📚 Complete Biology for Cambridge Secondary 1: Checkpoint Revision Guide | CIE Checkpoint Complete Biology 教材精讲与考点梳理
Complete Biology for Cambridge Secondary 1 is the core text for learners preparing for the CIE Checkpoint Biology test. It builds three key strands — scientific enquiry, biology content, and scientific literacy — through clear explanations, labelled diagrams, key word boxes, and Checkpoint-style questions.
《Complete Biology for Cambridge Secondary 1》是备战 CIE Checkpoint 生物测试的核心教材。它通过清晰的讲解、标注图、关键词框和 Checkpoint 风格题目，帮助学习者建立科学探究、生物学科内容和科学素养三条主线。
1. How to Use This Textbook | 如何高效使用本教材
Use the learning objectives at the start of each chapter as a revision checklist. Tick off each objective only when you can explain it aloud without looking at the book.
把每章开头的学习目标当作复习清单。只有当你能够不看书本、大声解释某个目标时，才把它勾掉。
Always draw and label diagrams from memory, especially cell structures, the digestive system, the heart, and flower parts. This is one of the most effective ways to prepare for Checkpoint questions.
一定要默画并标注示意图，尤其是细胞结构、消化系统、心脏和花的结构。这是备考 Checkpoint 最有效的方法之一。
After each section, answer the Checkpoint-style questions at the end of the chapter. Exam practice helps you recognise command words such as 'describe', 'explain', 'compare' and 'suggest'.
学完每个小节后，完成章末的 Checkpoint 风格题目。真题练习能帮助你识别 describe、explain、compare 和 suggest 等指令词。
2. Characteristics of Living Things | 生物的基本特征
All living organisms share seven life processes, often remembered by the acronym MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition.
所有生物都共有七大生命活动，通常用首字母缩写 MRS GREN 来记忆：运动、呼吸、感应、生长、生殖、排泄和营养。
| Life process | Meaning | Example |
|---|---|---|
| Movement | A change in position or place | A plant shoot bending towards light |
| Respiration | Releasing energy from food | Glucose broken down in cells |
| Sensitivity | Detecting and responding to stimuli | Pupil narrowing in bright light |
| Growth | Permanent increase in size | A seedling becoming taller |
| Reproduction | Producing new individuals | Seeds germinating |
| Excretion | Removing metabolic waste | Lungs removing carbon dioxide |
| Nutrition | Taking in and using food | Plants absorbing mineral ions |
Checkpoint questions often ask you to identify whether an object is living or non-living by testing it against these seven characteristics.
Checkpoint 题目常要求你根据这七大特征判断某一物体是生物还是非生物。
3. Cells and Organelles | 细胞与细胞器
Both animal and plant cells contain a cell membrane, cytoplasm and nucleus. Plant cells also have a cell wall, chloroplasts and a large permanent vacuole.
动物细胞和植物细胞都含有细胞膜、细胞质和细胞核。植物细胞还具有细胞壁、叶绿体和大型永久液泡。
| Organelle | Function |
|---|---|
| Nucleus | Controls the cell and contains genetic material |
| Cell membrane | Controls movement of substances in and out |
| Cytoplasm | Site of chemical reactions |
| Chloroplast | Absorbs light for photosynthesis |
| Cell wall | Provides support and shape in plant cells |
| Vacuole | Stores cell sap and helps keep the cell firm |
When asked to compare plant and animal cells, use a two-column table or a labelled diagram. Always mention the three extra structures found in plant cells.
当题目要求比较植物细胞和动物细胞时，使用两栏表格或标注图。一定要提到植物细胞多出的三种结构。
Specialised cells are adapted to their function. For example, root hair cells have a long extension to absorb water, and red blood cells have no nucleus to carry more haemoglobin.
特化细胞适应其功能。例如，根毛细胞有长长的突起以吸收水分，红细胞没有细胞核以便携带更多血红蛋白。
4. Levels of Organisation | 组织的层级
In multicellular organisms, cells are organised into tissues, tissues into organs, and organs into organ systems. This hierarchy is a common Checkpoint topic.
在多细胞生物中，细胞构成组织，组织构成器官，器官构成器官系统。这个层级关系是 Checkpoint 常见考点。
Examples include muscle cells forming muscle tissue, muscle tissue forming the heart, and the heart working with blood vessels in the circulatory system.
例如，肌细胞构成肌肉组织，肌肉组织构成心脏，心脏与血管共同组成循环系统。
Learn one plant example too: palisade mesophyll cells form leaf tissue, and the leaf is an organ of the shoot system.
还要掌握一个植物例子：栅栏叶肉细胞构成叶片组织，叶是地上枝系统的一个器官。
5. Movement in and out of Cells | 物质进出细胞
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. It is a passive process and does not require energy.
扩散是粒子从高浓度区域向低浓度区域的净运动。这是一种被动过程，不需要能量。
Osmosis is the diffusion of water molecules through a partially permeable membrane. Water moves from a dilute solution to a more concentrated solution.
