Year 11 Edexcel Biology Core Knowledge Summary | Year 11 Edexcel 生物核心知识点梳理

📚 Year 11 Edexcel Biology Core Knowledge Summary | Year 11 Edexcel 生物核心知识点梳理

This article provides a concise yet comprehensive summary of the core topics required for the Year 11 Edexcel IGCSE Biology syllabus. Covering cell biology, biochemistry, physiology, genetics, and ecology, these notes help reinforce key concepts and prepare students for their examinations.

本文为 Year 11 Edexcel IGCSE 生物教学大纲中的核心主题提供了简洁而全面的总结，涵盖细胞生物学、生物化学、生理学、遗传学和生态学，帮助学生巩固关键概念并准备考试。

1. Cell Structure and Organisation | 细胞结构与组织

All organisms are built from cells, which are the basic structural and functional units of life. Cells can be classified as prokaryotic (e.g. bacteria) or eukaryotic (plants, animals, fungi).

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。细胞可分为原核细胞（如细菌）和真核细胞（植物、动物、真菌）。

Prokaryotic cells lack a membrane-bound nucleus and organelles; their DNA floats freely in the cytoplasm as a circular chromosome. Eukaryotic cells have a true nucleus containing linear DNA and membrane-bound organelles such as mitochondria and chloroplasts.

原核细胞没有膜包裹的细胞核和细胞器；它们的 DNA 作为环状染色体在细胞质中自由存在。真核细胞拥有真正的细胞核，内含线性 DNA，以及线粒体、叶绿体等膜包裹的细胞器。

Viruses are not cells. They are small particles consisting of genetic material (DNA or RNA) surrounded by a protein coat, and they can only reproduce inside living host cells.

病毒不是细胞。它们是由遗传物质（DNA 或 RNA）和蛋白质外壳组成的小颗粒，只能在活的宿主细胞内繁殖。

The table below compares key features of plant, animal and bacterial cells.

下表比较了植物细胞、动物细胞和细菌细胞的关键特征。

Feature	Plant Cell	Animal Cell	Bacterial Cell
Cell wall	Present (cellulose)	Absent	Present (peptidoglycan)
Chloroplasts	Present	Absent	Absent
Permanent vacuole	Large, central	Small, temporary	Absent
Nucleus	Present	Present	Absent (nucleoid region)
DNA form	Linear chromosomes	Linear chromosomes	Circular chromosome + plasmids

Specialised cells have structures adapted to perform specific functions. For example, root hair cells possess long extensions to maximise water absorption; red blood cells are biconcave discs with no nucleus to pack more haemoglobin for oxygen transport.

特化细胞具有适应特定功能的结构。例如，根毛细胞有长突起以增加水分吸收；红细胞是双凹圆盘状，无细胞核以携带更多的血红蛋白运输氧气。

Levels of organisation: similar cells form tissues, tissues work together to form organs, and organs are organised into organ systems such as the digestive system or the circulatory system.

组织层次：相似的细胞构成组织，组织构成器官，器官再组成器官系统，如消化系统或循环系统。

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2. Biological Molecules and Food Tests | 生物分子与食物测试

Carbohydrates are made up of simple sugars like glucose (C₆H₁₂O₆). Many glucose units join to form complex carbohydrates such as starch, glycogen and cellulose.

碳水化合物由葡萄糖（C₆H₁₂O₆）等单糖组成。许多葡萄糖单元连接形成复杂的碳水化合物，如淀粉、糖原和纤维素。

Lipids (fats and oils) consist of three fatty acid molecules bonded to one glycerol molecule. Proteins are polymers composed of amino acid chains that fold into specific shapes.

脂质（脂肪和油）由三分子脂肪酸与一分子甘油结合而成。蛋白质是由氨基酸链组成的聚合物，可折叠成特定形状。

DNA (deoxyribonucleic acid) is the molecule of inheritance. It has a double helix structure made up of nucleotides, each containing a sugar, a phosphate group and a nitrogenous base (A, T, C, G).

DNA（脱氧核糖核酸）是遗传的分子。它具有双螺旋结构，由核苷酸组成，每个核苷酸包含一个糖、一个磷酸基团和一个含氮碱基（A、T、C、G）。

Key food tests: Benedict’s solution tests for reducing sugars (blue → brick-red on heating). Iodine solution tests for starch, turning from orange-brown to blue-black.

关键食物测试：本尼迪克特试剂检测还原糖（加热后由蓝色变为砖红色）。碘液检测淀粉，由橙棕色变为蓝黑色。

The Biuret test detects proteins: a few drops of sodium hydroxide solution and copper sulfate solution produce a purple colour. The ethanol emulsion test identifies lipids: an oily layer mixed with ethanol forms a cloudy white emulsion when water is added.

双缩脲试验检测蛋白质：加入几滴氢氧化钠溶液和硫酸铜溶液会产生紫色。乙醇乳浊液试验检测脂质：样品与乙醇混合后加水形成乳白色浑浊液。

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3. Enzymes | 酶

Enzymes are biological catalysts made of protein. They speed up metabolic reactions without being used up, by lowering the activation energy. Each enzyme has an active site that is complementary to a specific substrate.

