📚 Year 7 CAIE Biology: Core Knowledge Checklist | CAIE 七年级生物核心知识点梳理
Year 7 Biology introduces students to the fundamental concepts of life science, from the smallest building blocks of living organisms to entire ecosystems. This revision guide summarises the essential knowledge needed to succeed in the CAIE assessment, covering cells, classification, body systems, plant biology, reproduction, and ecology.
七年级生物带领学生认识生命科学的基本概念，从生物的最小组成单位到整个生态系统。这份复习指南总结了在 CAIE 考试中取得好成绩所需的核心知识，涵盖细胞、分类、人体系统、植物生物学、生殖和生态学。
1. Characteristics of Living Things | 生物的基本特征
All living organisms share a set of life processes that distinguish them from non-living matter. These are often remembered by the acronym MRS GREN, which stands for Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition.
所有生物都拥有一套共同的生命活动，将它们与非生命物质区分开来。通常用首字母缩写 MRS GREN 来记忆这些特征，即运动 (Movement)、呼吸 (Respiration)、感应 (Sensitivity)、生长 (Growth)、生殖 (Reproduction)、排泄 (Excretion) 和营养 (Nutrition)。
Movement refers to an action by an organism that changes its position or the position of part of its body. Respiration is the chemical reaction in cells that releases energy from nutrient molecules. Sensitivity is the ability to detect and respond to changes in the surroundings. Growth is a permanent increase in size and mass. Reproduction is the production of offspring. Excretion is the removal of toxic waste products of metabolism. Nutrition is the intake and use of nutrients for energy, growth and repair.
运动指生物体改变自身位置或身体部位的动作。呼吸是细胞内将营养物质中的能量释放出来的化学反应。感应是探测并响应周围环境变化的能力。生长是体型和质量的永久性增加。生殖是产生后代。排泄是清除代谢产生的有毒废物。营养是摄入并利用营养物质以获得能量、生长和修复。
2. Cell Structure | 细胞结构
A cell is the basic structural and functional unit of all living organisms. Animal cells contain a cell membrane, cytoplasm, nucleus and mitochondria. The cell membrane controls the movement of substances in and out. The cytoplasm is a jelly-like material where chemical reactions take place. The nucleus contains genetic material and controls cell activities. Mitochondria are the sites of aerobic respiration, releasing energy.
细胞是所有生物体结构和功能的基本单位。动物细胞含有细胞膜、细胞质、细胞核和线粒体。细胞膜控制物质的进出。细胞质是胶状物质，化学反应在此进行。细胞核含有遗传物质并控制细胞活动。线粒体是有氧呼吸的场所，释放能量。
Plant cells have the same basic parts as animal cells, but they also possess three additional structures: a rigid cell wall made of cellulose for support, a large permanent vacuole containing cell sap that helps maintain turgor, and chloroplasts that absorb light energy for photosynthesis.
植物细胞具有与动物细胞相同的基本结构，但还多出三种额外的构造：由纤维素构成的坚硬细胞壁，起支持作用；含有细胞液的大中央液泡，帮助维持细胞膨压；以及吸收光能进行光合作用的叶绿体。
3. From Cells to Systems | 从细胞到系统
In multicellular organisms, cells are organised into hierarchical levels. Similar cells that work together form a tissue. Different tissues combine to form an organ, which performs a specific function. Organs that work together make up an organ system, and all organ systems together form the complete organism.
在多细胞生物中，细胞按照层级组织起来。相似且共同工作的细胞构成组织。不同的组织组合形成器官，执行特定功能。共同工作的器官构成器官系统，所有器官系统共同构成完整的生物体。
For example, muscle cells form muscle tissue; this tissue, together with nervous tissue, helps build the stomach. The stomach, along with the liver, pancreas and intestines, forms the digestive system. Several systems, like the digestive, respiratory and circulatory systems, keep the human body alive.
例如，肌肉细胞形成肌肉组织；肌肉组织与神经组织一起构成胃。胃与肝脏、胰腺和肠道等共同组成消化系统。消化系统、呼吸系统和循环系统等多个系统协同工作，维持人体生命。
4. Classification of Living Organisms | 生物分类
Scientists classify organisms into groups based on shared features. The largest groups are kingdoms. The five-kingdom system includes Animals, Plants, Fungi, Protists (or Protoctists) and Prokaryotes (bacteria). Within the animal kingdom, vertebrates are further divided into five classes: fish, amphibians, reptiles, birds and mammals.
科学家根据共同特征将生物分类成不同类群。最大的类群是界。五界系统包括动物界、植物界、真菌界、原生生物界和原核生物界（细菌）。在动物界中，脊椎动物进一步分为五个纲：鱼类、两栖类、爬行类、鸟类和哺乳类。
Key distinguishing features include body covering, method of reproduction and whether the animal is warm-blooded or cold-blooded. For instance, mammals have hair or fur, give birth to live young and feed milk; birds have feathers and lay hard-shelled eggs; fish have scales and gills.