渗透是水分子通过半透膜的扩散。水从较稀溶液向较浓溶液移动。
Animal cells can burst in pure water and shrink in concentrated salt solution. Plant cells become turgid in water and plasmolysed in strong sugar solution.
动物细胞在纯水中会胀破，在浓盐水中会皱缩。植物细胞在水中变得硬挺，在浓糖水中发生质壁分离。
| Process | Particles | Membrane | Energy needed? |
|---|---|---|---|
| Diffusion | Any particles | No membrane needed | No |
| Osmosis | Water only | Partially permeable membrane | No |
6. Plant Nutrition and Photosynthesis | 植物营养与光合作用
Plants make their own food by photosynthesis. Chlorophyll in chloroplasts traps light energy and uses it to combine carbon dioxide and water into glucose and oxygen.
植物通过光合作用制造自身食物。叶绿体中的叶绿素捕获光能，并利用光能将二氧化碳和水合成葡萄糖和氧气。
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The reaction takes place in chloroplasts, requires light and chlorophyll, and is essential for almost all food chains because it converts light energy into chemical energy.
该反应在叶绿体中进行，需要光能和叶绿素。它把光能转化为化学能，因此对几乎所有食物链都至关重要。
To test a variegated leaf for starch, first boil it, then place it in hot ethanol to remove chlorophyll, and finally add iodine solution. A blue-black colour indicates starch.
要检验斑叶中的淀粉，先将叶片煮沸，再放入热乙醇中脱去叶绿素，最后滴加碘液。变为蓝黑色说明含有淀粉。
The starch test shows that photosynthesis produces starch and that only green, illuminated parts of the leaf make it.
淀粉检验表明光合作用产生淀粉，而且只有绿色、受光照的叶片部位才能产生淀粉。
7. Human Nutrition and Digestion | 人体营养与消化
A balanced diet contains carbohydrates, proteins, lipids, vitamins, minerals, water and dietary fibre. Each nutrient has specific uses in the body.
均衡膳食包含碳水化合物、蛋白质、脂类、维生素、矿物质、水和膳食纤维。每种营养素在体内都有特定作用。
- Carbohydrates provide energy; proteins support growth and repair; lipids provide long-term energy and insulation.
- 碳水化合物提供能量；蛋白质支持生长和修复；脂类提供长期能量和保温。
- Vitamins and minerals are needed in small amounts, for example vitamin C for healthy connective tissue and iron for haemoglobin.
- 维生素和矿物质需要量很少，例如维生素 C 维持结缔组织健康，铁用于合成血红蛋白。
- Dietary fibre aids peristalsis in the intestine, and water is needed for chemical reactions and transport.
- 膳食纤维有助于肠道蠕动，水则是化学反应和运输所必需的。
Digestion breaks large insoluble food molecules into small soluble molecules that can be absorbed into the blood. Enzymes speed up these reactions.
消化将大分子不溶性食物分解为可吸收的小分子可溶性物质。酶加速这些反应。
Amylase breaks down starch into maltose, protease breaks down protein into amino acids, and lipase breaks down lipids into fatty acids and glycerol.
淀粉酶将淀粉分解为麦芽糖，蛋白酶将蛋白质分解为氨基酸，脂肪酶将脂类分解为脂肪酸和甘油。
In the small intestine, digested food is absorbed by villi, which provide a large surface area and a network of blood capillaries.
在小肠中，消化后的食物由绒毛吸收。绒毛提供了巨大的表面积和丰富的毛细血管网。
8. Respiration and Gas Exchange | 呼吸与气体交换
Respiration is the release of energy from glucose inside cells. It is not the same as breathing, which is the movement of air into and out of the lungs.
呼吸作用是在细胞内从葡萄糖释放能量的过程。它不同于呼吸运动，后者是空气进出肺部的过程。
glucose + oxygen → carbon dioxide + water + energy
葡萄糖 + 氧气 → 二氧化碳 + 水 + 能量
Aerobic respiration requires oxygen and releases a relatively large amount of energy. It takes place in mitochondria.
有氧呼吸需要氧气，释放相对较多的能量。它发生在线粒体中。
Gas exchange in the lungs occurs in alveoli. Oxygen diffuses into the blood, and carbon dioxide diffuses out. Alveoli have thin walls, a large surface area and a good blood supply.
肺内的气体交换在肺泡进行。氧气扩散进入血液，二氧化碳扩散出来。肺泡壁薄、表面积大且血液供应充足。
During inhalation, the diaphragm contracts and moves down while the intercostal muscles raise the ribcage. This increases the volume of the thorax and lowers its pressure.
吸气时，膈肌收缩向下移动，肋间肌使胸腔上提。胸腔容积增大，压力降低，空气进入肺。
9. Transport in Living Things | 生物体内的运输
In humans, the circulatory system transports oxygen, nutrients, hormones and waste products. It consists of the heart, blood vessels and blood.
在人体中，循环系统运输氧气、营养物质、激素和代谢废物。它由心脏、血管和血液组成。
The heart has four chambers: left atrium, left ventricle, right atrium and right ventricle. The left side pumps oxygenated blood to the body, while the right side pumps deoxygenated blood to the lungs.
