📚 Year 9 Cambridge Science: Core Knowledge Review | 剑桥九年级科学核心知识点梳理
Year 9 Cambridge Science develops a deep understanding of fundamental concepts in biology, chemistry and physics. This guide highlights the core knowledge areas that students must master to excel at this level and build a strong foundation for IGCSE. From cells and chemical reactions to forces and energy, these key topics are presented with clear explanations and bilingual support.
剑桥九年级科学课程帮助学生深入理解生物学、化学和物理学的基本概念。本指南重点梳理了该阶段必须掌握的核心知识领域，为IGCSE打下坚实基础。从细胞、化学反应到力与能量，这些关键主题都配有清晰的中英双语解释。
1. Cells and Organisation | 细胞与组织结构
All living organisms are made of cells. Plant and animal cells share common structures such as the nucleus, cytoplasm, cell membrane and mitochondria. Plant cells also have a rigid cell wall, chloroplasts for photosynthesis and a large permanent vacuole.
所有生物都由细胞组成。植物细胞和动物细胞共有的结构包括细胞核、细胞质、细胞膜和线粒体。植物细胞还具有坚硬的细胞壁、进行光合作用的叶绿体以及一个大的中央液泡。
Cells are organised into tissues, organs and organ systems. For example, muscle cells form muscle tissue, which works together with other tissues to make the heart, an organ. The heart is part of the circulatory system, which transports substances around the body.
细胞组织形成组织、器官和器官系统。例如，肌细胞构成肌肉组织，肌肉组织与其他组织共同构成器官——心脏。心脏是循环系统的一部分，负责在体内运输物质。
Microscopes are essential for studying cells. The total magnification is calculated by multiplying the eyepiece lens magnification by the objective lens magnification.
显微镜是研究细胞的重要工具。总放大倍数等于目镜放大倍数乘以物镜放大倍数。
Key cell structures and their functions:
关键细胞结构及其功能：
- Nucleus – contains genetic material and controls cell activities. | 细胞核 – 包含遗传物质，控制细胞活动。
- Mitochondria – site of aerobic respiration, releasing energy. | 线粒体 – 有氧呼吸的场所，释放能量。
- Chloroplasts – absorb light energy for photosynthesis (plant cells). | 叶绿体 – 吸收光能进行光合作用（植物细胞）。
- Cell wall – provides structural support and protection (plant cells). | 细胞壁 – 提供结构支撑和保护（植物细胞）。
2. Photosynthesis and Respiration | 光合作用与呼吸作用
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water. The word equation is:
光合作用是绿色植物和一些其他生物利用阳光将二氧化碳和水合成营养物质的过程。文字方程式为：
Carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
Photosynthesis takes place in chloroplasts and requires chlorophyll. The glucose produced is used for respiration, stored as starch or converted into cellulose for cell walls.
光合作用在叶绿体中进行，需要叶绿素。产生的葡萄糖用于呼吸作用，以淀粉形式储存或转化为纤维素用于细胞壁。
Aerobic respiration releases energy from glucose in the presence of oxygen. The word equation is:
有氧呼吸在有氧气参与下从葡萄糖中释放能量。文字方程式为：
Glucose + oxygen → carbon dioxide + water (+ energy)
葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）
Anaerobic respiration occurs without oxygen and produces less energy. In yeast, it converts glucose into ethanol and carbon dioxide (fermentation). In muscle cells, it produces lactic acid.
无氧呼吸在没有氧气的情况下发生，产生较少能量。在酵母中，它将葡萄糖转化为乙醇和二氧化碳（发酵）。在肌肉细胞中，它产生乳酸。
3. Genetics and Inheritance | 遗传与变异
Heredity is the passing of characteristics from parents to offspring through genes, which are segments of DNA located on chromosomes. Humans have 46 chromosomes arranged in 23 pairs.
遗传是指特征通过基因从父母传递给后代。基因是位于染色体上的DNA片段。人类有46条染色体，排列成23对。
Alleles are different versions of a gene. Dominant alleles mask the effect of recessive alleles. Genotype refers to the genetic makeup, while phenotype is the observable characteristic.
等位基因是基因的不同版本。显性等位基因会掩盖隐性等位基因的作用。基因型是指基因组成，表现型是可观察到的特征。
Punnett squares can predict the probability of inheriting a particular characteristic. For example, crossing two heterozygous parents (Bb) for brown eyes (B dominant, b recessive) gives a 3:1 ratio of brown to blue eyes in the offspring.
庞纳特方格可以预测遗传特定特征的概率。例如，棕眼（B显性，b隐性）的杂合父母（Bb）杂交，后代中棕眼与蓝眼的比例为3:1。
Variation can be continuous (height, weight) or discontinuous (blood group, tongue rolling). Both genetic and environmental factors cause variation.
变异可以是连续的（身高、体重）或不连续的（血型、卷舌）。遗传因素和环境因素都会导致变异。
4. Ecosystems and Adaptations | 生态系统与适应
An ecosystem includes all the organisms in a particular area along with the non-living (abiotic) components like light, water and soil. Organisms interact as producers, consumers and decomposers in food chains and webs.
生态系统包括特定区域内所有生物以及非生物成分（如光、水和土壤）。生物在食物链和食物网中作为生产者、消费者和分解者相互作用。
Energy flows through an ecosystem from the Sun to producers (plants) via photosynthesis, then to consumers. Only about 10% of the energy is passed to the next trophic level; energy is lost as heat through respiration.
能量通过生态系统从太阳流向生产者（植物）经过光合作用，再流向消费者。只有大约10%的能量传递到下一个营养级；能量通过呼吸作用以热的形式散失。
Adaptations are features that help organisms survive in their environment. Examples include thick fur in arctic animals for insulation, long roots in desert plants to access water, and streamlined bodies in fish for efficient swimming.
适应是帮助生物在其环境中生存的特征。例如北极动物的厚毛用于保温，沙漠植物的长根获取水分，鱼类流线型身体便于高效游泳。
Predator-prey relationships can cause population cycles. If prey numbers increase, predator numbers may also increase, leading to a decline in prey, which then causes predators to decrease.
捕食者-猎物关系可导致种群周期。猎物数量增加，捕食者数量也可能增加，导致猎物减少，进而使捕食者减少。
5. Atoms, Elements and Compounds | 原子、元素与化合物
All matter is made of atoms. An element is a substance made of only one type of atom, listed in the Periodic Table. Compounds contain two or more different elements chemically bonded together, such as water (H₂O) and carbon dioxide (CO₂).
所有物质都由原子构成。元素是由同一种原子组成的物质，列于周期表中。化合物含有两种或两种以上不同元素通过化学键结合，如水（H₂O）和二氧化碳（CO₂）。
Atoms consist of protons, neutrons and electrons. Protons have a positive charge, electrons negative, and neutrons no charge.
Published by TutorHao | Year 9 Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图