📚 Year 9 Edexcel Biology: Summer Preparation and Bridging Course | Year 9 Edexcel 生物：暑期预习与衔接课程
Welcome to your summer bridging course for Year 9 Edexcel Biology. This programme is designed to solidify your Key Stage 3 knowledge and introduce the core concepts you will encounter at GCSE level. You will explore the fundamental principles of life, from cellular structure and enzyme action to the intricate workings of human body systems, plant biology and ecology. Each section is carefully crafted to build confidence, deepen understanding and prepare you for the demands of the Edexcel specification.
欢迎参加 Year 9 Edexcel 生物的暑期衔接课程。本课程旨在巩固你在 KS3 阶段所学的知识，并引入 GCSE 阶段将要接触的核心概念。你将探索生命的基本原理，从细胞结构和酶的作用，到人体系统、植物生物学和生态学的精妙运作。每个部分都经过精心设计，以建立信心、加深理解，并为你应对 Edexcel 大纲的要求做好准备。
1. The Seven Life Processes – What Makes Something Alive? | 七大生命过程 – 什么使物体具有生命？
All living organisms share seven life processes, often remembered by the acronym MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition.
所有生物体都具有七大生命过程，常以首字母缩写 MRS GREN 记忆：运动 (Movement)、呼吸 (Respiration)、感应 (Sensitivity)、生长 (Growth)、生殖 (Reproduction)、排泄 (Excretion) 和营养 (Nutrition)。
Movement can be obvious, like an animal running, or subtle, such as a plant turning towards light. Respiration is the release of energy from food molecules – it happens in every living cell, not just during breathing. Sensitivity refers to detecting and responding to changes in the surroundings.
运动可以是明显的，如动物的奔跑；也可以是细微的，如植物向光弯曲。呼吸是指从食物分子中释放能量，它发生在每一个活细胞中，而不仅仅是呼吸空气。感应是指探测并响应周围环境的变化。
In Edexcel GCSE Biology, you will revisit these processes at greater depth, so learning to recognise them in different organisms now will give you a head start. Remember that even single-celled organisms like bacteria perform all seven processes.
在 Edexcel GCSE 生物学中，你将更深入地学习这些过程，因此现在学会在不同生物体中识别它们会给你一个领先优势。请记住，即便是细菌这样的单细胞生物，也能完成所有七大过程。
2. Exploring Cells – The Building Blocks of Life | 探索细胞 – 生命的基石
Cells are the basic structural and functional units of all living things. The main organelles in an animal cell include the nucleus, which contains genetic material; cytoplasm, where most chemical reactions occur; the cell membrane, which controls what enters and leaves; mitochondria, the site of aerobic respiration; and ribosomes, where proteins are synthesised.
细胞是所有生物体的基本结构和功能单位。动物细胞的主要细胞器包括：细胞核，内含遗传物质；细胞质，是大多数化学反应发生的场所；细胞膜，控制物质的进出；线粒体，是有氧呼吸的场所；核糖体，是合成蛋白质的地方。
Plant cells have all of the above, plus a rigid cell wall made of cellulose for support, a large permanent vacuole that stores sap and helps maintain turgor pressure, and often chloroplasts, which contain chlorophyll for photosynthesis.
植物细胞除了上述结构外，还有一个由纤维素构成的坚韧细胞壁，起支持作用；一个充满细胞液的大液泡，帮助维持膨压；以及通常含有叶绿体的结构，叶绿体中的叶绿素可进行光合作用。
When comparing animal and plant cells, ask yourself: which structures are unique to plants? The cell wall, vacuole and chloroplasts are the three key differences that exam questions regularly target.
比较动物和植物细胞时，问问自己：哪些结构是植物特有的？细胞壁、液泡和叶绿体是考试中经常考查的三个关键区别。
3. Movement of Substances: Diffusion, Osmosis and Active Transport | 物质运动：扩散、渗透与主动运输
Substances move into and out of cells by three main processes. Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration, down a concentration gradient. It is a passive process that requires no energy.
