。
The heart is a muscular organ that pumps blood. It has four chambers: two upper atria and two lower ventricles. The right side pumps deoxygenated blood to the lungs, while the left side pumps oxygenated blood to the rest of the body.
心脏是一个泵送血液的肌肉器官。它有四个腔室：两个上方的房室和两个下方的心室。右侧将缺氧血泵送至肺，左侧将富氧血泵送至全身。
Blood travels in three types of blood vessels. Arteries carry blood away from the heart under high pressure; they have thick, elastic walls. Veins return blood to the heart at lower pressure and contain valves to prevent backflow. Capillaries are tiny, thin-walled vessels where exchange of substances occurs.
血液在三种血管中流动。动脉在高压下将血液带离心脏，它们有厚而有弹性的管壁。静脉在较低压力下将血液送回心脏，并含有瓣膜以防止倒流。毛细血管是微小、壁薄的血管，是物质交换的场所。
Blood is composed of red blood cells, white blood cells, platelets and plasma. Red blood cells contain haemoglobin, which binds oxygen. Plasma carries dissolved nutrients, hormones and waste products.
血液由红细胞、白细胞、血小板和血浆组成。红细胞含有血红蛋白，能结合氧气。血浆运载溶解的营养物质、激素和废物。
8. Plant Structure and Photosynthesis | 植物结构与光合作用
Plants are producers: they make their own food using sunlight, carbon dioxide and water through photosynthesis. The equation for photosynthesis is:
植物是生产者：它们通过光合作用利用阳光、二氧化碳和水制造自己的食物。光合作用的方程式为：
Carbon dioxide + Water → Glucose + Oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
Photosynthesis takes place in the chloroplasts of plant cells, mainly in the leaves. Chlorophyll absorbs light energy, which is used to convert CO₂ and H₂O into glucose. Oxygen is released as a by-product.
光合作用在植物细胞（主要是叶片）的叶绿体中进行。叶绿素吸收光能，用于将 CO₂ 和 H₂O 转化为葡萄糖。氧气作为副产品被释放。
The structure of a leaf is adapted for photosynthesis. The upper epidermis is transparent to let light through; palisade mesophyll cells are packed with chloroplasts; spongy mesophyll has air spaces for gas diffusion; and stomata allow gases to enter and leave.
叶子的结构适应光合作用。上表皮透明，允许光线通过；栅栏组织的细胞充满叶绿体；海绵组织具有气隙供气体扩散；气孔则允许气体进出。
Plants also have transport systems: xylem carries water and minerals from roots to leaves, and phloem transports dissolved sugars from leaves to other parts of the plant.
植物也有运输系统：木质部将水和矿物质从根部输送到叶片，韧皮部将溶解的糖从叶片运输到植物其他部分。
9. Reproduction in Humans | 人类生殖
Human reproduction involves the joining of a sperm cell from the male and an egg cell (ovum) from the female. This process, called fertilisation, creates a new individual with genetic material from both parents.
人类生殖涉及来自男性的精子和来自女性的卵子（卵细胞）的结合。这一过程称为受精，产生一个拥有双亲遗传物质的新个体。
The male reproductive system includes the testes, which produce sperm and the hormone testosterone. Sperm travel through the sperm ducts and are mixed with fluids from the seminal vesicles and prostate gland to form semen.
男性生殖系统包括睾丸，它们产生精子和睾酮激素。精子通过输精管，并与来自精囊和前列腺的液体混合形成精液。
The female reproductive system includes the ovaries, which release eggs and produce oestrogen. During ovulation, an egg travels down the oviduct (fallopian tube) to the uterus, where the fertilised egg may implant.
女性生殖系统包括卵巢，它们释放卵子并产生雌激素。排卵期间，卵子沿输卵管移动至子宫，受精卵可以在子宫着床。
After fertilisation, the zygote divides and becomes an embryo, which embeds in the lining of the uterus. The placenta provides oxygen and nutrients to the developing foetus and removes waste. The foetus is protected by amniotic fluid.
受精后，合子分裂并成为胚胎，植入子宫内膜。胎盘为发育中的胎儿提供氧气和营养物质并清除废物。胎儿由羊水保护。
10. Ecosystems and Food Chains | 生态系统与食物链
An ecosystem is a community of living organisms interacting with their non-living environment. All organisms in an ecosystem rely on each other for food and energy.
生态系统是生物群落与其非生物环境相互作用的体系。生态系统中的所有生物都依靠彼此获得食物和能量。
A food chain shows how energy passes from one organism to another. It typically starts with a producer, then primary consumer, secondary consumer, tertiary consumer and sometimes a top predator. Arrows represent the direction of energy flow.