关键的区分特征包括体表覆盖物、生殖方式以及动物是温血还是冷血。举例来说，哺乳动物有毛发或毛皮，胎生并哺乳；鸟类有羽毛，产硬壳卵；鱼类有鳞片和鳃。
5. Photosynthesis and Plant Nutrition | 光合作用与植物营养
Plants make their own food through photosynthesis. This process takes place in chloroplasts and uses light energy to convert carbon dioxide and water into glucose and oxygen. The overall word equation is:
植物通过光合作用制造自己的食物。这一过程发生在叶绿体中，利用光能将二氧化碳和水转化为葡萄糖和氧气。总的文字方程式是：
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The balanced chemical equation can be written as:
配平的化学方程式可以写成：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Leaves are adapted for photosynthesis: they are broad and flat to capture sunlight, thin for gas diffusion, and contain many chloroplasts. Veins bring water and carry away sugars. Plants also need mineral ions, such as nitrates for making proteins and magnesium for making chlorophyll.
叶片在结构上适应光合作用：它们宽大而扁平以捕捉阳光，薄以利于气体扩散，并含有大量叶绿体。叶脉输送水分并运走糖类。植物还需要矿物质离子，如硝酸盐用于制造蛋白质，镁用于合成叶绿素。
6. The Human Digestive System | 人体消化系统
The digestive system breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. Food passes through the mouth, oesophagus, stomach, small intestine, large intestine and rectum, before leaving the body through the anus.
消化系统将大而不溶的食物分子分解成小而可溶的分子，以便被血液吸收。食物依次经过口腔、食道、胃、小肠、大肠和直肠，最后通过肛门排出体外。
Digestion involves both mechanical and chemical processes. Chewing in the mouth and churning in the stomach are mechanical. Chemical digestion uses enzymes: amylase in saliva breaks down starch into sugars; protease in the stomach breaks down protein; lipase in the small intestine breaks down fats. The small intestine is the main site of nutrient absorption into the bloodstream.
消化包括物理性消化和化学性消化。口腔的咀嚼和胃的蠕动是物理性消化。化学消化利用酶：唾液中的淀粉酶将淀粉分解成糖；胃中的蛋白酶分解蛋白质；小肠中的脂肪酶分解脂肪。小肠是营养物质吸收进血液的主要场所。
7. The Respiratory System | 呼吸系统
The respiratory system provides oxygen to the blood and removes carbon dioxide. Air enters through the nose or mouth, passes down the trachea, and into the bronchi, which divide into bronchioles ending in tiny air sacs called alveoli.
呼吸系统为血液提供氧气并排出二氧化碳。空气通过鼻或口进入，沿气管下行，进入支气管，支气管再分支为细支气管，末端是微小的气囊，称为肺泡。
Gas exchange takes place in the alveoli. Oxygen diffuses from the air into the blood, and carbon dioxide diffuses from the blood into the air. Breathing movements are driven by the diaphragm and intercostal muscles. During inhalation, the diaphragm contracts and flattens, and the ribcage moves up and out, increasing the volume of the chest cavity and drawing air in.
气体交换在肺泡中进行。氧气从空气中扩散进血液，二氧化碳从血液扩散到空气中。呼吸运动由膈肌和肋间肌驱动。吸气时，膈肌收缩变平，肋骨上提外扩，胸腔容积增大，气体被吸入。
It is important to distinguish between breathing and respiration. Breathing is the physical process of moving air in and out of the lungs, while respiration is the chemical release of energy inside cells.
区分呼吸运动与呼吸作用很重要。呼吸运动是将空气吸入和排出肺部的物理过程，而呼吸作用是在细胞内释放能量的化学过程。
8. The Circulatory System | 循环系统
The circulatory system transports substances around the body. It consists of the heart, blood vessels and blood. The heart is a muscular pump with four chambers: two atria and two ventricles. The right side pumps deoxygenated blood to the lungs, while the left side pumps oxygenated blood to the rest of the body.
循环系统将物质运输到全身。它由心脏、血管和血液组成。心脏是一个有四个腔室的肌肉泵：两个心房和两个心室。右侧将缺氧血泵送到肺部，左侧将富氧血泵送到身体其他部位。
Blood flows through arteries, veins and capillaries. Arteries carry blood away from the heart at high pressure; veins carry blood back to the heart and have valves to prevent backflow; capillaries are tiny vessels where material exchange happens. Blood is composed of plasma, red blood cells, white blood cells and platelets. Red blood cells contain haemoglobin, which binds oxygen.
