📚 Year 10 CAIE Biology: Core Knowledge Review | Year 10 CAIE 生物：核心知识点梳理
Welcome to your Year 10 CAIE Biology revision guide. This article summarises the essential topics you'll encounter in the first year of the IGCSE course, covering life processes, cells, molecules, enzymes, nutrition, transport, gas exchange and respiration. These core concepts form the foundation for more advanced study. Let's dive in.
欢迎来到 Year 10 CAIE 生物复习指南。本文总结了 IGCSE 课程第一年的核心主题，涵盖生命活动、细胞、分子、酶、营养、运输、气体交换和呼吸。这些核心概念为后续学习奠定基础。让我们开始吧。
1. Characteristics of Living Organisms | 生物的特征
All living organisms share seven life processes, often remembered by the acronym MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition. Movement can be locomotion or internal transport; respiration releases energy from food; sensitivity involves responding to stimuli; growth is a permanent increase in size; reproduction produces offspring; excretion removes metabolic waste; nutrition is taking in materials for energy and growth.
所有生物共用七个生命过程，常以缩写 MRS GREN 记忆：运动、呼吸、感应、生长、繁殖、排泄和营养。运动可以是移动或内部运输；呼吸从食物中释放能量；感应是对刺激作出反应；生长是体积的永久增大；繁殖产生后代；排泄清除代谢废物；营养是摄入物质用于能量和生长。
Viruses are not considered living because they cannot carry out these processes independently without a host cell.
病毒不被视为生物，因为它们在离开宿主细胞时无法独立完成这些生命过程。
2. Cell Structure and Organisation | 细胞结构与组织
Animal and plant cells both have a cell membrane, cytoplasm, nucleus, mitochondria and ribosomes. The nucleus contains DNA and controls cell activities; mitochondria are sites of aerobic respiration; ribosomes synthesise proteins; cytoplasm is where many chemical reactions occur; the cell membrane controls the entry and exit of substances.
动物细胞和植物细胞都具有细胞膜、细胞质、细胞核、线粒体和核糖体。细胞核含有DNA并控制细胞活动；线粒体是有氧呼吸的场所；核糖体合成蛋白质；细胞质是许多化学反应发生的部位；细胞膜控制物质的进出。
Plant cells also have a cellulose cell wall, a large permanent vacuole and chloroplasts. The cell wall provides structural support; the vacuole contains cell sap and helps maintain turgor pressure; chloroplasts absorb light energy for photosynthesis.
植物细胞还具有纤维素细胞壁、一个大的永久液泡和叶绿体。细胞壁提供结构支持；液泡含有细胞液并帮助维持膨压；叶绿体吸收光能进行光合作用。
ample, a muscle cell forms muscle tissue, which makes up the stomach, part of the digestive system.
多细胞生物的组织层次：细胞 → 组织 → 器官 → 器官系统 → 生物体。例如，肌细胞形成肌肉组织，肌肉组织构成胃，胃是消化系统的一部分。
3. Movement Across Membranes | 跨膜运输
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient. It is a passive process that does not require energy. Oxygen and carbon dioxide move in and out of cells by diffusion.
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。这是一个被动的过程，不消耗能量。氧气和二氧化碳通过扩散进出细胞。
Osmosis is the diffusion of water molecules through a partially permeable membrane from a region of higher water potential to a region of lower water potential. In plant cells, water entry by osmosis causes turgidity, while water loss leads to plasmolysis.
渗透是水分子通过部分透性膜从水势较高区域向水势较低区域的扩散。在植物细胞中，水通过渗透进入导致细胞膨胀，失水则导致质壁分离。
Active transport is the movement of particles against a concentration gradient, using energy from respiration. Root hair cells absorb mineral ions from the soil by active transport, even when the concentration inside the cell is higher.
主动运输是逆浓度梯度移动粒子，利用呼吸作用提供的能量。根毛细胞通过主动运输从土壤吸收矿质离子，即使细胞内浓度更高。
4. Biological Molecules | 生物分子
Carbohydrates include simple sugars like glucose and complex polysaccharides like starch and glycogen. Glucose is used in respiration to release energy. Starch is the main storage carbohydrate in plants. The test for starch uses iodine solution, which turns blue-black. Reducing sugars are tested with Benedict's solution upon heating, giving a brick-red precipitate.