物质通过三种主要方式进出细胞。扩散是粒子从较高浓度区域向较低浓度区域的净运动，沿着浓度梯度进行。这是一个被动过程，不需要能量。
Osmosis is a special case of diffusion: the movement of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane. In biology, we often describe solutions as hypotonic, isotonic or hypertonic relative to the cytoplasm.
渗透是扩散的一种特殊情况：水分子通过部分透性膜从稀溶液向浓溶液的净运动。在生物学中，我们常相对于细胞质将溶液描述为低渗、等渗或高渗。
Active transport, however, moves substances against their concentration gradient – from low to high concentration. This process requires energy from respiration and is vital for absorbing mineral ions in plant roots and glucose in the kidney.
然而，主动运输是逆浓度梯度进行的——从低浓度向高浓度运输。这一过程需要来自呼吸作用的能量，对于植物根部吸收矿质离子和肾脏重吸收葡萄糖至关重要。
For GCSE, you must be able to define each term and explain practical examples, such as why a potato strip gains mass in distilled water (osmosis) and how nitrate ions enter root hairs (active transport).
在 GCSE 中，你必须能够定义每个术语并解释实际例子，例如为什么土豆条在蒸馏水中质量会增加（渗透），以及硝酸根离子如何进入根毛细胞（主动运输）。
4. Enzymes – Biological Catalysts | 酶 – 生物催化剂
Enzymes are globular proteins that speed up biochemical reactions by lowering the activation energy. They are highly specific and function according to the lock-and-key model: the active site of the enzyme is complementary in shape to its substrate.
酶是球状蛋白质，通过降低活化能来加速生化反应。它们具有高度专一性，并按照锁钥模型发挥作用：酶的活性部位在形状上与其底物互补。
Each enzyme operates best at a particular temperature and pH. As temperature rises to an optimum (around 37 °C for human enzymes), the rate increases, but beyond this point the enzyme denatures – its active site loses shape permanently. Extremes of pH also cause denaturation.
每种酶在特定的温度和 pH 下活性最佳。当温度升高到最适温度（人体酶约为 37 °C）时，反应速率增加，但超过该温度后酶会变性——其活性部位永久失去原有形状。极端的 pH 也会导致变性。
You can investigate enzyme activity using catalase from potato or liver breaking down hydrogen peroxide into water and oxygen. Another common practical is measuring how amylase digests starch at different pH levels.
你可以通过土豆或肝脏中的过氧化氢酶分解过氧化氢生成水和氧气来探究酶活性。另一个常见实验是测定不同 pH 条件下淀粉酶对淀粉的消化速率。
Remember the key factors affecting enzyme action: temperature, pH, substrate concentration and enzyme concentration. Exam questions often ask you to interpret graphs showing rate against one of these variables.
记住影响酶作用的关键因素：温度、pH、底物浓度和酶浓度。考试题常要求你解释表示反应速率随其中某个变量变化的曲线图。
5. The Human Digestive System and Enzyme Action | 人体消化系统与酶的作用
The digestive system breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. It consists of a muscular tube running from the mouth to the anus, together with associated organs like the liver and pancreas.
消化系统将大分子、不溶性的食物分解为小分子、可溶性的物质，以便被吸收到血液中。它由一条从口腔到肛门的肌肉管道以及肝脏、胰脏等相关器官组成。
Digestion involves both mechanical breakdown (chewing, churning in the stomach) and chemical digestion by enzymes. The three main digestive enzymes are amylase, protease and lipase. Their sources, substrates and products are summarised below.
消化包括机械性分解（咀嚼、胃的搅拌）和酶的化学性消化。三种主要的消化酶是淀粉酶、蛋白酶和脂肪酶。它们的来源、底物和产物总结如下。
| Enzyme | Produced in | Substrate | Products | Optimal pH |
|---|---|---|---|---|
| Amylase | Salivary glands, pancreas | Starch | Maltose | ~7 (neutral) |
| Protease | Stomach, pancreas | Protein | Amino acids | ~2 (acidic) / ~7 |
| Lipase | Pancreas | Lipids (fats) | Glycerol and fatty acids | ~7–8 |
Bile, produced by the liver and stored in the gall bladder, emulsifies fats – breaking large fat globules into smaller droplets to increase the surface area for lipase action. It also neutralises stomach acid, creating alkaline conditions in the small intestine.
