📚 Core Knowledge Review of Year 7 Cambridge Biology | Year 7 Cambridge 生物：核心知识点梳理
Year 7 Cambridge Biology introduces students to the fundamental concepts of life science, laying the groundwork for future studies. From understanding what makes something alive to exploring cells, organ systems, ecosystems, and plant biology, this stage builds both knowledge and scientific skills. The following revision guide covers all essential topics, providing clear explanations and key facts to help students consolidate their learning.
Year 7 剑桥生物带领学生走进生命科学的基础世界，为后续学习打下坚实基础。从认识什么是生命，到探究细胞、器官系统、生态系统以及植物生物学，这个阶段既积累知识也培养科学技能。下面的复习指南涵盖了所有核心主题，用清晰的解释和关键事实帮助同学们巩固所学内容。
1. Characteristics of Living Things | 生物的特征
All living organisms share seven life processes, commonly summarised by the acronym MRS GREN. Movement refers to an organism’s ability to change place or position. Respiration is the chemical reaction that releases energy from food. Sensitivity means detecting and responding to changes in the surroundings. Growth is a permanent increase in size and mass. Reproduction is the production of offspring. Excretion removes waste products of metabolism. Nutrition is the intake of materials for energy and growth.
所有生物都具备七大生命过程，常以首字母缩写 MRS GREN 来记忆。运动指生物改变位置的能力；呼吸作用是从食物中释放能量的化学反应；感应性是对环境变化进行探测并作出反应；生长是体积和质量的水久增加；生殖产生后代；排泄清除代谢废物；营养则是摄取物质以获取能量和生长。
For example, a rabbit runs (movement), breathes to release energy (respiration), reacts to danger (sensitivity), grows from a young to adult (growth), gives birth to live young (reproduction), excretes urine (excretion), and eats grass (nutrition). A plant bends towards light (movement and sensitivity), respires day and night, increases in height, produces seeds, excretes oxygen, and absorbs minerals.
例如，兔子奔跑（运动），呼吸释放能量（呼吸作用），对危险作出反应（感应性），从幼体长大为成体（生长），产下活仔（生殖），排尿（排泄），吃草（营养）。植物向光弯曲（运动和感应性），昼夜呼吸，长高，产生种子，排出氧气，吸收矿物质。
2. Cells – The Building Blocks of Life | 细胞——生命的基本单位
All living organisms are made of cells. Animal cells typically contain a cell membrane, cytoplasm, nucleus, and mitochondria. The cell membrane controls what enters and leaves the cell; cytoplasm is where chemical reactions occur; the nucleus contains genetic material; and mitochondria release energy through respiration.
所有生物都由细胞构成。动物细胞通常包括细胞膜、细胞质、细胞核和线粒体。细胞膜控制物质的进出；细胞质是化学反应发生的场所；细胞核含有遗传物质；线粒体通过呼吸作用释放能量。
Plant cells have the same basic parts as animal cells, plus three extra structures: a rigid cell wall made of cellulose, which provides support; chloroplasts that contain chlorophyll for photosynthesis; and a large permanent vacuole filled with cell sap, which helps maintain turgor.
植物细胞除了具备动物细胞的基本结构外，还有三种额外结构：由纤维素组成的坚哽细胞壁，提供支撑；含有叶绿素的叶绿体，进行光合作用；一个充满细胞液的大液泡，帮助保持紧涨状态。
| Structure (结构) | Animal Cell (动物细胞) | Plant Cell (植物细胞) |
| Cell membrane 细胞膜 | Yes 有 | Yes 有 |
| Cytoplasm 细胞质 | Yes 有 | Yes 有 |
| Nucleus 细胞核 | Yes 有 | Yes 有 |
| Mitochondria 线粒体 | Yes 有 | Yes 有 |
| Cell wall 细胞壁 | No 无 | Yes 有 |
| Chloroplasts 叶绿体 | No 无 | Yes 有 |
| Large vacuole 大液泡 | No 无 | Yes 有 |
To study cells, a light microscope is used. The total magnification is calculated by multiplying the eyepiece lens magnification by the objective lens magnification. It is important to handle slides carefully and follow the rules for focusing.
观察细胞要使用光学显微镜。总放大倍数等于目镜放大倍数乘以物镜放大倍数。操作时要小心移动玻片，并遵守调焦规则。
3. Classification of Living Organisms | 生物的分类
Scientists classify organisms to identify and study them more easily. The largest groups are kingdoms; further divisions include phylum, class, order, family, genus, and species. Year 7 focuses on the animal kingdom, especially vertebrates, and simple plant classification.