碳水化合物包括葡萄糖等单糖以及淀粉和糖原等多糖。葡萄糖用于呼吸作用释放能量。淀粉是植物中主要的储存碳水化合物。淀粉测试使用碘液，会变成蓝黑色。还原糖测试使用本尼迪克特溶液加热，产生砖红色沉淀。
Proteins are made of long chains of amino acids. The biuret test detects proteins: the reagent turns purple. Lipids (fats and oils) are composed of fatty acids and glycerol. The ethanol emulsion test produces a cloudy white layer when lipid is present.
蛋白质由氨基酸长链组成。双缩脲测试检测蛋白质：试剂变为紫色。脂质（脂肪和油）由脂肪酸和甘油组成。乙醇乳浊液测试在有脂质存在时产生乳白色层。
DNA is a large molecule that stores genetic information. While not tested in food tests, it is vital for inheritance and protein synthesis.
DNA是储存遗传信息的大分子。虽然在食物测试中不涉及，但对遗传和蛋白质合成至关重要。
5. Enzymes | 酶
Enzymes are protein catalysts that speed up biochemical reactions without being consumed. Each enzyme has an active site with a specific shape complementary to its substrate. The lock-and-key model explains how only the correct substrate fits into the active site to form an enzyme-substrate complex.
酶是蛋白质催化剂，加速生化反应而自身不被消耗。每个酶都有一个活性位点，其形状与底物专一互补。锁钥模型解释了只有正确的底物才能嵌入活性位点，形成酶-底物复合物。
Enzyme activity is affected by temperature and pH. As temperature rises, activity increases to an optimum; beyond this, the enzyme denatures as its active site loses shape. Each enzyme has an optimum pH, and extreme pH values also cause denaturation.
酶活性受温度和pH影响。温度升高时，活性增加到最适温度；超出此温度，酶变性，活性位点失去形状。每种酶都有最适pH，极端pH也会导致变性。
Amylase is an example that breaks down starch into maltose in the mouth and small intestine. It works best at around pH 7 and body temperature.
淀粉酶是一个例子，在口腔和小肠中将淀粉分解为麦芽糖。它在pH约7和体温下活性最佳。
6. Photosynthesis and Plant Nutrition | 光合作用与植物营养
en. The balanced symbol equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Chlorophyll in chloroplasts traps light energy, converting it into chemical energy stored in glucose.
光合作用是植物利用光能制造葡萄糖的过程。文字方程式：二氧化碳 + 水 → 葡萄糖 + 氧气。平衡符号方程式：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。叶绿体中的叶绿素捕获光能，将其转化为储存在葡萄糖中的化学能。
The rate of photosynthesis is limited by factors such as light intensity, carbon dioxide concentration and temperature. A plant can be destarched by keeping it in the dark, and then a starch test on a leaf can indicate whether photosynthesis has occurred.
光合作用的速率受光照强度、二氧化碳浓度和温度等因素的限制。将植物置于暗处可使其脱淀粉，然后对叶片进行淀粉测试可以显示是否进行了光合作用。
Plants also need mineral ions: nitrate ions for making amino acids and proteins, and magnesium ions for chlorophyll synthesis. Deficiencies cause stunted growth and yellowing of leaves (chlorosis).
植物还需要矿质离子：硝酸盐离子用于制造氨基酸和蛋白质，镁离子用于合成叶绿素。缺乏会导致生长迟缓和叶片黄化（萎黄病）。
7. Human Digestive System | 人体消化系统
Digestion breaks down large insoluble food molecules into small soluble molecules that can be absorbed into the blood. The digestive system includes the mouth (chewing and salivary amylase), oesophagus, stomach (pepsin and hydrochloric acid), small intestine (duodenum receives bile and pancreatic juice; ileum is the site of absorption) and large intestine (water reabsorption).
消化将大的不溶性食物分子分解为小的可溶性分子，以便吸收进入血液。消化系统包括口腔（咀嚼和唾液淀粉酶）、食道、胃（胃蛋白酶和盐酸）、小肠（十二指肠接收胆汁和胰液；回肠是吸收的部位）和大肠（水分重吸收）。
Digestive enzymes: amylase breaks down starch into maltose; proteases break down proteins into amino acids; lipase breaks down fats into fatty acids and glycerol. Bile, produced by the liver and stored in the gall bladder, emulsifies fats to increase surface area for lipase action.