食物链显示能量如何从一个生物传递到另一个生物。它通常从生产者开始，然后是初级消费者、次级消费者、三级消费者，有时还有顶级捕食者。箭头代表能量流动的方向。
All food chains begin with producers – green plants that make glucose by photosynthesis. Consumers cannot make their own food; herbivores eat plants, carnivores eat other animals, and omnivores eat both. Decomposers, such as bacteria and fungi, break down dead material and recycle nutrients.
所有食物链都从生产者开始——通过光合作用制造葡萄糖的绿色植物。消费者不能自己制造食物；食草动物吃植物，食肉动物吃其他动物，杂食动物两者都吃。分解者，如细菌和真菌，分解死亡物质并循环养分。
In a stable ecosystem, population sizes are controlled by factors such as competition, predation and disease. Energy is lost at each trophic level, so numbers decrease along the food chain.
在稳定的生态系统中，种群大小受竞争、捕食和疾病等因素控制。能量在每个营养级都会损失，因此沿食物链数量递减。
11. Adaptations and Variation | 适应性与变异
All organisms have adaptations that help them survive in their specific habitat. These can be structural, behavioural or physiological. For example, a camel has long eyelashes to keep out sand, and a polar bear has thick fur and fat for insulation.
所有生物都具有帮助它们在特定栖息地生存的适应性。这些可以是结构性的、行为性的或生理性的。例如，骆驼有长长的睫毛来阻挡沙子，北极熊有厚实的皮毛和脂肪来保暖。
Variation is the difference between individuals of the same species. Some variation is genetic and can be inherited, such as eye colour or blood group. Other variation is caused by the environment, such as body weight or language spoken.
变异是同一物种个体之间的差异。有些变异是遗传的，可以遗传给后代，如眼睛颜色或血型。其他变异由环境引起，如体重或所说的语言。
Inherited characteristics are carried on genes, which are small sections of DNA located on chromosomes. Humans have 46 chromosomes in most cells, arranged in 23 pairs. One pair determines sex: XX for female, XY for male.
遗传特征由基因携带，基因是位于染色体上的DNA小片段。人类大多数细胞中有46条染色体，排列成23对。其中一对决定性别：XX为女性，XY为男性。
Over many generations, natural selection can lead to evolution. Organisms with variations better suited to their environment are more likely to survive and reproduce, passing on those advantageous genes.
经过许多代，自然选择可以导致进化。具有更适应环境的变异特征的个体更有可能存活和繁殖，从而将这些有利基因传递下去。
12. Health and Lifestyle | 健康与生活方式
Good health requires a balanced diet, regular exercise and avoiding harmful substances. A balanced diet includes the right amounts of carbohydrates, proteins, lipids, vitamins, minerals, water and fibre.
良好的健康需要均衡饮食、定期运动并避免有害物质。均衡饮食包括适量的碳水化合物、蛋白质、脂质、维生素、矿物质、水和纤维素。
Malnutrition can result from too little or too much food, or from a lack of specific nutrients. For example, vitamin C deficiency causes scurvy, and iron deficiency leads to anaemia. Obesity is linked to heart disease, diabetes and joint problems.
营养不良可能源于食物过少或过多，或缺乏特定营养物质。例如，缺乏维生素C会导致坏血病，缺铁会导致贫血。肥胖与心脏病、糖尿病和关节问题有关。
Regular exercise keeps the heart and lungs healthy, strengthens muscles, helps maintain a healthy weight, and can improve mental well-being. Physical activity uses energy and reduces the risk of many diseases.
定期运动有助于保持心肺健康、增强肌肉、维持健康体重，并能改善心理健康。体育活动消耗能量，降低多种疾病的风险。
Smoking damages the respiratory and circulatory systems. It causes lung cancer, chronic bronchitis and emphysema. Alcohol consumption can damage the liver and brain, and drugs can affect mood, behaviour and organ function.
吸烟损害呼吸系统和循环系统，会导致肺癌、慢性支气管炎和肺气肿。饮酒会损害肝脏和大脑，药物会影响情绪、行为和器官功能。
A healthy lifestyle also includes good hygiene, enough sleep and mental relaxation. Avoiding stress and maintaining positive relationships are important for keeping the body and mind in balance.
健康的生活方式还包括良好的卫生、充足的睡眠和精神放松。避免压力、保持积极的人际关系对维持身心平衡很重要。
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