科学家将生物分类以便更好地识别和研究。最大的分类群是界，之下依次为门、纲、目、科、属、种。Year 7 主要学习动物界，特别是脊椎动物，以及简单的植物分类。
Vertebrates are animals with a backbone. They are divided into five main classes: fish, amphibians, reptiles, birds, and mammals. Each class has distinct features related to body covering, reproduction, and temperature regulation.
脊椎动物是有脊柱的动物，分为五大类：鱼类、两栖类、爬行类、鸟类和哺乳类。每一类在体表覆盖物、生殖方式和体温调节上都有明显特征。
| Class (纲) | Features (特征) | Examples (例子) |
| Fish 鱼类 | Wet scales, gills, lay eggs in water 湿滑鳞片，鳃，在水中产卵 | Salmon, shark 鲑鱼，鲨鱼 |
| Amphibians 两栖类 | Moist skin, lay eggs in water, aquatic larvae 潮湿皮肤，在水中产卵，幼体水生 | Frog, salamander 青蛙，蝾螈 |
| Reptiles 爬行类 | Dry scaly skin, lay leathery eggs on land 干燥鳞片皮肤，在陆地产革质卵 | Snake, lizard 蛇，蜥蜴 |
| Birds 鸟类 | Feathers, beak, lay hard-shelled eggs, warm-blooded 羽毛，喙，产硬壳卵，恒温 | Eagle, penguin 鹰，企鹅 |
| Mammals 哺乳类 | Hair or fur, feed young with milk, warm-blooded 毛发，用乳汁哺育幼体，恒温 | Human, whale 人类，鲸 |
Invertebrates, lacking a backbone, include groups such as arthropods (insects, arachnids, crustaceans), molluscs, and worms. Plants can be classified into flowering plants and non-flowering plants like mosses and ferns.
无脊椎动物没有脊柱，包括节肢动物（昆虫、蛛形纲、甲壳类）、软体动物和蠕虫等。植物可分为开花植物和非开花植物，如苔藓和蕨类。
4. Levels of Organisation | 组织的层次
In multicellular organisms, cells are organised into higher levels of structure. Similar cells working together form a tissue. Different tissues combine to form an organ, which carries out a specific function. Organs work together in an organ system. The whole body is the organism.
在多细胞生物体内，细胞组成更高层次的结构。相似的细胞共同构成组织；不同组织组合成器官，执行特定功能；器官协同工作构成器官系统；整个身体即是一个生物体。
For example, muscle cells form muscle tissue, which makes up the stomach (an organ). The stomach, together with the mouth, intestines, and other parts, forms the digestive system, which is one system within the human organism.
例如，肌肉细胞构成肌肉组织，肌肉组织组成胃（器官）。胃与口腔、肠等器官共同构成消化系统，是人体这一生物体中的一个系统。
- Cell → Tissue → Organ → Organ System → Organism
- 细胞 → 组织 → 器官 → 器官系统 → 生物体
5. The Human Digestive System | 人体消化系统
Digestion breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. Mechanical digestion involves physical breakdown, such as chewing in the mouth and churning in the stomach. Chemical digestion uses enzymes to break down nutrients.
消化作用将大块不溶的食物分子分解为可溶的小分子以便吸收进入血液。物理性消化包括口内咀嚼和胃的搅动；化学性消化则利用酶来分解营养物质。
Carbohydrates are broken down into simple sugars by carbohydrase (e.g. amylase). Proteins are broken down into amino acids by protease. Fats (lipids) are broken down into fatty acids and glycerol by lipase. These enzymes work best at specific pH levels and temperatures.
碳水化合物被碳水化合物酶（如淀粉酶）分解为单糖；蛋白质被蛋白酶分解为氨基酸；脂肪被脂肪酶分解为脂肪酸和甘油。这些酶在特定酸碱度和温度下活性最高。
| Organ (器官) | Function (功能) |
| Mouth 口腔 | Chewing (mechanical digestion) and amylase in saliva starts starch breakdown / 咀嚼，唾液淀粉酶开始分解淀粉 |
| Oesophagus 食道 | Transports food to stomach by peristalsis / 通过蠕动将食物推入胃中 |
| Stomach 胃 | Churns food and adds protease and hydrochloric acid / 搅拌食物，分泌蛋白酶和盐酸 |
| Small intestine 小肠 | Completes digestion and absorbs nutrients into blood / 完成消化，将营养吸收进入血液 |
| Large intestine 大肠 | Absorbs water and forms faeces / 吸收水分，形成粪便 |
6. The Respiratory System | 呼吸系统
The respiratory system provides oxygen for aerobic respiration and removes carbon dioxide. Air enters through the nose or mouth, passes the trachea, and moves into two bronchi, each leading to a lung. Inside the lungs, bronchi branch into smaller bronchioles ending in tiny air sacs called alveoli.