由肝脏产生并储存在胆囊中的胆汁能乳化脂肪——将大的脂肪球打碎成小油滴，从而增加脂肪酶作用的表面积。它还能中和胃酸，为小肠创造碱性环境。
6. The Heart and Circulation – Delivering Life | 心脏与循环 – 输送生命
The human circulatory system consists of the heart, blood vessels and blood. It is a double circulatory system: the right side pumps deoxygenated blood to the lungs, while the left side pumps oxygenated blood to the rest of the body.
人体循环系统由心脏、血管和血液组成。它是一个双循环系统：右心将缺氧血泵入肺部，左心将富氧血泵送到全身。
The heart has four chambers: right atrium, right ventricle, left atrium and left ventricle. Ventricles have thicker walls than atria because they pump blood further. The left ventricle wall is the thickest, as it needs to generate enough pressure to send blood through the aorta to the entire body.
心脏有四个腔室：右心房、右心室、左心房和左心室。心室的壁比心房厚，因为它们要将血液泵送到更远的部位。左心室的壁最厚，因为它需要产生足够的压力，将血液经主动脉输送到全身。
Arteries carry blood away from the heart; they have thick, muscular, elastic walls to withstand high pressure. Veins return blood to the heart and contain valves to prevent backflow. Capillaries are tiny, thin-walled vessels where exchange of gases, nutrients and waste occurs.
动脉将血液带离心脏；它们具有厚实、有肌肉和弹性的管壁，以承受高压。静脉将血液送回心脏，并含有瓣膜以防止倒流。毛细血管是微小、壁薄的血管，是气体、营养物质和废物交换的场所。
Blood is composed of plasma, red blood cells (which contain haemoglobin to carry oxygen), white blood cells (defence against pathogens) and platelets (blood clotting). Understanding the adaptation of each component is a key skill.
血液由血浆、红细胞（含血红蛋白以运输氧气）、白细胞（防御病原体）和血小板（凝血）组成。理解每种成分的适应性是一项关键技能。
7. The Respiratory System and Gas Exchange | 呼吸系统与气体交换
Ventilation is the physical movement of air into and out of the lungs. When you breathe in, the diaphragm contracts and flattens, and the intercostal muscles raise the ribcage. This increases the volume of the thorax, lowering pressure and drawing air in.
呼吸通气是空气进出肺部的物理运动。吸气时，膈肌收缩变平，肋间肌使胸廓上提。这增加了胸腔容积，降低了压力，从而将空气吸入。
Gas exchange happens in the alveoli – millions of tiny air sacs at the ends of bronchioles. The alveoli are adapted for efficient diffusion: they have very thin walls (one cell thick), a large total surface area, a rich blood supply and a steep concentration gradient maintained by ventilation and blood flow.
气体交换发生在肺泡——细支气管末端数以百万计的微小气囊中。肺泡具有适应高效扩散的结构：壁极薄（仅一个细胞厚）、巨大的总表面积、丰富的血液供应，以及通气和血流维持的陡峭浓度梯度。
Oxygen diffuses from the alveolar air into the blood, where it binds to haemoglobin in red blood cells. Carbon dioxide diffuses in the opposite direction, from the blood plasma into the alveoli to be exhaled.
氧气从肺泡空气扩散进入血液，与红细胞中的血红蛋白结合。二氧化碳则沿相反方向从血浆扩散进入肺泡，被呼出体外。
In Year 9, you should be able to label a diagram of the respiratory system (trachea, bronchi, bronchioles, lungs, alveoli, diaphragm, intercostal muscles) and explain the bell jar model used to demonstrate ventilation.
