📚 Year 7 OCR Biology: Core Knowledge Organiser | 七年级OCR生物：核心知识点梳理
Welcome to your complete revision guide for Year 7 OCR Biology. This article breaks down the essential topics you need to master, from cells and reproduction to ecosystems and classification. Use this organiser to consolidate your understanding and boost your confidence for assessments.
欢迎阅读七年级OCR生物复习指南。本文梳理了必须掌握的核心主题，从细胞、繁殖到生态系统和分类。利用这份知识梳理巩固理解，增强应对测验的信心。
1. Cells – The Building Blocks of Life | 细胞——生命的基本单位
All living organisms are made of cells. Cells are the basic structural and functional units of life. Most cells are too small to be seen with the naked eye, so we use microscopes to observe them. Every cell is surrounded by a cell membrane that controls what enters and leaves.
所有生物都由细胞构成。细胞是生命的基本结构和功能单位。大多数细胞小到肉眼无法看见，因此我们使用显微镜来观察它们。每个细胞都被一层细胞膜包裹，细胞膜控制着物质的进出。
There are two main types of cells: animal cells and plant cells. Both contain a nucleus (which holds genetic material), cytoplasm (where chemical reactions occur), mitochondria (for respiration) and ribosomes (for protein synthesis). Plant cells have three extra structures: a rigid cell wall made of cellulose, a large permanent vacuole filled with cell sap, and chloroplasts that carry out photosynthesis.
细胞主要有两种类型：动物细胞和植物细胞。两者都包含细胞核（储存遗传物质）、细胞质（化学反应发生的场所）、线粒体（进行呼吸作用）和核糖体（合成蛋白质）。植物细胞还有三个额外的结构：由纤维素构成的坚硬细胞壁、充满细胞液的大液泡，以及进行光合作用的叶绿体。
- Animal cell: no cell wall, no chloroplasts, small or temporary vacuoles.
- 动物细胞：没有细胞壁，没有叶绿体，液泡小而临时。
- Plant cell: cell wall present, chloroplasts present, large central vacuole.
- 植物细胞：有细胞壁，有叶绿体，有大中央液泡。
2. Microscopes and Magnification | 显微镜与放大
A light microscope uses a series of lenses to magnify tiny objects. The main parts include the eyepiece lens, objective lenses, stage, mirror or light source, and focusing knobs. The specimen is placed on a glass slide and usually covered with a coverslip. Stains such as iodine can be used to make structures more visible.
光学显微镜使用一系列透镜来放大微小物体。主要部件包括目镜、物镜、载物台、反光镜或光源以及调焦旋钮。样本放在载玻片上，通常盖上盖玻片。可使用碘液等染色剂使结构更清晰。
Total magnification = Eyepiece magnification × Objective magnification
总放大倍数 = 目镜放大率 × 物镜放大率
hen drawing what you see, always write the magnification used and label the key parts clearly.
例如，如果目镜是10×，物镜是40×，总放大倍数就是10 × 40 = 400倍。在绘制观察到的图像时，一定要注明使用的放大倍数，并清晰标注关键结构。
3. Levels of Organisation | 生物体的层次结构
Unicellular organisms, like bacteria and amoeba, consist of a single cell that performs all life processes. Multicellular organisms, including humans and plants, are built from many cells. These cells are organised into increasingly complex levels.
单细胞生物，如细菌和变形虫，由一个执行所有生命过程的细胞构成。多细胞生物，包括人类和植物，由许多细胞组成。这些细胞按照越来越复杂的层次进行组织。
f similar cells working together, such as muscle tissue. An organ is made of different tissues working together, like the heart. An organ system is a group of organs that carry out a major function, such as the digestive system.
从低到高的组织层次为：细胞 → 组织 → 器官 → 器官系统 → 生物体。组织是一群相似细胞协同工作，例如肌肉组织。器官由不同组织协同工作构成，比如心脏。器官系统是一组器官共同执行一项主要功能，如消化系统。
In the digestive system, the mouth, oesophagus, stomach, small intestine and large intestine are organs that work together to break down food and absorb nutrients. Enzymes help speed up digestion.
在消化系统中，口腔、食道、胃、小肠和大肠等器官协同工作，分解食物并吸收营养。酶帮助加速消化过程。
4. The Skeletal and Muscular Systems | 骨骼与肌肉系统
The human skeleton provides support, protection, and movement. It protects vital organs: the skull protects the brain, the ribcage protects the heart and lungs, and the backbone protects the spinal cord. Bones also produce blood cells in the bone marrow and store minerals such as calcium.
人体骨骼提供支撑、保护和运动功能。它保护重要器官：颅骨保护大脑，肋骨保护心脏和肺，脊柱保护脊髓。骨骼还在骨髓中制造血细胞，并储存钙等矿物质。
Joints are places where two or more bones meet. Movable joints, like the hinge joint in the knee and the ball-and-socket joint in the shoulder, allow bones to move. Ligaments hold bones together, while cartilage reduces friction between bones.