呼吸系统为有氧呼吸提供氧气，并排出二氧化碳。空气通过鼻或口进入，经过气管，进入左右支气管到达肺部。在肺内，支气管分支成细支气管，末端为称为肺泡的微小气囊。
Gas exchange takes place in the alveoli. Oxygen diffuses from the air in the alveoli into the blood capillaries, while carbon dioxide diffuses from the blood into the alveoli to be exhaled. The huge number of alveoli provides a large surface area, and their thin walls make diffusion efficient.
气体交换发生在肺泡中。氧气从肺泡内的空气扩散到毛细血管血液中，二氧化碳则从血液扩散到肺泡内被呼出。数量巨大的肺泡提供了很大的表面积，而薄壁使扩散更为高效。
The breathing mechanism involves the diaphragm and intercostal muscles. When inhaling, the diaphragm contracts and flattens, and the ribcage moves up and out, increasing the chest volume and lowering pressure to draw air in. Exhalation is largely passive, with the diaphragm relaxing.
呼吸运动依靠膈肌和肋间肌。吸气时，膈肌收缩变平，肋骨向上向外移动，胸腔容积增大、压力降低，空气被吸入。呼气则大多被动，膈肌放松回弹。
7. The Circulatory System | 循环系统
The circulatory system transports oxygen, nutrients, hormones, and waste products around the body. It consists of the heart, blood vessels, and blood. Humans have a double circulatory system: blood passes through the heart twice in one complete circuit – once to the lungs (pulmonary circulation) and once to the rest of the body (systemic circulation).
循环系统负责在全身运输氧气、营养物质、激素和废物。它由心脏、血管和血液组成。人类具有双循环系统：血液在一次完整循环中两次经过心脏——一次流向肺部（肺循环），一次流向身体其余部分（体循环）。
The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. Deoxygenated blood enters the right atrium, goes to the right ventricle, and is pumped to the lungs. Oxygenated blood returns to the left atrium, moves to the left ventricle, and is pumped out through the aorta to the body.
心脏有四个腔室：右心房、右心室、左心房和左心室。缺氧血液进入右心房，流入右心室，被泵入肺部。富氧血液返回左心房，进入左心室，通过主动脉泵往全身。
Blood contains red blood cells (carry oxygen using haemoglobin), white blood cells (fight infection), platelets (help clotting), and plasma (transport medium). Arteries carry blood away from the heart under high pressure; veins return blood under lower pressure with valves; capillaries link arteries and veins and allow exchange of substances.
血液含有红细胞（用血红蛋白运输氧气）、白细胞（抵抗感染）、血小板（协助凝血）和血浆（运输介质）。动脉将血液在高压下运离心脏；静脉在较低压力下将血液送回，并有瓣膜防止倒流；毛细血管连接动脉和静脉，进行物质交换。
8. Plant Nutrition and Transport | 植物的营养与运输
Plants make their own food through photosynthesis. This process occurs in chloroplasts using light energy to convert carbon dioxide and water into glucose and oxygen. The balanced equation is:
植物通过光合作用制造养料。这一过程在叶绿体中进行，利用光能把二氧化碳和水转化为葡萄糖和氧气。其方程式为：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Glucose is used immediately for respiration to release energy, or it is stored as starch. Plants also need mineral ions, such as nitrates for making proteins and magnesium for making chlorophyll. These minerals are absorbed from the soil through root hair cells.
葡萄糖可立即用于呼吸作用释放能量，也可转化为淀粉储存。植物还需要矿物质离子，如用于合成蛋白质的硝酸盐和合成叶绿素的镁。这些矿物质通过根毛细胞从土壤中吸收。
Transport in plants occurs through two main tissues: xylem and phloem. Xylem carries water and dissolved minerals from the roots to the leaves. The flow is one-way and driven by transpiration (loss of water vapour from leaves). Phloem transports sugars (mainly sucrose) from leaves to other parts of the plant where they are needed – this is called translocation and can move in both directions.
植物体内的运输依靠两种主要组织：木质部和韧皮部。木质部将水和溶解的矿物质从根运送到叶，流向单向，由蒸腾作用（叶片水分蒸发）驱动。韧皮部将糖（主要是蔗糖）从叶运送到植物体其他需要处，这一过程称为转运，可以双向进行。
9. Reproduction in Flowering Plants | 开花植物的生殖
Flowering plants reproduce sexually through flowers. The male parts (stamens) consist of the anther, which produces pollen grains containing male gametes, and a filament. The female part (carpel) includes the stigma, style, and ovary, which contains ovules that house female gametes.