在 Year 9，你应该能够标注呼吸系统的示意图（气管、支气管、细支气管、肺、肺泡、膈肌、肋间肌），并能解释用于演示通气过程的钟罩模型。
8. Respiration – Releasing Energy from Food | 呼吸作用 – 从食物中释放能量
Respiration is not the same as breathing; it is a chemical process that releases energy in ALL living cells. The energy is used for muscle contraction, maintaining body temperature, active transport and building new molecules.
呼吸作用不同于呼吸通气；它是在所有活细胞中释放能量的化学过程。这些能量用于肌肉收缩、维持体温、主动运输以及合成新的分子。
is: glucose + oxygen → carbon dioxide + water (+ energy). The balanced symbol equation is:
有氧呼吸需要氧气并释放大量能量。文字方程式为：葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）。配平的符号方程式为：
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
c acid (+ some energy). This causes muscle fatigue and an oxygen debt, repaid by breathing heavily after exercise to oxidise lactic acid.
无氧呼吸发生在氧气不足时。在动物体内，方程式为：葡萄糖 → 乳酸（+ 少量能量）。这会导致肌肉疲劳和氧债，运动后的急促呼吸就是为了通过氧化乳酸来偿还氧债。
In yeast and some plants, anaerobic respiration produces ethanol and carbon dioxide instead of lactic acid. This process is called fermentation and is used in baking and brewing.
在酵母菌和某些植物中，无氧呼吸产生乙醇和二氧化碳，而不是乳酸。这一过程称为发酵，被用于烘焙和酿酒。
9. Photosynthesis – How Plants Make Food | 光合作用 – 植物如何制造食物
Photosynthesis is the process by which green plants and some other organisms use light energy to convert carbon dioxide and water into glucose and oxygen. It takes place inside chloroplasts, where chlorophyll captures light energy.
光合作用是绿色植物和某些其他生物利用光能，将二氧化碳和水转化为葡萄糖和氧气的过程。它发生在叶绿体内部，叶绿素在其中捕获光能。
se + oxygen (in the presence of light and chlorophyll). The balanced chemical equation is:
文字方程式为：二氧化碳 + 水 → 葡萄糖 + 氧气（在光和叶绿素的作用下）。配平的化学方程式为：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Several factors affect the rate of photosynthesis: light intensity, carbon dioxide concentration, temperature and the amount of chlorophyll. At low light intensity, the rate is limited by light; as light increases, another factor, like CO₂ concentration, may become limiting.
有几个因素会影响光合作用的速率：光照强度、二氧化碳浓度、温度和叶绿素含量。在低光照强度下，光成为限制因素；随着光照增强，另一个因素，如二氧化碳浓度，可能变为新的限制因素。
Glucose produced in photosynthesis is used immediately for respiration, converted to starch for storage, turned into cellulose for cell walls, or combined with other molecules to form proteins and lipids. Plants also require mineral ions (nitrates, magnesium) absorbed from the soil for healthy growth.
光合作用制造的葡萄糖可立刻用于呼吸作用，也可转化为淀粉储存，转化为纤维素构建细胞壁，或与其他分子结合形成蛋白质和脂质。植物还需要从土壤中吸收矿质离子（硝酸盐、镁离子）来实现健康生长。
10. Transport in Plants – Xylem and Phloem | 植物中的运输 – 木质部与韧皮部
Plants have two specialised transport tissues. Xylem transports water and dissolved mineral ions from the roots to the stem and leaves. This upward flow, known as the transpiration stream, is driven by the evaporation of water from the leaves (transpiration).
植物有两种专门的运输组织。木质部将水和溶解的矿质离子从根部运输到茎和叶。这种向上的流动称为蒸腾流，它由叶片水分的蒸发（蒸腾作用）所驱动。
Xylem vessels are composed of dead, hollow cells arranged end-to-end, with no end walls, forming a continuous tube. They are strengthened by lignin, which makes them strong and waterproof.
木质部导管由死细胞首尾相连而成，没有端壁，形成连续管道。它们由木质素加固，因此既坚固又防水。
Phloem transports dissolved sugars (mainly sucrose) and amino acids both upwards and downwards from sources (e.g. leaves) to sinks (e.g. roots, fruits, growing tips). This process is called translocation and requires energy.