心脏有四个腔室：左心房、左心室、右心房和右心室。左侧将含氧血泵到全身，右侧将脱氧血泵到肺。
Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries link them and exchange materials with tissues.
动脉将血液运离心脏，静脉将血液送回心脏，毛细血管连接两者并与组织交换物质。
In plants, xylem transports water and mineral ions from the roots to the leaves, while phloem transports glucose from the leaves to growing and storage regions.
在植物中，木质部将水和矿物质离子从根部运输到叶，韧皮部将葡萄糖从叶运输到生长和储存部位。
10. Reproduction in Plants and Humans | 植物的繁殖与人类生殖
Flowers are the reproductive organs of many plants. The male parts are the stamens, which produce pollen in the anthers, and the female parts are the carpels, which contain ovules in the ovary.
花是许多植物的生殖器官。雄蕊是雄性器官，在花药中产生花粉；雌蕊是雌性器官，在子房内含有胚珠。
Pollination is the transfer of pollen from an anther to a stigma. Fertilisation occurs when the male gamete fuses with the female gamete inside the ovule.
传粉是花粉从花药传到柱头的过程。当雄配子与胚珠内的雌配子融合时，就发生受精。
After fertilisation, the ovule becomes a seed and the ovary becomes a fruit. Seed dispersal reduces competition and helps colonise new habitats.
受精后，胚珠发育成种子，子房发育成果实。种子传播减少竞争并有助于开拓新栖息地。
In humans, the male gamete is the sperm produced in the testes, and the female gamete is the egg produced in the ovaries. Fertilisation normally occurs in the oviduct.
人类男性配子是睾丸产生的精子，女性配子是卵巢产生的卵子。受精通常发生在输卵管。
The fertilised egg implants in the uterus and develops into an embryo. The placenta allows exchange of oxygen, nutrients and waste between mother and embryo without mixing their blood.
受精卵着床于子宫并发育为胚胎。胎盘使母体和胚胎之间交换氧气、营养物质和废物，但双方血液不混合。
11. Ecosystems and Feeding Relationships | 生态系统与食物关系
A food chain shows the transfer of energy from producers to consumers. Producers are usually green plants that photosynthesise; consumers eat other organisms.
食物链显示能量从生产者到消费者的传递。生产者通常是进行光合作用的绿色植物；消费者以其他生物为食。
Food webs are made of several interconnected food chains. They show that most organisms eat more than one type of food and may be eaten by several predators.
食物网由多条相互联系的食物链组成。它表明大多数生物不只吃一种食物，也可能被多种捕食者取食。
Energy is lost at each trophic level through respiration, heat, movement and uneaten parts. This means food chains are usually short, rarely exceeding five levels.
能量在每一营养级都会通过呼吸、产热、运动及未被取食的部分而散失。因此食物链通常较短，很少超过五级。
Predator and prey populations often show cyclical changes. A large prey population supports more predators, which then reduces the prey population, causing predator numbers to fall again.
捕食者和猎物种群常呈周期性变化。大量猎物可养活更多捕食者，捕食者增多又使猎物减少，随后捕食者数量再次下降。
Decomposers such as bacteria and fungi break down dead organisms and return nutrients to the soil, acting as nature's recyclers.
细菌和真菌等分解者分解死去的生物，将养分归还土壤，是自然界的再循环者。
12. Variation and Classification | 变异与分类
Variation means differences between individuals of the same species. It can be continuous, such as height, or discontinuous, such as blood group or eye colour in humans.
变异是指同一物种个体之间的差异。变异可为连续变异，如身高；也可为不连续变异，如血型或人眼颜色。
Continuous variation gives a range of values and is usually influenced by many genes and the environment. Discontinuous variation falls into distinct groups with no intermediate forms.
连续变异呈现一系列数值，通常受多个基因和环境共同影响。不连续变异则分为截然不同的类别，没有中间类型。
The five vertebrate classes can be identified by their body coverings, reproduction and body temperature: fish, amphibians, reptiles, birds and mammals.
根据体表覆盖物、繁殖方式和体温，可将脊椎动物分为五个纲：鱼类、两栖类、爬行类、鸟类和哺乳类。
| Class | Body covering | Reproduction | Thermoregulation |
|---|---|---|---|
| Fish | Scales, slimy skin | Lay eggs in water | Cold-blooded |
| Amphibians | Moist skin | Lay eggs in water | Cold-blooded |
| Reptiles | Dry scaly skin | Lay soft-shelled eggs on land | Cold-blooded |
| Birds | Feathers | Lay hard-shelled eggs | Warm-blooded |
| Mammals | Hair or fur | Give birth to live young, suckle milk | Warm-blooded |
Keys are used to identify organisms. A dichotomous key presents two contrasting choices at each step until the organism is identified.
检索表用于鉴定生物。二叉式检索表每一步给出两个相反的选项，直到鉴定出该生物。
Binomial naming gives each species a two-part Latin name: the genus followed by the species. For example, Homo sapiens is the scientific name for modern humans.
双名法赋予每个物种一个由两部分组成的拉丁名：属名在前，种名在后。例如，Homo sapiens 是现代人的学名。
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