关节是两块或多块骨头连接的地方。可动关节，如膝盖的铰链关节和肩膀的球窝关节，使骨头能运动。韧带将骨骼连接在一起，软骨则减少骨间的摩擦。
Muscles work in pairs to move bones at a joint. These are called antagonistic pairs. For example, to bend the arm, the biceps contracts and the triceps relaxes. To straighten the arm, the triceps contracts and the biceps relaxes.
肌肉成对工作，以带动关节处的骨骼运动，这称为拮抗肌对。例如，弯曲手臂时，肱二头肌收缩，肱三头肌舒张；伸直手臂时，肱三头肌收缩，肱二头肌舒张。
5. Reproduction in Plants | 植物的繁殖
Plants can reproduce sexually and asexually. Sexual reproduction involves flowers, pollination and fertilisation. The male sex cell (pollen) is produced in the anther, while the female sex cell (ovule) is inside the ovary. Pollination is the transfer of pollen from the anther to the stigma, which can be carried out by wind, insects or other animals.
植物可以进行有性繁殖和无性繁殖。有性繁殖涉及花、传粉和受精。雄性生殖细胞（花粉）在花药中产生，雌性生殖细胞（胚珠）位于子房内。传粉是花粉从花药转移到柱头的过程，可以由风、昆虫或其他动物完成。
After pollination, a pollen tube grows down from the stigma to the ovary. The male nucleus travels down this tube and fuses with the female nucleus inside the ovule – this is fertilisation. The fertilised ovule develops into a seed, and the ovary becomes the fruit. Seeds are dispersed by wind, water, animals or explosive mechanisms to reduce competition.
传粉后，花粉管从柱头向下长至子房。雄性细胞核沿花粉管向下移动，与胚珠内的雌性细胞核融合——这就是受精。受精后的胚珠发育成种子，子房发育成果实。种子通过风、水、动物或弹射机制传播，以减少竞争。
| Method of seed dispersal 种子传播方式 | Examples 例子 |
|---|---|
| Wind 风力 | Dandelion, sycamore 蒲公英、枫树 |
| Animal (in fur or eaten) 动物（粘附或取食） | Burdock, berries 牛蒡、浆果 |
| Water 水流 | Coconut 椰子 |
| Explosive 弹射 | Pea pods, touch-me-not 豌豆荚、凤仙花 |
6. Reproduction in Humans | 人类的繁殖
Humans reproduce sexually. The male reproductive system includes the testes, which produce sperm, and the penis. Sperm are released into the female's body during sexual intercourse. The female reproductive system includes the ovaries, which release eggs, the oviducts (fallopian tubes), the uterus and the vagina.
人类进行有性繁殖。男性生殖系统包括产生精子的睾丸和阴茎。性交时精子被输送到女性体内。女性生殖系统包括释放卵子的卵巢、输卵管、子宫和阴道。
During the menstrual cycle, an egg is released from an ovary approximately every 28 days – this is ovulation. If the egg is fertilised by a sperm, it can implant in the lining of the uterus and develop into a baby. If not, the lining is shed during menstruation (a period).
在月经周期中，大约每28天会从卵巢释放一个卵子——这就是排卵。如果卵子被精子受精，便可在子宫内膜着床并发育成胎儿。如果没有受精，内膜会在月经期脱落。
Puberty is the stage when a child's body becomes capable of reproduction. Boys experience voice deepening, growth of facial and body hair, and increased muscle mass. Girls develop breasts, wider hips and start menstruation. These changes are controlled by hormones.
青春期是儿童身体获得繁殖能力的阶段。男孩会出现声音变低沉、胡须和体毛生长、肌肉量增加。女孩乳房发育、臀部变宽并开始月经。这些变化由激素控制。
7. Variation and Classification | 变异与分类
Variation is the differences between individuals of the same species. It can be continuous, such as height and weight, which show a range of values, or discontinuous, such as blood group or eye colour, which fall into distinct categories. Variation arises from genetic factors, environmental factors, or a combination of both.
变异是指同一物种个体之间的差异。它可以是连续的，如身高和体重，表现出一个数值范围；也可以是不连续的，如血型或眼色，分为几个明显类别。变异由遗传因素、环境因素或二者共同作用产生。
Classification helps us organise living things into groups based on shared characteristics. The five kingdoms are: Animalia, Plantae, Fungi, Protoctista and Prokaryota. Within the animal kingdom, vertebrates are further divided into five classes: mammals, birds, reptiles, amphibians and fish.