开花植物通过花进行有性生殖。雄性部分（雄蕊）包括产生花粉粒（含有雄配子）的花药和花丝。雌性部分（心皮）包括柱头、花柱和子房，子房内的胚珠含有雌配子。
Pollination is the transfer of pollen from an anther to a stigma. It can be self-pollination (same flower or same plant) or cross-pollination (between different plants of the same species). Wind-pollinated flowers often have dull petals and feathery stigmas; insect-pollinated flowers are usually brightly coloured and produce nectar.
传粉是花粉从花药传到柱头的过程，可以是自花传粉（同一朵花或同一植株）或异花传粉（同种不同植株间）。风媒花通常花瓣不鲜艳，柱头呈羽毛状；虫媒花则色彩鲜艳、产生花蜜。
After pollination, a pollen tube grows down the style to the ovule. Fertilisation occurs when the male gamete fuses with the female gamete to form a zygote. The zygote develops into an embryo inside a seed; the ovary develops into a fruit, which protects the seeds and aids dispersal.
传粉后，花粉管沿花柱伸向胚珠。受精发生在雄配子与雌配子结合形成受精卵时。受精卵在种子内发育成胚；子房发育成果实，保护种子并帮助传播。
Seeds are dispersed by wind, water, animals, or explosive mechanisms. Dispersal reduces competition and helps colonise new areas. Germination requires water, oxygen, and a suitable temperature.
种子靠风力、水流、动物或弹射机制进行传播。传播减少了竞争，有助于占据新生境。萌发需要水分、氧气和适宜的温度。
10. Ecosystems and Feeding Relationships | 生态系统与营养关系
An ecosystem includes all the living organisms in a habitat and the non-living factors they interact with. A food chain shows the flow of energy from producers to consumers. Producers (plants) make food via photosynthesis. Primary consumers eat plants, secondary consumers eat primary consumers, and so on. Decomposers break down dead matter, recycling nutrients.
生态系统包含栖息地中的所有生物以及它们与之互动的非生物因素。食物链显示了能量从生产者到消费者的流动。生产者（植物）通过光合作用制造食物；初级消费者吃植物；次级消费者吃初级消费者，以此类推。分解者分解死物，回收营养物质。
Food webs are made of many interlinked food chains, showing the real feeding relationships in a community. Energy is lost at each trophic level, mostly as heat from respiration, so food chains rarely have more than four or five levels.
食物网由多条相互连接的食物链构成，真实反映群体中的取食关系。能量在每个营养级都会损失，主要因呼吸作用以热的形式散失，因此食物链很少超过四到五个层级。
Organisms may compete for resources such as food, light, water, and mates. The size of a population can be affected by predation, disease, pollution, and changes in habitat. A stable ecosystem has balanced populations and nutrient cycles.
生物会为资源而竞争，如食物、光照、水份和配偶。种群大小会受到捕食、疾病、污染和栖息地变化的影响。一个稳定的生态系统具有平衡的种群和物质循环。
11. Adaptation and Variation | 适应与变异
Adaptations are features that help organisms survive in their environment. They can be structural (e.g., thick fur in polar bears for insulation), behavioural (e.g., birds migrating to warmer places), or physiological (e.g., venom production in snakes).
适应是帮助生物在环境中生存的特征，可以是结构性的（如北极熊的厚毛保暖）、行为性的（如鸟类迁徙到温暖地区）或生理性的（如蛇产生毒液）。
Variation refers to differences between individuals of the same species. Some variation is genetic and inherited (e.g., eye colour), while some is environmental (e.g., speaking different languages). Continuous variation shows a range of values without distinct categories (e.g., height); discontinuous variation falls into distinct groups (e.g., blood type).
变异指同一物种个体间的差异。有些变异是遗传的（如眼色），有些则是环境导致的（如所说的语言不同）。连续变异呈现一系列值而无清晰类别（如身高）；不连续变异则分为明显类群（如血型）。
Over many generations, natural selection can lead to evolution. Individuals with traits better suited to the environment are more likely to survive and reproduce, passing on those advantageous alleles. This explains how species become well adapted.
经过许多世代，自然选择可导致进化。具有更适应环境性状的个体更可能存活并繁殖，将这些有利等位基因传递下去。这解释了物种为何能很好适应环境。
12. Microorganisms and Their Roles | 微生物及其作用
Microorganisms (microbes) are tiny living things that can only be seen with a microscope. They include bacteria
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