酶是由蛋白质构成的生物催化剂。它们通过降低活化能来加快代谢反应，而自身不被消耗。每种酶都有一个与特定底物互补的活性位点。

The lock-and-key model describes how the substrate fits precisely into the enzyme’s active site, forming an enzyme-substrate complex, which then breaks down to release products and the unchanged enzyme.

Enzyme + Substrate → Enzyme-Substrate Complex → Enzyme + Product

锁钥模型描述底物精确地契合酶的活性位点，形成酶-底物复合物，随后分解成产物并释放出不变的酶。

Enzyme activity is affected by temperature and pH. As temperature rises, enzyme activity increases up to an optimum (around 37°C in humans); beyond this, the enzyme denatures, and the active site loses its shape. Each enzyme also has an optimum pH; extreme pH values cause denaturation.

酶活性受温度和 pH 影响。温度升高，酶活性增加，直到最适温度（人类约 37°C）；超过此温度，酶会变性，活性位点形状改变。每种酶也有最适 pH；极端的 pH 值会导致变性。

At low substrate concentrations, increasing substrate concentration raises the rate of reaction because more active sites are occupied. Eventually, the rate reaches a maximum when all active sites are saturated.

在底物浓度较低时，增加底物浓度能提高反应速率，因为更多活性位点被占据。最终当所有活性位点饱和时，速率达到最大值。

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4. Movement of Substances | 物质进出细胞

Diffusion is the net movement of particles from a region of high concentration to a region of low concentration, down a concentration gradient. It is a passive process that does not require energy.

扩散是粒子从高浓度区域向低浓度区域的净移动，顺浓度梯度进行，是被动过程，不需要能量。

Osmosis is the diffusion of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution, down the water potential gradient. In animal cells, too much water uptake causes lysis, while too much water loss leads to crenation.

渗透是水分子通过半透膜从稀溶液向较浓溶液的扩散，沿水势梯度进行。动物细胞吸水过多会导致破裂（溶血），失水过多则皱缩。

Active transport moves substances against a concentration gradient, from low to high concentration, using energy released from ATP. Root hair cells use active transport to absorb mineral ions from the soil, even when the ion concentration is lower in the soil than in the root.

主动运输利用 ATP 释放的能量，使物质逆浓度梯度从低浓度向高浓度移动。根毛细胞利用主动运输从土壤中吸收矿物离子，即使土壤中的离子浓度低于根内。

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5. Human Digestive System | 人类消化系统

The human digestive system breaks down large insoluble molecules into small soluble molecules that can be absorbed into the bloodstream. Digestion involves both mechanical breakdown (chewing, stomach churning) and chemical breakdown by enzymes.

人类消化系统将大的不可溶分子分解为可溶的小分子，以便被吸收到血液中。消化包括物理性消化（咀嚼、胃的搅拌）和酶的化学性消化。

In the mouth, salivary amylase begins starch digestion. The stomach produces pepsin (a protease) and hydrochloric acid, which kills bacteria and provides the optimum acidic pH for pepsin. The small intestine receives pancreatic juices containing amylase, protease and lipase, as well as bile from the liver.

口腔中，唾液淀粉酶开始消化淀粉。胃分泌胃蛋白酶和盐酸，盐酸能杀菌并为胃蛋白酶提供最适酸性 pH。小肠接收胰液，内含淀粉酶、蛋白酶和脂肪酶，以及来自肝脏的胆汁。

Bile emulsifies fats into smaller droplets, increasing the surface area for lipase action. Final digestion produces glucose, amino acids, fatty acids and glycerol.

胆汁将脂肪乳化成小滴，增加脂肪酶作用的表面积。最终消化产生葡萄糖、氨基酸、脂肪酸和甘油。

Absorption occurs mainly in the small intestine. The ileum is lined with villi and microvilli, which provide a huge surface area. Each villus contains a lacteal (for fat absorption) and blood capillaries (for glucose and amino acids).

吸收主要在小肠中进行。回肠内壁有绒毛和微绒毛，提供了巨大的表面积。每个绒毛内有乳糜管（吸收脂肪）和毛细血管（吸收葡萄糖和氨基酸）。

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6. Transport in Plants | 植物运输

Xylem vessels transport water and dissolved mineral ions from the roots up to the leaves. Xylem cells are dead, hollow tubes strengthened with lignin. Phloem tubes transport sucrose and amino acids up and down the plant; this process is called translocation.

木质部导管将水和溶解的矿物离子从根部向上运输到叶片。木质部细胞是死细胞，中空并被木质素加强。韧皮部管将蔗糖和氨基酸在植物体内上下运输；这个过程称为转运。

Transpiration is the loss of water vapour from the leaves, mainly through stomata. It creates a suction force (transpiration pull) that draws water up the xylem in a continuous column. The rate of transpiration is increased by higher light intensity, higher temperature, greater wind speed and lower humidity.

蒸腾作用是水分以水蒸气形式从叶片（主要通过气孔）散失的过程。它产生一种吸力（蒸腾拉力），将水以连续水柱的形式沿木质部向上拉。蒸腾速率随光照增强、温度升高、风速加大和湿度降低而增加。

Guard cells control the opening and closing of stomata. When turgid, stomata open

Published by TutorHao | Year 11 Biology Revision Series | aleveler.com

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