韧皮部将溶解的糖类（主要是蔗糖）和氨基酸从源（如叶片）向上和向下运输到库（如根、果实、生长点）。这一过程称为易位，需要消耗能量。
Factors affecting transpiration rate include light intensity, temperature, humidity and wind speed. A potometer can be used to measure the rate of water uptake as an estimate of transpiration rate.
影响蒸腾速率的因素包括光照强度、温度、湿度和风速。可以使用气泡蒸腾计测量吸水速率，从而估算蒸腾速率。
11. Ecology: Food Chains and Ecosystems | 生态学：食物链与生态系统
An ecosystem consists of a community of living organisms interacting with each other and their non-living environment. All energy entering ecosystems comes from the Sun, captured by producers (plants and algae) during photosynthesis.
生态系统由生物群落及其相互之间和与非生物环境之间的相互作用组成。进入生态系统的所有能量都来自太阳，由生产者（植物和藻类）通过光合作用捕获。
. Each stage is called a trophic level. Arrows represent the direction of energy transfer.
食物链显示了能量从一个生物体到下一个生物体的流动：生产者 → 初级消费者 → 次级消费者 → 三级消费者。每个阶段称为一个营养级。箭头表示能量传递的方向。
However, energy is lost at each level, mostly as heat from respiration, uneaten parts and waste. This limits the length of food chains and explains why biomass pyramids are usually pyramid-shaped, with less biomass at higher trophic levels.
然而，能量在每个营养级都会损失，主要是通过呼吸作用以热的形式散失，以及未被食用的部分和排泄物。这限制了食物链的长度，并解释了为什么生物量金字塔通常呈金字塔形，越高的营养级生物量越少。
Field techniques such as quadrats and transects are used to estimate population sizes, distribution and biodiversity. You will apply these in required practicals at GCSE.
样方和样线等野外调查技术被用于估算种群大小、分布和生物多样性。在 GCSE 要求完成的实验中，你将应用这些方法。
12. Introduction to Genetics – DNA, Genes and Inheritance | 遗传学简介 – DNA、基因与遗传
Deoxyribonucleic acid (DNA) is a double-stranded molecule twisted into a double helix. It carries the genetic instructions used in the growth, development and functioning of all living organisms. A gene is a short section of DNA that codes for a specific protein.
脱氧核糖核酸 (DNA) 是一种双链分子，扭曲成双螺旋结构。它携带着所有生物体生长、发育和运作所需的遗传指令。基因是 DNA 的一小段，编码一种特定的蛋白质。
Chromosomes, found in the nucleus, are long threads of tightly coiled DNA. Human body cells contain 46 chromosomes, arranged in 23 pairs. Gametes (sperm and egg cells) have only 23 single chromosomes, so that fertilisation restores the normal diploid number.
染色体存在于细胞核中，是长条紧密缠绕的 DNA。人体细胞含有 46 条染色体，排列成 23 对。配子（精子和卵细胞）只有 23 条单链染色体，这样受精后可恢复正常的二倍体数目。
Alleles are different versions of the same gene. A dominant allele is always expressed if present (shown with a capital letter, e.g. B), while a recessive allele is only expressed if two copies are present (lower case, e.g. b). This leads to terms like homozygous dominant (BB), heterozygous (Bb) and homozygous recessive (bb).
等位基因是同一基因的不同版本。显性等位基因只要存在就会表达（用大写字母表示，如 B），而隐性等位基因只有在拥有两个拷贝时才会表达（用小写字母，如 b）。由此产生了纯合显性 (BB)、杂合 (Bb) 和纯合隐性 (bb) 等术语。
Monohybrid crosses can be modelled using Punnett squares to predict the probability of offspring inheriting certain traits. Understanding simple genetic diagrams will form a foundation for GCSE genetics topics.
单基因杂交可以通过旁氏方格（Punnett squares）来模拟，以预测后代遗传特定性状的概率。理解简单的遗传图解将为 GCSE 的遗传学课题奠定基础。
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