分类帮助我们根据共同特征将生物分成不同类群。五界分别为：动物界、植物界、真菌界、原生生物界和原核生物界。在动物界中，脊椎动物又分为五个纲：哺乳纲、鸟纲、爬行纲、两栖纲和鱼纲。
| Vertebrate class 脊椎动物纲 | Key features 关键特征 | Examples 例子 |
|---|---|---|
| Mammals 哺乳动物 | Hair/fur, warm-blooded, produce milk 体表被毛，恒温，泌乳 | Human, lion 人类、狮子 |
| Birds 鸟类 | Feathers, beak, lay hard-shelled eggs 羽毛，喙，产硬壳卵 | Eagle, penguin 鹰、企鹅 |
| Reptiles 爬行动物 | Dry scaly skin, cold-blooded, lay leathery eggs 干燥鳞片皮肤，变温，产软壳卵 | Snake, lizard 蛇、蜥蜴 |
| Amphibians 两栖动物 | Moist skin, cold-blooded, lay eggs in water 湿润皮肤，变温，水中产卵 | Frog, salamander 青蛙、蝾螈 |
| Fish 鱼类 | Scales, gills, fins, cold-blooded 鳞片，鳃，鳍，变温 | Salmon, shark 鲑鱼、鲨鱼 |
8. Food Chains and Webs | 食物链与食物网
A food chain shows how energy is transferred from one organism to another in the form of food. It always starts with a producer – a green plant or algae that makes its own food through photosynthesis. Primary consumers eat producers, secondary consumers eat primary consumers, and so on.
食物链表示能量如何以食物的形式从一个生物转移到另一个生物。它总是从生产者开始——通过光合作用制造食物的绿色植物或藻类。初级消费者吃生产者，次级消费者吃初级消费者，依此类推。
ox. The arrows represent the direction of energy flow. A food web consists of many interconnected food chains, showing a more realistic feeding relationship in an ecosystem. Decomposers, such as bacteria and fungi, break down dead organisms and waste, returning nutrients to the soil.
一个简单的食物链：草 → 兔 → 狐狸。箭头表示能量流动的方向。食物网由许多相互连接的食物链组成，能更真实地展示生态系统中的取食关系。分解者，如细菌和真菌，分解死亡的生物和废物，将养分归还土壤。
If a population in a food web changes, it affects other organisms. For example, if rabbits decrease due to a disease, foxes may have less food, and the grass population may increase. This shows interdependence.
如果食物网中的某个种群数量发生变化，就会影响其他生物。例如，如果兔子因疾病而减少，狐狸的食物就会减少，草的数量则可能增加。这体现了相互依存关系。
9. Adaptations and Habitats | 适应与栖息地
A habitat is the natural environment where an organism lives. Organisms have adaptations – special features or behaviours that help them survive in their habitat. These can be structural (physical features), behavioural, or physiological.
栖息地是生物生存的自然环境。生物具有适应——帮助它们在栖息地生存的特殊特征或行为。这些适应可以是结构上的（身体特征）、行为上的或生理上的。
Desert animals like the fennec fox have large ears to lose heat and sandy-coloured fur for camouflage. Camels have humps that store fat (not water) and can close their nostrils to keep out sand. Cacti have thick stems to store water and spines instead of leaves to reduce water loss.
沙漠动物如耳廓狐有大耳朵以散热，沙色皮毛用于伪装。骆驼的驼峰储存脂肪（而不是水），并能关闭鼻孔阻挡沙尘。仙人掌有肥厚的茎储水，叶子退化成刺以减少水分流失。
Polar bears have a thick layer of blubber under the skin and white fur for insulation and camouflage. Many animals also show daily or seasonal rhythms, such as nocturnal behaviour or hibernation, to cope with changes in their environment.
北极熊皮下有厚厚的脂肪层，白色的皮毛既能保暖又能伪装。许多动物还表现出昼夜或季节性节律，如夜行行为或冬眠，以应对环境变化。
10. Ecosystems and Interdependence | 生态系统与相互依存
An ecosystem is a community of living organisms interacting with each other and their non-living environment. It includes abiotic factors like sunlight, temperature, water and soil, as well as biotic factors such as predators, prey and competitors.
生态系统是生物群落与其非生物环境相互作用的统一整体。它包括非生物因素（如阳光、温度、水分和土壤）以及生物因素（如捕食者、猎物和竞争者）。
Interdependence means that organisms depend on each other for survival. Key relationships include predation (one organism hunts and eats another), competition (organisms compete for resources like food, water and space), and mutualism (both species benefit). For example, bees and flowers show mutualism: bees get nectar, flowers get pollinated.
相互依存意味着生物为了生存而彼此依赖。主要关系包括捕食（一个生物猎食另一个）、竞争（生物为食物、水和空间等资源而竞争）和互利共生（双方都受益）。例如，蜜蜂和花表现出互利共生：蜜蜂获得花蜜，花被授粉。
Changes in the environment, such as pollution, deforestation or climate change, can upset the balance of an ecosystem. Conservation efforts aim to protect habitats and biodiversity. Simple things like recycling and planting trees can help maintain healthy ecosystems.
环境变化，如污染、森林砍伐或气候变化，会破坏生态系统的平衡。保护措施旨在保护栖息地和生物多样性。像回收利用和植树这样的小事有助于维持生态系统的健康。
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