血液流经动脉、静脉和毛细血管。动脉在高压下将血液带离心脏；静脉将血液送回心脏，并具有防止倒流的瓣膜；毛细血管是物质交换的微小血管。血液由血浆、红细胞、白细胞和血小板组成。红细胞含有血红蛋白，能与氧气结合。
9. Reproduction in Flowering Plants | 开花植物的生殖
Flowers are the reproductive organs of plants. A typical flower has male parts called stamens, which consist of an anther that produces pollen and a filament. The female part is the carpel, made up of a stigma, style and ovary containing ovules. Some flowers have both male and female parts, while others are unisexual.
花是植物的生殖器官。一朵典型的花具有称为雄蕊的雄性部分，由产生花粉的花药和花丝组成。雌性部分为心皮，由柱头、花柱和含有胚珠的子房组成。有些花同时具有雄性和雌性部分，而另一些则是单性花。
Pollination is the transfer of pollen from an anther to a stigma. It can be cross-pollination or self-pollination. After pollination, a pollen tube grows down the style to deliver the male nucleus to the ovule for fertilisation. The fertilised ovule develops into a seed, and the ovary becomes a fruit. Seeds are dispersed by wind, water, animals or explosion to reduce competition.
传粉是花粉从花药转移到柱头上的过程，可以是异花传粉或自花传粉。传粉后，花粉管沿花柱生长，将雄核送至胚珠完成受精。受精后的胚珠发育成种子，子房发育成果实。种子通过风、水、动物或弹射传播，以减少竞争。
10. Food Chains and Ecosystems | 食物链与生态系统
All organisms in an ecosystem are linked by feeding relationships. A food chain shows the transfer of energy from one organism to another. It always begins with a producer, usually a green plant that makes its own food through photosynthesis. Primary consumers (herbivores) eat producers, secondary consumers eat primary consumers, and so on.
生态系统中的所有生物通过摄食关系相互联系。食物链展示了能量从一个生物体转移到另一个的过程。它总是从生产者开始，通常是通过光合作用制造食物的绿色植物。初级消费者（植食动物）取食生产者，次级消费者取食初级消费者，依此类推。
Decomposers, such as bacteria and fungi, break down dead organic matter and return nutrients to the soil. Food chains rarely exist in isolation; they form interlinked food webs. Energy is lost at each trophic level, mostly as heat from respiration, which explains why food chains are usually short and why there are fewer organisms at higher levels.
分解者，如细菌和真菌，分解死去的有机物并将养分归还土壤。食物链很少单独存在，它们构成相互连接的食物网。每个营养级都有能量损耗，主要以呼吸热的形式散失，这就解释了为什么食物链通常较短以及高营养级生物数量较少。
11. Microorganisms | 微生物
Microorganisms, or microbes, are tiny living things that can only be seen with a microscope. They include bacteria, viruses, fungi and protozoa. While many are harmless or beneficial, some cause diseases. Bacteria are single-celled organisms without a nucleus, and they reproduce rapidly by binary fission. Viruses are not cells; they invade host cells to reproduce.
微生物是只能用显微镜才能看到的微小生物，包括细菌、病毒、真菌和原生动物。它们中许多无害甚至有益，但也有一些会引发疾病。细菌是没有细胞核的单细胞生物，通过二分裂快速繁殖。病毒不是细胞，它们侵入宿主细胞进行复制。
Beneficial microbes are used in making yoghurt and bread (yeast), in decomposing waste, and in producing antibiotics. Harmful microbes can cause illnesses such as flu, food poisoning and tooth decay. Good hygiene, cooking, refrigeration and vaccination help prevent the spread of harmful microbes.
有益微生物被用于制作酸奶和面包（酵母）、分解废物以及生产抗生素。有害微生物可能导致流感、食物中毒和龋齿等疾病。良好的卫生习惯、彻底烹饪、冷藏和接种疫苗有助于防止有害微生物的传播。
12. Variation, Adaptation and Survival | 变异、适应与生存
Variation is the differences between individuals of the same species. Some variation is inherited through genes, while some is caused by the environment. For example, eye colour is inherited, but a suntan is environmental. Continuous variation (like height) shows a range, whereas discontinuous variation (like blood group) puts individuals into distinct groups.
变异是指同一物种个体之间的差异。有些变异通过基因遗传，有些则由环境引起。例如，眼睛颜色是遗传的，而晒黑是环境引起的。连续变异（如身高）表现出一个范围，而不连续变异（如血型）将个体归入截然不同的类别。
Adaptations are features that help an organism survive in its habitat. A cactus has thick, waxy skin and spines to reduce water loss in a desert; a polar bear has thick fur and blubber to stay warm. Adaptations can be structural, behavioural or physiological. Individuals with advantageous adaptations are more likely to survive and reproduce, passing these traits to the next generation—a process called natural selection.
适应是帮助生物体在栖息地生存的特征。仙人掌有厚实的蜡质表皮和刺，以减少在沙漠中的水分流失；北极熊有厚毛皮和脂肪来保暖。适应可以是结构上的、行为上的或生理上的。具有优势适应特征的个体更有可能生存并繁殖，并将这些性状传给下一代，这一过程称为自然选择。
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