消化酶：淀粉酶分解淀粉为麦芽糖；蛋白酶分解蛋白质为氨基酸；脂肪酶分解脂肪为脂肪酸和甘油。胆汁由肝脏产生并储存在胆囊中，它乳化脂肪以增加脂肪酶作用的表面积。
The ileum is adapted for absorption with villi that increase surface area. Each villus has a network of blood capillaries to absorb glucose and amino acids, and a lacteal to absorb fatty acids and glycerol.
回肠适应吸收功能，具有增大表面积的绒毛。每个绒毛有毛细血管网吸收葡萄糖和氨基酸，还有乳糜管吸收脂肪酸和甘油。
8. Transport in Plants | 植物运输
Xylem tissue transports water and dissolved mineral ions from the roots up to the stems and leaves. Xylem vessels are composed of dead cells with lignin, forming hollow tubes. The movement of water is driven by transpiration pull, explained by the cohesion-tension theory: water molecules stick together (cohesion) and are pulled up as water evaporates from leaves.
木质部组织将水和溶解的矿质离子从根部向上运输到茎和叶。木质部导管由含有木质素的死细胞组成，形成中空管道。水的运动由蒸腾拉力驱动，内聚力-张力理论解释：水分子相互黏附（内聚力），当水分从叶片蒸发时被向上拉动。
Phloem tissue transports sucrose and amino acids from sources (where they are made or stored) to sinks (where they are used) in a process called translocation. This movement can go up or down the plant.
韧皮部组织将蔗糖和氨基酸从源（制造或储存的部位）运输到库（使用的部位），这一过程称为输导作用。这种移动可以在植物体内向上或向下进行。
Transpiration is the loss of water vapour from leaves through stomata. Factors increasing transpiration include higher light intensity, temperature, wind and lower humidity. Wilting occurs when water loss exceeds water uptake.
蒸腾作用是水蒸气通过叶片上的气孔流失。增强蒸腾作用的因素包括光照强度高、温度高、风大和湿度低。当失水超过吸水时发生萎蔫。
9. The Circulatory System | 循环系统
The mammalian heart has four chambers: right atrium, right ventricle, left atrium and left ventricle. Valves between atria and ventricles, and at the exits of arteries, prevent backflow of blood. The heart pumps blood in a double circulatory system: the right side pumps deoxygenated blood to the lungs (pulmonary circulation), and the left side pumps oxygenated blood to the rest of the body (systemic circulation).
哺乳动物心脏有四个腔室：右心房、右心室、左心房和左心室。房室之间以及动脉出口处的瓣膜防止血液倒流。心脏驱动双循环系统：右侧将缺氧血泵送到肺部（肺循环），左侧将富氧血泵送到全身（体循环）。
Blood vessels include arteries, which carry blood away from the heart under high pressure and have thick muscular walls; veins, which return blood to the heart and contain valves; and capillaries, which are tiny, thin-walled vessels where exchange of substances occurs.
血管包括动脉，它将血液带离心脏，压力高，壁厚且有肌肉；静脉，它将血液送回心脏，含有瓣膜；毛细血管，是微小的薄壁血管，物质交换在此发生。
Blood consists of plasma (transporting dissolved substances like carbon dioxide, glucose and urea), red blood cells (containing haemoglobin for oxygen transport), white blood cells (defend against pathogens) and platelets (involved in blood clotting).
血液由血浆（运输二氧化碳、葡萄糖和尿素等溶解物质）、红细胞（含有血红蛋白，运输氧气）、白细胞（防御病原体）和血小板（参与凝血）组成。
10. Gas Exchange and Respiration | 气体交换与呼吸
Gas exchange in humans takes place in the alveoli of the lungs. Alveoli are adapted by having a huge combined surface area, very thin walls (one cell thick), a moist lining and a dense network of blood capillaries for rapid diffusion of oxygen into the blood and carbon dioxide out.
人体气体交换在肺泡中进行。肺泡的适应性包括巨大的总表面积、极薄的壁（一个细胞厚）、湿润的内壁和密集的毛细血管网，使氧气能快速扩散入血，二氧化碳扩散出。
Ventilation (breathing) involves the diaphragm and intercostal muscles. During inhalation, the diaphragm contracts and flattens, the intercostal muscles contract to raise the ribs, increasing thoracic volume and decreasing pressure, drawing air in. Exhalation reverses this process, with muscles relaxing and volume decreasing.
肺通气（呼吸）涉及膈肌和肋间肌。吸气
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